Rozprawy doktorskie: „Habitat loss”

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De, Souza Maira. "Predicting biodiversity loss in insular neotropical forest habitat patches". Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/52054/.

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Neotropical forests have experienced high rates of biodiversity loss as a result of burgeoning land-use changes. Habitat conversion into cropland, pastures, and more recently hydroelectric lakes, are leading drivers of forest loss and fragmentation of pristine forests in the world’s most biodiverse region. This thesis aims to improve our understanding of the impacts of habitat fragmentation on biodiversity loss in Neotropical forests by evaluating the patterns of floristic changes and vertebrate extinctions in forest patches. Two approaches at different scales were conducted. First, a systematic literature review was carried out on the effects of fragmentation on Neotropical primates at a continental-scale. Second, biodiversity inventories were conducted on medium and large bodied vertebrates (including mammals, birds and tortoises) and trees ≥10 cm diameter at breast height at 37 islands and three continuous forest sites within the Balbina Hydroelectric Reservoir in Brazilian Amazonia. Patch area was a key driver of species persistence for all study taxa, yet other factors were also important. Hunting pressure exerted a strong influence on patterns of primate persistence within 760 fragments, and edge effects, including edge-related ground-fires, were the main predictors of floristic transitions using data from 87 quarter hectare forest-plots at Balbina. Additionally, matrix composition and species life-history traits played a key role in explaining patterns of species persistence. This study therefore highlights the importance of considering anthropogenic stressors in assessing the effects of land-use change to explain patterns of species persistence in forest patches, aside from including parameters related to the matrix and ecological life history traits of focal species. As conservation recommendations, prioritising large (>100 ha) patches, increasing their protection, and enhancing connectivity of surrounding habitats becomes clearly important. For future Amazonian dams, it is recommended that engineers should consider the overall topography of planned reservoirs to maximise landscape connectivity and/or reject plans targeting unfavourable river basins.

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Desrochers, Rachelle. "Habitat Loss and Avian Range Dynamics through Space and Time". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20374.

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The species–area relationship (SAR) has been applied to predict species richness declines as area is converted to human-dominated land covers.In many areas of the world, however, many species persist in human-dominated areas, including threatened species. Because SARs are decelerating nonlinear, small extents of natural habitat can be converted to human use with little expected loss of associated species, but with the addition of more species that are associated with human land uses. Decelerating SARs suggest that, as area is converted to human-dominated forms, more species will be added to the rare habitat than are lost from the common one. This should lead to a peaked relationship between richness and natural area. I found that the effect of natural area on avian richness across Ontario was consistent with the sum of SARs for natural habitat species and human-dominated habitat species, suggesting that almost half the natural area can be converted to human-dominated forms before richness declines. However, I found that this spatial relationship did not remain consistent through time: bird richness increased when natural cover was removed (up to 4%), irrespective of its original extent. The inclusion of metapopulation processes in predictive models of species presence improves predictions of diversity change through time dramatically. Variability in site occupancy was common among bird species evaluated in this study, likely resulting from local extinction-colonization dynamics. Likelihood of species presence declined when few neighbouring sites were previously occupied by the species. Site occupancy was also less likely when little suitable habitat was present. Consistent with expectations that larger habitats are easier targets for colonists, habitat area was more important for more isolated sites. Accounting for the effect of metapopulation dynamics on site occupancy predicted change in richness better than land cover change and increased the strength of the regional richness–natural area relationship to levels observed for continental richness–environment relationships suggesting that these metapopulation processes “scale up” to modify regional species richness patterns making them more difficult to predict. It is the existence of absences in otherwise suitable habitat within species’ ranges that appears to weaken regional richness–environment relationships.

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Young, Eric R. "Evaluating and monitoring habitat loss using satellite remote sensing imagery". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28153.

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Habitat loss is widely acknowledged as the leading cause of extinctions and is occurring at an alarming rate and affecting biodiversity globally. I measured the rate of habitat loss using satellite-based land cover change data. First, I modelled the potential suitable habitat of the Marbled Murrelet on Vancouver Island using two techniques and compared those results to in-situ field measurements. Both modelling techniques predicted declines in suitable habitat between the years, although one technique was better at predicting suitable habitat. I also compared rates of habitat loss in areas of high species endangerment to those with lower endangerment over a 15-year period in three Canadian ecozones. In two ecozones, rates of habitat loss were higher in sites of high species at risk richness than those with low richness. These results underscore the importance of using remote sensing data as a monitoring tool critical habitat for species at risk in Canada.

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Warren-Thomas, Eleanor. "Rubber plantations in the Indo-Burma biodiversity hotspot : habitat loss, biodiversity and economics". Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66569/.

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Natural rubber is in high demand for the manufacture of tyres, and rubber plantations are expanding globally. Southeast Asia is the epicentre of rubber cultivation, where deforestation to make way for rubber has been occurring for decades. This process has caused substantial biodiversity loss and carbon emissions. Expansion has recently shifted northwards into mainland Southeast Asia (the Indo-Burma biodiversity hotspot) due to the development of hardier rubber varieties that can survive longer dry seasons and cooler climates. The northward shift has been exacerbated by replacement of rubber with oil palm further south. Profitability and extent of rubber are comparable to oil palm, but rubber has received far less attention and scrutiny from civil society. Future demand for natural rubber is predicted to require 4.3 – 8.5 million ha of additional plantation area by 2024, relative to a 2010 baseline. Profits accruing from logging and conversion of forest to rubber in Cambodia are shown to be very high. The carbon prices that would be needed for a REDD+ program in Indo- Burma to match costs of forest conservation where rubber is a threat, are $30 – 51 tCO2-1. These prices are far higher than those currently paid on carbon markets or through carbon funds, highlighting the importance of supply-chain initiatives, environmental governance and full valuation of ecosystem services for defending forests from conversion to rubber. Agroforestry methods for cultivating rubber in Thailand were found to produce yields comparable to monocultural methods, while providing modest benefits for bird and butterfly diversity. Agroforests did not support any species of conservation concern, and contiguous forests are irreplaceable for the conservation of forest biodiversity. Functional diversity of birds was found not to differ between rubber agroforests and monocultures, and species that feed primarily on nectar and fruit were extremely scarce in both types of rubber plantation.

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Staude, Ingmar René. "Local biodiversity erosion in south brazilian grasslands even with slight landscape habitat loss". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/173601.

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So, Rachel I. "Does Additional Habitat Protection Facilitate the Recovery of Species Protected by the Endangered Species Act?" Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30910.

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Earlier studies have found that endangered species recovery is only weakly associated with the tools enabled by the U.S. Endangered Species Act (ESA). With habitat loss often cited as a leading cause of species declines, we tested whether the recovery of ESA-listed species is instead associated with the protection of critical habitat (CH) by protected areas. We tested the relationship for 299 species using recovery indices derived from the biennial status reports to Congress (1990-2010), as well as NatureServe and IUCN population status data. We found no overall relationship between recovery and the extent to which CH is protected. However, restricting the analysis to recovering species, listed species with larger areas of protected (R2 = 0.158) or strictly protected (R2 = 0.194) CH fared better than species with less protected or strictly protected CH areas. Declining species (199 of 273 species studied) fared no better with more protected habitat. We conclude that the abatement of habitat loss alone does not necessarily facilitate recoveries for the majority of ESA-listed species. We also note that the weak relationships we observed in this study may be reflective of poor recovery status estimates.

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Atkinson, Philip W. "The wintering ecology of the Twite Carduelis flavirostris and the consequences of habitat loss". Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267539.

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Herse, Mark Richard. "Landscape ecology of two species of declining grassland sparrows". Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35786.

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Master of Science
Department of Biology
Alice Boyle
Species extinctions over the past two centuries have mainly been caused by habitat destruction. Landscape change typically reduces habitat area, and can fragment contiguous habitat into remnant patches that are more subject to anthropogenic disturbance. Furthermore, changes in the landscape matrix and land-use intensification within remaining natural areas can reduce habitat quality and exacerbate the consequences of habitat loss and fragmentation. Accordingly, wildlife conservation requires an understanding of how landscape structure influences habitat selection. However, most studies of habitat selection are conducted at fine spatial scales and fail to account for landscape context. Temperate grasslands are a critically endangered biome, and remaining prairies are threatened by woody encroachment and disruptions to historic fire-grazing regimes. Here, I investigated the effects of habitat area, fragmentation, woody cover, and rangeland management on habitat selection by two species of declining grassland-obligate sparrows: Henslow’s Sparrows (Ammodramus henslowii) and Grasshopper Sparrows (A. savannarum). I conducted >10,000 bird surveys at sites located throughout eastern Kansas, home to North America’s largest remaining tracts of tallgrass prairie, during the breeding seasons of 2015 and 2016. I assessed the relative importance of different landscape attributes in determining occurrence and within-season site-fidelity of Henslow’s Sparrows using dynamic occupancy models. The species was rare, inhabited <1% of sites, and appeared and disappeared from sites within and between seasons. Henslow’s Sparrows only settled in unburned prairie early in spring, but later in the season, inhabited burned areas and responded to landscape structure at larger scales (50-ha area early in spring vs. 200-ha during mid-season). Sparrows usually settled in unfragmented prairie, strongly favored Conservation Reserve Program (CRP) fields embedded within rangeland, avoided trees, and disappeared from hayfields after mowing. Having identified fragmentation as an important determinant of Henslow’s Sparrow occurrence, I used N-mixture models to test whether abundance of the more common Grasshopper Sparrow was driven by total habitat area or core habitat area (i.e. grasslands >60 m from woodlands, croplands, or urbanized areas). Among 50-ha landscapes containing the same total grassland area, sparrows favored landscapes with more core habitat, and like Henslow’s Sparrows, avoided trees; in landscapes containing ~50–70% grassland, abundance decreased more than threefold if half the grassland area was near an edge, and the landscape contained trees. Effective conservation requires ensuring that habitat is suitable at spatial scales larger than that of the territory or home range. Protecting prairie remnants from agricultural conversion and woody encroachment, promoting CRP enrollment, and maintaining portions of undisturbed prairie in working rangelands each year are critical to protecting threatened grassland species. Both Henslow’s Sparrows and Grasshopper Sparrows were influenced by habitat fragmentation, underscoring the importance of landscape features in driving habitat selection by migratory birds. As habitat loss threatens animal populations worldwide, conservation efforts focused on protecting and restoring core habitat could help mitigate declines of sensitive species.

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Robillard, Cassandra. "Prioritizing Areas for Habitat Conservation in the Face of Climate and Land-Use Change". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34499.

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The selection of sites for biodiversity conservation is best done if it anticipates future challenges and efficiently accomplishes targets, given limited funding for such efforts. The first chapter of this thesis discusses how conservation practitioners might manage and enhance long-term survival for species whose ranges must shift as climate changes, across regions that present significant mobility barriers. I describe recommendations highlighting connectivity, refugia from climate change, adaptation, and restoration within agricultural landscapes in North America, but these recommendations are transferable elsewhere. The second chapter examines patterns of change in agricultural intensity and land price within Canada’s species-rich farmland between 1986 and 2011, and creates sequential cost-efficient plans to conserve resident species-at-risk within that time period, to determine how environmental and cost changes erode the efficiency of conservation plans. While sites initially selected as cost-efficient remained so through time, total plan costs increased, decreasing each plan’s ability to represent all species for a given budget. This emphasizes the urgent need for conservation within Canada’s farmland.

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Miguel, Pedro Henrique. "Efeito de fragmentação de habitat sobre a associação entre ectoparasitos e morcegos na Mata Atlântica /". Rio Claro, 2019. http://hdl.handle.net/11449/183643.

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Orientador: Ariovaldo Pereira da Cruz Neto
Resumo: A perda de habitat é vista como um dos principais efeitos decorrentes das perturbações da paisagem causada pelo homem aos ambientes naturais. Essa gera maior isolamento dos fragmentos e diminui as áreas de contato entre habitat e matriz, com efeitos negativos sobre a biodiversidade. Os efeitos da perda de habitat nos padrões de biodiversidade são geralmente analisados usando dados de distribuição de espécies e / ou abundância relativa. No entanto, eles não podem ser identificados em populações em que esses efeitos ainda não foram refletidos na abundância e incidência de espécies, e não nos informam sobre os mecanismos causais subjacentes às respostas diferenciais de espécies ou populações a essas perturbações. Uma opção para preencher esta lacuna é concentrar-se em quantificar a miríade de processos fisiológicos em que diferentes espécies lidam com ambientes em mudança. Os morcegos apresentam uma grande diversidade morfológica, fisiológica e comportamental, estando presentes em uma diversa variedade de nichos ecológicos, estabelecendo diversas relações críticas para a manutenção dos ecossistemas onde ocorrem. Os morcegos frugívoros estão entre os mais importantes dispersores de sementes do Neotrópico. Juntamente com os morcegos, investigações com seus ectoparasitas específicos são de grande relevância, visto que, os ectoparasitas exercem pressões seletivas importantes sobre a evolução dos seus hospedeiros. Assim, perda de habitat pode trazer importantes mudanças para as popul... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Habitat loss is seen as one of the main effects of man-made landscape disturbances on natural environments. This generates greater isolation of the fragments and reduces the contact areas between habitat and matrix, with negative effects on biodiversity. The effects of habitat loss on biodiversity patterns are generally analyzed using species distribution and / or relative abundance data. However, they cannot be identified in populations where these effects have not yet been reflected in species abundance and incidence, and do not inform us of the causal mechanisms underlying the differential responses of species or populations to these disturbances. One option to bridge this gap is to focus on quantifying the myriad physiological processes in which different species deal with changing environments. Bats have a great morphological, physiological and behavioral diversity, being present in a diverse variety of ecological niches, establishing several critical relationships for the maintenance of the ecosystems where they occur. Fruit bats are among the most important seed dispersers of the Neotropic. Together with bats, investigations with their specific ectoparasites are of great relevance, as ectoparasites exert important selective pressures on their host evolution. Thus, habitat loss can bring about major changes to bat populations and in some biotic interactions such as parasitism. In this context, we use some physiological analysis to (1) evaluate the impacts of habitat los... (Complete abstract click electronic access below)
Mestre

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Hatfield, Jack Henry. "The impacts of habitat loss and fragmentation upon the maintenance of biodiversity in tropical ecosystems". Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/63830.

