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Yarnell, Sarah Munro. "Spatial heterogeneity of Rana boylii habitat : physical processes, quantification and ecological meaningfulness /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Dyson, Kirstie Elizabeth. "Biodiversity and ecosystem processes in heterogeneous environments /." St Andrews, 2008. http://hdl.handle.net/10023/698.
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Jones, Jeffrey W. "Predicting measures of diversity for forest regeneration using site and overstory variables a regression approach /." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3548.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains v, 50 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 35-38).
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Mealor, Michael A. "Spatial heterogeneity in ecology." Thesis, University of Stirling, 2005. http://hdl.handle.net/1893/53.
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This project predominantly investigated the implications of spatial heterogeneity in the ecological processes of competition and infection. Empirical analysis of spatial heterogeneity was carried out using the lepidopteran species Plodia interpunctella. Using differently viscous food media, it was possible to alter the movement rate of larvae. Soft Foods allow the movement rate of larvae to be high, so that individuals can disperse through the environment and avoid physical encounters with conspecifics. Harder foods lower the movement rate of larvae, restricting the ability of individuals to disperse away from birth sites and avoid conspecifics encounters. Increasing food viscosity and lowering movement rate therefore has the effect of making uniform distributed larval populations more aggregated and patchy. Different spatial structures changed the nature of intraspecific competition, with patchy populations characterised by individuals experiencing lower growth rates and greater mortality because of the reduced food and space available within densely packed aggregations. At the population scale, the increased competition for food individuals experience in aggregations emerges as longer generational cycles and reduced population densities. Aggregating individuals also altered the outcome of interspecific competition between Plodia and Ephestia cautella. In food media that allowed high movement rates, Plodia had a greater survival rate than Ephestia because the larger movement rate of Plodia allowed it to more effectively avoid intraspecific competition. Also the faster growth rate, and so larger size, of Plodia allowed it to dominate interspecific encounters by either predating or interfering with the feeding of Ephestia. In food that restricts movement, the resulting aggregations cause Plodia to experience more intraspecific encounters relative to interspecific, reducing its competitive advantage and levelling the survival of the two species. Spatial structure also affected the dynamics of a Plodia-granulosis virus interaction and the evolution of virus infectivity. Larval aggregation forced transmission to become limited to within host patches, making the overall prevalence of the virus low. However potentially high rates of cannibalism and multiple infections within overcrowded host aggregations caused virus-induced mortality to be high, as indicated by the low host population density when virus is presented. Also aggregated host populations cause the evolution of lower virus infectivity, where less infective virus strains maintain more susceptible hosts within the aggregation and so possess a greater transmission rate. The pattern of variation in resistance of Plodia interpunctella towards its granulosis virus was found using two forms of graphical analysis. There was a bimodal pattern of variation, with most individuals exhibiting either low or high levels of resistance. This pattern was related to a resistance mechanism that is decreasingly costly to host fitness.
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du, Plessis Darren Scott. "Temporal interactions with flamingo foraging plasticity: ecological effects on basal resources and benthic heterogeneity." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29623.
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The role of predation as a structuring agent of communities has been a focal area of research in marine ecology. Conversely, studies focusing on foraging plasticity, particularly by shorebirds, and consequences for benthic community structure, heterogeneity and ecosystem functioning have been limited in marine soft-sediments. Temporal interactions with foraging plasticity is an even greater knowledge gap. The primary goal of this dissertation was to expand on current understanding of foraging plasticity and the broader ecological role of Greater Flamingos as predators in marine sedimentary ecosystems. The specific aim was to test the long-term effects of different foraging structure sizes (which is a subtle form of foraging plasticity) on sedimentary assemblages following foraging disturbances. In situ comparisons of large and small foraging structures created by the flamingos with adjacent non-foraged sediments (controls) indicated that small channels had greater concentrations of sediment organic matter relative to large channels following feeding. Additionally, small feeding structures supported greater abundances of the burrowing amphipod Urothoe grimaldii and the grazing gastropod Assiminea globulus along with elevated size-specific sediment deposition rates. These results shed light on the differential timedependent impacts flamingo foraging plasticity can generate on basal trophic resources and higher consumers. Results also showed that irrespective of size, feeding channels made by flamingos generally became enriched with microalgae following foraging, with this enrichment effects spilling over into non-foraged controls sediments. This indicates that foraging by flamingos has the potential to create resource islands that become enriched with microalgae over time, with effects spilling over into adjacent non-foraged areas. Importantly, these positive effects may oppose the negative effects of bioturbation by burrowing sandprawns on productivity, which is a dominant process in the study area. This study emphasizes the importance of Greater Flamingos in regulating basal resource supply, community structure and spatio-temporal heterogeneity and has highlighted the need for predation models within sedimentary environments to incorporate time-dependent effects of foraging plasticity into current thinking.
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Afán, Asencio Isabel. "Ecological response of marine predators to environmental heterogeneity and spatio-temporal variability in resource availability." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/398990.
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Seabirds have evolved within an open and dynamic environment, the ocean. As meso-top predators, seabirds are greatly influenced by the oceanographic conditions driving marine productivity, and therefore, distribution of their prey. Consequently, seabirds’ behaviour and, ultimately, life-history traits are greatly influenced, by the ever-changing oceanographic conditions. However, oceanographic conditions are currently changing at ever-increasing rates due to global warming and human harvest impacting marine ecosystems. Thus, seabirds have become particularly vulnerable to these changes. Accordingly, in this thesis, we investigated the ecological responses of seabirds, in terms of foraging and breeding performance, to the spatio-temporal variability of environmental conditions imposed by oceans and exacerbated by climate and human stressors. In particular, we (i) identified the climate and human stressors impacting the world’s ocean, (ii) investigated the actual scale at which seabirds interact with their environment, (iii) assessed how seabirds respond to oceanographic variability by changing their foraging and reproductive strategies and (iv) proposed an integrative tool for the design of marine reserves protecting seabirds and their environment.
The objectives of this thesis were accomplished through advanced procedures in the fields of satellite remote sensing and animal tracking. Our results confirmed the unprecedented changes experienced by oceans in the last decades. However, we were able to provide deepest insights on the uneven distribution of climate and human driven environmental changes. When investigating the link between such environmental variability and seabirds’ behaviour, we found that dynamic processes as ocean currents were key factors determining the scale at which seabirds interact with their environment. Environmental features driving the spatiotemporal distribution of prey (e.g. sea surface temperature, chlorophyll-a, sea fronts and persistent areas of productivity) along with industrial fisheries played a fundamental role in determining the foraging distribution of seabirds. However, seabirds’ foraging strategies were largely constrained by limitations imposed by their central-place foraging behaviour and by dynamic factors such as prevalent winds, which influenced individual decision-
making in heading directions when foraging. Intra and interspecific competition for resources also modulated foraging distributions, avoiding conspecifics or segregating foraging areas among sympatric species in appropriate stages. In general, we have provided a complete picture of environmental processes affecting seabirds. We argue that this information would be extremely useful for designing suitable management and conservation strategies. Thus, we finally proposed an adaptive framework for delimitation of more meaningful marine reserves that maximises conservation targets for seabirds, while accounting for human activities, environmental and biological factors largely driven seabird performance and, remarkably, the dynamism inherent to marine systems.
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Kendall, Bruce Edward. "Spatial structure and transient periodicity in biological dynamics." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/187496.
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Structure, in its many forms, is a central theme in theoretical population ecology. At a mathematical level, it arises as nonuniformities in the topology of nonlinear dynamical systems. I investigate a mechanism wherein a chaotic time series can have episodes of nearly periodic dynamics interspersed with more 'typical' irregular dynamics. This phenomenon frequently appears in biological models, and may explain patterns of alternating biennial and irregular dynamics in measles epidemics. I investigate the interaction between spatial structure and density-dependent population regulation with a simple model of two logistic maps coupled by diffusive migration. I examine two different consequences of spatial structure: scale-dependent interactions ("nonlocal interactions") and spatial variation in resource quality ("environmental heterogeneity"). Nonlocal interactions allow three general dynamical regimes: in-phase, out-of-phase, and uncorrelated. With environmental heterogeneity, the dynamics of the total population size can be approximated by a logistic map with the mean growth parameter of the two patches; the dynamics within a single patch are often less regular. Adding environmental heterogeneity to non-local interactions has little qualitative effect on the dynamics when the differences between patches are small; when the differences are large, uncorrelated dynamics are most likely to be seen, and there are interesting consequences for the stability of source-sink systems. A third type of structure arises when individuals differ from one another. Accurate prediction of extinction risk in small populations requires that a distinction be made between demographic stochasticity (variation among individuals) and environmental stochasticity (variation among years or sites). I describe and evaluate two tests to determine whether all the variation in population survivorship can be explained by demographic stochasticity alone. Both tests have appropriate probabilities of type I error, unless the survival probability is very low or very high. Small amounts of environmental stochasticity are often not detected by the tests, but the hypothesis of demographic stochasticity alone is consistently rejected when environmental stochasticity is large. I also show how to factor out deterministic sources of variability, such as density-dependence. I illustrate these tests with data on a population of Acorn Woodpeckers.
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Star, Bastiaan, and n/a. "Space matters : modeling selection in spatially heterogeneous environments." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080507.151534.
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Selection in spatially heterogeneous environments is a convenient explanation for the high levels of genetic variation observed in natural populations. Indeed, theoretical studies predict that spatial heterogeneity leads to higher levels of variation in a variety of selection models. These models, however, have assumed quite restrictive parameters (e.g., two alleles, fixed gene flow and specific selection schemes). Therefore, the effect on spatial heterogeneity is still poorly understood for a wider range of parameters (e.g., multiple alleles, different levels of gene flow and more general selection schemes). We have relaxed some of the assumptions that have limited the previous models and studied the effect of spatial heterogeneity using simple single-locus viability selection models.
First, we investigate the rarity of the parts of fitness space maintaining variation for multiple alleles and different levels of gene flow by randomly sampling that space using a "fitness space" approach. The volume of fitness space maintaining variation is always larger in a spatial model compared to a single-population model regardless of gene flow. Moreover, this volume is relatively larger for higher numbers of alleles, indicating that spatial heterogeneity is more efficient maintaining higher levels of variation.
Second, we investigate the ease with which a more natural process of recurrent mutation and selection evolves to the particular area of fitness space maintaining variation using a "construction" approach. Depending on the amount of gene flow, the construction approach leads to both higher and lower levels of variation compared to a single-population model. Thus, spatial heterogeneity can both constrain and promote the ease with which a natural process of mutation and selection evolves to maintain variation. Also, the construction approach results in variation being maintained in a more stable subset of the volume of fitness space than the volume that resulted from the fitness space approach.
Third, we investigate the effect of higher and lower levels of spatial environmental heterogeneity using the construction approach. The different levels of heterogeneity and gene flow interact to influence the amount of variation that is eventually maintained and this interaction effect is especially strong for intermediate levels of gene flow. More heterogeneous environments can maintain higher levels of variation, but selection in these environments also results in a higher level of migration load, lowering the final amount of adaptation that is achieved by the simulated evolutionary process.
Finally, we investigate effect of genetic drift and finite populations using the construction approach. Interestingly, two different effects emerge for smaller and larger populations; in smaller populations genetic drift lowers the amount of variation as expected, whereas, more surprisingly, genetic drift increases the amount of variation in larger populations.
Overall, spatial heterogeneity has profound effects on the outcome of selection, resulting in elevated levels of genetic variation for a wide variety of parameters.
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Memory, Andrew Edmund. "What Factors Influence the Success of Senecio (Asteraceae) in Canterbury, New Zealand? A Phylogenetic and Ecological Study." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/7468.
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Senecio is one of the largest genera in the Asteraceae family with 28 Senecio species in New Zealand and over 1200 species worldwide. Native Senecio in the Canterbury region are typically naturally uncommon and exhibit extreme fluctuations in population size. Contrary to native Senecio, exotic Senecio in the Canterbury region are thriving. Why some exotic species thrive in a novel environment while native species decline has been an area of intense study since the era of Darwin. However, despite extensive study, we are still unsure about the underlying mechanisms of this phenomenon. This thesis looks at several hypotheses that have been proposed to explain differences in success between native and exotic species including four that have been frequently mentioned in the literature: phylogenetics, natural enemy release and biotic resistance, allopolyploidy and habitat modification.
In order to determine if phylogenetic relatedness influences the abundance and distribution of Senecio species in Canterbury, DNA phylogenies of New Zealand’s Senecio were constructed using nuclear (ITS, ETS) and plastid (trnL, trnL-F and psbA-trnH) DNA sequences. The resulting cladograms were used to determine the areas of origin of New Zealand’s Senecio lineages, the identity of their closest relatives and lineages and species that are of allopolyploid origin. The data provided by the phylogenetic analyses was to provide context for analyses of ecological data of 86 native and exotic Senecio populations from the Canterbury region. My results indicate that phylogenetic relatedness is a poor predictor of the amount of folivory experienced by Senecio, although some natural enemies of native and exotic Senecio displayed a positive preference for Senecio depending on their clade. The strongest effects on Senecio and the occurrences of their natural enemies came from the surrounding land use which influenced the amount of folivory and the abundances of natural enemies on Senecio. Enemy release and biotic resistance were land use specific within Canterbury and by themselves cannot explain the variance in folivory when applied to a landscape scale. According to my results, the biggest factor influencing Senecio folivory, abundance and distribution in the Canterbury region is change in the surrounding land use.
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Rodriguez-Buriticá, Susana. "Effects of the spatial heterogeneity formed by Ambrosia dumosa on individual and population growth of the invasive annual grass Schismus barbatus." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1233264311.
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Silver, Rebecca Berkovitz. "An ecological approach to understanding heterogeneity in early antisocial trajectories : the role of parents, peers, and teachers /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1188882941&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Results of a study of 241 children participating in the Wisconsin Study of Families and Work (WSFW), an ongoing longitudinal study of familes and child development. Includes bibliographical references (leaves 99-112). Also available for download via the World Wide Web; free to University of Oregon users.
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Pawson, Stephen. "Effects of landscape heterogeneity and clearfell harvest size on beetle (Coleoptera) biodiversity in plantation forests." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1332.