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Habitat loss and fragmentation are major threats to biodiversity on a global scale. Human modified landscapes now comprise large areas of the globe, heavily contributing to the observed decline in biodiversity. By understanding the processes governing species communities in these fragmented landscapes we may be better able to manage them in a way that provides conservation benefits. The first part of this thesis focuses on dispersal in complex landscapes with Chapter 2 taking a regional view, examining connectivity across the whole Brazilian Atlantic Forest from a functional perspective and Chapter 3 investigating movement within local landscapes. We found that from the perspective of its fauna the Brazilian Atlantic Forest is functionally fragmented, with few areas remaining that are able to support large populations. At the local scale species exhibited clear threshold responses to changing forest cover with dispersal ability and home range size important determinants. The second part analyses bird diversity patterns across fragmented landscapes. Chapter 4 looks at alpha-diversity and composition, considering different land-uses and habitat types across a fragmentation gradient. Chapter 5 examines beta-diversity within habitats as well as between habitat types and landscapes. Bird community composition was found to differ between land use types as well as between habitats. Plantation forest matrices were able to mitigate isolation and area effects, retaining forest species. Beta-diversity within habitats was found to remain constant, whereas between habitat beta-diversity was high when comparing contrasting habitats. Turnover between habitat types is able to offset decreases in alpha-diversity, contributing to the maintenance of gamma-diversity. At the landscape level dissimilarity patterns were heavily governed by forest cover, suggesting a range of habitat amounts are needed to preserve the full bird community. Overall, although habitat loss and fragmentation are highly detrimental for biodiversity, mitigation via management changes are possible.

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Edgel, Robert John. "Habitat Selection and Response to Disturbance by Pygmy Rabbits in Utah". BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3928.

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The pygmy rabbit (Brachylagus idahoensis) is a sagebrush (Artemisia sp.) obligate that depends on sagebrush habitats for food and cover throughout its life cycle. Invasive species, frequent fires, overgrazing, conversion of land to agriculture, energy development, and many other factors have contributed to recent declines in both quantity and quality of sagebrush-steppe habitats required by pygmy rabbits. Because of the many threats to these habitats and the believed decline of pygmy rabbit populations, there is a need to further understand habitat requirements for this species and how they respond to disturbance. This study evaluated habitat selection by pygmy rabbits in Utah and assessed response of this small lagomorph to construction of a large-scale pipeline (i.e. Ruby pipeline) in Utah. We collected habitat data across Utah at occupied sites (pygmy rabbit occupied burrows) and compared these data to similar measurements at unoccupied sites (random locations within sagebrush habitat where pygmy rabbits were not observed). Variables such as horizontal obscurity, elevation, percent understory composed of sagebrush and other shrubs, and sagebrush decadence best described between occupied (active burrow) and unoccupied (randomly selected) sites. Occupied sites had greater amounts of horizontal obscurity, were located at higher elevations, had greater percentage of understory comprised of sagebrush and shrubs, and had less decadent sagebrush. When considering habitat alterations or management these variables should be considered to enhance and protect existing habitat for pygmy rabbits. The Ruby pipeline was a large-scale pipeline project that required the removal of vegetation and the excavation of soil in a continuous linear path for the length of the pipeline. The area that was disturbed is referred to as the right of way (ROW). From our assessment of pygmy rabbit response to construction of the Ruby pipeline, we found evidence for habitat loss and fragmentation as a result of this disturbance. The size of pygmy rabbit space-use areas and home ranges decreased post construction, rabbits shifted core-use areas away from the ROW, and there were fewer movements of collared rabbits across the ROW. Mitigation efforts should consider any action which may reduce restoration time and facilitate movements of rabbits across disturbed areas.

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Bogstedt, Carl. "How do corridors connecting two separated landscapes affect the ability of trophic metacommunities to survive habitat loss?" Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176548.

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With an increasing worldwide infrastructure more habitats are fragmented by roads and buildings, which can cause a reduction in biodiversity up to 75%. One way to counteract this is by predicting the outcome, with the help of theoretical models, before it happens. In this study I used a Bayesian network model on a fragmented landscape, to test how well trophic metacommunities are able to persist habitat loss, when increasing dispersal between the fragments in the landscapes by implementing corridors. By implementing just three corridors, the species with the highest trophic level went extinct at a considerable later stage, and by just implementing 10 corridors, the metapopulation capacity for all species in all trophic levels increased. Similar results were obtained when changing the way the species extinction probabilities react to their resources being extinct, which further strengthen the efficacy of corridors. The results from this study suggests that increasing connectivity between landscape fragments, and therefore promoting dispersal of organisms, would help the conservation of biodiversity.

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Rielly, Elizabeth Wheeler. "Spatial variation drives patterns of community composition and trophic relationships in a marine system". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/345225.

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Biology
Ph.D.
Examining how ecological processes are influenced by spatial variation can provide valuable insights into how communities are formed and how they may change in dynamic landscapes. In this thesis I address three objectives surrounding the spatial and temporal variation in species’ recruitment and predation, the influence of habitat isolation on consumer-resource relationships, and the influence of habitat fragmentation on a multi-trophic system. I used marine invertebrates, specifically crustaceans, bivalves, and sessile species as a model system. First, I address the spatial and temporal variation in local and regional processes in a multispecies assemblage of marine sessile invertebrates. Using diverse communities of marine sessile invertebrates as a model system I tested the hypothesis that spatial and temporal variation in recruitment and predation would shape local communities, and that both recruitment and predation would have significant effects on the abundance and structure of adult communities. I found that both recruitment and predation vary through time and space leading to the emergence of regional community divergence. I also address how habitat isolation interacts with top-down and bottom-up processes in seagrass ecosystems. Spatial structure of the habitat may mediate top-down and bottom-up controls of species abundances through decreased habitat connectivity and increased habitat isolation. I manipulated top down and bottom up processes by excluding mesograzers, adding resources, or altering both factors in isolated and contiguous patches of artificial seagrass. I then measured epiphyte recruitment, epiphyte abundances, and macroalgae abundance. I paired this with epiphyte sampling from isolated natural seagrass patches. I found that habitat isolation significantly decreased the abundance of epiphytes settling on seagrass blades due to dispersal limitation for epiphytic invertebrates. I found that consumers had strong effects on epiphyte biomass in continuous habitats, but not isolated habitats. Resource additions increased macroalgae cover and epiphyte biomass only in isolated habitats. The results suggest that isolated habitats may be nutrient limited and that top-down effects are stronger in continuous habitats, while bottom-up effects may dominate in isolated habitats. In my third objective, I address how habitat fragmentation may alter marine food webs. I examined whether predation rates, prey, and predator behavior differed between continuous and fragmented seagrass habitat in a multi-trophic context at two sites in Barnegat Bay, NJ. I hypothesized that blue crab predation rates and foraging would decrease in fragmented seascapes, due to a reduction in adult blue crab densities, increasing survival rates of juvenile blue crabs and hard clams. I expected hard clams to exhibit weaker predator avoidance behavior in fragmented habitats because of decreased predation. I found that species’ responses to fragmentation were different based on trophic level. Clams experienced higher predation and burrowed deeper in continuous habitats at both sites. Densities of blue crabs, the primary predator of hard clams, were higher in continuous habitats at both sites. Predation on juvenile blue crabs was significantly higher in fragmented seagrass at one site. Our results suggest that in fragmented seascapes, the impact of fragmentation on higher trophic level predators may drive predation rates and prey responses across the seascape, which may lead to trophic cascades in fragmented habitats.
Temple University--Theses

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Matthews, Thomas James. "Analysing and modelling the impact of habitat fragmentation on species diversity : a macroecological perspective". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1d71c6fe-06eb-4135-bdb3-874bb273bcb1.

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The destruction and fragmentation of natural habitat is the leading driver of the current extinction crisis. As a result, a research area has emerged focused on studying ecology in islands of natural habitat surrounded by a sea of anthropogenic land uses, so called ‘habitat islands’. However, this research has largely been undertaken on small-medium scales, generally in single systems. Furthermore, many habitat island studies have used previous results and theory derived in the context of oceanic island research. Thus, this thesis aims to examine a variety of macroecological and biogeographical patterns using a large number of purely habitat datasets sourced from both the literature and my own sampling, with the objective of teasing out any general statistical patterns. The various macroecological and biogeographical patterns can be grouped under four broad headings: 1) species–area relationships (SAR), 2) nestedness, 3) species abundance distributions (SADs), and 4) species incidence functions (function of area). Overall, it was found that there were few hard macroecological generalities that hold in all cases across habitat island systems. This is because most habitat island systems are highly disturbed environments, with a variety of confounding variables and undesirable species (e.g. species associated with human land uses) acting to modulate the patterns of interest. Nonetheless, some clear patterns did emerge. In particular, it was found that the power model was by the far the best general SAR model for habitat islands. The slope of the island species–area relationship (ISAR) was related to the matrix type surrounding archipelagos, such that habitat island ISARs were shallower than true island ISARs. Significant compositional and functional nestedness was rare in habitat island datasets, although island area was seemingly responsible for what nestedness was observed. Species abundance distribution models were found to provide useful information for conservation in fragmented landscape, but the presence of undesirable species substantially affected the shape of the SAD. Species incidence function curves were found to vary across space for a given species, but not in any systematic manner. In conclusion, this thesis finds that the application of standard island biogeography theory to habitat islands is too simplistic. It is hoped that the results of this thesis will act as a catalyst for a more macroecological approach to habitat island research, and a starting point for the development of an integrated theory of habitat islands.

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Vidal, Mariana Morais. "Risco de extinção e a persistência de redes de interação entre plantas e frugívoros". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-15122014-113558/.

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A dispersão de sementes por vertebrados é um processo ecológico muito importante para a manutenção da biodiversidade, especialmente nas regiões tropicais. Estas interações mutualistas podem ser rompidas devido à caça e a perda e fragmentação de habitats, na medida em que estas ameaças podem levar os parceiros mutualistas à extinção. No presente trabalho, buscamos entender as consequências de possíveis extinções de aves frugívoras sobre a organização de sistemas de dispersão de sementes na floresta Atlântica brasileira. Primeiro, nós caracterizamos o papel que cada uma das espécies desempenha em estruturar as redes de interação de que fazem parte. Em seguida, investigamos possíveis correlatos biológicos deste papel estrutural e vimos que as plantas com sementes pequenas e com períodos de frutificação extensos tendem a ser estruturalmente mais importantes. Por outro lado, características morfológicas (tamanho do bico e massa corpórea) e ecológicas (abundância e grau de frugivoria) não se mostraram relevantes em explicar o papel das aves nas redes de dispersão de sementes. O risco de extinção, no entanto, está associado ao papel estrutural das espécies de aves, de tal modo que aves mais ameaçadas tendem a ser mais importantes para a estrutura das redes. Estes resultados indicam que a perda de espécies ameaçadas pode ter consequências para a organização dos sistemas de dispersão de sementes de que fazem parte. Em um capítulo posterior, buscamos entender como os sistemas de dispersão de sementes responderiam a crescentes perdas de habitat. Com base em dados empíricos, estimamos uma sequência de extinções de aves decorrentes da perda de habitat na floresta Atlântica. Simulamos esta sequência de extinções em redes de dispersão de sementes provenientes de uma área protegida, avaliando os impactos de tais remoções de espécies sobre a organização das interações. Nossos resultados sugerem relativa robustez das redes de dispersão de sementes à remoção de espécies decorrente da perda de habitat. Por outro lado, a estrutura das redes parece colapsar quando a porcentagem de habitat é reduzida a menos de 30% da paisagem. É possível que um limiar de riqueza de espécies gere também um limiar na resposta da estrutura das redes à perda de habitat. Por fim, em um capítulo de perspectivas sobre os impactos da defaunação, avaliamos a importância de grandes vertebrados frugívoros como dispersores de sementes. Sugerimos que a inclusão de aspectos da história natural dos grandes frugívoros na abordagem de redes complexas pode trazer novas contribuições e permitir avanços nos estudos que investigam como esses dispersores podem influenciar a dinâmica das comunidades de plantas. Considerando o conjunto de resultados apresentados nesta tese, ilustramos como a abordagem de redes pode ser útil ao se estudar sistemas com muitos elementos, como é o caso da dispersão de sementes. Contribuímos para um melhor entendimento dos aspectos da biologia das espécies que influenciam a posição que ocupam dentro das redes de dispersão de sementes. Ademais, procuramos combinar princípios da ecologia de paisagens e análises de redes complexas para entender as consequências da perda de habitat sobre a organização de sistemas de dispersão de sementes
Seed dispersal by vertebrates is a key ecological process for biodiversity maintenance, particularly in tropical regions. These mutualistic interactions can be disrupted due to hunting and habitat loss and fragmentation, threats that may lead mutualistic partners to extinction. In the present work, we seek to understand the consequences of possible extinctions of frugivorous birds on the organization of seed dispersal systems in the Brazilian Atlantic forest. First, we described the role each species plays in structuring the interaction networks they are part of. Then, we investigated potential biological correlates of these structural roles and we found that plants with small seeds and long fruiting periods tend to be more important to network structure. On the other hand, morphological traits (bill size and body mass) and ecological traits (abundance and degree of frugivory) were not relevant to explain the role bird species play in seed dispersal networks. Extinction risk, however, is associated with the structural role of bird species, so that higher-risk species tend to me more important for network structure. Our results suggest that the loss of higher-risk bird species may affect the organization of seed dispersal systems. In a later chapter, we seek to understand how seed dispersal systems would respond to increasing habitat loss. Based on empirical data, we estimated a sequence of bird species extinctions following habitat loss in the Atlantic forest. We simulated that sequence of extinctions in seed dispersal networks from a protected area, evaluating the impacts of such species deletions on the organization of interactions. Our results point out relative robustness of seed dispersal networks to removal of species due to habitat loss. On the other hand, the structure of the networks seems to collapse when the percentage of habitat cover shrinks to less than 30% of the landscape. It is possible that a threshold in species richness creates a threshold in network structure response to habitat loss. Finally, in a chapter of perspectives on the impacts of defaunation, we evaluated the importance of large frugivorous vertebrates as seed dispersers. We suggest that the inclusion of aspects of the natural history of large frugivores in complex networks may allow new insights and advances in studies investigating how these seed dispersers can influence the dynamics of plant communities. Considering the overall results presented in this work, we illustrate how the network approach can be useful when studying systems with many components, such as seed dispersal. We contribute to a better understanding of the biological aspects that affect the position species occupy within seed dispersal networks. Furthermore, we combined principles from landscape ecology and analysis of complex networks to understand the consequences of habitat loss on the organization of seed dispersal systems

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Leite, Cristina Camargo Banks. "Conservação da comunidade de aves de sub-bosque em paisagens fragmentadas da Floresta Atlântica". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-23092009-103114/.

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Florestas tropicais comportam dois terços de todas as espécies existentes no mundo, mas a perda de habitat, fragmentação e alteração na qualidade do habitat estão levando esta biodiversidade à extinção. Apesar de haver uma extensa literatura sobre este assunto, há um consenso geral de que o conhecimento gerado por muitos estudos é dependente do contexto e permeado por dificuldades metodológicas, como a alta correlação entre os fenômenos ocorrentes em paisagens alteradas pela ação humana e a miríade de respostas biológicas encontradas entre espécies. Desta forma, há ainda muita incerteza sobre a generalidade dos padrões observados e sua efetiva aplicação para a conservação de áreas naturais. Assim, nesta tese o objetivo foi de contribuir para esta discussão ao responder as seguintes perguntas: (i) Qual papel que bordas ecossistêmicas e efeitos de borda desenvolvem em comunidades naturais? (ii) A comunidade de aves é afetada pela fragmentação do habitat de maneira semelhante em matas primárias e secundárias? (iii) Seriam os efeitos de área e de borda análogos, e estariam estes associados em uma relação causal? (iv) Como a comunidade de aves se comporta com relação à variação na cobertura florestal, configuração do fragmento e qualidade do habitat, e será possível separar o efeito de cada variável? (v) Diferenças no protocolo amostral poderiam alterar as estimativas de atributos da comunidade e mudar a magnitude dos padrões ecológicos observados assim como a probabilidade de detectá-los? E (vi) qual estratégia é mais eficiente em identificar locais com alta integridade da comunidade, espécies indicadoras ou métricas indicadoras, como métricas da paisagem? Para responder estas perguntas foram usados dados provenientes de mais de 7000 aves capturadas com redes de neblina em 65 pontos amostrais localizados em seis paisagens de diferentes proporções de cobertura florestal e graus de perturbação na Mata Atlântica do Planalto Atlântico Paulista. Os resultados mostram que: (i) bordas estão presentes tanto em habitats naturais quanto alterados pela ação humana e produzem grandes efeitos sobre espécie e comunidades; (ii) apesar de matas secundárias possuírem uma comunidade de aves empobrecida, a forma como as aves são afetadas pela fragmentação nestes habitats é semelhante a matas primárias; (iii) efeitos de borda não são apenas análogos, mas podem ser a causa dos efeitos de área de fragmento; (iv) os efeitos de mudanças na cobertura florestal, configuração do fragmento e qualidade do habitat são altamente correlacionados e só podem ser separados com o uso de técnicas estatísticas que controlem explicitamente esta correlação; (v) a forma como o protocolo de amostragem é estruturado temporalmente afeta os padrões encontrados da relação espécie-área em paisagens fragmentadas; e por fim, (vi) métricas indicadoras, produzem resultados mais fortes e consistentes do que espécies indicadoras na identificação de áreas com alta integridade da comunidade. Assim, conclui-se que as aves de sub-bosque na Mata Atlântica são fortemente afetadas pela perda de habitat, fragmentação e mudanças na qualidade do habitat, mas esta influência é muito dependente do contexto temporal e espacial em que o estudo é realizado. Ainda, devido à baixa consistência dos resultados obtidos com amostras de curta duração, aliado ao grande poder explicativo dos modelos contendo métricas da paisagem, métricas indicadoras devem ser consideradas como a melhor estratégia para a identificação de áreas com alta integridade da comunidade.
Tropical forests hold two thirds of all species in the world, but alterations in habitat cover, fragmentation and quality are driving tropical biodiversity to the brink of extinction. Despite the extended literature on this subject, there is a general agreement that the knowledge gained from many of these studies are context-specific and pervaded by methodological difficulties, such as high inter-correlations among many phenomena in human-altered landscapes and diverse biological responses to landscape change that depend on species traits. Because of these issues, there is great uncertainty about the generality of observed patterns and the effective application of results in the conservation of natural areas. Thus, in this thesis the aim was to bring light to some of these concerns by answering the following questions: (i) What is the role of ecosystem boundaries and edge effects on natural communities? (ii) Do bird communities show similar patterns of responses to habitat fragmentation in secondary forests as those previously reported for primary forest? (iii) Are edge and area effects on bird species functionally similar and even causally associated? (iv) How does a tropical understory bird community respond to the highly inter-correlated variation in forest cover, patch configuration and habitat quality; and is it possible to set these influences apart? (v) Could differences in sampling protocol alter community estimates or change the magnitude of ecological trends and the probability of detecting them? And (vi), which strategy is more efficient in identifying sites with the highest community integrity, indicator species or structural indicators, such as landscape metrics? To address these questions I used data from more than 7000 birds captured using mist nets in 65 sites from six landscapes with different proportions of forest cover and habitat degradation in the Atlantic Forest of Brazil. The results showed that: (i) edges are ubiquitous features of natural and human-altered landscapes and strongly influence most species; (ii) even though the bird community in secondary forests is degraded relative to primary communities, birds from these areas show similar responses to edge and area effects found for primary forests; (iii) edge effects are not only functionally similar, but might also be the main drivers of area effects in fragmented landscapes; (iv) the effects of changes in forest cover, patch configuration and habitat quality are highly confounded and without the use of analyses that explicitly model this correlation it is impossible to pull apart the relative influence of each variable; (v) the way the sampling protocol is designed temporally affects the perceived patterns of how species respond to area effects; and finally, (vi) structural indicators generate stronger and more consistent results than indicator species in predicting changes in community integrity. In conclusion, the results show that understorey birds are highly affected by changes in habitat cover, fragmentation and habitat quality in the Atlantic forest, but this influence is strongly dependent on the temporal and spatial context of the study. Also, because of the low consistency of results obtained from short-surveys, and the large explanatory power of models containing landscape metrics, structural indicators should be viewed as the best strategy for identifying sites with high community integrity.

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Alves, Rafael Souza Cruz. "Efeito da quantidade de floresta na predação de sementes e frugivoria em diferentes tipos de ambientes /". Rio Claro, 2020. http://hdl.handle.net/11449/192129.

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Orientador: Milton Cezar Ribeiro
Resumo: Alterações antrópicas no nível de paisagens afetam de maneiras distintas os diversos grupos de animais e plantas. Tais alterações afetam a composição de espécies e estrutura de comunidades de mamíferos e aves, resultando na perda de funções ecológicas essenciais para a manutenção das florestas. Dentre os processos que podem ser mais afetados inclui-se a frugivoria e a predação de sementes. Desta forma, avançar os conhecimentos de como a paisagem e os tipos de ambientes influenciam tais processos é essencial para a proposição de estratégias que beneficiem a conservação da biodiversidade e manutenção de processos ecológicos. Este estudo tem por objetivo responder qual a contribuição relativa da proporção de vegetação florestal, do tipo de ambiente e sua interação sobre a predação de sementes e frugivoria. Estudamos quatro tipos de ambientes: interior de floresta continua, fragmento florestal, borda de floresta e corredor florestal. O estudo foi realizado em uma região de ecótono entre os biomas Amazônia e Cerrado no estado de Mato Grosso, Brasil. Nessa região foram selecionadas 17 paisagens, representando um gradiente de quantidade de floresta de 10% a 86% em um raio de 3 km. Nessas paisagens avaliamos a frugivoria utilizando frutos artificiais e a predação de sementes utilizando sementes de amendoim e girassóis. Nossos resultados sugerem que a frugivoria por aves foi positivamente relacionada a proporção florestal para aves de médio e grande porte, bem como para a frugivoria t... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Human changes at the landscape level affect different groups of animals and plants in different ways. Such changes affect species composition and mammal and bird community structure, resulting in the loss of essential ecological functions for forest maintenance. Among the most affected processes are the frugivory and seed predation. Thus, advancing the knowledge of how the landscape and environment types influence such processes is essential for proposing strategies that benefit the conservation of biodiversity and the maintenance of ecological processes. This study aims to assess the relative contribution of forest vegetation proportion, environment type and their interaction on seed predation and frugivory. We studied four environment types: continuous forest interior, forest fragment, forest edge and forest corridor. The study was carried out in an ecotone region between Amazon and Cerrado biomes in Mato Grosso state, Brazil. In this region, 17 landscapes were selected ranging from 10% to 86% of forest cover in a radius of 3 km. In each landscape we evaluated frugivory using artificial fruits and seed predation using peanut and sunflower seeds. Our results suggest that frugivory by birds was positively related to forest proportion for medium and large birds, as well as to total frugivory by birds, however the magnitude of the effect varied according to the group of birds. Frugivory by small mammals, on the other hand, showed a negative relationship with forest proportion, ... (Complete abstract click electronic access below)
Mestre

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Tang, Wai-wah. "A review of habitat loss and coastal development of Hong Kong with special reference to Lantau Island". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B4378432x.

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Feswick, April Amanda Melissa. "Conserving biodiversity in agriculture-dominated landscapes: Loss of natural habitat drives lepidopteran declines at multiple spatial scales". Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27132.

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The expansion of agriculture throughout the world has precipitated serious biodiversity losses. Countries with relatively extensive natural habitats, such as Canada, continue to intensify agricultural land uses, threatening to expand the scope of the present mass extinction. This thesis tests likely mechanisms of butterfly species decline in agricultural landscapes of varying intensities in the most biologically diverse region of Canada. I measured site variables such as the richness of plants suitable for larval development, patch area and shape index, and landscape variables such as heterogeneity and land-cover within buffers that varied in size from 100m to 1000m. Several rare species were not present in the agricultural sites, whereas a few species typically associated with disturbed habitat were present and abundant among most study sites. I found that agricultural intensification acts across landscapes to reduce butterfly species richness by reducing the proportion of natural habitat available. This effect was especially pronounced at 100m to 200m distances, suggesting a threshold effect beyond which the proportion of natural land is less critical to butterfly biodiversity. Within-site factors, such as plant species richness and habitat area were not affected by agricultural intensity, nor did they affect butterfly species richness and abundance. These results suggest that the mechanism linking butterfly species decline to agriculture, at least for butterflies in this region, is the loss of small habitat remnants.

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Tang, Wai-wah, i 鄧偉華. "A review of habitat loss and coastal development of Hong Kong with special reference to Lantau Island". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B4378432X.

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Xie, Yujing, i 谢玉静. "Habitat loss and fragmentation under urbanization: the spatio-temporal dynamics of causes, processes andconsequences at landscape level". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50662302.