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Compared to natural forests, fast-growing plantations of exotic species such as Pinus radiata are often perceived as marginal habitat or unsuitable habitat for most native species. By studying Coleoptera (beetles) in a variety of landscape elements (pasture, native forest and different aged Pinus radiata stands) in a highly modified and fragmented landscape in New Zealand I aimed to determine the value of exotic plantation forests for native biodiversity, and how these species are affected by different sized clearfell harvest areas. Pitfall trap sampling of beetles showed that plantation forest stands can provide suitable complimentary habitat to native forest for many species. Rarefied species richness of Carabidae, Scarabaeidae and Scolytinae was not significantly different between habitats, however, habitat types differed significantly in their beetle community composition. Comparing different production habitats, Pinus radiata stands had a beetle community composition most similar to native forest. However, a small minority of species, e.g., Dichrochile maura, were restricted to native forest habitat highlighting the importance of retaining indigenous ecosystems within plantations. Unlike human modified habitats, native forests did not provide suitable habitat for exotic species. Clearfell harvesting is controversial and its impact on biodiversity is a key constraint for many forest certification programs, such as that administered by the Forest Stewardship Council (FSC). Despite this, no replicated manipulative experimental studies of the impact of different sized clearfell harvest areas on biodiversity have been undertaken at scales relevant to the New Zealand forest industry. One potential model of the impact of different clearfell harvest sizes is the concept of a threshold size. A threshold scenario may occur where clearfell harvest impacts increase at a rate disproportionate to the change in clearfell size over a small range of harvest areas, but impacts remain relatively unchanged either side of the threshold zone. I sampled Coleoptera in experimentally created 0.01, 0.05, 0.5, 5.0, 50 and 500 ha clearfells within Pinus radiata plantations in the central North Island of New Zealand. The wide range of clearfell harvest sizes, including some very small areas, such as 0.01 ha was instigated in an attempt to document potential clearfell harvest size thresholds. Rarefied native beetle species richness was higher in harvest areas compared to adjacent mature plantation stands. The beetle species richness in 5 ha and 500 ha harvest areas was significantly greater species than that in small 0.01 - 0.5 ha harvest areas. Although, the high beetle diversity recorded in 500 ha clearfells should be treated with caution due to confounding spatial autocorrelation. The degree of change in beetle community composition increased with increasing clearfell harvest area. Beetle assemblages in large harvest areas were less similar to their paired adjacent mature forest than smaller harvest areas. Although, constrained multivariate ordination techniques did show a short-term change in beetle species composition between recently clearfelled harvest areas of as little as 0.05 ha and adjacent mature P. radiata stands. The colonisation by open-habitat disturbance-adapted species was a key driver of this change, some species dispersed into clearfelled stands in significant densities within days post-harvest. Overall, there were no distinct short-term trends to the change in species richness as a function of increasing harvest area that would suggest an ecological impact threshold response. If short-term outcomes of clearfell harvesting are ameliorated by successful recolonisation, the long-term spatial arrangement of different aged stands becomes more important for the maintenance of biodiversity at the landscape level than short-term consequences of harvesting. By sampling selected beetle taxa in 1, 2, 4, 8, 16 and 26 year-old stands, I found that the abundance of seven out of eight of the species selected for analysis recovered to levels similar to those in adjacent mature forest within the timeframe of a single harvest rotation. Individual species utilised different aged stands, indicating different life-history strategies. For example, open-habitat, disturbance-adapted species such as Cicindela tuberculata and Sitona discoideus were prominent in young stands, and forest species such as Pycnomerus sophorae and Paracatops phyllobius were highly abundant in older stands. These alternative life-history strategies highlight the benefits of maintaining a mixture of different aged stands to increase biodiversity at the landscape level. This thesis fills an important gap in our knowledge of biodiversity in production landscapes. I show that plantation forests have value as complimentary habitat to native forest and they make an important contribution to the maintenance of biodiversity at the landscape level. Although clearfell harvesting is a severe disturbance to the forest ecosystem, the long-term recovery of beetle populations suggests that harvesting is not the key limiting factor to the enhancement of biodiversity in the plantation forests studied. This unusual situation is possibly the result of prior land-use history, as many plantations were established on degraded pastoral land, and harvest-sensitive species are unlikely to have survived this initial land-use change. As such, the severity of the long-term impacts of clearfell harvesting on biodiversity are likely to be context specific and will vary accordingly. The importance of spatial heterogeneity of habitat elements, including different aged plantation stands and native forest remnants, needs to be investigated in more detail to determine what limits biodiversity in this plantation landscape. Key points to consider are the proximity to, and proportion of, native forest cover in the landscape and the degree of connectivity among native remnants. It is these landscape-level attributes that may determine biodiversity at a regional scale, and more emphasis should be placed on landscape scale factors and there interaction with stand specific forest management practices. For example, the spatial mosaic of harvesting areas may need to be of a finer-scale when there are fewer native remnants within the landscape.
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Botes, Antoinette. "Heterogeneity of dung beetle (Coleoptera: Scarabaeidae) assemblages in northern KwaZulu-Natal, South Africa: conservation implications." Diss., University of Pretoria, 2001. http://hdl.handle.net/2263/29639.
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Investigating the extent of local scale heterogeneity in assemblages is necessary to achieve a sound understanding of the processes giving rise to local assemblage patterns and the variation between them. Moreover, a clear understanding of local scale heterogeneity of assemblages is imperative in the development of effective regional conservation strategies. Previous studies examined the local scale heterogeneity in dung beetle assemblages between mixed woodland and sand forest habitats in Tembe Elephant Park, KwaZulu-Natal. Sand forest is an endangered habitat type in southern Africa which, when disturbed, opens up and changes towards mixed woodland. Reversion to the original sand forest structure after disturbance has never been recorded. Dung beetle assemblages were found to be homogenous within, but significantly heterogenous between, habitat types. It was therefore suggested that disturbance of sand forest (elephant foraging inside, and human occupation outside the Park) was likely to affect the assemblage structure of dung beetles in sand forest. Therefore, the aim of this study was to determine the effect of human- and elephant-induced disturbance on dung beetle assemblages in sand forest. Furthermore, disturbed sand forest dung beetle assemblages were predicted to be more similar to mixed woodland than to undisturbed sand forest assemblages. Disturbance by elephants causes sand forest vegetation structure to change to that of mixed woodland and this resulted in elephant-disturbed sand forest dung beetle assemblages becoming more similar to mixed woodland assemblages. Assemblages in human disturbed sand forest were unique and associated with human-related activities. The reliability and predictability of dung beetle indicator (species specific to a particular habitat type) and detector species (species indicative of the direction of habitat change) identified for Tembe in a previous study were tested. The results of this study largely supported the suite of bioindicator species first identified. Detector species were found to provide information complimentary to the indicator species and vegetation data available for sand forest. In addition, an identification key for the dung beetle species collected in Tembe Elephant Park to date was compiled. This key facilitates the use of dung beetle assemblages in indicator and monitoring systems in this reserve by providing a rapid and effective means of identifying the dung beetle species. The abundance-body size relationships of the dung beetle assemblages in mixed woodland, undisturbed and disturbed sand forests were also determined. Four hypotheses that account for the relationship between body size and abundance or its variants, were tested here, namely the energy equivalence rule, interspecific competition, differential extinction, and the biomass frequency distribution hypothesis. The disturbed sand forest assemblages were used to test whether disturbance alters the relationships between the macroecological variables (i.e. body size, abundance and biomass) and their interrelationships. This study provided some support for the biomass hypothesis. The major relationship between body size and abundance held despite human- and elephant-induced disturbance. Nonetheless, this study indicates that human- and elephant-induced disturbance alter sand forest dung beetle assemblages and may have significant implications for other taxa that occupy this endangered habitat type. Monitoring of the impacts of large herbivores on sand forest in reserves should thus be continued, and dung beetles provide one effective means by which this can be achieved.Dissertation (MSc (Entomology))--University of Pretoria, 2006.
Zoology and Entomology
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Schulz, Benjamin [Verfasser]. "Ecological and molecular mechanisms in plants to cope with environmental heterogeneity: a case study in Viola elatior / Benjamin Schulz." Gießen : Universitätsbibliothek, 2016. http://d-nb.info/1081627441/34.
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Law, Alan. "Evaluation of the ecological impacts of beaver reintroduction on aquatic systems." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/20767.
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The extent and quality of freshwater systems is declining globally. Combined with past drainage, straightening and flow regulation, current systems are often functional but not pristine. Conservation, creation and restoration of freshwater systems is common but requires significant planning, resources and active monitoring and may only be a short-term solution to the long-term problem of destruction and loss of riparian zones. Beavers (Castor spp.) have the ability to create physical and biological habitat heterogeneity through the construction of woody debris dams, thereby restoring lost natural discontinuities in freshwater systems. Beavers may thus offer a natural, more passive solution to the need for wetland restoration or creation and the problem of homogenisation of watercourses. As such, numerous beaver reintroductions and introductions have been undertaken based in part on restoring this lost natural heritage. However, it is crucial to be able to predict the potential effects on existing biota of physical modifications by beavers to ecosystems, especially in the light of further population expansion, whilst also disentangling these effects from other influences, namely herbivory. The impact of beavers on aquatic systems was studied using a combination of field-based surveys and experiments, using aquatic plants and macro-invertebrates as indicators of hydromorphological changes and to quantify the effects of direct foraging. The research presented in this thesis demonstrates beaver adaptive foraging behaviours between terrestrial and aquatic habitats, whilst feeding highly selectively, optimally and opportunistically, using the white water lily (Nymphaea alba) as a model species. The effects of beaver foraging on the aquatic plant resource and diversity was low over short time spans (e.g. 1 year), but when selective foraging was assessed over greater time scales (e.g. 10 years) the effects of foraging were distinct. Significant changes in aquatic plant height, biomass, richness, diversity and composition were observed over this time period due to selective grazing on large rhizomatous species (e.g. Menyanthes trifoliata). These direct effects occurred even though changes in water levels, which are commonly believed to be the main driver of beaver influence on aquatic vegetation, were negligible. In a separate study in Sweden where beavers commonly constructed dams, with ponds then forming upstream, the aquatic plant and coleoptera species richness and composition differed in comparison to adjacent non-beaver created wetlands. Therefore, having a range of wetland types in the environment increases physical and biological heterogeneity creating unique niches that are exploited by disparate taxa. The construction of a series of dams within a single reach of stream flowing through a Scottish agricultural landscape also increased physical habitat diversity. Distinctive macroinvertebrate assemblages and modified functional diversity were associated with each dominant habitat type in the stream, resulting in increased landscape scale richness. The findings of this thesis confirm that beaver engineering and foraging has the potential to create unique and highly heterogeneous wetland and stream habitats within landscapes that enhances richness and diversity for multiple species groups. This thesis also supports part of the rationale for the trial reintroduction of beaver to Scotland that beavers can restore degraded habitats.
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Barrett, Rowan Douglas Hilton. "Experimental evolution of Pseudomonas fluorescens in simple and complex environments." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97902.
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Determining the factors responsible for the origin and maintenance of diversity remains a difficult problem in evolutionary biology. There is extensive theoretical work which suggests that environmental heterogeneity plays a major role. This theory argues that diversification is ultimately due to divergent natural selection for alternative resources. In this thesis I investigate adaptation and the evolution of diversity in experimental populations of the asexual bacterium Pseudomonas fluorescens. In all experiments I introduce clonal isolates of Pseudomonas to a novel environment and allow evolution to occur through the substitution of random mutations. Adaptation can then be quantified by comparing evolved genotypes to the ancestor. These experiments show that when Pseudomonas is selected in a complex environment containing several resources, sympatric genotypes adapt to use different resources, leading to the evolution of genetically diverse populations. In environments containing just a single resource, most genotypes adapt to use the same resource and no such diversity is observed. Adaptation in the experimental populations is caused by the fixation of beneficial mutations of intermediate fitness effect. My results highlight the value of microbial model systems for answering evolutionary questions and provide strong evidence for the role of ecological factors in the origin of diversity.
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Kassen, Rees M. "Experimental studies on the fate of diversity in heterogeneous environments." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36966.
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Environmental heterogeneity has often been suggested as a general explanation for patterns of diversity at scales ranging from individuals within populations to communities within landscapes. I evaluate this proposition using laboratory experiments with two microbial species, the unicellular chlorophyte Chlamydomonas reinhardtii and the common bacterium Pseudomonas fluorescens. These experiments contrast the fate of diversity following selection in heterogeneous and homogeneous environments. Specifically, I show that (1) an individual's breadth of adaptation evolves to match the amount of environmental variation, specialists evolving in environments that remain constant through time and generalists evolving in environments that vary through time irrespective of the scale at which environmental variation occurs relative to the lifetime of an individual; (2) the maintenance of diversity in a spatially heterogeneous environment is context-dependent, diversity being more readily maintained when environmental conditions are very different and genotypes are widely divergent; (3) selection in heterogeneous environments represents a plausible mechanism for two well-known patterns of diversity at large spatial scales, namely that between species diversity and both productivity and disturbance. This thesis thus demonstrates that environmental heterogeneity is a plausible, and perhaps very general, factor responsible for the diversity of natural communities.
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Hoekstra, Jonathan M. "The role of habitat quality in shaping evolutionary dynamics, population dynamics, and conservation planning /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5179.
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Antão, Laura H. "Effects of ecological scaling on biodiversity patterns." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/13606.
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Biodiversity is determined by a myriad of complex processes acting at different scales. Given the current rates of biodiversity loss and change, it is of paramount importance that we improve our understanding of the underlying structure of ecological communities. In this thesis, I focused on Species Abundance Distributions (SAD), as a synthetic measure of biodiversity and community structure, and on Beta (β) diversity patterns, as a description of the spatial variation of species composition. I systematically assessed the effect of scale on both these patterns, analysing a broad range of community data, including different taxa and habitats, from the terrestrial, marine and freshwater realms. Knowledge of the scaling properties of abundance and compositional patterns must be fully integrated in biodiversity research if we are to understand biodiversity and the processes underpinning it, from local to global scales. SADs depict the relative abundance of the species present in a community. Although typically described by unimodal logseries or lognormal distributions, empirical SADs can also exhibit multiple modes. However, the existence of multiple modes in SADs has largely been overlooked, assumed to be due to sampling errors or a rare pattern. Thus, we do not know how prevalent multimodality is, nor do we have an understanding of the factors leading to this pattern. Here, I provided the first global empirical assessment of the prevalence of multimodality across a wide range of taxa, habitats and spatial extents. I employed an improved method combining two model selection tools, and (conservatively) estimated that ~15% of the communities were multimodal with strong support. Furthermore, I showed that the pattern is more common for communities at broader spatial scales and with greater taxonomic diversity (i.e. more phylogenetically diverse communities, since taxonomic diversity was measured as number of families). This suggests a link between multimodality and ecological heterogeneity, broadly defined to incorporate the spatial, environmental, taxonomic and functional variability of ecological systems. Empirical understanding of how spatial scale affects SAD shape is still lacking. Here, I established a gradient in spatial scale spanning several orders of magnitude by decomposing the total extent of several datasets into smaller subsets. I performed an exploratory analysis of how SAD shape is affected by area sampled, species richness, total abundance and taxonomic diversity. Clear shifts in SAD shape can provide information about relevant ecological and spatial mechanisms affecting community structure. There was a clear effect of area, species richness and taxonomic diversity in determining SAD shape, while total abundance did not exhibit any directional effect. The results supported the findings of the previous analysis, with a higher prevalence of multimodal SADs for larger areas and for more taxonomically diverse communities, while also suggesting that species spatial aggregation patterns can be linked to SAD shape. On the other hand, there was a systematic departure from the predictions of two important macroecological theories for SAD across scales, specifically regarding logseries distributions being selected only for smaller scales and when species richness and number of families were proportionally much smaller than the total extent. β diversity quantifies the variation in species composition between sites. Although a fundamental component of biodiversity, its spatial scaling properties are still poorly understood. Here, I tested if two conceptual types of β diversity showed systematic variation with scale, while also explicitly accounting for the two β diversity components, turnover and nestedness (species replacement vs species richness differences). I provided the first empirical analysis of β diversity scaling patterns for different taxa, revealing remarkably consistent scaling curves. Total β diversity and turnover exhibit a power law decay with log area, while nestedness is largely insensitive to scale changes. For the distance decay of similarity analysis, while area sampled affected the overall dissimilarity values, rates of similarity were consistent across large variations in sampled area. Finally, in both these analyses, turnover was the main contributor to compositional change. These results suggest that species are spatially aggregated across spatial scales (from local to regional scales), while also illustrating that substantial change in community structure might occur, despite species richness remaining relatively stable. This systematic and comprehensive analysis of SAD and community similarity patterns highlighted spatial scale, ecological heterogeneity and species spatial aggregation patterns as critical components underlying the results found. This work expanded the range of scales at which both theories deriving SAD and community similarity studies have been developed and tested (from local plots to continents). The results here showed strong departures from two important macroecological theories for SAD at different scales. In addition, the overall findings in this thesis clearly indicate that unified theories of biodiversity (or assuming a set of synthetic minimal assumptions) are unable to accommodate the variability in SADs shape across spatial scales reported here, and cannot fully reproduce community similarity patterns across scales. Incorporating more realistic assumptions, or imposing scale dependent assumptions, may prove to be a fruitful avenue for ecological research regarding the scaling properties of SAD and community similarity patterns. This will allow deriving new predictions and improving the ability of theoretical models to incorporate the variability in abundance and similarity patterns across scales.
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Thomas, Jonathan Armstrong White Joseph Daniel. "Modeling canopy foliar traits and disturbance interactions in central Texas woodlands." Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5337.
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Sherman, Craig D. H. "The importance of fine-scale environmental heterogeneity in determing levels of genotypic diversity and local adaptation." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060726.114643/index.html.