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Landscape modification, especially those human-dominated changes, has been widely considered as one of the key drivers inducing the degradation of environment and ecosystem. The consequent habitat loss and fragmentation, which are closely related to ecological process, have attracted much scholarly attention. However, very few studies have systematically examined their causes and consequences at the landscape level. Integrating human activities into consideration in a holistic way remains poorly understood in particular. This thesis reports a systematic study of habitat loss and fragmentation under urbanization. This research distinguishes itself from previous works in its investigation of the spatio-temporal dynamics of causes and consequences of habitat loss and fragmentation, and its endeavor to disentangle habitat fragmentation from simple habitat loss in terms of their processes and effects. The Shenzhen River cross-border watershed, shared by Hong Kong Special Administrative Region and Shenzhen, is used as a case to illustrate how these ideas can work in practice. The study period spans from 1988 to 2008.The main contents of the study include analysis of the processes and causes of habitat loss and fragmentation, and dynamic consequences on water quality and ecosystem services for biodiversity conservation at spatial and temporal scales. Various methods are employed, mainly including conventional and newly developed landscape metrics (such as the Urbanization Isolation Effect (UIE) and Habitat Isolation Degree (HID)), a spatial statistical approach based on the Geographically Weighted Regression (GWR) model, spatio-temporal analyses and cross-border comparison. Major findings of the research are highlighted as follows. First, habitat loss and fragmentation show great spatial heterogeneity as well as temporal variation due to extensive and rapid urban sprawl in the study area. Second, by adopting the GWR model, it is found that human-related factors have played a significant role in determining not only the “amount” but also the “location” of habitat loss. Third, by using two new landscape metrics, namely the UIE and HID, both the extent (urban sprawl) and intensity (population density) of urbanization are suggested to have significant influences in habitat isolation. Fourth, water quality in the watershed is recognized to be closely correlated with habitat loss and fragmentation, and the correlations show major discrepancies between the Hong Kong and the Shenzhen sides. Moreover, by proposing a compound indicator (NP/MPS) for measuring habitat fragmentation (independent of simple habitat loss), it is found that habitat loss has exerted a bigger influence on water quality degradation than habitat fragmentation. Fifth, by integrating habitat connectivity into the evaluation of ecosystem services for biodiversity conservation, both the habitat size and connectivity are recognized to be important in explaining the degradation of ecosystem services value. Habitat size has played a dominant role in the overall change of ecosystem services value, whereas the role of connectivity (fragmentation) is more critical when the “stepping stones” sites are lost. The study provides a new framework to examine the habitat loss and fragmentation under urbanization at the landscape level. The efforts show great effectiveness in providing sound and useful information for future landscape planning, biodiversity conservation and watershed management.
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Geography
Doctoral
Doctor of Philosophy

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McWilliams, Chris. "Habitat loss and species interactions : an in silico investigation of the structure and dynamics of ecological communities". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701387.

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De, Camargo Rafael Xavier. "Ecological Responses of Avian Species to Land Cover Metrics at the Landscape-Level and Across Broad Spatial Extent". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37113.

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Human activities have transformed natural landscapes into human-dominated areas at unprecedented rates in the last centuries. Land cover transformation is associated with loss of natural habitat, thus a threat to biodiversity. Because habitat loss will likely continue in the future due to population growth and increase demand for natural resources, an important question in ecological studies is whether land cover features (i.e. amount, variety, shape, configuration) can be used as predictors to estimate species loss from habitat modification. This thesis investigates the predictive ability of landscape features in predicting species distributions at the landscape level and across large regions. It tests several predictions from classic hypotheses such as the species-area relationship and habitat fragmentation, utilizing a macroecological approach. Response variables (e.g. species richness, species’ probability of occurrence) and independent variables (e.g. proportion of natural areas, metrics of fragmentation, temperature, etc.) are analysed in cell sizes of 25-900km2 covering large regions (e.g. southern Ontario, New York State). Bird species were chosen as the main biological model. Most literature assumes that species richness should vary positively as a function of remaining natural area, following the well-known species–area relationship (i.e. classic SAR). Prior studies have shown that avian species richness has a peaked, rather than a monotonic increasing, relationship with the proportion of natural land cover in landscapes of southern Ontario. The first chapter of the thesis showed improvements in the predictive power of classic SARs by proposing the “Lost-habitat SAR”, which demonstrates that richness of open-habitat species can be predicted when we partition human-dominated land cover into an ‘‘available human-dominated’’ component and ‘‘lost’’ habitat (i.e. parts of the landscape that can no longer be utilized by any species). The second chapter addresses a current contention in the literature about the effect of habitat fragmentation beyond habitat amount at the landscape level. Specifically, I tested the effect of fragmentation (e.g. number of patches) on both avian richness and the probability of occurrence (pocc) of individual species, after controlling for habitat amount in 991 landscapes, each 100-km2, in southern Ontario. The analysis showed that overall species richness responds primarily to habitat amount, and that the effect of habitat fragmentation, holding the total amount of habitat constant, is negligible. The probability of occurrence of a few bird species did relate negatively to the size, number and isolation of the patches within the landscape. We argue that the evidence is inconsistent with the hypothesis that reducing habitat fragmentation would be an effective conservation strategy for birds at the landscape level. Chapter 3 tested the speculation in the climate change literature that habitat loss may impede the colonization or movement of species whose ranges are shifting northwards in response to climate. Using the same 100-km2 landscapes of southern Ontario, I examined individual bird species’ probability of occupancy as a function of the amount of remaining natural land cover for three groups of species: i) those whose northern range limit falls within the study area, ii) those whose southern range limit is in the study area, and iii) those whose ranges cover the entire study area. The results showed that the probability of occupancy of southern-edge species is a positive function of the amount of natural land cover (forest) in the landscape, while the probability of occupancy of northern-edge species is a negative function of natural land cover. Hence, I conclude that at southern range limits species faces the dual stresses of climatic warming and habitat conversion. Whereas, at northern (potentially expanding) range edges, partially disturbed landscapes are more readily occupied than undisturbed landscapes. In the final chapter, I challenge widely accepted hypothesis that habitat loss causes biodiversity loss by testing whether conserving natural land cover would conserve species diversity. More specifically, I tested whether broad-extent relationships between avian species richness and natural land cover are independent of: 1) whether species distribution data come from systematic censuses (atlases) versus range maps, and 2) the grain size of the analysis in grid cells covering southern Ontario, CA, and New York State, US. My findings showed that over regional extents, range-map-based richness relates strongly to temperature, irrespective of spatial grain, and that censused species richness relates to temperature less strongly. Moreover, range-map richness is a negative function of the proportion of natural land cover, while realized richness is a peaked function. Therefore, I conclude that conserving natural land cover would not conserve species diversity in southern Ontario or in New York State, since greater natural cover does not imply higher richness. We argue that habitat loss has become a panchreston. It may be misguiding conservation biology strategies by focusing on a threat that is too general to be usefully predictive.

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Vatka, E. (Emma). "Boreal populations facing climatic and habitat changes". Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203607.

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Abstract Anthropogenic climate change and habitat loss and deterioration affect populations worldwide. Climate warming has changed phenologies of many species across trophic levels. Some predator populations now experience temporal mismatches with their prey, as timings of peak prey abundance and of the predator’s highest food demands no longer meet. The temporal mismatch hypothesis suggests that the population’s recruitment rate is related to its degree of synchrony with the food resources needed to feed offspring. However, species’ and populations’ responses to climate warming differ. Human land use alters and destroys habitats of countless species. For example, many boreal forest bird populations have declined, presumably due to intensive forestry. It has decreased the amount of dead wood, causing a threat to saproxylic species. Identification of the key characteristics of high-quality habitats is essential for conservation planning and for developing sustainable forestry. As individuals are suspected to settle in habitats that maximize their fitness, analysis of nest site selection can be used to identify the key habitats. My dissertation concerns the impacts of climate change and habitat deterioration on boreal populations. I use hole-nesting passerines as model species. By utilizing long-term data I show that breeding phenologies of Parus major and Poecile montanus, but not of Cyanistes caeruleus, have shifted earlier. Also, the timing of the food peak has advanced, improving the synchrony between P. montanus and caterpillars. In P. major and C. caeruleus, synchrony has remained good. However, the positive effect of good synchrony on breeding success seems to be conditional, arising only in certain circumstances, such as in years of high caterpillar abundance. I suggest that in boreal populations temperature affects timing of breeding mostly as a proximate factor. The availability of standing decaying trees used for nesting sites was the most important habitat characteristic determining the nest site selection of P. montanus. Remote sensing data alone was insufficient to produce reliable models, as the ecologically important small-scale factor can only be determined by direct field surveys. Omission of forest thinning in selected forest sites would ensure the continuous availability of decaying wood with positive influence on biodiversity in managed forests
Tiivistelmä Ihmisen aiheuttama habitaattien katoaminen ja huononeminen sekä ilmastonmuutos vaikuttavat populaatioihin kaikkialla maailmassa. Ilmaston lämpeneminen on muuttanut monien lajien fenologioita eri trofiatasoilla. Osalla saalistajalajien populaatioista suurin ravinnontarve ei enää ajoitu samaan aikaan saaliin runsaushuipun kanssa. Ajoituksen eriaikaisuus -hypoteesin mukaan todennäköisyys populaatioon rekrytoitumiselle riippuu synkronian asteesta saaliin kanssa. Ilmaston lämpenemisen vaikutuksissa lajeihin ja populaatioihin on kuitenkin vaihtelua. Ihmisen maankäyttö muuttaa ja tuhoaa lukuisien lajien elinympäristöjä. Esimerkiksi useiden boreaalisten metsien lintupopulaatioiden pienentymistä on selitetty intensiivisellä metsätaloudella. Lahopuun määrä metsissä on vähentynyt, mikä on uhka lahopuusta riippuvaisille lajeille. Korkealaatuisten habitaattien keskeisten piirteiden tunnistaminen on tärkeää luonnonsuojelun ja kestävän metsätalouden suunnittelulle. Koska yksilöiden oletetaan valitsevan niiden kelpoisuutta maksimoivia elinympäristöjä, pesäpaikanvalinta-analyysiä voidaan käyttää tärkeiden habitaattipiirteiden tunnistamiseen. Tarkastelen väitöskirjassani ilmastonmuutoksen ja habitaattien laadun vaikutuksia boreaalisiin populaatioihin. Mallilajeina käytän koloissa pesiviä varpuslintuja. Hyödyntämällä pitkäaikaisaineistoja osoitan, että lisääntymisen ajoittuminen on aikaistunut tali- ja hömötiaisella, mutta ei sinitiaisella. Myös ravintohuippu on aikaistunut, mikä on parantanut synkroniaa hömötiaisen ja sen pääasiallisen ravinnon eli toukkien välillä. Tali- ja sinitiaisella synkronia on pysynyt hyvänä. Hyvän synkronian myönteinen vaikutus lisääntymismenestykseen vaikuttaa kuitenkin ehdolliselta: se tulee esiin vain tietyissä olosuhteissa, kuten vuosina jolloin toukkia on runsaasti. Kevään lämpötilat näyttävät vaikuttavan pesinnän ajoittumiseen erityisesti proksimaattisena tekijänä. Pesäpaikkoina toimivien seisovien lahopuiden määrä on tärkein hömötiaisen pesäpaikanvalintaa määräävä tekijä. Kaukokartoitusaineisto yksinään ei riitä luotettavien mallien tuottamiseen, sillä ekologisesti tärkeät pienen skaalan tekijät voidaan kartoittaa vain suorin maastomittauksin. Metsien harventamatta jättäminen valituilla laikuilla turvaisi lahopuun jatkuvan saatavuuden, mikä vaikuttaisi myönteisesti talousmetsien biodiversiteettiin

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Zanirato, Gisele Lamberti [UNESP]. "A influência da perda e da fragmentação do habitat sobre a ocupação e o padrão de atividade do tamanduá-bandeira (Myrmecophaga tridactyla)". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151071.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Com a expansão dos centros urbanos e das atividades agrícolas, as áreas do bioma Cerrado no estado de São Paulo vêm sendo transformadas em paisagens altamente fragmentadas constituídas em grande parte por fragmentos pequenos. A perda e a fragmentação do habitat tem sido um dos principais fatores responsáveis pelo declínio populacional e pela extinção local de espécies com baixa densidade populacional, baixa taxa de reprodução, alta demanda por espaço e especialista alimentar, como o tamanduá-bandeira (Myrmecophaga tridactyla). É conhecido que algumas espécies de mamíferos modificam seus padrões de atividade frente às perturbações antrópicas e até em relação aos efeitos da perda de habitat. Diante disso, os objetivos deste estudo foram avaliar se a área e o isolamento do fragmento, a porcentagem de vegetação nativa e a disponibilidade hídrica da paisagem são importantes para explicar a ocupação dos fragmentos pelo tamanduá-bandeira, e verificar se há diferenças no padrão de atividade entre as populações de tamanduás que ocupam os fragmentos menores (< 2.015 ha) e a população que ocupa o fragmento maior (10.285 ha). Os dados de presença e ausência dos tamanduás-bandeira em cada um dos vinte fragmentos de vegetação nativa localizados no nordeste do estado de São Paulo foram coletados através de armadilhas fotográficas. A influência da temperatura e da pluviosidade na probabilidade de detecção dos tamanduás e a importância das variáveis de fragmento e de paisagem na probabilidade de ocupação dos fragmentos pela espécie foram avaliadas através de modelos de ocupação de estação única. O Critério de Informação de Akaike corrigido (AICc) foi utilizado para a seleção dos melhores modelos e o teste de Mardia Watson Wheeler foi usado para verificar possíveis diferenças no padrão de atividade entre as populações que ocupam os fragmentos menores e a população presente no fragmento maior. O padrão de atividade dos tamanduás não foi influenciado pela área do fragmento, no entanto, a probabilidade de ocupação dos fragmentos pela espécie foi maior nos fragmentos com áreas maiores e em fragmentos com maior porcentagem de vegetação nativa ao redor. Portanto, a conservação de fragmentos maiores e de fragmentos com maior porcentagem de vegetação nativa ao redor é de grande importância para a conservação de tamanduás-bandeira no nordeste do estado de São Paulo.
With the expansion of urban areas and agricultural activities, the Cerrado’s areas in São Paulo state have been transformed in highly fragmented landscapes consisting largely of small fragments. Habitat loss and fragmentation have been one of the main factors responsible for population decline and local extinction of species with low population density, low reproduction rate, high spatial demand and diet specialist, such as the giant anteater (Myrmecophaga tridactyla). It is known that some species of mammals modify their activity patterns in face of anthropic disturbances and even in relation to the habitat loss effects. On this, the aims of this study were to evaluate if the patch’s area and the isolation, the native vegetation percentage and water availability in the landscape are important to explain the patches occupancy by the giant anteater, and verify if there are differences in the activity pattern between the anteaters populations that inhabit the smaller patches (<2,015 ha) and the population that occupies the larger patch (10,285 ha). The presence and absence data of the giant anteaters in each one of the twenty patches of native vegetation located in the northeast of the São Paulo state were collected through camera traps. The temperature and rainfall influence on the detection probability of the anteaters and the importance of the patch and landscape variables on the occupancy probability of the patches by the species were evaluated through single-season occupancy models.The corrected Akaike Information Criterion (AICc) was used to select the best models and the Mardia Watson Wheeler test was used to verify possible differences in the activity pattern between the populations that inhabit the smaller patches and the population present in the larger patch. The activity pattern of the anteaters was not influenced by the patch’s area, however, the occupancy probability of the patches by the species was higher in the larger patches and in patches with higher native vegetation percentage around. Therefore, the conservation of larger patches and of the patches with higher native vegetation percentage around them is of great importance for the anteater conservation in the northeast of the São Paulo state.

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Poor, Erin Elizabeth. "A multiscale analysis and quantification of human impacts on Sumatran tiger (Panthera tigris sumatrae) habitat in Riau, Sumatra". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85130.

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Worldwide, we are losing biodiversity at unprecedented rates, and due to deforestation, degradation and poaching, Southeast Asian wildlife is facing extreme threats. Indonesia recently eclipsed Brazil in having the world's highest deforestation rate, largely due to the rise of the palm oil industry. Indonesia contains multiple biodiversity hotspots and endangered species such as the Sumatran tiger (Panthera tigris sumatrae). While Riau Province, Sumatra, produces approximately 20% of the world's palm oil, tigers still inhabit parts of Riau, though their habitat and prey are understudied. Thus, in this research, I aim to assess and quantify how tiger habitat has changed, how it will continue to change, and provide recommendations on how to improve the landscape for tigers. I create the first accuracy-assessed land cover maps of Riau, and then predict land cover change from 2016 – 2050. Using this newly created land cover map, I assess whether Tesso Nilo National Park, Bukit Tigapuluh National Park, and Rimbang Baling Wildlife Reserve are effective at preventing deforestation. Next, I examine human impacts within Tesso Nilo specifically, due to its suitability for oil palm and its potential as a stepping stone for wildlife movement from the western, mountains to the eastern peatlands of Sumatra. Finally, I examine impacts of human presence within Rimbang Baling on felid-prey relationships. I predict that by 2050, over 60% of natural forest in Riau will be lost, and all protected areas only confer low levels of protection. I determined that Tesso Nilo National Park has nearly 2500 km of roads within it and no areas within the park are untouched by humans. Wildlife detections were low near the boundary of Rimbang Baling and there was evidence of humans negatively impacting mousedeer (Tragulus spp) behavior. I suggest focusing on securing the habitat within Rimbang Baling and Bukit Tigapuluh to ensure habitat for dispersing tigers from the western mountains, in addition to, and perhaps before focusing on restoring Tesso Nilo and creating wildlife corridors. While tiger recovery in Riau will be difficult, with education, dedication, persistence and intelligent planning, tigers may be able to persist in this unique ecosystem in the long-term.
Ph. D.

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Donaldson, Lynda. "Conservation and ecology of wetland birds in Africa". Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31812.

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Conservation managers worldwide are increasingly faced with the challenges of managing and protecting fragmented landscapes, largely as a consequence of human activities. Over recent decades, ecological theory has made a significant contribution to the development of landscape-scale conservation and practice. However, recommendations accounting for what is practically achievable in the modern-day landscape are currently lacking, while criteria for conservation planning and prioritisation continue to neglect the role of habitat networks at the required spatial scale for the long-term persistence of biodiversity. In this thesis, I test and apply ideas surrounding the complexities of managing and conserving species in a landscape context, using a suite of bird species endemic to papyrus (Cyperus papyrus) swamps in East and Central Africa as a model system. In the face of large-scale habitat loss and degradation, practical measures that account for the fragmented nature of this system, the needs of multiple specialist species, and the reliance on this habitat by local people, are urgently required. I first review the concepts originating from reserve design theory to provide a decision-making framework for those involved in landscape-scale conservation amid 21st century challenges to biodiversity, highlighting the key principles to be considered for informed choices to be made. Second, I show that the needs of local people can be compatible with conservation planning in the tropics, and may play an important part in maintaining habitat quality for species residing in historically disturbed landscapes. Third, I develop a novel framework to make an explicit link between metapopulation dynamics and conservation planning. Despite differences in the patch-level dynamics of individual species, areas of habitat where populations of multiple species are resistant to extinction, and resilient because of high chances of (re)colonization can be identified, highlighting where resources could be invested to ensure species have the capacity to respond to future change. Finally, I simulate the metapopulation dynamics of the papyrus-endemic birds to demonstrate that the optimal conservation strategy for the long-term persistence of all species residing in a network depends on the characteristics of individual species, and the total area that can be protected. Overall, this thesis develops and tests the ecological theory used in spatial conservation planning, emphasising the importance of habitat disturbance and interspecific ecological differences for the effective management of habitat networks. The results increase the evidence base for the conservation of wetland birds in Africa, as well as for species residing in fragmented landscapes more generally.

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Lawson, Laté Ayao. "Essays on economic growth energy use and biodiversity loss". Electronic Thesis or Diss., Strasbourg, 2019. http://www.theses.fr/2019STRAB011.

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L'impact de l'activité économique et de l'augmentation de la population sur l'environnement soulève de profondes questions sur l'avenir des sociétés humaines et des ressources environnementales. En ceci, les "Limites de la Croissance" ("Limits to Growth", Meadows, Meadows, Behrens et Randers, 1974) mettent en garde les sociétés humaines contre la possibilité d'un effondrement social si les tendances actuelles d'exploitation de ressources naturelles et de dégradation de l'environnement suivent leur court. La richesse de la nature étant primordiale à la richesse des nations, cette thèse en sciences économiques au travers de quatre contributions théoriques et empiriques traite de la possibilité d'une cohabitation pacifique des sociétés humaines avec la nature et discute des politiques de conservation de la nature. Nos résultats théoriques et empiriques montrent d'une part que l'expansion de l'habitat humain se fait au détriment des autres espèces biologiques (animales et végétales). D'autre part, nous montrons que les efforts actuels de conservation des espèces biologiques sont fortement orientés vers des forets dont la richesse en biodiversité s'avère douteuse. Finalement, nous montrons qu'une utilisation de plus en plus croissante des énergies primaires, donc à forts impacts écologiques, est encore à attendre des pays en développement. En termes de politiques environnementales, nos travaux appellent davantage à la réduction de l'empreinte écologique des sociétés humaines. Ceci inclut : Une exploitation favorisant la régénération des forêts et non la réduction des aires déjà couvertes ; L'élargissement des aires protégées surtout dans les pays en développement ; Une incitation des individus à orienter les préférences vers la demande de biens à faibles empreintes écologiques
The impact of economic activities and increasing population on the environment raise profound interrogations towards the future of human societies and environmental resources. In this, the "Limits to Growth" (Meadows, Meadows, Behrens and Randers, 1974) warn human societies about the possibility of social collapse if current trends of exploitation of natural resources and environmental degradation remain unchanged. The wealth of nature being essential to the wealth of nations, this thesis in economics through four theoretical and empirical contributions addresses the possibility of a peaceful cohabitation between human and nature and discusses conservation policies of nature. Our theoretical and empirical results show on the one hand that human habitat is being expanded to the detriment of other biological species (animal and plant). On the other hand, we show that current efforts to conserve biological species are strongly oriented towards forests whose richness in biodiversity is doubtful. Finally, we show that an increasingly growing consumption of primary energies, therefore with strong ecological impacts, is still to be expected from developing countries. In terms of environmental policies, our work advocates for a reduction of the ecological footprint of human societies. This includes policies promoting forest regeneration and not the reduction of covered areas, expansion of protected areas, especially in developing countries and incentives for individuals to orient preferences towards the demand for goods with low ecological impacts

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Mulligan, Margaret R. "POPULATION LOSS OF GOLDENSEAL, HYDRASTIS CANADENSIS L., (RANUNCULACEAE), IN OHIO". Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1066347702.

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Castor, Kathleen B. "Regulatory Methodology and Unmitigated Wetland Loss in Southwest Florida". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7272.

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This research used Geographical Information System (GIS) data to estimate the acreage of wetland loss due to small-scale activities (taking into account exempt, permitted, and unauthorized activities) in the Southwest District of the Department of Environmental Protection (DEP) between 2006 and 2011 and compared that net loss with the unmitigated wetland net loss that DEP documented during that time for authorized activities and violations that were discovered. The comparison allowed an estimation of the extent of undocumented small-scale unmitigated wetland loss that occurred during those six years. DEP records show that 88% of non-compliance cases remain unresolved, and the net loss of wetlands that was documented by DEP is 28.66 acres. The change in acreage of DEP-regulated wetlands (and wetlands on agricultural parcels) as determined by GIS analysis is 1,250 acres gained. However, evidence shows that some of the water features categorized as wetlands in the GIS interface are reservoirs which may not be providing the functions necessary to mitigate for wetland loss. Evidence also shows that many small-scale wetland alterations were not detected by remote sensing, indicating that there is a great level of uncertainty in the GIS interpretation. Consequently, achievement of the No Net Loss goal in Florida cannot be determined using documented alterations, nor can it be determined by use of medium-high resolution aerial imagery. The analysis can be extrapolated to the rest of Florida, where State wetland protection regulations are constant.

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Wilber, Samantha. "North American River Otter (Lontra canadensis) Presence and Habitat Analysis in Florida as Compared to Historical Data". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6052.

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North American river otters are considered common in the state of Florida, but their populations have not been studied since the 1980’s. Since that time, Florida’s human population has more than doubled, and many natural areas of Florida have been developed. The aim of this study was to determine the presence or absence of river otters at locations in Florida which they historically inhabited. Forty-six sample sites where otters were historically found were obtained from the Florida Museum of Natural History Mammals Master Database (FMNH MMD). These sites were condensed to two focus areas, in and around Alachua and Collier Counties, where the sites were most highly clustered. Each site was surveyed to determine the presence or absence of river otters and to determine the suitability of the site’s environment for otter habitation. Sites with favorable habitat features for otters were surveyed a second time. River otters were not found at any site. Only 9 of the 46 sites had permanent water and only 8 of those had other habitat features preferred by otters. Therefore, only 17.39% of sites that historically supported otters likely still have the ability to do so. Loss of water over time is most likely the result of human disturbances such as the draining, damming, and canalizing of wetlands. As a result of this loss of natural habitat, river otters have become increasingly common in urban areas wither preferred habitat features, even if they are man-made. The increased presence near humans may have led to the apparently inaccurate assumption that otters are common, and, therefore, do not need protection.

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Zanirato, Gisele Lamberti. "A influência da perda e da fragmentação do habitat sobre a ocupação e o padrão de atividade do tamanduá-bandeira (Myrmecophaga tridactyla) /". São José do Rio Preto, 2017. http://hdl.handle.net/11449/151071.