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Sudo, Masaaki. "Ecological significance of the environmental heterogeneity between the upper and lower surfaces of a single leaf as a determinant of acarine predator-prey relationship." Kyoto University, 2014. http://hdl.handle.net/2433/188750.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第18312号
農博第2037号
新制||農||1020(附属図書館)
学位論文||H26||N4819(農学部図書室)
31170
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 天野 洋, 教授 田中 千尋, 教授 松浦 健二
学位規則第4条第1項該当
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Stanton, Nicole Lynn. "How does your prairie (re)grow?: Interactions of seed additions with resource availability, heterogeneity, and disturbance on recruitment and diversity in a restored tallgrass prairie." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18205.
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Master of ScienceDivision of Biology
John M. Blair
Temperate grasslands are among the most threatened biomes in the world, with the largest historical losses due to conversion to agricultural land. While much of this biome has already been converted, there is concern the last remaining remnants in North America will be converted in response to increasing demand for crops used for ethanol production. Thus, restoring grasslands post-anthropogenic disturbance is increasingly important for conserving grassland biodiversity. Two major challenges for prairie restorations are establishing the many subdominant and rarer species found in native prairie, and offsetting the typical decline in richness and diversity over time as restorations age. Repeated seed addition of targeted species is commonly used to override low and declining plant richness and diversity. While this is generally effective early in restoration (i.e., as communities are establishing), its effectiveness in later stages (i.e., when established communities are often losing diversity) remains unknown. I investigated plant community responses to combinations of resource manipulations and disturbances coupled with a seed addition in a 15-yr old restored grassland to test the hypothesis that spatial resource heterogeneity increases the rate of colonization into established prairie restoration communities. Seeds were added to a long-term restoration experiment involving soil depth manipulations (deep, shallow) crossed with nutrient manipulations (reduced N, ambient N, enriched N). Seedling emergence was generally low and only 8 of the 14 forb species added were detected in the first growing season. I found no effect of increased resource heterogeneity on the abundance or richness of seedlings. There was a significant nutrient effect (p<0.1, α=0.1) on seedling abundance, with higher emergence in the enriched N than the ambient N treatment. I also found unexpected nutrient effects on richness, diversity and Mean C (Mean C = Σ CoCi*Ai, where CoC=Coefficient of Conservatism and A=relative abundance of the ith species). All values, except Mean C, were higher in the enriched N treatment than in either the reduced or ambient N treatments. Mean C was lowest in the enriched N treatment, and highest in the whole-plot control, suggesting that the majority of species contributing to higher richness and diversity in the enriched N treatment were “weedier” species. In a separate experiment, I found no effect of small-scale disturbances (aboveground biomass removal or soil disturbance) on seedling abundance or seedling richness. I did find a marginal effect of disturbance type on seedling richness (p=0.11, α=0.1), with higher seedling richness in the soil disturbance than the aboveground biomass removal treatment. I did not find any disturbance effects on community response variables. These results indicate that recruitment from seed additions into well-established restored communities is relatively low in the first year following a seed addition, regardless of resource availability and heterogeneity. Follow-up studies to determine recruitment rates in subsequent years are needed to elucidate whether recruitment responses are driven more by individual species differences or by environmental mechanisms.
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Cabanellas, Reboredo Miguel. "Socio-ecological approach of the recreational squid shery." Doctoral thesis, Universitat de les Illes Balears, 2014. http://hdl.handle.net/10803/145976.
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El creciente impacto de la pesca recreativa sobre el declive de los stocks, hace necesario considerar el role que este sector desempeña sobre la dinámica poblacional de los recursos explotados. Uno de los recursos que sufre una fuerte explotación, tanto por el sector comercial como por el sector recreativo, es el calamar Europeo Loligo vulgaris. Esta Tesis afronta el reto de poner en relieve el potencial impacto que este sector ejerce sobre esta especie. Para ello, aspectos clave de la vida del calamar, la dinámica de la pesquería recreativa y sus interacciones han sido abordadas. Con esta tesis ofrecemos información clave para la comprensión de los patrones de esfuerzo desarrollados por la pesca de recreo, lo cuales guardan una estrecha relación con las agregaciones reproductoras en costa de esta especie. Esta Tesis demuestra el importante papel de la pesca recreativa en la explotación y dinámica poblacional de este valorado recurso.
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Johnson, Linda Gail. "Effects of habitat patch size and isolation on the population structure of two siphonarian limpets." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1005364.
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Habitat fragmentation is a fundamental process that determines trends and patterns of distribution and density of organisms. These patterns and trends have been the focus of numerous terrestrial and marine studies and have led to the development of several explanatory hypotheses. Systems and organisms are dynamic and no single hypothesis has adequately accounted for these observed trends. It is therefore important to understand the interaction of these processes and patterns to explain the mechanisms controlling population dynamics. The main aim of this thesis was to test the effect of patch size and isolation on organisms with different modes of dispersal. Mode of dispersal has previously been examined as a factor influencing the effects that habitat fragmentation has on organisms. Very few studies have, however, examined the mode of dispersal of marine organisms because it has long been assumed that marine animals are not directly influenced by habitat fragmentation because of large-scale dispersal. I used two co-occurring species of siphonariid limpets with different modes of dispersal to highlight that not only are marine organisms affected by habitat fragmentation but that they are affected in different ways. The two species of limpet, Siphonaria serrata and Siphonaria concinna, are found within the same habitat and have the same geographic range along the South African coastline, however, they have different modes of dispersal and development. The effect of patch size on organism density has been examined to a great extent with varied results. This study investigated whether habitat patch size played a key role in determining population density and limpet body sizes. The two species are found on the eastern and southern coasts of South Africa were examined across this entire biogeographic range. Patch size was found to have a significant effect on population density of the pelagic developer, S. concinna, but not the direct developing S. serrata. Patch size did play a role in determining limpet body size for both species. S. concinna body size was proposed to be effected directly by patch size whilst S. serrata body size was proposed to be affected indirectly by the effects of the S. concinna densities. The same patterns and trends were observed at five of the seven examined regions across the biogeographic range. The trends observed for S. concinna with respect to patch size conform to the source-sink hypothesis with large habitat patches acting as the source populations whilst the small habitat patches acted as the sink populations. Many previous studies have focused on the effects of habitat patch size at one point in time or over one season. I tested the influence of habitat patch size on the two species of limpets over a period of twelve months to determine whether the trends observed were consistent over time or whether populations varied with time. S. concinna showed a consistently significant difference between small and large patches; whilst S. serrata did not follow a consistent pattern. The mode of dispersal for the two limpets was used to explain the different trends shown by the two species. This examination allowed for the determining of source and sink populations for S. concinna through the examination of fluctuations in limpet body sizes and population densities at small and large habitat patches over twelve months. The direct developing S. serrata trends could not be explained using source-sink theory, as populations were independent from one another. S. serrata demonstrated body size differences at small and large patches which, may be explained by interspecific and intraspecific competition. Habitat isolation is known to play an important role in determining the structure of assemblages and the densities of populations. In this study the population density of the pelagic developing S. concinna showed a weak influence of degree of isolation whilst that of the direct developing S. serrata did not, which may be because of habitat patches along the South African coastline not having great enough degrees of isolation. The population size-structure was influenced directly influenced by isolation for S. concinna, whilst the different population size structure for S. serrata may be explained by assemblage co-dependence. The mode of dispersal showed effects on the relationship of population density and population size-structure with habitat size and isolation. This study indicates the importance of investigating patterns and processes across a range of spatial and temporal scales to gain a comprehensive understanding of factors effecting intertidal organisms.
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Hamilton, Grant Stewart. "The influence of habitat heterogeneity on patterns of connectivity among rabbit populations in southern Queensland." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/37153/6/37153_Digitised_Thesis.pdf.
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Patterns of connectivity among local populations influence the dynamics of regional systems, but most ecological models have concentrated on explaining the effect of connectivity on local population structure using dynamic processes covering short spatial and temporal scales. In this study, a model was developed in an extended spatial system to examine the hypothesis that long term connectivity levels among local populations are influenced by the spatial distribution of resources and other habitat factors.
The habitat heterogeneity model was applied to local wild rabbit populations in the semi-arid Mitchell region of southern central Queensland (the Eastern system). Species' specific population parameters which were appropriate for the rabbit in this region were used. The model predicted a wide range of long term connectivity levels among sites, ranging from the extreme isolation of some sites to relatively high interaction probabilities for others. The validity of model assumptions was assessed by regressing model output against independent population genetic data, and explained over 80% of the variation in the highly structured genetic data set. Furthermore, the model was robust, explaining a significant proportion of the variation in the genetic data over a wide range of parameters.
The performance of the habitat heterogeneity model was further assessed by simulating the widely reported recent range expansion of the wild rabbit into the Mitchell region from the adjacent, panmictic Western rabbit population system. The model explained well the independently determined genetic characteristics of the Eastern system at different hierarchic levels, from site specific differences (for example, fixation of a single allele in the population at one site), to differences between population systems (absence of an allele in the Eastern system which is present in all Western system sites). The model therefore explained the past and long term processes which have led to the formation and maintenance of the highly structured Eastern rabbit population system.
Most animals exhibit sex biased dispersal which may influence long term connectivity levels among local populations, and thus the dynamics of regional systems. When appropriate sex specific dispersal characteristics were used, the habitat heterogeneity model predicted substantially different interaction patterns between female-only and combined male and female dispersal scenarios. In the latter case, model output was validated using data from a bi-parentally inherited genetic marker. Again, the model explained over 80% of the variation in the genetic data.
The fact that such a large proportion of variability is explained in two genetic data sets provides very good evidence that habitat heterogeneity influences long term connectivity levels among local rabbit populations in the Mitchell region for both males and females. The habitat heterogeneity model thus provides a powerful approach for understanding the large scale processes that shape regional population systems in general. Therefore the model has the potential to be useful as a tool to aid in the management of those systems, whether it be for pest management or conservation purposes.
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Dadalt, Letícia Piccinini. "Padrões de diversidade da vegetação lenhosa da região do Alto Camaquã, Rio Grande do Sul, Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26601.
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A diversidade beta pode ser definida como a mudança na composição de espécies entre locais em uma determinada área geográfica. Quantificar a contribuição relativa dos diferentes fatores que a afetam é essencial para entender como é mantida a diversidade das comunidades. Nosso estudo tem foco na vegetação lenhosa da região do Alto Camaquã, sul do Brasil (ca.30-31° S, 52-54° W), que está inserida no bioma Pampa e é caracterizada por ampla heterogeneidade ambiental com mosaicos de floresta e campo naturais. Com o objetivo de responder quais fatores tem mais influência na estruturação da comunidade de plantas lenhosas dessa região, distribuímos sistematicamente 60 unidades amostrais onde foram levantadas todas as espécies de plantas lenhosas. Primeiramente particionamos a diversidade beta através de RDA parcial e verificamos que as variáveis ambientais – que incluem variáveis climáticas, topográficas e edáficas – explicaram 28,4% da variação na composição de espécies, a distância geográfica explicou 16,6%, 14,7% foi compartilhado entre os dois componentes e 40,3% permaneceu não explicado. Com isso ficou claro que fatores determinísticos são mais importantes na estruturação das comunidades lenhosas. Em uma posterior análise de árvore de regressão multivariada, as variáveis climáticas foram selecionadas como as mais influentes. Além disso, a região de estudo é uma das mais bem conservadas do Estado. Portanto, em um segundo momento, investigamos a influência de fatores adicionais na diversidade beta das comunidades lenhosas, considerando o histórico de 300 anos de presença de manejo com pecuária familiar do Alto Camaquã. A partir de dados de um zoneamento agroecológico, exploramos a influência das diferentes tipologias de pecuária sobre dois estratos das comunidades de plantas lenhosas, plântulas e adultos, controlando o efeito da variação climática através de correlações matriciais. Encontramos que o manejo não está relacionado com o turnover de espécies de plântulas, contudo explica 12% da variação da diversidade beta de arbóreas. Concluímos, portanto, que a heterogeneidade climática da região gera heterogeneidade ambiental, sendo esta a principal determinante da diversidade das comunidades, apesar de processos neutros também influenciarem, em menor proporção. A presença do manejo não afeta de forma equitativa a comunidade de plantas lenhosas, contribuindo para a heterogeneidade florística da região.Beta diversity can be defined as the shift in species composition among sites in a geographical area of interest. Quantifying the relative contributions of different processes that affect beta diversity is essential for understanding how diversity is maintained in communities. Our study focuses on the woody vegetation of the Alto Camaquã region, southernmost Brazil (c. 30-31° S, 52-54° W), which is within the domain of the Pampa biome and presents wide environmental heterogeneity showing natural forest-grassland patches. Aiming to answer which factors are most influential in the structuring of the woody plant communities, we systematically placed 60 sampling plots throughout the study area for vegetation survey. We partitioned beta diversity through partial RDA and verified that the environmental variables - which include climatic, topographic and edaphic variables - explained 28.4% of the variation in species composition, geographic distance accounted for 16.6%, 14.7% was shared between the two components and 40.3% of the variation remained unexplained. The deterministic processes are clearly the most important in structuring the woody communities. Further analysis using multivariate regression tree selected the climatic variables as the most influential. The study region shows a well conserved physiognomy, regardless of its 300-years history of land use for family cattleraising; hence in a second moment we investigated additional factors affecting diversity patterns of the plant communities surveyed, starting from available agroecological zoning data for land management. We explored the effect of the different typologies of family cattle-raising over two strata of the woody vegetation community, seedling and adult plants, controlling the effect of climate heterogeneity using matrix correlations (partial Mantel tests). We found that land management is not correlated with the species turnover of seedlings, yet explains 12% of the variation in the adult plants beta diversity. We concluded, hence, that climatic heterogeneity creates habitat heterogeneity, being the main determinant of community diversity, although neutral processes are also influent. Land management does not affect the woody plant community evenly, thus contributing to the floristic heterogeneity of the region.
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Close, Andrew John. "The organization of complex ecological structures : a study of the functional role of heterogeneity in the formation of hierarchically structured populations of Canada geese Branta canadensis (Linnaeus 1758)." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612617.
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The translocation of organisms to new bio-geographical regions has significant and negative impacts upon native biodiversity and socio-economic development. Biological invasions are dynamic multi-step processes. In order to alleviate the impacts attributed to the introduction of non-native species, it is essential to understand the processes that determine the outcomes of each step of the invasion process. Recent studies argue that environmental heterogeneity is fundamental to the outcome of each stage of the invasion process. Indeed, environmental heterogeneity has been shown to increase the invasive potential of non-native species. Heterogeneity is defined as the condition of diversity and non-uniformity of structure and is found throughout complex and dynamical biological systems. It can be categorized into two discrete forms; endogenous and exogenous heterogeneity. Interactions between endogenous processes and exogenous factors generate ecological patterns and structures that demonstrate distinct spatial and temporal signatures at multiple and contrasting scales. This study examined the functional role of heterogeneity in the formation of complex scale-dependent ecological structures within an invasive non-native species system, namely of Canada geese Branta canadensis (Linnaeus 1758). A graph theoretic approach was used to quantify the degree of connectivity within the study system. Findings indicated that the underlying complexity in the distribution of ecological patterns and structures was best explained by two theoretical models previously described in the literature: the small-world effects models and the scale-free graph.
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Faria, Denise Matias de. "Dinâmica e sucessão de algas epifíticas em lagoa rasa subtropical (Lagoa Mangueira, Rio Grande do Sul,Brasil)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131700.