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Orientador: Rita de Cassia Bianchi
Banca: Natália Mundim Tôrres
Banca: Guilherme de Miranda Mourão
Resumo: Com a expansão dos centros urbanos e das atividades agrícolas, as áreas do bioma Cerrado no estado de São Paulo vêm sendo transformadas em paisagens altamente fragmentadas constituídas em grande parte por fragmentos pequenos. A perda e a fragmentação do habitat tem sido um dos principais fatores responsáveis pelo declínio populacional e pela extinção local de espécies com baixa densidade populacional, baixa taxa de reprodução, alta demanda por espaço e especialista alimentar, como o tamanduá-bandeira (Myrmecophaga tridactyla). É conhecido que algumas espécies de mamíferos modificam seus padrões de atividade frente às perturbações antrópicas e até em relação aos efeitos da perda de habitat. Diante disso, os objetivos deste estudo foram avaliar se a área e o isolamento do fragmento, a porcentagem de vegetação nativa e a disponibilidade hídrica da paisagem são importantes para explicar a ocupação dos fragmentos pelo tamanduá-bandeira, e verificar se há diferenças no padrão de atividade entre as populações de tamanduás que ocupam os fragmentos menores (< 2.015 ha) e a população que ocupa o fragmento maior (10.285 ha). Os dados de presença e ausência dos tamanduás-bandeira em cada um dos vinte fragmentos de vegetação nativa localizados no nordeste do estado de São Paulo foram coletados através de armadilhas fotográficas. A influência da temperatura e da pluviosidade na probabilidade de detecção dos tamanduás e a importância das variáveis de fragmento e de paisagem na probabilidade...
Abstract: With the expansion of urban areas and agricultural activities, the Cerrado's areas in São Paulo state have been transformed in highly fragmented landscapes consisting largely of small fragments. Habitat loss and fragmentation have been one of the main factors responsible for population decline and local extinction of species with low population density, low reproduction rate, high spatial demand and diet specialist, such as the giant anteater (Myrmecophaga tridactyla). It is known that some species of mammals modify their activity patterns in face of anthropic disturbances and even in relation to the habitat loss effects. On this, the aims of this study were to evaluate if the patch's area and the isolation, the native vegetation percentage and water availability in the landscape are important to explain the patches occupancy by the giant anteater, and verify if there are differences in the activity pattern between the anteaters populations that inhabit the smaller patches (<2,015 ha) and the population that occupies the larger patch (10,285 ha). The presence and absence data of the giant anteaters in each one of the twenty patches of native vegetation located in the northeast of the São Paulo state were collected through camera traps. The temperature and rainfall influence on the detection probability of the anteaters and the importance of the patch and landscape variables on the occupancy probability of the patches by the species were evaluated through single-season ... (
Mestre

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Gregorini, Marina Zanin. "Efeitos da perda e fragmentação de habitat sobre felinos: ecologia e genética de paisagem como ferramentas para a conservação". Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/3462.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Nosso trabalho teve como objetivo investigar o efeito da perda e fragmentação de habitat sobre os felinos (Carnivora: Felidae), testando hipóteses relacionadas ao tema, bem como fazendo inferências para a conservação. Apresentamos aqui três capítulos no formato de artigo científico e uma breve discussão geral, que consiste na compreensão geral proveniente dos resultados dos três primeiros. Iniciamos essa tese com uma revisão sistemática e quantitativa da literatura sobre o efeito da perda e fragmentação do habitat sobre felinos. Esse trabalho consistiu no passo inicial dessa tese, pois permitiu identificar as lacunas de conhecimento, tendências gerais e metodologias eficientes a serem aplicadas nas outras etapas do trabalho. No entanto, nossa revisão se estende além da avaliação do “estado da arte”, pois testamos também hipóteses relativas a alocação do esforço de pesquisa.
Nosso trabalho teve como objetivo investigar o efeito da perda e fragmentação de habitat sobre os felinos (Carnivora: Felidae), testando hipóteses relacionadas ao tema, bem como fazendo inferências para a conservação. Apresentamos aqui três capítulos no formato de artigo científico e uma breve discussão geral, que consiste na compreensão geral proveniente dos resultados dos três primeiros. Iniciamos essa tese com uma revisão sistemática e quantitativa da literatura sobre o efeito da perda e fragmentação do habitat sobre felinos. Esse trabalho consistiu no passo inicial dessa tese, pois permitiu identificar as lacunas de conhecimento, tendências gerais e metodologias eficientes a serem aplicadas nas outras etapas do trabalho. No entanto, nossa revisão se estende além da avaliação do “estado da arte”, pois testamos também hipóteses relativas a alocação do esforço de pesquisa.

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Keeton, Jenna M. "The Vulnerability of Littoral Structures Under Multiyear Drought Conditions". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7585.

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Climate change is associated with altered environmental conditions and shifting mosaics of suitable habitats for organisms. Climate change in the form of drought can shift important lake shoreline habitats downslope, altering the lakes chemistry and habitat availability. Additionally, negative biological consequences can occur after a loss of submerged habitat along shorelines, hereafter littoral habitat. The objective of this study is to evaluate whether littoral habitat is lost (cobble, coarse woody habitat (fallen trees; CWH), and aquatic vegetation) under drought conditions across the United States. I used the National Lakes Assessment physical habitat data collected in summer 2012, when 75% of the U.S. experienced drought. I calculated the probability of cobble, CWH, and aquatic vegetation loss with lake level decline. I found cobble and CWH were highly vulnerable, where just 1 meter of lake level loss would result in nearly 100% habitat loss. Aquatic vegetation exhibited vulnerability but at a higher threshold. Multiyear drought will continue into the future with scientists estimating increases in drought frequency and severity, and we do not yet understand how or if aquatic animals will be resilient to a loss of littoral habitat. For example, previous research suggests food webs may be slow to recovery following littoral habitat loss. We must continue to evaluate the biological and environmental consequences of littoral habitat loss under drought conditions to successfully manage lakes and reservoirs into the future.

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Martins, Thais Kubik. "Determinantes ecológicos do risco de extinção: abundância local, amplitude de nicho, capacidade de dispersão e a resposta das espécies de pequenos mamíferos à fragmentação florestal no Planalto Atlântico Paulista". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-19042012-101419/.

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Alterações antrópicas nos ecossistemas, em especial a perda e a fragmentação de habitat, são consideradas as principais causas do grande aumento nas extinções de espécies nas últimas décadas. Uma vez que o risco de extinção varia grandemente entre as espécies, os determinantes ecológicos associados à chance de extinção têm sido um tema central e muito debatido na literatura ecológica. Atributos ecológicos relacionados à raridade, como amplitude de nicho e abundância local, e a capacidade de dispersão são recorrentemente citados na literatura como determinantes do risco de extinção local. A partir de dados de ocorrência em fragmentos, matas contínuas e áreas de agricultura, e de captura-recaptura em três grades de 2 ha em mata continua, no Planalto Atlântico Paulista, investigamos o efeito desses três atributos ecológicos sobre o risco de extinção local em espécies de pequenos mamíferos. Utilizamos a abordagem de seleções de modelos e o critério de Akaike (AICc) para avaliar qual das hipóteses existentes na literatura sobre a relação destes atributos com o risco de extinção é mais plausível. Foram realizadas duas seleções de modelos: uma considerando os três atributos para sete espécies; e outra considerando apenas a amplitude de nicho e abundância local para 18 espécies. Os resultados de ambas as seleções indicam a amplitude de nicho como determinante principal do risco de extinção local, que aumenta à medida que a amplitude de nicho diminui. Abundância local apresentou uma importância secundária, com um efeito positivo sobre o risco de extinção, mas que é mais forte para espécies com menor amplitude de nicho. Este resultado é consistente com a idéia de que a abundância local é influenciada pelo grau de especialização e pela capacidade competitiva das espécies, a qual está negativamente relacionada à capacidade de colonização através de uma demanda conflitante. Como a capacidade de dispersão variou pouco entre as espécies estudadas e a capacidade de colonização é determinada também pela taxa de crescimento populacional, é possível que o risco de extinção das espécies de pequenos mamíferos especialistas de habitat seja secundariamente definido pela taxa de crescimento populacional
Anthropogenic disturbances, particularly habitat loss and fragmentation, are considered the main causes of the increased extinction rates observed in the last decades. Since the risk of extinction is extremely variable among species, the ecological determinants of the chance of extinction have been in the center of the debates in the ecological literature. Ecological traits associated with rarity, as niche breadth and local abundance, and dispersal ability are recurrently mentioned in the literature as the main determinants of the risk of local extinction. Using data on occurrence in fragments, continuous forest and areas of agriculture, and on capture-recapture in three 2-ha grids in continuous forest, in the Atlantic Plateau of São Paulo, we investigate the effects of these three ecological traits on the risk of local extinction in small mammals. We used a model selection approach and the Akaike criterion (AICc) to evaluate which of the existing hypotheses on the relationship of these traits with the extinction risk is most plausible. Two model selections were run: one considering the three traits and seven species, and another considering only niche breadth and local abundance and 18 species. The results from both selections point to niche breadth as the main determinant of the risk of local extinction. Local abundance was secondarily important, with a positive effect on extinction risk, which is stronger among the species with smaller niche breadth. This result is consistent with the idea that local abundance is influenced by species degree of ecological specialization and competitive ability, which is negatively related to colonization ability through a trade-off. As dispersal ability varied little among studied species, and colonization ability is also determined by population growth rate, it is possible that the risk of extinction among habitat specialist small mammals is secondarily defined by population growth rate

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Graß, Ingo [Verfasser], i Nina [Akademischer Betreuer] Farwig. "Habitat loss and exotic plant invasions disrupt plant-animal mutualisms in a heterogeneous South African landscape / Ingo Graß. Betreuer: Nina Farwig". Marburg : Philipps-Universität Marburg, 2014. http://d-nb.info/105193494X/34.

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Heer, Henriette [Verfasser], Ralf B. [Gutachter] Schäfer i Stefan [Gutachter] Ruzika. "Mathematical models of species dispersal and the resilience of metapopulations against habitat loss / Henriette Heer ; Gutachter: Ralf B. Schäfer, Stefan Ruzika". Landau : Universität Koblenz-Landau, Campus Landau, 2021. http://d-nb.info/1230798900/34.

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Chambers, Joanne. "Terrestrial habitat requirements of a suite of anuran species inhabiting a semi-arid region of South East Queensland". Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16610/1/Joanne_Chambers_Thesis.pdf.

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Hypothesised causes of the observed world-wide decline of amphibian populations are varied and in some cases contentious. Insufficient information relating to the autecology of many amphibian species can cause erroneous speculations regarding critical habitat requirements and hence management programs designed to enhance population viability are often unsuccessful. Most amphibians display a bi-phasic life history that involves occupation of an aquatic breeding habitat and terrestrial habitats that are used for foraging, and shelter from predation and environmental stress. However, the focus of most amphibian research is centred on the breeding habitat, with limited research being conducted into the terrestrial habitat requirements of most amphibian species. Barakula State Forest is a large continuous area of open woodland situated in the semi-arid region of Queensland. The forest supports 21 species of endemic anurans, many of which use ephemeral waterbodies for breeding. This area is, therefore, an ideal location to test the relative importance of terrestrial habitat on the distribution of a suite of frogs that display different morphological and physiological characteristics. On the landscape scale, the attributes of the terrestrial environment at three survey areas within Barakula were similar. However, at the patch scale, ground truthing showed there were considerable variations in vegetation and ground cover attributes within and between each survey site. Measured properties of the soil also tended to vary within and between sites. Soil texture ranged from sandy to heavy clay, soil pH ranged from 3.9 to 6.4 and soil moisture varied considerably. Agar models, used for testing evaporative moisture loss at different microhabitats, retained significantly higher levels of moisture when positioned in the buried microhabitat during summer, but in winter, models that were placed under leaf litter retained higher levels of moisture. Variations in levels of moisture loss at the five different microhabitats were evident within and between the survey sites. Despite a prolonged drought, 1844 native frogs representing 17 species were pitfall trapped. Members from the family Myobatrachidae comprised 94% of these captures, and burrowing species accounted for 75% of total captures. Species were not randomly distributed within or between the survey sites. Vegetation attributes and soil properties played a significant role in influencing the catch rates and traplines that supported similar vegetation and soil attributes also tended to catch similar species. Capture rates of six of the seven burrowing species were significantly influenced by soil properties. When given a choice of four different microhabitats created in enclosures, individuals from five species showed varying responses to habitat choice during night time activity. During daylight all species tended to avoid bare areas and burrowing species tended to burrow under some form of cover. Pseudophryne bibronii metamorphs showed a significant avoidance to soils with high pH. The number of Limnodynastes ornatus metamorphs was significantly and positively correlated with moisture levels surrounding a breeding area. Limnodynastes ornatus metamorphs tended to avoid areas that did not support some form of cover. Embryos from the terrestrial egg laying P. bibronii translocated to sites with varying levels of soil pH, suffered increased mortality where the soil pH was >4.8. In the laboratory, embryonic survival was not significantly different between the four pH treatments. There was a significant influence of fungal infection on survival rates and ranked fungal infection was significantly different between the four pH treatments. The terrestrial environment at the three survey sites has provided sufficient protection from environmental elements to allow a large diversity of anurans to persist for long periods without access to permanent water. Management must consider the importance of the non-breeding habitat when defining buffer zones, restoration programs and conservation strategies to ensure that the complete set of ecological requirements for frog species are provided.

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Chambers, Joanne. "Terrestrial habitat requirements of a suite of anuran species inhabiting a semi-arid region of South East Queensland". Queensland University of Technology, 2008. http://eprints.qut.edu.au/16610/.