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A Lagoa Mangueira é uma extensa lagoa rasa subtropical localizada no sul do estado do Rio Grande do Sul, Brasil. É um ambiente que varia de oligo à mesotrófico, com extensa área litoral colonizada por macrófitas aquáticas, fornecendo grande área de substrato para o desenvolvimento da comunidade aderida. A parte sul da lagoa é caracterizada pela alta transparência e alto pH, e a parte norte é mais rasa com alta concentração de ácidos húmicos devido a interação com banhado. Devido sua forma e posição geográfica a lagoa sofre constante ação dos ventos de direção NE, com mudanças para o quadrante SE-SO durante as frentes frias. O vento neste ambiente é um fator regulador da hidrodinâmica, afetando espacial e temporalmente as comunidades aquáticas (fitoplâncton, zooplâncton, e peixes), podendo ser considerado um distúrbio constante no ambiente. Entretanto, ainda há uma lacuna quanto à contribuição das algas epifíticas para a teia trófica, bem como a resposta dessa comunidade à hidrodinâmica. O Capítulo 1 apresenta um estudo que testou se as diatomáceas epifíticas respondem a heterogeneidade espacial da lagoa durante dois verões em três pontos distantes (Norte, Centro e Sul). Verificou-se que as diatomáceas exibem um gradiente longitudinal NS e a área central assume características semelhantes aos pontos Norte e Sul dependendo da dinâmica do vento. No Capítulo 2, foi avaliada a sucessão das algas epifíticas no Sul da lagoa, durante 60 dias no verão de 2012, para investigar os fatores reguladores do desenvolvimento da comunidade in situ, considerando o zooplâncton como potencial predador. O estudo evidenciou que a fase avançada da sucessão foi dominada por diatomáceas fortemente aderidas e adaptadas às altas médias da velocidade do vento (±15 m s-1). O epifíton mostrou-se uma grande fonte de produtividade primária para a teia trófica e fortes correlações provaram que a comunidade sustentou o controle bottom-up da comunidade zooplanctônica. O Capítulo 3 descreve o estudo que testou a resposta do epifíton à dinâmica do vento (velocidade e direção) durante frentes frias (inverno de 2013) em três situações diferentes: comunidade natural, sucessão em um banco de macrófitas e um mesocosmo (protegido da ação do vento). O epifíton revelou-se resiliente, uma vez que o vento favoreceu a colonização e estabilização, recuperando-se rapidamente após o distúrbio. O mesocosmo diminuiu a ação do vento atrasando a deposição das células metafíticas para início da colonização e a sucessão só começou após um grande distúrbio (vento 10 m s-1) que nivelou a água do mesocosmo e a água circundante. Dominância de diatomáceas foi registrada em todos os experimentos. As diversidades das comunidades de todos os experimentos responderam à dinâmica do vento, sendo mais baixas quando a velocidade do vento excedeu a média encontrada para o período (5 m s -1).Mangueira Lake is a large shallow subtropical lake located in the Southern Rio Grande do Sul State, Brazil. The lake ranges from oligo to -mesotrophic conditions and presents a large littoral zone covered by macrophytes, providing large area for attached community development. The southern area of the lake is characterized by high transparency and high pH and the northern area is shallower with high concentration of humic acids because of its interaction with the wetland. Due to its shape and geographic position, the lake undergoes constant wind action from NE direction and from SE‒SW during cold-fronts. The wind regulates the hydrodynamics in this environment affecting spatial and temporally the aquatic communities (phytoplankton, zooplankton and fishes), and can be considered a constant disturbance. However, epiphytic algae contribution for food-web, as well as their responses to hydrodynamics, are still a lack. Chapter 1 presents a study in which we tested if epiphytic diatoms respond to the lake spatial heterogeneity during two summers in three distant sites (North, Center and South). As a result we noted that diatoms exhibited a longitudinal gradient from NS whereas the center area assumes characteristics similar to both North and South areas depending on wind dynamics. In Chapter 2, we investigated epiphyton succession during 60 days in southern part of the lake in the summer of 2012, aiming to describe the driving factors of the community development in situ, considering zooplankton as a potential grazer. The study highlighted that the advanced phase of succession was dominated by tightly attached diatoms adapted to high wind mean velocity (±15 m s-1). We also showed that epiphyton was great source of primary production for the food-web and strong correlations proved that the community is handling zooplankton bottom-up control. Chapter 3 describes a study that tested the response of the epiphyton to the wind dynamics (velocity and direction) during cold-fronts (2013 Winter) in three different situations: natural community, succession in a macrophyte bank and in an enclosure (protected from the wind). As a result, epiphyton revealed to be resilient once wind favored colonization and stabilization, rapidly recovering after disturbance. The enclosure acted buffering wind forces delaying succession derived by settlement of metaphytic cells and the succession only started after a huge disturbance (wind 10 m s-1) which leveled the enclosure water and the lake water. Dominance of diatoms was registered in all experiments. The communities‟ diversities responded to wind dynamics, whereas all experiments showed lower diversities when wind velocity exceeded the system‟s means (5 m s-1).
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Ruocco, Ana Maria Cirino [UNESP]. "Impacto da construção de Pequenas Centrais Hidrelétricas (PCHs) sobre a comunidade de macroinvertebrados aquáticos associados a pedrais: um estudo de caso no rio Sapucaí-Mirim (SP)." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/123955.
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Atualmente, a instalação de pequenas centrais hidrelétricas (PCHs) tem sido a alternativa mais visada quando a questão é suprir a demanda energética considerando-se os menores impactos ambientais possíveis. Contudo, são escassos os trabalhos que avaliam as alterações causadas por esses empreendimentos. Este estudo procurou avaliar o impacto da construção de uma PCH sobre a fauna de macroinvertebrados aquáticos associados aos ambientes de pedrais. Para isso, amostras de macroinvertebrados foram coletadas em dois pedrais localizados no rio Sapucaí-Mirim (SP); o primeiro deles considerado como um pedral funcional, ou seja, que mantém as características naturais do rio, e o segundo, um pedral alagado em decorrência da instalação de uma PCH. As amostragens foram realizadas em dois períodos do ano e os dados avaliados através de análises multivariadas. Concluímos que a implantação da PCH acarretou alterações na composição e estrutura da comunidade de macroinvertebrados, com redução nos valores de riqueza, abundância e diversidade desses animais. Além disso, destacamos o fato de a construção de pequenas barragens interferirem no processo de transporte e sobrevivência dos organismos, alterando os sistemas a jusante. Assim, sugerimos que a manutenção de pedrais ao longo do rio é fundamental para conservação da biodiversidade aquática regional
Small hydroelectric power plants are the most used alternative to generate and provide electricity with less environmental impact. Nevertheless, there are few studies which evaluate the environmental alterations caused by these projects. The present study aimed to evaluate the impacts of a small hydroelectric power plant on the aquatic macroinvertebrate fauna associated to riffles. The macroinvertebrates were sampled in two riffles in the Sapucaí-Mirim River (São Paulo State, Brazil); the first one was considered as functional, maintaining the natural characteristics of the river; the second riffle was considered as non-functional due to its permanent flooding after the building of the small hydroelectric power plant. The samplings were carried out in two seasonal periods and the data were analyzed through multivariate analysis. It was concluded that the implementation of the small hydroelectric power plant caused compositional and structural alterations of the macroinvertebrate fauna, with reduction of richness, abundance and diversity of these organisms. In addition, it was highlighted the interference of the small hydroelectric power plants in the downstream transportation and survival of organisms, changing downstream systems. It is suggested that maintaining riffles along the river allow the conservation of regional aquatic biodiversity
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Ruocco, Ana Maria Cirino. "Impacto da construção de Pequenas Centrais Hidrelétricas (PCHs) sobre a comunidade de macroinvertebrados aquáticos associados a pedrais : um estudo de caso no rio Sapucaí-Mirim (SP) /." Botucatu, 2014. http://hdl.handle.net/11449/123955.
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Orientador: Marcos Gomes NogueiraBanca: Vírgínia Sanches Uieda
Banca: paulo Augusto Zaitune Pamplin
Resumo: Atualmente, a instalação de pequenas centrais hidrelétricas (PCHs) tem sido a alternativa mais visada quando a questão é suprir a demanda energética considerando-se os menores impactos ambientais possíveis. Contudo, são escassos os trabalhos que avaliam as alterações causadas por esses empreendimentos. Este estudo procurou avaliar o impacto da construção de uma PCH sobre a fauna de macroinvertebrados aquáticos associados aos ambientes de pedrais. Para isso, amostras de macroinvertebrados foram coletadas em dois pedrais localizados no rio Sapucaí-Mirim (SP); o primeiro deles considerado como um pedral funcional, ou seja, que mantém as características naturais do rio, e o segundo, um pedral alagado em decorrência da instalação de uma PCH. As amostragens foram realizadas em dois períodos do ano e os dados avaliados através de análises multivariadas. Concluímos que a implantação da PCH acarretou alterações na composição e estrutura da comunidade de macroinvertebrados, com redução nos valores de riqueza, abundância e diversidade desses animais. Além disso, destacamos o fato de a construção de pequenas barragens interferirem no processo de transporte e sobrevivência dos organismos, alterando os sistemas a jusante. Assim, sugerimos que a manutenção de pedrais ao longo do rio é fundamental para conservação da biodiversidade aquática regional
Abstract: Small hydroelectric power plants are the most used alternative to generate and provide electricity with less environmental impact. Nevertheless, there are few studies which evaluate the environmental alterations caused by these projects. The present study aimed to evaluate the impacts of a small hydroelectric power plant on the aquatic macroinvertebrate fauna associated to riffles. The macroinvertebrates were sampled in two riffles in the Sapucaí-Mirim River (São Paulo State, Brazil); the first one was considered as functional, maintaining the natural characteristics of the river; the second riffle was considered as non-functional due to its permanent flooding after the building of the small hydroelectric power plant. The samplings were carried out in two seasonal periods and the data were analyzed through multivariate analysis. It was concluded that the implementation of the small hydroelectric power plant caused compositional and structural alterations of the macroinvertebrate fauna, with reduction of richness, abundance and diversity of these organisms. In addition, it was highlighted the interference of the small hydroelectric power plants in the downstream transportation and survival of organisms, changing downstream systems. It is suggested that maintaining riffles along the river allow the conservation of regional aquatic biodiversity
Mestre
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Lopes, Sergio de Faria. "Padrões florísticos e estruturais das Florestas Estacionais Semideciduais do Triângulo Mineiro, MG." Universidade Federal de Uberlândia, 2010. https://repositorio.ufu.br/handle/123456789/13258.
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The semideciduous seasonal forests (SSF) of southeastern Brazil have a high floristic diversity, accompanied by a high beta diversity, even between nearby fragments. However, nowdays these forests have been represented by a large number of small fragments, a landscape pattern typical for this region. In addition to the processes related to fragmentation, the human impact, in particular on the remaining forests, is an important force to modify plant communities, generating spatial and temporal heterogeneity and changing the composition and community structure. To determine the floristic composition and structure of forest remnants is an important way to help the maintenance and conservation of these natural relics. The objective of this study was to increase the knowledge about the flora of semideciduous seasonal forests of the Triângulo Mineiro, through a study of the composition and structure of the tree component, in ten forest fragments located in five municipalities of region. The Triângulo Mineiro is located in the far west of Minas Gerais State, defined by the geographical coordinates 18º29 19º40 S e 47º30 - 49º53 W. The site of sampling in each fragment was an hectare plot placed as central as possible in the FES. All alive individual trees with CAP (circumference at breast height, 1.30 m) ≥ 15 cm were sampled, identified and measured. A similarity analysis was done using the Jaccard's coefficient. A data ordination was carried out using the Detrended Correspondence Analysis (DCA). To complement this, we used a dichotomous hierarchical division by TWINSPAN. Stratification was realized by species and not by individuals, using a nonparametric statistical analysis by quartile and median. An analysis of variance (ANOVA) was used to test the differences between the soil and among fragments, and a post-hoc comparison of the means was done using the Tukey test at 5%. A structured matrix was created with the information (scores) obtained from the evaluation of the array, severity and duration of selected environmental impacts, besides the information about the environment array and of the edge type. A correlation analysis was done between the scores of the impact matrix and the variables of the tree community structure. Finally, the species were classified according to the sucessional groups, dispersal syndromes and deciduousness. The FES of the Triângulo Mineiro have a high species richness, consisting of 242 tree species, distributed in 163 genus and 58 families. Out of the 242 species, only Copaifera langsdorffii Desf. and Hymenaea courbaril L. occurred in all fragments. The levels of floristic similarity between the areas were low, indicating a high heterogeneity in relation to tree species. The classification by TWINSPAN separated the areas into two groups in the first division. The fragments of Uberaba, Água Fria and Ipiaçu formed a distinct group, due to lack of Siparuna guianensis, specie considered as an indicator for the others fragments. As for environmental groups, the FES of the Triângulo Mineiro showed a pattern formed by zoochoric species, early secondary and perennial, which coincides with the pattern found for the tropical season forests. The methodology applied in this study for stratification analysis was effective for the recognition of three tree layers. The variations found for the values of quartile and median represent the historical development of the succession of each fragment, allowing vertical variations in the occupation by species characteristic of certain strata. The analysis of the vertical structure of the FES of the Triângulo Mineiro allowed clearly to see the division of species and their ecological groups exercising their functions in each of the strata. The FES of the region are characterized by a variation in soil types and can be, divided into two groups: the areas of eutrophic and dystrophic soils. However, there was no relationship between these groups and the diversity in the fragments. Areas of extremely dystrophic soils showed high species richness. The species diversity of the fragments increased in areas characterized by intermediaries disturbances leves and / or when inserted in forest gradients. Species richness decreased with the severity of human impacts and edge effects and also with the conservation degree of the fragments. The mechanisms for generation and maintenance of the tree species richness and diversity of semideciduous seasonal forests of the Triângulo Mineiro respond to variation in levels of natural and anthropogenic disturbances, in other words, the historical use and occupation of the area, mainly by the availability for use by the owners, directly influences the natural dynamics of forest succession and allows the development to mature stages.As florestas estacionais semideciduais (FES) da região Sudeste do Brasil apresentam alta diversidade florística, acompanhada por uma alta diversidade beta, mesmo entre fragmentos próximos. Contudo, atualmente essas florestas compõem um grande número de pequenos fragmentos, constituindo um padrão de paisagem típico para essa região. Além dos processos relacionados a fragmentação, os impactos antrópicos em particular sobre os remanescentes florestais são uma importante força capaz de modificar as comunidades vegetais por meio da heterogeneidade espacial e temporal determinando a composição e estrutura da comunidade. Determinar os padrões florísticos e estruturais desses remanescentes é uma importante meta no auxílio da manutenção e conservação desses relictos naturais. O objetivo geral deste trabalho foi o de verificar se os fragmentos de florestas estacionais semideciduais no Triângulo Mineiro são floristica e estruturalmente distintos e se eventuais diferenças são explicadas por propriedades químicas do solo ou pela natureza e intensidade de perturbações antrópicas. O estudo foi realizado em dez fragmentos localizados em cinco municípios do Triângulo Mineiro, definidos pelas coordenadas geográficas 18º29 19º40 S e 47º30 - 49º53 O. O sitio de amostragem em cada fragmento sempre perfez amostras nucleares de um hectare na formação de FES. Em Todos os indivíduos arbóreos vivos com CAP (circunferência à altura do peito, 1,30 m) ≥ 15 cm foram amostrados, identificados e mensurados. Foi realizado uma análise de similaridade utilizando-se do coeficiente de Jaccard. Também foi utilizado uma ordenação dos dados por meio da Análise de Correspondência Destendenciada (DCA). De forma complementar, utilizou-se a divisão hierárquica dicotômica por TWINSPAN. A estratificação foi realizada por espécie e não por indivíduos, utilizando-se uma análise não paramétrica, dada por quartil e mediana. Foi realizada uma análise de variância (ANOVA), para testar as diferenças entre os solos dos fragmentos, e teste de Tukey a 5% de probabilidade, para comparação de médias. Criou-se uma matriz estruturada com informações (pontuações) obtidas a partir da avaliação da extensão, severidade e duração dos impactos ambientais selecionados, além de informações sobre a matriz de entorno e o tipo de borda. Foram feitas análises de correlação entre as pontuações da matriz de impacto e as variáveis da estrutura da comunidade arbórea. Por fim, as espécies foram classificadas quanto aos grupos sucessionais, síndrome de dispersão e deciduidade foliar. As FES do Triângulo Mineiro apresentam riqueza de 242 espécies arbóreas, distribuídas em 163 gêneros e 58 famílias. Das 242 espécies, apenas Copaifera langsdorffii Desf. e Hymenaea courbaril L. ocorreram em todos os fragmentos. Os níveis de similaridade florística entre as áreas foram baixos, evidenciando uma elevada heterogeneidade regional em relação às espécies arbóreas. A classificação feita pelo TWINSPAN separou as áreas em dois grupos na primeira divisão. Os fragmentos de Uberaba, Água Fria e Ipiaçu formaram um grupo distinto, devido a ausência de Siparuna guianensis Aubl., espécie considerada como indicadora do grupo formado pelos demais fragmentos. Em relação aos grupos ecológicos, os fragmentos de FES do Triângulo Mineiro foram constituídos por espécies zoocóricas, secundárias iniciais e perenifólias, o que coincide com o padrão encontrado para as florestas tropicais estacionais. As variações encontradas para os valores de quartil e mediana representam o histórico do desenvolvimento sucessional de cada fragmento, possibilitando variações na ocupação vertical por espécies características de determinados estratos. A análise da estrutura vertical das FES do Triângulo Mineiro permitiu visualizar claramente a divisão das espécies e respectivos grupos ecológicos exercendo funções ecossistêmicas diferentes em cada um dos estratos: sub-bosque, intermediário e dossel. As FES da região são caracterizadas por uma variação nas classes de solo, sendo divididas em dois grupos: as áreas sobre solos eutróficos e aquelas sobre solos distróficos. Entretanto, não houve relação entre estes grupos com a diversidade nos fragmentos. A diversidade de espécies dos fragmentos aumentou nas áreas caracterizadas sob distúrbios intermediários e/ou quando inseridos em gradientes florestais e diminui com a severidade dos impactos e maiores efeitos de borda e também com o grau de conservação dos fragmentos. Os mecanismos de geração e manutenção da riqueza e diversidade das florestas estacionais semideciduais do Triângulo Mineiro respondem às variações nos níveis de perturbações naturais e antrópicas, ou seja, o histórico de uso e ocupação da área, principalmente pela disposição de uso pelos proprietários, influencia diretamente na dinâmica natural da floresta e possibilita a sucessão a estádios de desenvolvimentos mais maduros.
Doutor em Ecologia e Conservação de Recursos Naturais
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Marques, Sara Isabel Ferreira. "Mammal choices in heterogeneous landscape of the Baixo Vouga Lagunar." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/13762.
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Mestrado em Biologia Aplicada - Ecologia, Biodiversidade e Gestão de EcossistemasThe relation between landscape structure and species distribution is a major question in landscape ecology. Terrestrial mammals are particularly susceptible to the spatial features, such as habitat type and landscape complexity, as well as to resource availability (e.g. shelter and food supply). The main objective of this thesis was to describe and understand the patterns of terrestrial non-volant mammal species richness, distribution and abundance in the heterogeneous landscape of Baixo Vouga Lagunar, north-western Portugal. Thus, small mammals and carnivores were sampled using three different strategies: a capture programme focused on small mammals (Rodentia and Eulipotyphla), and sign surveys and camera trapping for carnivores. In general, wetland habitats, such as reed beds, rushes and marshlands, seemed to favour small mammal fauna, being reed bed the habitat with the highest values of diversity. Furthermore, carnivore richness appeared to be favoured by the length of freshwater lines, and consequently by the associated riparian vegetation. Contrary, exotic forest was negatively related to both small mammal fauna and carnivore richness, and presented the lowest small mammal diversity. Overall, carnivore richness was mainly driven by landscape features, rather than by human influence and prey availability, or a combination of them. Surprisingly, prey availability seemed not to influence carnivore richness, probably as a consequence of a spatiallly wide availability of small mammals through the landscape matrix. Although at a fine-scale of the landscape, heterogeneity did not seem to influence the abundance of small mammals, at a broad-scale, the landscape matrix seems to promote small mammal diversity, since species distribution fluctuated throughout the patchy landscape. Contrasting, carnivore richness was negatively influenced by landscape heterogeneity and fragmentation, since the landscape is mainly composed by open habitats. Overall, the main findings of this study support the importance of hedgerow habitats (e.g. riparian gallery) to carnivore assemblage by providing water, shelter and enhancing landscape connectivity, and of wetland habitats for small mammal community. Furthermore, the results obtained revealed the reduced biological value of monocultures, especially forests of exotic species. This study reinforces the importance of the Baixo Vouga Lagunar region to wildlife and provides crucial information to develop adequate management and conservation guidelines.
A relação entre a estrutura da paisagem e a distribuição das espécies é um dos temas centrais da ecologia da paisagem. Os mamíferos terrestres são particularmente suscetíveis às características físicas do ambiente, como o tipo de habitat e a complexidade da paisagem, assim como à disponibilidade de recursos (e.g. abrigo e alimento). O principal objetivo deste estudo centrou-se na descrição e compreensão dos padrões de distribuição, abundância e riqueza específica dos mamíferos terrestres na paisagem heterogénea do Baixo Vouga Lagunar. Para tal foi amostrada a comunidade de micromamíferos e carnívoros com recurso a três metodologias distintas: programa de captura de micromamíferos (Rodentia e Eulipotyphla), e prospeção de indícios de presença e armadilhagem fotográfica de carnívoros. No geral, os resultados mostraram que os habitats húmidos, como os caniçais, juncais e sapais, favorecem a fauna de micromamíferos, sendo o caniçal o habitat que registou valores mais elevados de diversidade. Para além disso, a riqueza específica de carnívoros evidenciou ser favorecida pelo comprimento das linhas de água doce, e consequentemente pela vegetação ripícola associada. Pelo contrário, a floresta exótica composta por eucaliptos apareceu negativamente correlacionada com ambos os grupos de mamíferos, apresentando os valores mais baixos de riqueza específica de micromamíferos. As características da paisagem mostraram ser o fator mais importante para a riqueza de carnívoros, quando comparadas com a disponibilidade de presas e influência humana, ou com a combinação destes. Surpreendentemente, a disponibilidade de presas não influenciou a riqueza de carnívoros, o que pode ser uma consequência da ampla disponibilidade espacial de micromamíferos pela matriz da paisagem. Embora a uma pequena escala a heterogeneidade da paisagem pareça não influenciar a abundância de micromamíferos, à escala da paisagem o mosaico de habitats parece promover a diversidade de micromamíferos. Esta conclusão assenta sobre a distribuição das diversas espécies que varia pelas manchas de diferentes habitats. Por outro lado, a riqueza específica de carnívoros foi negativamente influenciada pela heterogeneidade e fragmentação da paisagem, a qual é composta maioritariamente por habitats abertos. Os principais resultados deste estudo suportam a importância dos habitats lineares para a comunidade de carnívoros no Baixo Vouga Lagunar, nomeadamente a galeria ripícola, e dos habitats húmidos para a fauna de micromamíferos, que lhes fornecem alimento. Revelaram ainda o reduzido valor biológico das monoculturas, em particular florestas de espécies exóticas. Este estudo reforça assim importância do Baixo Vouga Lagunar para a vida selvagem, e fornece bases essenciais para o desenvolvimento de medidas adequadas de gestão e conservação para a região.
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Huynh, Huy. "Estimating the maximum probability of categorical classes with applications to biological diversity measurements." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44868.
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The study of biological diversity has seen a tremendous growth over the past few decades. Among the commonly used indices capturing both the richness and evenness of a community, the Berger-Parker index, which relates to the maximum proportion of all species, is particularly effective. However, when the number of individuals and species grows without bound this index changes, and it is important to develop statistical tools to measure this change. In this thesis, we introduce two estimators for this maximum: the multinomial maximum and the length of the longest increasing subsequence. In both cases, the limiting distribution of the estimators, as the number of individuals and species simultaneously grows without bound, is obtained. Then, constructing the 95% confidence intervals for the maximum proportion helps improve the comparison of the Berger-Parker index among communities. Finally, we compare the two approaches by examining their associated bias corrected estimators and apply our results to environmental data.
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Rathwell, Kaitlyn. "MANAGING WATER QUALITY IN AHETEROGENEOUS LANDSCAPE : A SOCIAL NETWORK PERSPECTIVE." Thesis, Stockholms universitet, Stockholm Resilience Centre, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-50956.
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Understanding how humans and ecosystems interact across landscapes is an importantchallenge for the development of sustainable societies. Human dominated landscapes arefrequently heterogeneous in their distribution of ecosystems and the associated goods andservices. It can be difficult to create management strategies that cater to diverse demandsfrom different resource managers, while at the same time promoting healthy functioningof ecosystems held in common. I use a social network perspective to analyze howmunicipal management units connect to each other with regards to a water resource intwo watersheds in Québec, Canada. I test the importance of collaborative network ties formunicipalities’ engagement in water quality management activities. I assess ifmunicipalities with different ecosystems, namely agriculture and tourism, engagedifferently in water quality management activities and if they have different socialnetworks. I assess the role of third party actor groups such as Government Ministries andNon-Governmental Organizations that connect municipalities across the diverselandscape. Third party actor groups are instrumental in connecting municipalities acrossa diverse landscape. Municipalities with ecosystems facilitating tourism have morecollaborative ties in the water quality management network and are more engaged inwater quality management activities than municipalities managing for agriculturalproduction. An asymmetry in collaborations and activity engagement for water qualitymanagement has implications for the capacity of the region to encourage basin scalewater management.
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Silveira, Guilherme Augusto da. "Influência de fatores espaciais e ambientais na estrutura da comunidade de invertebrados em nascentes tropicais." Universidade Federal de Juiz de Fora (UFJF), 2016. https://repositorio.ufjf.br/jspui/handle/ufjf/2331.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Nascentes são ecossistemas estáveis, onde a conectividade aquático-terrestre e a complexidade de microhabitats que apresentam permitem que estes ambientes suportem uma fauna diversa. Considerando a importância das nascentes na manutenção da biodiversidade de organismos aquáticos e sua relevância econômica e ecológica, aliado à escassez de estudos em ambientes tropicais, o presente estudo objetivou testar os modelos das teorias de nicho e neutra, bem como quantificar a importância do espaço e das variáveis ambientais como agentes estruturadores das comunidades de invertebrados em nascentes. Foram obtidas três amostras compostas de substratos (pedras, areia e folhiço) em quinze nascentes de cinco localidades no município de Juiz de Fora, Minas Gerais, Brasil. Um total de 11.239 invertebrados foram identificados. As nascentes do tipo helocreno, com área alagada difusa, e reocreno, cuja água ao sair do solo forma imediatamente um riacho apresentaram maior abundância e riqueza de invertebrados que limnocreno, nascentes que formam poça. A composição da fauna também diferiu entre os três tipos estudados, o que pode ser explicado pela heterogeneidade ambiental encontrada nestas nascentes e pelas diferenças físicas e químicas entre os diferentes tipos. Os resultados da análise de Redundância parcial mostraram que 23% da variação total da composição da fauna de invertebrados foram explicados pelas variáveis ambientais profundidade, temperatura da água, oxigênio dissolvido, pH, matéria orgânica e frações de areia média e areia muito fina, 4% foram explicados pela variação espacial e outros 12% pela interação entre estes fatores. Os 61% restantes corresponde à fração residual resultante de interações bióticas e outras variáveis não analisadas. Estes resultados podem ser relacionados ao efeito combinado entre os mecanismos enfatizados pela teoria de nicho e pela teoria neutra, e, portanto, estão de acordo com a abordagem de metacomunidades, seguindo o modelo de sorteamento de espécies de dinâmica de comunidades. Assim, pode-se concluir que os fatores ambientais e espaciais explicam parcialmente a estruturação da comunidade de invertebrados em nascentes, com maior importância dos filtros ambientais.
Springs are stable ecosystems, where the water-land connectivity and the complexity of microhabitats allow these environments to support a diverse fauna. Considering the importance of springs in the maintenance of biodiversity of aquatic organisms and their economic and ecological relevance and regarding with the lack of studies in tropical environments, the present study aimed to identify the influence of abiotic variables and spacial factors in the structuring of invertebrate communities in springs through a theoretical ecology approach. Three composite substrate samples (rocks, sand and litter) were obtained from 15 springs in five different areas in the city of Juiz de Fora, Minas Gerais, Brazil. A total of 11,239 invertebrates were identified. Helocrenes and rheocrene springs showed greater invertebrate abundance when compared to the limnocrene and the fauna composition differed between the three types of spring studied, which may be explained by the environmental heterogeneity found in helocrenes springs and physical and chemical differences between the different types. Results on the partial redundancy analysis showed that 23% of the total variation of the invertebrate fauna composition was explained through the measured environmental variables, while other 4% was explained by spatial variation; this can be related to the combined effect between mechanisms emphasized by the niche theory and neutral theory, and thus a agreeing with the metacommunities approach. So, we conclude that the environmental factors and space can partially explain the structure of invertebrate communities in springs, with greater importance of the environmental filters, the remainder being possibly explained by the biotic interactions and other non-analyzed variables.
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Monarch, Elizabeth Anne. "Ground-flora Composition and Diversity of Young and Mature Wildfire-Regenerated Jack Pine Stands." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397712396.
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Carrié, Romain. "Hétérogénéité des paysages et des pratiques agricoles - Effets sur la diversité des abeilles sauvages et la pollinisation." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0104/document.
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L’importance écologique et agronomique des abeilles sauvages dans les paysages agricoles rend cruciale la gestion de ces insectes pollinisateurs. Les abeilles sauvages utilisent plusieurs habitats dans les paysages agricoles, comme les milieux semi-naturels (bois, haies, prairies permanentes), mais aussi les parcelles agricoles. L’objectif de ce travail est de caractériser la structure des communautés de pollinisateurs et le succès de pollinisation le long de gradients de composition et de configuration des milieux semi-naturels ainsi que d’intensité des pratiques agricoles à l’échelle paysagère. Par une approche basée sur les trais écologiques, traduisant des différences d’utilisation des ressources par les abeilles sauvages, nous avons mis en évidence que i) les abeilles sauvages peu mobiles, les espèces solitaires mais aussi les espèces terricoles (nids souterrains) sont plus abondantes dans des parcelles agricoles entourées d’une forte proportion de prairies permanentes faiblement fragmentées, ii) les parcelles entourées d’une forte quantité de lisières forestières présentent une abondance plus importante d’espèces peu mobiles, d’espèces tardives, sociales et polylectiques, iii) les espèces oligolectiques sont filtrées (exclues) dans les paysages fortement boisés car ce sont des espèces profitant de ressources fournies par la mosaïque cultivée. Nous avons aussi mis en évidence que l’effet positif de la proportion en milieux semi-naturels sur la diversité des abeilles sauvages était plus important dans des paysages à la mosaïque agricole gérée de façon intensive. Nous montrons par ailleurs que l’intensité locale des pratiques agricoles peut autant influencer la diversité des abeilles sauvages que la proportion de milieux semi-naturels environnants. Enfin, nous montrons que, suivant les situations, l’abondance des espèces d’abeilles sauvages dominantes ou la présence d’un assemblage d’espèces peu communes peut expliquer le succès de pollinisation. Il semblerait que, dans le cas où le succès de pollinisation répond à l’occurrence d’espèces peu communes, la proportion de milieux semi-naturels aurait une influence positive sur le succès de pollinisation par les abeilles sauvages. Ce travail de thèse démontre l’importance d’espèces peu communes, dépendantes des milieux semi-naturels, pour le succès de pollinisation mais aussi la relation positive entre l’abondance de certains groupes d’espèces et la proportion de milieux semi-naturels. Ce travail permet donc de soutenir l’hypothèse selon laquelle les milieux semi-naturels sont garants du maintien de la diversité des abeilles sauvages et des services rendus par ces dernières. Cependant, l’effet positif des milieux semi-naturels sur la diversité des abeilles sauvages est variable, puisque il dépend des pratiques agricoles à l’échelle locale et paysagère. Les préconisations d’aménagement paysager et de modifications des pratiques ne peuvent donc être faites indépendamment les unes des autresThe ecological and agricultural importance of wild bees in farmlands stresses the needs for management strategies for these insect pollinators. Wild bees use multiple habitats in agricultural landscapes, such as semi-natural habitats (woodlands, hedgerows, permanent grasslands) and crop fields. This study aims to characterize the community structure of wild bees and assess pollination delivery along gradients of landscape heterogeneity – based on the composition and configuration of semi-natural habitats – and landscape-wide intensity of farming practices. Using a trait-based approach, based on traits determining resource-use by wild bee species, we showed that i) the least mobile species, solitary bees and ground-nesting species were more abundant in crop fields surrounded by large amounts of little-fragmented permanent grasslands, ii) crop fields surrounded by high amount of woodland edges supported a greater abundance of little-mobile bee species, late-emerging bees, social bees and polylectic bees, iii) oligolectic bee species were filtered out in highly forested landscapes, because these species could thrive on resources provided by the crop mosaic. We also found that the positive effect of the proportion of semi-natural habitats on bee diversity was greater in landscapes with intensively managed crop mosaic. Moreover, we showed that the local intensity of farming practices had as much influence on bee diversity as the proportion of semi-natural habitats. Finally, we showed that, depending on situations, the abundance fluctuations of dominant bee species or the occurrence of an assemblage of uncommon bee species can explain variations in pollination success. In the cases where pollination success responded to the occurrence of uncommon species, the proportion of semi-natural habitats had a positive influence on pollination delivery provided by wild bees. This study shows the importance of some uncommon species, dependent on semi-natural habitats, for pollination delivery but also the positive relationship between the abundance of some species groups and the proportion of semi-natural habitats. This work therefore confirms the hypothesis that semi-natural habitats sustain the diversity of wild bee communities and pollination delivery. However, the positive effect of semi-natural habitats on bee diversity depends on farming practices at the local and landscape scale. Therefore, recommendations on the management of landscape heterogeneity and changes in farming practices cannot be given independently from each other
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Lage, Mayara Ribeiro. "Caracteriza??o de ?reas degradadas pela extra??o de cascalho: substrato, estrutura horizontal e flor?stica da regenera??o natural." UFVJM, 2016. http://acervo.ufvjm.edu.br/jspui/handle/1/1379.