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Hypothesised causes of the observed world-wide decline of amphibian populations are varied and in some cases contentious. Insufficient information relating to the autecology of many amphibian species can cause erroneous speculations regarding critical habitat requirements and hence management programs designed to enhance population viability are often unsuccessful. Most amphibians display a bi-phasic life history that involves occupation of an aquatic breeding habitat and terrestrial habitats that are used for foraging, and shelter from predation and environmental stress. However, the focus of most amphibian research is centred on the breeding habitat, with limited research being conducted into the terrestrial habitat requirements of most amphibian species. Barakula State Forest is a large continuous area of open woodland situated in the semi-arid region of Queensland. The forest supports 21 species of endemic anurans, many of which use ephemeral waterbodies for breeding. This area is, therefore, an ideal location to test the relative importance of terrestrial habitat on the distribution of a suite of frogs that display different morphological and physiological characteristics. On the landscape scale, the attributes of the terrestrial environment at three survey areas within Barakula were similar. However, at the patch scale, ground truthing showed there were considerable variations in vegetation and ground cover attributes within and between each survey site. Measured properties of the soil also tended to vary within and between sites. Soil texture ranged from sandy to heavy clay, soil pH ranged from 3.9 to 6.4 and soil moisture varied considerably. Agar models, used for testing evaporative moisture loss at different microhabitats, retained significantly higher levels of moisture when positioned in the buried microhabitat during summer, but in winter, models that were placed under leaf litter retained higher levels of moisture. Variations in levels of moisture loss at the five different microhabitats were evident within and between the survey sites. Despite a prolonged drought, 1844 native frogs representing 17 species were pitfall trapped. Members from the family Myobatrachidae comprised 94% of these captures, and burrowing species accounted for 75% of total captures. Species were not randomly distributed within or between the survey sites. Vegetation attributes and soil properties played a significant role in influencing the catch rates and traplines that supported similar vegetation and soil attributes also tended to catch similar species. Capture rates of six of the seven burrowing species were significantly influenced by soil properties. When given a choice of four different microhabitats created in enclosures, individuals from five species showed varying responses to habitat choice during night time activity. During daylight all species tended to avoid bare areas and burrowing species tended to burrow under some form of cover. Pseudophryne bibronii metamorphs showed a significant avoidance to soils with high pH. The number of Limnodynastes ornatus metamorphs was significantly and positively correlated with moisture levels surrounding a breeding area. Limnodynastes ornatus metamorphs tended to avoid areas that did not support some form of cover. Embryos from the terrestrial egg laying P. bibronii translocated to sites with varying levels of soil pH, suffered increased mortality where the soil pH was >4.8. In the laboratory, embryonic survival was not significantly different between the four pH treatments. There was a significant influence of fungal infection on survival rates and ranked fungal infection was significantly different between the four pH treatments. The terrestrial environment at the three survey sites has provided sufficient protection from environmental elements to allow a large diversity of anurans to persist for long periods without access to permanent water. Management must consider the importance of the non-breeding habitat when defining buffer zones, restoration programs and conservation strategies to ensure that the complete set of ecological requirements for frog species are provided.

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Coristine, Laura Elizabeth. "Climate Change Impacts on Biodiversity". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35245.

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Conservation is plagued by the issue of prioritization - what to conserve and where to conserve it - which relies on identification and assessment of risks. In this body of work, I identify some of the risks related to climate change impacts on biodiversity, as well as potential solutions. Climate changes are underway across nearly all terrestrial areas and will continue in response to greenhouse gas emissions over centuries. Other extinction drivers, such as habitat loss due to urbanization, commonly operate over localized areas. Urbanization contributes, at most, less than 2% of the total range loss for terrestrial species at risk when averaged within an ecodistrict (Chapter 2). Documented impacts of climate change, to date, include: extinction, population loss, reduction in range area, and decreased abundance for multiple taxonomic groups. Examining species’ and populations’ physiological limits provides insight into the mechanistic basis, as well as geography, of climate change impacts (Chapter 3). Climate changes, and the ecological impacts of climate changes, are scale-dependent. Thus, the biotic implications are more accurately assessed through comparisons of local impacts for populations. Under a scenario of climate change, equatorward margins may be strongly limited by climatic conditions and not by biotic interactions. Yet, geographic responses at poleward margins do not appear directly linked to changes in breeding season temperature (Chapter 4). New ideas on how regions with attenuated climate change (climate refugia) may be used to lower species climate-related extinction risk while simultaneously improving habitat connectivity should be considered in the context of potential future consequences (i.e. range disjunction, alternative biological responses) (Chapter 5). Contemporary climate refugia are identifiable along multiple climatic dimensions, and are similar in size to current protected areas (Chapter 6). Determining how, when, and where species distributions are displaced by climate change as well as methods of reducing climatic displacement involves integrating knowledge from distribution shift rates for populations, occurrence of climate refugia, and dispersal barriers. Such assessments, in the Yellowstone to Yukon region, identify dramatically different pathways for connectivity than assessments that are not informed by considerations of species richness and mobility (Chapter 7).

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Silva, Leonardo Henrique da. "Seleção de dormitórios pelos micos-leões-pretos : uma comparação entre floresta contínua e fragmento /". Rio Claro, 2019. http://hdl.handle.net/11449/183152.

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Orientador: Laurence Marianne Vincianne Culot
Resumo: A seleção de dormitórios pelos primatas pode ser influenciada por diversos fatores, como a predação, termorregulação e defesa de território. Nosso objetivo foi investigar quais desses fatores influenciam a seleção de dormitórios pelos micos-leões-pretos e se há divergência nas características dos dormitórios entre uma floresta contínua e um fragmento. Estudamos dois grupos de mico-leões-pretos, um numa floresta contínua e um num fragmento na região do Pontal do Paranapanema, São Paulo, Brasil. Nós coletamos os dados sobre as características físicas dos dormitórios e das árvores disponíveis no habitat. Usamos testes de Mann-Whitney para comparar as características físicas dos dormitórios com as árvores disponíveis e Funções de Seleção de Recursos (RSF) para entender quais dessas características são mais importantes na escolha dos dormitórios. Os micos-leões-pretos usaram árvores mais altas, com menor número de conexões de copas e com um alto grau de cobertura de copa para dormir, quando comparado às árvores disponíveis. Os dormitórios usados pelo grupo da floresta contínua eram maiores, com as primeiras ramificações inferiores mais altas e com menor número de conexão de copas do que os dormitórios usados pelo grupo do fragmento. Nossos resultados evidenciam a presença de estratégias anti-predação pelos grupos de micos-leões-pretos, com o grupo da floresta contínua apresentando um processo de seleção de dormitórios mais refinado, no qual a seleção apenas de árvores que possuam ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Sleeping site selection by primates can be influenced by several factors, such as predation, thermoregulation and territorial defense. Our objective was to investigate which of these factors influence the sleeping site selection by black lion tamarins and if there is divergence in the characteristics of the sleeping sites between a continuous forest and a fragment. We studied two groups of black lion tamarins, one in a continuous forest and one in a small and isolated fragment in the Pontal do Paranapanema, São Paulo, Brazil. We collected data on the physical characteristics of the sleeping sites and available trees within the both habitats. We used Mann-Whitney tests to compare the physical characteristics of the sleeping sites with available trees and Resource Selection Functions (RSF) to understand which of these characteristics are most important in choosing the sleeping sites. Black lion tamarins used taller trees, with a fewer canopy connections, and a higher degree of canopy cover compared to the available trees. The sleeping sites used by the continuous forest group were larger, with the first lower ramifications higher and with fewer number of canopy connections than the sleeping sites used by the fragment group. Our results evidenced the presence of anti-predation strategies by both black lion tamarin groups, with the continuous forest group presenting a more refined sleeping site selection process, in which the selection of only trees with a larger set of character... (Complete abstract click electronic access below)
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Cateau, Eugénie. "Réponse des coléoptères saproxyliques aptères aux perturbations anthropiques des forêts et des paysages". Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0045/document.

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Dans un contexte de changement climatique, des dispositifs sont mis en place par les politiques publiques pour permettre le déplacement de la biodiversité et la recolonisation de nouveaux milieux (TVB, trame de vieux bois. . . ). Ces dispositifs semblent adaptés pour les espèces animales les plus mobiles. Or, les espèces ayant une faible capacité de déplacement représentent un enjeu important pour l'e‑cacité des dispositifs mis en place. Un grand nombre de ces espèces demeurent aujourd'hui mal connues. En forêt, les coléoptères saproxyliques aptères de litière sont des espèces ayant des capacités de déplacement et de dispersion limitées en raison de leurs petites tailles, de leurs aptérismes et de leurs exigences trophiques. Ces espèces constituent le modèle biologique de cette étude pour comprendre comment des espèces à faible capacité de déplacement peuvent évoluer dans les forêts et les paysages anthropisés, dans l'espace et le temps. L'échantillonnage par tamisage de litière de dix arbres par peuplement en utilisant un Winkler et une extraction par Berlese, a montré une puissance d'échantillonnage moyenne de 97.2% pour six forêts. Des relevés mensuels sur deux ans ont permis de caractériser la phénologie des espèces, à savoir qu'elles sont i/ présentes dans la litière toute l'année, ii/ davantage abondantes au printemps et en automne et iii/ ne présentent pas de variation interannuelle. Nous avons comparé la richesse spécique et la répartition des espèces, entre les forêts subnaturelles et les peuplements exploités des montagnes Pyrénéennes. Ceci a montré que les espèces sont peu impactées par l'exploitation sylvicole traditionnelle, mais présentent une grande variabilité de répartition qui semble liée à l'impact anthropique passé. Le paysage fragmenté des Coteaux de Gascogne s'est avéré être très pauvre en coléoptères saproxyliques aptères. Étonnamment, dans ce territoire, les répartitions des espèces sont mieux expliquées par les caractéristiques des paysages que celles des forêts. Pour la moitié des espèces, leurs répartitions sont mieux expliquées par la composition du paysage en 1850 que celle d'aujourd'hui. Un seuil critique de 15% de proportion de forêts dans le paysage en 1850 a pu être mis en évidence pour une espèce (Dienerella clathrata). Nous avons montré que les espèces sont capables (au moins) de se déplacer à travers les haies, quelles que soient les caractéristiques de ces dernières. Si les espèces étaient présentes dans la forêt connectée à la haie, elles ont été échantillonnées dans cette dernière. Les capacités de déplacement de trois espèces ont été étudiées en laboratoire et montrent une vitesse moyenne de 1,6m.h-1. Ces deux éléments conrment le fait que ces espèces sont mobiles dans le paysage. L'ensemble de ces résultats, ainsi que le fait que les territoires les moins anthropisés soient les plus riches en coléoptères saproxyliques aptères, nous amènent à conclure que ce groupe taxonomique supporte bien les impacts humains de faible amplitude spatiale et temporelle, mais qu'ils sont peu résilients à une anthropisation importante dans le temps et dans l'espace
To enable species migration in a global warming context, public policies try to improve European natural network (Green and Blue infrastructure, old trees network...). These measures might be adapted to the high-dispersal species, but there is a lack of knowledge concerning the ability of the low-dispersal species to move using these networks. Lots of these species remain poorly known. Considering forest ecosystems, ightless saproxylic beetles are supposed to be dispersal limited species because of they are small, unable to y and have trophic exigencies. The aim of this study is to understand how dispersal limited species evolve temporally and spatially in the landscape. Flightless saproxylic beetles have been sampled by sieving litter in front of ten trees per stand, using a modied Winkler and extracted through an adapted Berlese. This standardization of the methods lead to sample an average of 97,2% of the species targeted in each forest. A monthly survey during two years has shown that the species are present in the litter throughout the year and that they are stable over two years. The best season to sample them appeared to be autumn and spring. Comparison between old growth forests and harvested stands in the French Pyrénnées has shown that harvesting does not impact signi cantly the target species. Their repartitions were highly dierent between the studied valleys, which is assumed to result from the dierence in the past human impact. In the highly fragmented landscape (Coteaux de Gascogne, SW France), very few ightless saproxylic species have been sampled. Surprisingly, this experiment has shown that the landscape characteristics explain better these dispersal limited species' repartitions than the forest characteristics. For half of them, landscape composition in the 1850's explain better the repartition than the current one. A threshold of 15% of forest cover appeared to be determinant for one species (Dienerella clathrata). We showed that the studied species use the edges (at least to move through them) whatever their characteristics may be. As soon as they are present in the forest, they are in the connected edge. Moving abilities of 3 species have been approached by measuring the running speed in laboratory. This experiment showed a mean of running speed of 1,6m.h -1. These dierent elements lead us to conclude that the ightless saproxylic beetles are mobile in the landscape. All these results, and the fact that species richness is correlated to the landscape anthropisation, leads us to conclude that this taxonomic group can support human impact at small spatial and temporal scale, but are poorly resilient to large and long anthropisation

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Eklöf, Anna. "Species extinctions in food webs : local and regional processes". Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-51815.

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Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. There is an urgent need of understanding how these species losses affect the ecological structure and functioning of our ecosystems. Ecological communities exist in a landscape but the spatial aspects of community dynamics have until recently to large extent been ignored. However, the community’s response to species losses is likely to depend on both the structure of the local community as well as its interactions with surrounding communities. Also the characteristics of the species going extinct do affect how the community can cope with species loss. The overall goal of the present work has been to investigate how both local and regional processes affect ecosystem stability, in the context of preserved biodiversity and maintained ecosystem functioning. The focus is particularly on how these processes effects ecosystem’s response to species loss. To accomplish this goal I have formulated and analyzed mathematical models of ecological communities. We start by analyzing the local processes (Paper I and II) and continue by adding the regional processes (Paper III, IV and V). In Paper I we analyze dynamical models of ecological communities of different complexity (connectance) to investigate how the structure of the communities affects their resistance to species loss. We also investigate how the resistance is affected by the characteristics, like trophic level and connectivity, of the initially lost species. We find that complex communities are more resistant to species loss than simple communities. The loss of species at low trophic levels and/or with high connectivity (many links to other species) triggers, on average, the highest number of secondary extinctions. We also investigate the structure of the post-extinction community. Moreover, we compare our dynamical analysis with results from topological analysis to evaluate the importance of incorporating dynamics when assessing the risk and extent of cascading extinctions. The characteristics of a species, like its trophic position and connectivity (number of ingoing and outgoing trophic links) will affect the consequences of its loss as well as its own vulnerability to secondary extinction. In Paper II we characterize the species according to their trophic/ecological uniqueness, a new measure of species characteristic we develop in this paper. A species that has no prey or predators in common with any other species in the community will have a high tropic uniqueness. Here we examine the effect of secondary extinctions on an ecological community’s trophic diversity, the range of different trophic roles played by the species in a community. We find that secondary extinctions cause loss of trophic diversity greater than expected from chance. This occurs because more tropically unique species are more vulnerable to secondary extinctions. In Paper III, IV and V we expand the analysis to also include the spatial dimension. Paper III is a book chapter discussing spatial aspects of food webs. In Paper IV we analyze how metacommunities (a set of local communities in the landscape connected by species dispersal) respond to species loss and how this response is affected by the structure of the local communities and the number of patches in the metacommunity. We find that the inclusion of space reduces the risk of global and local extinctions and that lowly connected communities are more sensitive to species loss. In Paper V we investigate how the trophic structure of the local communities, the spatial structure of the landscape and the dispersal patterns of species affect the risk of local extinctions in the metacommunity. We find that the pattern of dispersal can have large effects on local diversity. Dispersal rate as well as dispersal distance are important: low dispersal rates and localized dispersal decrease the risk of local and global extinctions while high dispersal rates and global dispersal increase the risk. We also show that the structure of the local communities plays a significant role for the effects of dispersal on the dynamics of the metacommunity. The species that are most affected by the introduction of the spatial dimension are the top predators.