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)
Um trecho da BR- 367, que liga a cidade de Diamantina ao distrito de Guinda, em Minas Gerais, perpassa por ?reas de campo rupestre na Serra do Espinha?o Meridional e apresenta diversas ?reas de empr?stimo, constitu?das por jazidas de material granular consumidas em obra rodovi?ria da pr?pria via entre as d?cadas de 1960 e 1980. Atualmente tais ?reas ainda apresentam-se fortemente degradadas, caracterizando-se pela fraca cobertura vegetal, exposi??o do solo e inexist?ncia de um sistema de drenagem superficial eficiente. Neste contexto, surge a necessidade de alternativas que tenham efic?cia na integra??o dos conhecimentos silviculturais e princ?pios ecol?gicos visando o retorno destas ?reas ?s condi??es pr?ximas das originais. Este trabalho teve como objetivo entender a rela??o entre vari?veis ambientais e a estrutura horizontal e flor?stica das esp?cies colonizadoras destes ambientes degradados. Foram selecionadas quatro ?reas degradadas, analisadas por fotografias a?reas referentes aos anos de 1960 e 1979 nas quais foi poss?vel detectar das ?reas degradadas pontuais. Para o estudo do substrato estratificou-se as quatro ?reas selecionadas para a coleta de amostras deformadas e indeformadas de forma preferencial. Obteve-se as propor??es de areia, silte, argila, dados de resist?ncia ? penetra??o, densidade de part?culas e aparente, porosidade total, micro e macro porosidade. Para a an?lises qu?micas foram coletadas entre 5 subamostras de cada estrato com o intuito de se obter uma amostra composta do substrato superficial (0-20 cm), de forma a representar a heterogeneidade ambiental de cada ?rea. Foram analisados: pH em ?gua; teores de P, K+, Mg2+, Ca2+ e Al3+; complexo sortivo (acidez potencial (H+Al), satura??o e soma por bases (V% e SB), CTC (T), CTC efetiva (t) e satura??o por alum?nio (m%) e mat?ria org?nica (MO). Os dados obtidos foram aferidos e submetidos a an?lises estat?sticas. Realizou-se an?lise de componentes principais (PCA) pelo software PCORD vers?o 6, de modo a sintetizar as vari?veis de maior relev?ncia na correla??o das vari?veis analisadas. Para levantamento da comunidade vegetal foi empregado o m?todo da interse??o na linha no qual em cada ?rea foram alocadas doze linhas com 10,0 m de comprimento, distribu?das em zigzag, seguindo as coletas de solo, para correlacionar caracter?sticas do solo e vegeta??o. Cada linha foi subdividida em dez unidades amostrais (UA) cont?nuas, totalizando 470 UAs e anotado a ocorr?ncia de esp?cies de h?bito herb?ceo, arbustivo e arb?reo. Foram calculadoss par?metros fitossociol?gicos: frequ?ncia absoluta (FA), frequ?ncia relativa (FR), cobertura absoluta (CA), cobertura relativa (CR) e o valor de import?ncia (VI). Para comparar os diferentes setores das ?reas estudadas quanto ao perfil de estrat?gias ecol?gicas de esp?cies herb?ceas, estas foram classificadas em sistemas de guildas de acordo com as estrat?gias de regenera??o, estratifica??o e dispers?o. Nas quatro ?reas analisadas foram amostrados 1.517 indiv?duos, pertencentes a 22 fam?lias e 109 esp?cies. A an?lise dos atributos f?sicos e qu?micos do substrato evidenciou alta limita??o ao desenvolvimento de plantas colonizadoras, apresentando como restri??es a alta resist?ncia a penetra??o e substratos de textura arenosa com baixa fertilidade natural. Verificou-se que houve rela??o entre os gradientes ambientais e a abund?ncia e composi??o flor?stica da vegeta??o colonizadora, ficando a maioria das esp?cies mais fortemente correlacionada com as vari?veis MO, H+Al e V al?m de propor??o de Areia, PT, DMG e RP.
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016.
A section of the BR-367, connecting the Diamantina town to the Guinda district, Minas Gerais, runs through areas of rupestrian field of Espinha?o Range and presents several loan areas, consisting of deposits of granular material consumed in road construction between the 1960?s and 1980?s, Currently, these areas are still heavily degraded, characterized by poor vegetation cover, soil exposure and the absence of an efficient surface drainage system. In this context, the need arises for alternatives that have effectiveness in the integration of silvicultural knowledge and ecological principles aiming the return of these areas to the conditions close to the originals. This work aimed to understand the relationship between environmental variables and the horizontal and floristic structure of the colonizing species of these degraded environments. Four degraded areas were selected, analyzed by aerial photographs referring to the years 1960 and 1979 in which it was possible to detect the degraded areas. For the study of the substrate, the four areas selected for the collection of deformed and undisturbed samples were stratified in a preferential way. The proportions of sand, silt, clay, penetration resistance data, particle and apparent density, total porosity, micro and macro porosity were obtained. For the chemical analyzes, 5 sub-samples of each stratum were collected with the aim of obtaining a composite sample of the surface substrate (0-20 cm), in order to represent the environmental heterogeneity of each area. The following parameters were analyzed: pH in water; Contents of P, K +, Mg2 +, Ca2 + and Al3 +; (S), saturation (V%), sum of bases (SB), CTC (T), effective CTC (t) and saturation by aluminum (m%) and organic matter. A PCA was performed by software PCORD version 6, in order to synthesize the variables of greater relevance in the correlation of the analyzed variables. Was used the method of the intersection in the line in which in each area were allocated twelve lines with 10.0 m in length, distributed in zigzag, following the soil collections, to correlate soil and vegetation characteristics. Each row was subdivided into ten continuous sample units (AU), totaling 470 POAs and the occurrence of species of herbaceous, shrub and arboreal habit. Phytosociological parameters were calculated: absolute frequency (AF), relative frequency (FR), absolute coverage (AC), relative coverage (CR), and importance value (VI). In order to compare the different sectors of the studied areas with respect to the profile of ecological strategies of herbaceous species, these were classified in guild systems according to the strategies of regeneration, stratification and dispersion. In the four areas analyzed, 1,517 individuals belonging to 22 families and 109 species were sampled. The analysis of the physical and chemical attributes of the substrate showed a high limitation to the development of colonizing plants, presenting as restrictions the high resistance to penetration and substrates of sandy texture with low natural fertility. It was verified that there was a relation between the environmental gradients and the abundance and floristic composition of the colonizing vegetation, being most of the species more strongly correlated with the variables MO, H+Al and V besides the proportion of Sand, PT, DMG and PR.
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Dufour, Claire. "Écologie de la divergence et de la coexistence : étude empirique chez deux espèces du genre Rhabdomys." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20233.
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Comprendre les mécanismes évolutifs permettant la persistance des populations face aux changements environnementaux est au centre des préoccupations tant scientifiques que sociétales, de par l'anthropisation grandissante. L'étude i) de la diversification des espèces dans des environnements contrastés et ii) de la coexistence entre ces espèces permet d'appréhender ces mécanismes. En effet, la coexistence entre espèces, et donc leur persistance, dépend de leur niveau de divergence, tant sur des caractères écologiques que reproducteurs. Les études empiriques présentées dans cette thèse portent sur la divergence de deux espèces soeurs chez la souris striée africaine : Rhabdomys bechuanae et Rhabdomys dilectus dilectus. La rencontre entre les deux distributions spécifiques dans un même macro-environnement m'a permis d'étudier la complexité des mécanismes de divergence et de coexistence à fine échelle. Pour cela, les réponses des espèces face à l'hétérogénéité environnementale et à l'interférence spécifique ont été étudiées sur 4 dimensions de la niche : i) la sélection d'habitat, ii) le comportement spatial, iii) le régime alimentaire et iv) le comportement social ainsi que sur le système de reconnaissance sexuelle. Les principaux résultats soulignent l'importance de la prise en compte des différentes dimensions de la niche et de leurs interactions dans l'étude de la divergence et de la coexistence. En effet, alors que la divergence entre les espèces est principalement caractérisée par une évolution en allopatrie de la sélection d'habitats et du système de reconnaissance sexuelle, la plasticité des comportements alimentaires et sociaux reflète la réponse des organismes à l'hétérogénéité spatio-temporelle de l'environnement. La réponse des espèces à l'interférence spécifique est, quant à elle, principalement due à la plasticité des comportements spatiaux (taille et chevauchement des domaines vitaux). Cette thèse se clos par une discussion sur l'apport de ces études micro-évolutives, tenant compte de la complexité des mécanismes de divergence et coexistence, à la compréhension des processus évolutifs à plus large échelle : lors de la radiation écologique d'un genreUnderstanding how evolutionary processes allow populations persistence facing environmental changes is a primary goal for both scientists and society. Studying i) species divergence in contrasted environments and ii) species co-existence gives us a better understanding of such processes. Indeed, species co-existence, and thus their persistence, depends on their degree of ecological or reproductive divergence. In this PhD, I developed a range of empirical studies aimed at understanding the divergence of two sister species: Rhabdomys bechuanae and Rhabdomys dilectus dilectus. In the area in which the two distributions of these species abut, I was able to design empirical protocols to more thoroughly understand mechanisms involved in both divergence and coexistence at a fine scale. The species responses to the heterogeneity of the environment and the species interference were studied on four niche dimensions i) habitat selection, ii) spatial behavior, iii) diet and iv) sociality, as well as the sexual recognition system. The emerging results point out that accounting for several niche dimensions and their interactions is pivotal to understand the mechanisms underlying both divergence and coexistence. Indeed, while species divergence is determined by the allopatric evolution of habitat selection and sexual recognition system, the plasticity of the diet and social behaviors reflects the response of the organisms to the spatiotemporal heterogeneity of the environment. Species' response to interspecific competition is mainly due to plasticity in spatial behaviors (home range size and overlap). I discuss the complexity of the evolutionary mechanisms leading to the divergence and coexistence of sister species and the contribution of these micro-evolutionary studies to the understanding of more general evolutionary processes such as ecological radiation
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Zeppilli, Daniela. "Role of the spatial heterogeneity on benthic diversity in the deep sea." Doctoral thesis, Università Politecnica delle Marche, 2010. http://hdl.handle.net/11566/242159.
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Lambert, Charlotte. "Top predators in marine ecosystem : their response to ocean spatio-temporal variability." Thesis, La Rochelle, 2016. http://www.theses.fr/2016LAROS010/document.
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Le milieu marin est un espace difficile à étudier et notre connaissance des cétacés et des oiseaux marins présente encore de nombreuses lacunes, notamment concernant leur distribution au large. Le milieu marin pélagique est caractérisé par une forte variabilité spatiotemporelle, les différents processus écologiques composant cet écosystème étant très dynamiques dans le temps et l'espace. Il est donc crucial pour ces espèces marines d'anticiper ces variations afin de se maintenir dans le milieu. Grâce à des campagnes en mer à grandes échelles réalisées en Manche, Golfe de Gascogne et Méditerranée occidentale, cette thèse vise à améliorer la connaissance de la distribution des cétacés et oiseaux marins dans ces régions, et explorer l'impact de la variabilité spatiotemporelle de l'océan sur leur écologie. Ce travail se focalise notamment sur deux échelles temporelles, les variations saisonnières et interannuelles. Dans un premier temps, nous étudierons les variations de préférences d'habitats des espèces étudiées à ces deux échelles. Les cétacés et oiseaux marins étant des espèces longévives caractérisées par de longues périodes d'apprentissage au début de leur vie, nous explorerons également comment la réponse à la saisonnalité varie en fonction de l'expérience chez une espèce commune dans la région, le fou de Bassan. Enfin, nous finirons par explorer les liens prédateurs-proies dans le Golfe de Gascogne, en considérant notamment l'accessibilité de ces proies en termes de taille et de profondeur. Ainsi, cette thèse nous permettra de discuter les implications de ce travail concernant l'écologie des cétacés et oiseaux marins, ainsi que leur conservationMarine ecosystem is hard to study and several gaps remain in our understanding of cetaceans and seabirds, particularly regarding their at-sea distributions. The pelagic ecosystem is characterised by an important spatiotemporal variability, thanks to the space and time dynamics of its constituting ecological processes. Top predators thus have to anticipate this variability to sustain themselves in the ecosystem. Based on large-scale surveys across waters of the English Channel, Bay of Biscay and north-western Mediterranean Sea, this thesis aimed at improving knowledge regarding the distribution of cetaceans and seabirds in the area, and to explore the impact of ocean spatiotemporal variability on their ecology. This work focused on two temporal scales, the seasonal and interannual variability. We first explored the variations of habitat preferences of studied species at these two temporal scales. Cetaceans and seabirds being long-lived species characterised by long learning periods in their early life, the response to seasonality was investigated according to age and experience in northern gannets, the most abundant seabird species in the area. Finally, the predator-prey association within the Bay of Biscay was also explored, by contrasting prey accessibility in terms of size and depth. The implications of this work regarding the ecology of marine top predators, as well as their conservation, are finally discussed
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Andolina, Cristina <1986>. "Trophic niche variability of fish populations and communities as a response to ontogeny, habitat heterogeneity and restoration." Doctoral thesis, Università Ca' Foscari Venezia, 2016. http://hdl.handle.net/10579/10331.
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Natural variability in ecosystems arises from intrinsic dynamics of both biotic and abiotic processes, which contribute to structure the variability within different levels of organization, from individuals to populations to communities. This study examined the natural variability of trophic organization as a response to different drivers of change, typical of transitional environments. Investigation was focused on fish populations of lagoon ecosystems and the variability of their trophic niche as a response to: (i) habitat heterogeneity, (ii) habitat restoration and (iii) ontogenetic development. Outcomes emerged from the three main topics highlighted the importance of the trophic adaptability of fish species that spend the entire life cycle (residents) or only one stage (migrants) within systems dominated by highly variable conditions and revealed the importance of the lagoonal habitats, including the most marginal ones and the restored ones, in supporting the trophic structure of the species investigated. In this context, management strategies of species of conservation and commercial interest should pay special attention to preserve those lagoonal habitats where populations live and reproduce, which are increasingly threatened by anthropic impact, and whose irreversible regression would result in severe loss of ecosystem functioning.
La variabilità naturale degli ecosistemi è il risultato delle dinamiche intrinseche dei processi biotici ed abiotici, che contribuiscono a strutturare la variabilità dei diversi livelli di organizzazione, dagli individui, alle popolazioni, alle comunità. Questo studio ha esaminato la variabilità naturale della struttura trofica come risposta a diversi fattori di cambiamento tipici degli ambienti di transizione. L’indagine è stata focalizzata sulle popolazioni ittiche di ecosistemi lagunari e la variabilità della loro nicchia trofica in risposta a tre fattori: (i) eterogeneità di habitat, (ii) processi di rinaturalizzazione dell’habitat e (iii) sviluppo ontogenetico. I risultati emersi dai tre temi principali hanno evidenziato l'importanza dell’adattabilità trofica delle specie ittiche che trascorrono l'intero ciclo di vita (residenti) o una parte di esso (migratrici) all'interno di tali sistemi dominati da condizioni instabili e hanno indicato l'importanza degli habitat lagunari, inclusi i più marginali e quelli in fase di ripristino, nel supportare la struttura trofica delle specie esaminate. In questo contesto, le strategie di gestione delle specie di interesse, sia conservazionistico che commerciale, dovrebbero includere la conservazione degli habitat lagunari in cui le popolazioni vivono e si riproducono, i quali sono sempre più minacciati dalle impatto antropico, e la cui regressione irreversibile si tradurrebbe in una grave alterazione del funzionamento degli ecosistemi.
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FERRARI, GIULIA. "Small mammals in a changing world: distributional, demographic and behavioural responses to environmental heterogeneity with implications for host-parasite-pathogen relationships." Doctoral thesis, country:NO, 2022. https://hdl.handle.net/10449/78818.
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The demography of species and their functional role in the environment are governed by the interplay between individual internal state, external abiotic and biotic conditions, as well as by interspecific interactions, including host-parasite relationships. Generally, these interactions in wild systems have been investigated by long-term studies, and the different components were so far rarely evaluated ensemble. In this dissertation, I implemented a multi-factorial niche-based approach to predict small mammals’ proximate responses to environmental, climatic and anthropic factors, and their implications for host-parasite-disease spatio-temporal patterns. For this purpose, live-trapping targeting the small mammal community was performed across a wide latitudinal (Norway and Italy) and altitudinal (from 500 to 2500 m a.s.l.) gradient. Through field experimental designs based on manipulation of anthropogenic food availability, and longitudinal transects across heterogeneous habitats, I assessed the drivers of small mammal community composition and demography, and the cascading effects on the parasitic load and the circulation of common and emergent pathogens. I found that small mammal survival depended on intrinsic seasonal cycles and was enhanced by food availability only where harsh climate conditions occurred. Conversely, population size was mainly determined by climate constraints and food availability. When opportunistic, dominant rodent and subordinate vole species were sympatric, they showed opposite demographic trends in presence of anthropogenic food, with the subordinate species decreasing both survival and population size, likely pointing at exploitative and interference competition (Paper I). When the spatial components of these patterns were explicitly accounted for, I found that rodents also decreased their spatial range in presence of anthropogenic food. As the local density of the most opportunistic species increased and evenness decreased, their tick burden was amplified at high tick environmental density, especially in heavier individuals, and diluted at lower tick availability. To sum up, the overlap and aggregation of primary and secondary hosts at feeding sites, and more in general in anthropic, fragmented landscapes, likely enhances the completion of the tick life-cycle, inducing tick-burden amplification in a simplified community of hosts (Paper II). Ticks could also thrive in milder climatic conditions due to climate change, as observed along the Alpine altitudinal gradient. Similarly, the composition and altitudinal distribution of the host community can be affected by climate-related abiotic conditions. In accordance with this expectation, I detected the occurrence of generalist species (e.g. bank vole) also at high altitudes, so resulting sympatric with harsh climate specialists, such as snow and field voles. This upward distributional shift of generalist species, and vectors alongside, were also accompanied by circulation of common rodent- and vector-borne pathogens that seemed to show altitudinal segregation, an aspect that needs further investigation (Paper III). Among these, some protozoans, such as Hepatozoon spp. (Paper IV), that may hold a strong epidemiological role along the food web. In conclusion, this dissertation elucidated some complex ecological relationships that involve small mammals in sensitive ecosystems. At macro- and micro-scale, we experimentally demonstrated the cascading consequences of climate and anthropic disturbances on small mammal communities and populations, and their implications for the health of humans and ecosystems.
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Escarpinati, Suzana Cunha. "Composição e dinâmica da família Chironomidae em dois períodos hidrológicos distintos, durante o ciclo fenológico de Mayaca fluviatilis Aublet, 1775." Universidade Federal de São Carlos, 2006. https://repositorio.ufscar.br/handle/ufscar/1914.
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Previous issue date: 2006-08-29The studied lake (Lagoa Mayaca) is located in a preservation area at the campus of the Universidade Federal de São Carlos. With the aim of analyzing the dynamic and the taxonomic composition of the Chironomidae, samples were taken through a transversal transect in two different periods (dry and wet season), comprehending the phenological cycle of Mayaca fluviatilis Aublet, 1775. From a total of 27 Chironomidae taxa, it was verified that the most abundant taxa in the dry season were: Cladopelma, Caladomyia sp1, Caladomyia riotarumensis, Djalmabatista pulcher, Ablablesmyia (Karelia), Tanytarsus rhabdomantis e Labrundinia. On the other hand, in the wet season the most representative were: Polypedilum (Asheum), Chironomus, Goeldichironomus, Endotribelos, Tanytarsus rhabdomantis, Caladomyia friederi, Ablablesmyia (Karelia), Labrundinia e Cricotopus. The greater taxonomic richness and number of specimens were registered in the sampled sites where Mayaca fluviatilis was present, indicating that the presence of this macrophyte was very important for structuring the studied community.
A lagoa estudada (Lagoa Mayaca) situa-se em uma área de preservação, dentro do campus da Universidade Federal de São Carlos. Com o objetivo de analisar a composição e a dinâmica taxonômica de Chironomidae, as coletas foram realizadas ao longo de um transecto transversal, em duas épocas distintas (estação de seca e de chuva), compreendendo o ciclo fenológico de Mayaca fluviatilis Aublet, 1775. Do total de 27 táxons de Chironomidae identificados, constatou-se que numericamente os táxons mais representativos para o período de estiagem foram: Cladopelma, Caladomyia sp1, Caladomyia riotarumensis, Djalmabatista pulcher, Ablablesmyia (Karelia), Tanytarsus rhabdomantis e Labrundinia. Já no período de chuva destacaram-se Polypedilum (Asheum), Chironomus, Goeldichironomus, Endotribelos, Tanytarsus rhabdomantis, Caladomyia friederi, Ablablesmyia (Karelia), Labrundinia e Cricotopus. A maior riqueza taxonômica e número de exemplares foram registrados nos pontos amostrais com presença de Mayaca fluviatilis, indicando que a presença desta macrófita foi de fundamental importância na estruturação da comunidade de larvas de Chironomidae estudada.
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Lucena, Isabela Codolo de. "Ecologia populacional de espécies lenhosas clonais em savana neotropical." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/1800.
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Previous issue date: 2013-04-12Universidade Federal de Sao Carlos
The aims of this thesis were: to investigate the heterogeneity of soils and to evaluate the contribution of clonal growth to the population dynamics of woody species under contrasting soil conditions. In the Cerrado-Pantanal ecotone (15º43 S; 56º04 W), the soil possesses typical features from both the soil of Cerrado in the Central Plateau and the soil of the Pantanal Plain. Given the variability of soil and pluviosity, our hypothesis is that clonal growth is the demographic parameter that most contributes to the population growth rate () of five woody species in this ecotone area. This study was carried out in five Cerrado areas. We identified four soil categories; three of them typic Litoplinthic Petric Plintosol, typic Dystrophic Yellow Latosol and Dystrophic Yellow Latosol with plinthite had not yet been described for the study site. The chemical attributes aluminum saturation, magnesium, calcium, pH and manganese explained 38.7% of the variability of the soils in the study sites. The spatial distribution of the edaphic attributes was heterogeneous. These attributes differed between the soils in the Cerrado Pantanal ecotone and the soils of Cerrado in the Central Plateau and of the Pantanal Plain. The population dynamics of Curatella americana, a dominant species with wide geographical distribution, was evaluated in Petric Plintosol (P) and in Yellow Latosol (L), in the dry and rainy seasons. Sexual reproduction and seedling growth were higher in P, whereas clonal growth was higher in L. The population growth rate (λ) was higher in P. The adult survival rate exerted the strongest effect on λ for the two soil categories and the dry and rainy seasons. The interaction between soil category and pluviosity exerted the strongest effect on λ. We also analyzed the dynamics of species with small populations (Bowdichia virgilioides and Roupala montana) and large populations (Curatella americana and Caryocar brasiliense), to determine which demographic parameters characterize woody clonal species with different sizes. For the species with small populations, the rate of sexual reproduction and the density of all life stages were smaller, whereas the clonal growth was higher. Small populations were more susceptible to variations in soil and pluviosity. The rates that most contributed to the λ of Bowdichia virgilioides and Roupala montana in L and P were: respectively, the survival of young ramets and immatures, in the dry season; and for both species, the survival of adults, in the rainy season. For C. americana and C.brasiliense, the survival of adults was the parameter that most contributed to λ, independently of soil category and season. The study indicated an heterogeneity of the superficial layer of the soil and of the soil categories that occur in this area. Soils with contrasting attributes exerted an important effect on the dynamics of woody clonal species. The survival of young and immature individuals, originated from clonal growth, was the rate that most contributed to the λ of the small-sized populations of woody clonal species B. virgilioides and R. montana , whereas the survival of adults was the rate that most contributed to the λ of the large-sized populations C. americana and C. brasiliense.
Os objetivos desta tese foram: investigar a heterogeneidade de solos e verificar qual a contribuição do crescimento clonal para a dinâmica de populações de espécies lenhosas sob condições edáficas contrastantes. Em Cerrado, zona de ecótono com o Pantanal (15º43 S; 56º04 W), o solo é constituído por características inerentes tanto ao solo de Cerrado do Planalto Central como da Planície do Pantanal. Diante da variabilidade de características edáficas e da pluviosidade, a hipótese é que o crescimento clonal apresente-se como o parâmetro demográfico que mais contribua para a taxa de crescimento populacional () de cinco espécies lenhosas nesta zona de ecótono. O estudo foi realizado em cinco remanescentes de Cerrado. Identificou-se quatro classes de solo, sendo que três destas Plintossolo Pétrico Litoplíntico típico, Latossolo Amarelo distrófico típico e Latossolo Amarelo distrófico com plintita ainda não haviam sido descritas para a região em estudo. Saturação por alumínio, magnésio, cálcio, pH e manganês explicaram 38,7% da variabilidade de solos. Houve heterogeneidade na distribuição espacial dos atributos edáficos. Tais atributos diferiram entre os remanescentes e entre solos de Cerrado do Planalto e da Planície do Pantanal. A dinâmica populacional de Curatella americana, espécie dominante e de ampla distribuição geográfica, foi avaliada em Plintossolo Pétrico (FF) e em Latossolo Amarelo (LAd), nas estações seca e chuvosa. A reprodução sexuada e o crescimento de plântulas foram maiores em FF, enquanto o crescimento clonal foi maior em LAd. A taxa de sobrevivência de adultos exerceu maior efeito sobre para as duas classes de solo e estações seca e chuvosa. A interação entre classe de solo e pluviosidade exerceu maior efeito sobre Também foi avaliada a dinâmica das populações de Bowdichia virgilioides e Roupala montana, Curatella americana e Caryocar brasiliense, para determinar quais parâmetros demográficos caracterizam espécies lenhosas clonais com diferentes tamanhos populacionais. A taxa de reprodução sexuada e a densidade de todos os estádios foram menores, enquanto o crescimento clonal foi maior para pequenas populações de espécies lenhosas. Pequenas populações foram mais suscetíveis às variações de solo e de pluviosidade. As taxas que mais contribuíram para de B. virgilioides e R. montana em LAd e em FF foram a sobrevivência de rametas jovens; na estação seca foi a sobrevivência de rametas jovens e de imaturos para as respectivas espécies e na estação chuvosa foi a sobrevivência de adultos para ambas as espécies. Para C. americana e C.brasiliense, a sobrevivência de adultos foi o parâmetro que mais contribuiu para independente da classe de solo e da estação do ano. O estudo comprovou a heterogeneidade da camada superficial do solo e das classes de solo que constituem esta área. Solos de características contrastantes exercem importante efeito sobre a dinâmica de espécies lenhosas clonais. A sobrevivência de indivíduos jovens e de imaturos, provenientes do crescimento clonal, foi a taxa que mais contribuiu para de populações pequenas de lenhosas clonais B. virgilioides e R. montana - ao passo que a sobrevivência de adultos contribuiu para de populações grandes C. americana e C.brasiliense.
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Kumba, Lubemba Sylvain. "Ecologie spatiale des espèces arborescentes de la Réserve Forestière de Yoko: structure spatiale et mise en évidence des facteurs écologiques responsables, Ubundu, Province Orientale, R.D. Congo." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209056.
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Les forêts tropicales renferment des peuplements arborescents dont la gestion et l’aménagement nécessitent des connaissances sur leur organisation spatiale et leur dynamique. Les analyses de la structure spatiale des espèces arborescentes peuvent être utilisées en forêts naturelles pour identifier les mécanismes sous-jacents qui structurent les peuplements forestiers afin d’améliorer la compréhension des relations entre les espèces. Cette étude a été menée dans la Réserve Forestière de Yoko (RFY) aux environs de Kisangani à l’est de la RD Congo (R.D.C). Elle consiste à analyser la structure spatiale horizontale des espèces les plus abondantes et à tenter d’identifier, à l’échelle locale, les facteurs et/ou processus écologiques potentiellement explicatifs pour en retirer des enseignements utiles à la gestion des massifs forestiers situés à proximité de Kisangani. Pour ce faire, une parcelle d’échantillonnage de 25 ha (500m 500m) a été délimitée dans le bloc sud de la RFY constitué d’une végétation ligneuse mixte et semi-décidue. Un inventaire forestier a permis d’analyser la composition floristique et structurale de la zone. Trois techniques (ou modèles statistiques) relevant de l’écologie spatiale pour l’analyse de la structure horizontale des espèces ont été utilisées :la méthode du voisin le plus proche de Clark & Evans (1954), la méthode d’échantillonnage aléatoire de Hines & Hines (1979), ces deux méthodes reposant sur une analyse à échelle unique de la parcelle d’étude, et la méthode de Ripley (1977) permettant non seulement une analyse multi-échelle mais aussi l’étude des relations intra et interspécifiques. Concernant ce point précis, les arbres ont été catégorisés en trois stades de développement sur la base de leurs diamètres (les jeunes, les immatures et les adultes). Une analyse comparative et théorique des trois méthodes a été effectuée.
Un total de 169 espèces appartenant à 36 familles dont 114 genres ont été identifiées, et la famille des Fabaceae dont la majorité des espèces appartiennent à la sous famille des Caesalpinioideae est apparue prépondérante. Trois espèces se sont révélées les plus abondantes et les plus représentatives du peuplement, et ont pour cette raison fait l’objet de toutes les analyses :Gilbertiodendron dewevrei J. Léonard (De Wild), Scorodophloeus zenkeri Harms et Uapaca guineensis Mull. Arg. Elles ont toutes les trois montré une structure agrégée, et cela à toutes les échelles d’analyse. Les agrégats observés présentent un rayon d’environ 25 m de distance. L’analyse en fonction du diamètre a indiqué une structure agrégée pour les plus petits diamètres et régulière pour les plus grands, et que l’agrégation diminue avec le diamètre. Les résultats montrent également que les structures spatiales observées dépendent de l’échelle d’analyse considérée et de la méthode utilisée. La méthode de Clark & Evans est sensible à la variation de l’étendue. À cet égard, l’échantillonnage aléatoire de Hines & Hines est apparu plus adaptée que celui de Clark & Evans. Les fonctions de Ripley et dérivées sont des outils efficaces et apportent plus d’information. Les analyses ont montré des associations positives entre G. dewevrei et S. zenkeri, ainsi qu’entre G. dewevrei et U. guineensis. Par contre, une indépendance a été constatée entre S. zenkeri et U. guineensis. Il apparaît également que les jeunes sont associés positivement aux adultes supposés reproducteurs, et que les immatures sont indépendants par rapport aux adultes. La dispersion faible ou limitée des graines à proximité des arbres parents en est le principal facteur endogène responsable. Ce facteur explique également les associations positives entre les jeunes et les adultes de la même espèce. La compétition entre des individus pour les besoins en espace, en lumière ou en nutriments dans le sol, explique la structure régulière observée ainsi que l’indépendance des immatures envers les adultes. La dispersion limitée n’est cependant pas le seul facteur explicatif de l’agrégation spatiale des arbres, d’autres facteurs tels que l’hétérogénéité environnementale (sol, topographie,…) ou la perturbation sont vraisemblablement aussi impliqués. La perturbation anthropique ou naturelle est un processus écologique qui devrait avoir joué un rôle déterminant dans l’organisation spatiale des communautés de la forêt. Combinée au phénomène de masting, aux effets de Janzen-Connell et aux ectomycorhizes, elle est très probablement à la base des structures spatiales et des relations spatiales observées entre les espèces de la RFY. / Tropical forests contain tree-stands with management and planning requires knowledge of their spatial organization and dynamics. Analyses of the spatial structure of tree species can be used in natural forests to identify the underlying mechanisms that structure of forest stands to improve the understanding of the relationships between species. This study was conducted in the Yoko Forest Reserve (YFR) around Kisangani in eastern DR Congo (DRC). It is to analyze the horizontal spatial structure of the most abundant species and to try to identify, on a local scale, factors and / or potentially explicative ecological processes to draw valuable lessons for the management of forest areas nearby Kisangani.
To do this, a sample plot of 25 ha (500m x 500m) was delineated in the southern block of the YFR consists of a mixed woody vegetation and semi-deciduous. A forest inventory was used to analyze the floristic and structural composition of the area. Three techniques (or statistical models) under spatial ecology for the analysis of the horizontal structure of the species were used: the nearest neighbor method of Clark & Evans (1954), the random sampling method Hines & Hines (1979), these two methods based on a single scale analysis of the study plot, and the method of Ripley (1977) allows not only a multi-scale analysis, but also the study of intra- and inter-relationships. Regarding this point, the trees were categorized into three stages of development on the basis of their diameters (young, immature and adult). A comparative and theoretical analysis of the three methods was performed.
A total of 169 species belonging to 36 families with 114 genera have been identified and the family Fabaceae which the majority of species belong to the subfamily Caesalpinioideae appeared decisive. Three species have proved the most abundant and the most representative of the stand, and for this reason the subject of all analyzes Gilbertiodendron dewevrei J. Léonard (De Wild) Scorodophloeus zenkeri Harms and Uapaca guineensis Mull. Arg. They all three showed an aggregated structure, and that all scales of analysis. Observed aggregates have a radius of about 25 m distance. The analysis based on the diameter indicated an aggregated structure for smaller diameters and regular for larger and that aggregation decreases with diameter. The results also show that the observed spatial structures depend on the considered analysis of scale and the method used. The method of Clark & Evans is sensitive to the variation in the extent. In this regard, the random sampling of Hines & Hines appeared more suitable than that of Clark & Evans. Ripley's functions and derivatives are effective tools and provide more information. Analyses showed positive associations between G. dewevrei and S. zenkeri, and between G. dewevrei and U. guineensis. By against, independence was found between S. zenkeri and U. guineensis. It also appears that young people are positively associated with the supposed breeding adults and immatures are independent compared to adults. The low or limited seed dispersal near parent trees is the main endogenous factor responsible. This factor also explains the positive associations between youth and adults of the same species. The competition between individuals to space requirements, light or nutrients in the soil, explains the observed regular structure and the independence of immature towards adults. Limited dispersal, however, is not the only factor explaining the spatial aggregation trees, other factors such as environmental heterogeneity (soil, topography, ) or disturbance are probably also involved. Anthropogenic or natural disturbance is an environmentally friendly process that should have played a decisive role in the spatial organization of forest communities. Combined with masting phenomenon, the effects of Janzen-Connell and Ectomycorrhizae, it is very probably the basis of spatial structures and spatial relationships observed between species of the YFR.
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
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Silva, Adilson de Oliveira. "Análise comparativa dos nichos espacial e alimentar de anuros em áreas de Caatinga e Mata Atlântica de Sergipe, Brasil." Universidade Federal de Sergipe, 2014. https://ri.ufs.br/handle/riufs/4404.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorDistinct environmental characteristics can directly affect community structure, they offer varying conditions and resources, which allows each area to establish different groups of species. In this study we analyzed two amphibian assemblages between October 2012 and September 2013 in two areas with different degrees of environmental heterogeneity, one in the Caatinga (Monument Natural Grota do Angico - MNGA ) and the other in the Atlantic Rainforest (Refugio de Vida Silvestre Mata do Junco - RVSMJ), both in the state of Sergipe. We used information about the spatial and food niches and their relationships with ecological and historical factors. We analyzed 1,332 records (999 - RVSMJ 333 - MNGA) of 28 species (22 - RVSMJ and 15 - MNGA, nine common to both areas). The food and space niche overlap was relatively high in both study sites. Nine types of microhabitats were used by the species being the most common, regardless of the area, soil (45.1 %), water (23.7 %) and leaflitter (8.6%). The most important preys in their diets were Formicidae and Coleoptera in both areas. Individuals in the Atlantic rainforest were relatively smaller than those of the Caatinga area suggesting differentiated investments between reproduction and growth between the areas. The results suggest that the assemblages from both areas are influenced by historical or phylogenetic factors only in the use of space assets. Their diets are strongly influenced by the availability of resources the environment offers.
Características ambientais distintas podem afetar diretamente a estruturação das comunidades, pois oferecem recursos e condições variadas, o que permite que em cada área, grupos diferenciados de espécies se estabeleçam. Nesse estudo duas taxocenoses de anfíbios anuros foram analisadas entre outubro de 2012 e setembro de 2013, em duas áreas com diferentes graus de heterogeneidade ambiental, uma na Caatinga (Monumento Natural Grota do Angico MNGA) e outra de Mata Atlântica (Refugio da Vida Silvestre Mata do Junco RVSMJ), ambas no estado de Sergipe. Foram utilizadas informações sobre os nichos espacial e alimentar e suas relações com fatores ecológicos e históricos. Foram tomados 1.332 registros (999 - RVSMJ e 333 - MNGA) pertencentes a 28 espécies (22 RVSMJ e 15 MNGA, sendo nove comuns as duas áreas). A sobreposição de nicho espacial e alimentar foi relativamente alta em ambas as áreas. Nove tipos de microhábitats foram utilizados pelas espécies sendo os mais comuns, independente da área, solo (45,1%), água (23,7%) e folhiço (8,6%). As presas mais importantes das dietas foram Formicidae e Coleoptera em ambas as áreas. Os indivíduos da Mata Atlântica foram relativamente menores que os da Catinga sugerindo investimentos diferenciados em reprodução e crescimento entre as áreas. Os resultados obtidos sugerem que as taxocenoses de ambas as áreas são influenciadas por fatores históricos ou filogenéticos somente na utilização dos recursos espaciais. Suas dietas são fortemente influenciadas pelas disponibilidades de recursos que o ambiente oferece.
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Saulino, Hugo Henrique Lanzi. "Entomofauna aquática do Ribeirão das Anhumas (Bacia hidrográfica do Rio Mogi-Guaçú, SP) : influência do represamento e do uso da terra na estrutura da comunidade." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/2063.
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Previous issue date: 2012-02-29Financiadora de Estudos e Projetos
Changes in river basins such as the deforestation of riparian vegetation, the expansion of agricultural activities and construction of dams, are examples of anthropogenic interference, which interferes with the diversity of aquatic insects in streams and rivers. This study aimed to investigate the distribution patterns of communities of aquatic insects in a longitudinal profile of the Ribeirão Anhumas, discontinued by the construction of five impoundments and the influence of different land uses. Sampling occurred in the river basin of the Ribeirão Anhumas in an area upstream and downstream of the five dams, on the towards headstream/mouth of the creek. We analyzed the concentration of potentially bioavailable metals (Fe, Mg, Mn, Cu, Zn, Ni, Cd and Cr) in sediment. For the sampling effort fauna, the quick sampler method was used for a period of two minutes. Specimens were identified to lowest possible taxonomic level and classified by feeding groups. The highest concentrations of metals in the sediment were recorded in parts of the dam 4 (R4), which is observed around sugar cane farming, the analysis indicated contamination by Ni. 2498 aquatic insects were identified, wich distributed in 92 genera. Polypedilum (Chironomidae, Diptera) was the taxon more representative of the community, as well as the guilds of the predators and gathering-colectors. The stretches with preserved riparian vegetation had the highest values of richness, taxonomic diversity and water quality score. The Student statistical test indicated that there were no significant differences in the abundance and richness between the streches. Diversity indices showed a decrease in diversity between the upstream and downstream sections, and longitudinal profile. We concluded that the basin of the Ribeirão Anhumas is well preserved, where there was no interference from lotic habitat discontinuity of the dams, as well as different land uses low-impact exercise on aquatic insect community.
Alterações em bacias hidrográficas, como o desmatamento da vegetação ripária, a expansão das atividades agrícolas e a construção de represas, são exemplos das interferências antrópicas, que interferem na diversidade de insetos aquáticos nos córregos e rios. O presente estudo teve como objetivo investigar padrões de distribuição de comunidades de insetos aquáticos em um perfil longitudinal do Ribeirão das Anhumas, descontinuado pela construção de cinco represamentos e pela influência de diferentes usos da terra. As coletas ocorreram na bacia hidrográfica do Ribeirão das Anhumas, a montante e a jusante de cinco represamentos, no sentido nascente/foz do ribeirão. Foram analisadas concentração de metais potencialmente biodisponíveis (Fe, Mg, Mn, Cu, Zn, Ni, Cd e Cr) no sedimento. A fauna foi coletada pelo método de varredura, por um período de dois minutos. Os exemplares foram identificados até o menor nível taxonômico possível e classificados por grupos funcionais. As maiores concentrações de metais no sedimento, foram registrados nos trechos da represa 4 (R4), cujo entorno observa-se atividade agrícola canavieira, as análises indicaram contaminação por Ni. Foram identificados 2.498 insetos aquáticos, distribuídos em 92 gêneros. Polypedilum (Chironomidae, Diptera) foi o táxon mais representativo da comunidade, e entre as guildas predominaram os predadores e coletores-juntadores. Nos trechos com vegetação ripária preservada verificaram-se os maiores valores de riqueza, diversidade taxonômica e do escore de qualidade da água. O teste estatístico de Student indicou que não houve diferenças significantes na abundância e riqueza entre os trechos analisados. Os índices de diversidade demonstraram um decréscimo da diversidade entre os trechos a montante e jusante, e no perfil longitudinal. Conclui-se que a bacia hidrográfica do Ribeirão das Anhumas está bem conservada, aonde não houve interferência da descontinuidade de habitat lótico das represas, bem como os diferentes usos da terra exercem baixo impacto sobre a comunidade de insetos aquáticos.
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Neves, Kelle Cristina. "AVALIAÇÃO DA RIQUEZA E ABUNDÂNCIA DE ESPÉCIES DE MAMÍFEROS DE MÉDIO E GRANDE PORTE EM FRAGMENTOS FLORESTAIS NO MUNICÍPIO DE GOIÂNIA, GOIÁS, BRASIL." Pontifícia Universidade Católica de Goiás, 2012. http://localhost:8080/tede/handle/tede/2512.
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Previous issue date: 2012-08-15The landscape constantly changed, caused mainly by human activities, have affected the size, shape and frequency of the landscape elements, and these fragmentation effects have been some of the major threats to biodiversity and changes in species behavior. This study was made in urban forest fragments in the city of Goiania, Goias with the intention of evaluating the richness, the abundance of the medium and large size mammals relating with the area size and the environment heterogeneity of the fragments. We only used the method of camera trapping (camera trap) to raise the wealth and abundance and we collected points of the vegetation structure along 11 forest fragments in areas between 9,76 and 126,95ha, testing such hypotheses: (1) the larger the forest fragment the larger the record of richness of the species, (2) the larger the forest fragment the larger the species abundance and (3) fragments found in abundance is explained by environmental variables fragments. We obtained 180 records of medium and large size mammals in a total of 20 species, 8 orders and 13 families. The species of greatest occurrence and registration was the coati (Nasua nasua). We recorded a specie classified as vulnerable according to IUCN and MMA, which is the Giant anteater (Myrmecophaga tridactyla) and White-lipped Peccary (Tayassu pecari) appears in the list of IUCN as near threatened. Medium and large size species when it comes to richnes and abundance did not obbey an area, they were found in the smaller area as much as in the larger area. The environmental heterogenety in the fragments also did not explain the abundance found in the areas, reforcing the need and how important is the maintenance and conservation of the Cerrado and of all of the areas sizes, which can serve as the only and temporary source (increasing the connectivity between species).
A paisagem constantemente alterada causada principalmente pelas atividades humanas tem afetado o tamanho, a forma e a frequência dos elementos da paisagem, e esses efeitos da fragmentação tem sido algumas das principais ameaças à biodiversidade e mudanças no comportamento das espécies. Este estudo foi realizado em fragmentos florestais urbanos no município de Goiânia, Goiás com o intuito de avaliar a riqueza, a abundância dos mamíferos de médio e grande porte relacionando com o tamanho da área e a heterogeneidade ambiental dos fragmentos. Utilizamos exclusivamente o método de armadilhas fotográficas (câmera trap) para levantar a riqueza e a abundância e coletamos pontos da estrutura da vegetação ao longo de 11 fragmentos florestais com áreas que variaram de 9,76 a 126,95 ha, testando as seguintes hipóteses (1) quanto maior o fragmento florestal maior a riqueza das espécies, (2) quanto maior o fragmento florestal maior a abundância das espécies e (3) abundância encontrada nos fragmentos é explicada pelas variáveis ambientais dos fragmentos. Foram obtidos 180 registros de mamíferos de médio e grande porte em um total de 20 espécies, 8 ordens e 13 famílias. A espécie de maior ocorrência e registro foi o quati (Nasua nasua). Registramos uma espécie classificada como vulnerável de acordo com a IUCN e MMA que foi o tamanduá-bandeira (Myrmecophaga tridactyla) e queixada (Tayassu pecari) que consta na lista da IUCN como quase ameaçada. As espécies de médio e grande porte quanto a riqueza e a abundância não necessariamente obedeceu a um crescimento com o aumento da área, elas foram encontradas tanto em fragmentos de menor área quanto de maior área. A heterogeneidade ambiental nos fragmentos também não explicou a abundância encontrada nas áreas reforçando a necessidade e a importância da manutenção e conservação do Cerrado e de todos os tamanhos de áreas, que podem servir como fonte única e/ou como temporária (aumentando a conectividade entre espécies).