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Le, Moine Rebecka. "The land use cover changes from 1992 to 2011 in Karbi Anglong, Assam, India". Thesis, Linköpings universitet, Ekologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-79347.

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With an increased human impact, natural resources are under great pressure. Deforestation is one effect of this, and the largest threat against biodiversity.. Changes in tropical habitats is a major concern for conservation biologists, due to its high biodiversity and rapid decreased area. Recently, developmental activities and habitat destruction have caused a major decline in the abundance of the terrestrial mega-fauna.This is especially evident in areas with a high human population and a rich mega-fauna as in India. The purpose of this project was to determine the land-use cover change (LUCC) in the area of Karbi Anglong, which lies in the middle of Assam, India. This was done by identifying different vegetation types from satellite images, from the years 1992, 2002 and 2011 using a remote sensing application (ERDAS) and ArcGIS. Interviews in the area werealso operated, and data about how animal use the corridors were used along with registered human-tiger conflicts. The results show that during the first period, a total of 360 km2 of the area changed vegetation type, mostly due to an increase of agricultural areas. The second largest change (79 km2) was an increase of moist mixed deciduous forest which seems to have taken over some of the semi evergreen forest’s previous area. If that is the case it is most likely an effect of selective logging from the local people, who use fire wood as fuel.All in all, there has been a great habitat loss along withfragmentation of the landscape. The conflict data shows that tigers are present between the core areas, and the interviews show that the migrations of other animals are also common.To maintain the high ecological values in Karbi Anglong, it is of great importance to maintain connectivity between core areas and stop further habitat loss and fragmentation.

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Gibbs, Mary Katherine E. "Species Declines: Examining Patterns of Species Distribution, Abundance, Variability and Conservation Status in Relation to Anthropogenic Activities". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23315.

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Humans are modifying the global landscape at an unprecedented scale and pace. As a result, species are declining and going extinct at an alarming rate. Here, I investigate two main aspects of species’ declines: what factors are contributing to their declines and how effective our conservation efforts have been. I assessed one of the main mechanisms for protecting species by looking at the Endangered Species Act (ESA) in the United States. I examined three separate indicators of species declines for different groups of species: range contractions in Canadian imperilled species, declines in abundance in global amphibian populations and increases in temporal variability in abundance in North American breeding birds. I found that change in recovery status of ESA listed species was only very weakly related to the number of years listed, number of years with a recovery plan, and funding. These tools combined explained very little of the variation in recovery status among species. Either these tools are not very effective in promoting species’ recovery, or species recovery data are so poor that it is impossible to tell whether the tools are effective or not. I examined patterns of species’ declines in three different groups in relation to a number of anthropogenic variables. I found high losses of Canadian imperiled bird, mammal, amphibian and reptile species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. This is consistent with the hypothesis that agricultural pesticide use, or something strongly collinear with it (perhaps intensive agriculture more generally), has contributed significantly to the decline of imperiled species in Canada. Global increases in UV radiation do not appear to be a major cause of amphibian population declines. At individual sites, temporal changes in amphibian abundance are not predictably related to changes in UV intensity. Variability in species’ abundance of North American breeding birds, after accounting for mean abundance, is not systematically higher in areas of high human-dominated land cover or climate change. Rather, it appears that areas with a high proportion of human-dominated cover come to have a higher proportion of highly abundant, and thus more variable, species.

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Alves, Suélen da Silva. "CULTIVO DE EUCALYPTUS REDUZ A DIVERSIDADE DA HERPETOFAUNA EM ÁREA DE CAMPO NO SUL DO BRASIL". Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/5321.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The expansion of forestation on grassland ecosystems has dramatically changed the landscape, as well as affected the biodiversity and the sustainability of these ecosystems around the world. Grasslands of southern South America hold high diversity and several cases of endemism, but historically are insufficiently protected in conservation units and experience drastic reduction due to cultivation of exotic trees as eucalyptus, black wattle and pine. Grasslands of Pampa biome in Brazilian territory are restricted to the state of Rio Grande do Sul, where recent estimates indicate that the grassyfields will disappear within the next few decades if the current scenario of changes in the productive matrix is maintained. In order to contribute with subsidies to conservation of grasslands ecosystems, the goal of this Dissertation was to study the spatial patterns in the distribution of herpetofauna (i.e. amphibians and reptiles), as well as environmental variables associated with native grasslands and eucalyptus plantation in the Pampa biome, Rio Grande do Sul state, Brazil. Thus, native grasslands and eucalyptus crops were characterized and compared regarding species richness, taxonomic composition, and abundance of amphibians and reptiles, using pitfall traps during eight sampling months (September 2012 to April 2013). The communities of amphibians and reptiles studied responded negatively to the replacement of native grasslands by arboreal crops because they were dominated by a few species in eucalyptus cultivation . Through nesting analysis and similarity tests, we recorded that reptiles responded strongly to habitat modification, since the community recorded in eucalypt was an impoverished subset of that recorded in native pasture, being still dominated by species commonly abundant in degraded areas. Amphibians responded strongly regarding species abundance and keenly to species richness, but did not respond to the gradient regarding taxonomic composition of the community. The environmental variables most strongly related to the pattern of segregation observed between native grasslands and eucalyptus cultivation were the percentage of low cover vegetation on soil and brightness. Our results indicate that eucalyptus forestation profoundly modify the structure of undergrowth vegetation, typical of grassland ecosystems and essential to the biology of several habitat-specialist species, including rare species. In this context, we emphasize that the habitat loss due to expanding forestation on grasslands configures a serious threat to conservation of the herpetofauna of the Pampa biome. Such effects can be minimized only after the adoption of specifically committed environmental policies to the conservation of grasslands ecosystems, until now so neglected.
A expansão da silvicultura sobre os ecossistemas campestres tem alterado dramaticamente a paisagem, bem como afetado a biodiversidade e a sustentabilidade desses ecossistemas ao redor do mundo. Os campos do sul da América do Sul detêm alta diversidade biológica e inúmeros casos de endemismos, mas historicamente são insuficientemente protegidos em Unidades de Conservação e experimentam drástica redução devido ao plantio de exóticas como o eucalipto, a acácia-negra e pinus. Os campos do bioma Pampa em território brasileiro estão restritos ao estado do Rio Grande do Sul, onde estimativas recentes apontam que estes desaparecerão dentro das próximas décadas se o corrente cenário de mudanças na matriz produtiva for mantido. A fim de contribuir com subsídios à preservação dos ecossistemas campestres, o objetivo dessa Dissertação foi estudar os padrões espaciais da distribuição da herpetofauna (i.e. anfíbios e répteis), bem como de variáveis ambientais associadas, em campo nativo e plantio de eucalipto localizados no bioma Pampa, Rio Grande do Sul, Brasil. Assim, campos nativos e cultivos de eucalipto foram caracterizados e comparados quanto à riqueza de espécies, composição taxonômica e abundância de anfíbios e répteis, utilizando armadilhas de interceptação e queda durante oito meses de coleta (setembro de 2012 à abril de 2013). As comunidades de anfíbios e répteis estudadas responderam negativamente à substituição dos campos nativos por cultivos arbóreos, pois foram dominadas por poucas espécies no cultivo de eucalipto. Através da análise de aninhamento e teste de similaridade, evidenciamos que os répteis responderam fortemente à alteração do hábitat, já que a comunidade registrada no eucalipto foi um subconjunto empobrecido daquela registrada no campo nativo, sendo ainda dominada por espécies comumente abundantes em áreas degradadas. Anfíbios responderam fortemente quanto à abundância das espécies e sutilmente quanto à riqueza específica, mas não responderam ao gradiente quanto à composição taxonômica da comunidade. As variáveis ambientais mais fortemente relacionadas ao padrão de segregação observado entre o campo nativo e o cultivo de eucalipto foram a porcentagem de vegetação rasteira recobrindo o solo e a luminosidade. Nossos resultados indicam que o cultivo de eucalipto altera profundamente a estrutura da vegetação rasteira, típica do ecossistema campestre e imprescindível à biologia de inúmeras espécies habitatespecialistas, incluindo espécies raras. Nesse sentido, enfatizamos que a perda de hábitat campestre devido à expansão da silvicultura configura séria ameaça à conservação da herpetofauna do bioma Pampa. Tais efeitos poderão ser minimizados somente após a adoção de políticas públicas ambientais especificamente comprometidas com a conservação dos ecossistemas campestres, até então negligenciados.

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Hutchison, Melissa Alice Sarah. "Interactions between habitat fragmentation and invasions: factors driving exotic plant invasions in native forest remnants, West Coast, New Zealand". Thesis, University of Canterbury. School of Biological Sciences, 2009. http://hdl.handle.net/10092/3218.

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Habitat fragmentation and biological invasions are widely considered to be the most significant threats to global biodiversity, and synergistic interactions between these processes have the potential to cause even greater biodiversity loss than either acting alone. The objective of my study was to investigate the effects of fragmentation on plant communities in native forest fragments, and to examine potential interactions between these effects and invasions by exotic plants at multiple spatial scales. I examined edge, area and landscape effects on plant invasions using empirical data from fragmented landscapes on the West Coast of New Zealand. My research revealed significant interactions between the amount of native forest cover in the landscape and the strength of edge and area effects on plant communities in forest fragments. The dominance of exotic plants in the community was highest at forest edges and decreased towards fragment interiors, however the interiors of very small fragments were relatively more invaded by exotic plants than those in larger fragments, reflecting a significant interaction between edge and area effects. Similarly, exotic dominance increased in more heavily deforested landscapes, but this effect was only apparent in very small fragments (<2 ha). The combined effects of small fragment size and low forest cover in the landscape appear to have promoted invasions of exotic plants in very small remnants. I explored the mechanisms underlying edge-mediated invasions in forest fragments and examined whether propagule availability and/or habitat suitability may be limiting invasions into fragments. Experimental addition of exotic plant propagules revealed that landscape forest cover interacted with edge effects on germination, growth and flowering rates of two short-lived, herbaceous species, and this appeared to be driven by elevated light and soil phosphorus levels at edges in heavily deforested landscapes. I also examined the role of traits in influencing plant responses to forest fragmentation. Different traits were associated with exotic invasiveness in edge and interior habitats of forest fragments, indicating that the traits promoting invasiveness were context dependent. Traits also had a major influence on responses of native plants to forest fragmentation, with generalist species appearing to benefit from fragmentation, as they can utilise both forest and open habitats, whereas native forest specialists have been negatively impacted by fragmentation.

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Oshima, Júlia Emi de Faria. "Movement ecology and spatial distribution of Tayassu pecari in heterogeneous tropical landscapes /". Rio Claro, 2019. http://hdl.handle.net/11449/183519.

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Orientador: Milton Cezar Ribeiro
Resumo: Modificações da cobertura do solo, perturbações antropogênicas e mudanças climáticas na região Neotropical têm sido associadas à crise da biodiversidade. Nesta tese, o objetivo principal foi investigar os efeitos que a estrutura da paisagem (incluindo a perturbação antropogênica) e a qualidade do habitat têm na distribuição espacial, nos padrões de movimento e na seleção de habitat da queixada - Tayassu pecari. Esta espécie é o único ungulado florestal Neotropical que forma grandes bandos e é uma espécie-chave nos ecossistemas florestais, pois sua extinção local pode causar perdas adicionais de biodiversidade por meio de efeitos em cascata. Ainda assim, pouco se sabe sobre uso do espaço e movimentos de queixadas em escala fina. Para tanto, estudamos a distribuição e movimentação da espécie em diferentes escalas e biomas do Brasil, investigando quais variáveis de paisagem influenciaram a mesma em diferentes escalas e ordens de seleção. Nossos resultados mostram fortes efeitos negativos da modificação da paisagem e fragmentação do habitat na distribuição de queixadas, restando apenas 47% do território brasileiro com áreas adequadas para a espécie. Verificamos que menos da metade de todas as áreas protegidas nos biomas Cerrado e Mata Atlântica têm um habitat adequado para a queixada. Para a análise do movimento, rastreamos 30 indivíduos com colares de GPS de julho de 2013 a outubro de 2016 no Pantanal e no Cerrado do estado do Mato Grosso do Sul. Nossos principais resultados mos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Land cover modifications, anthropogenic disturbances and climate change in the Neotropical region have been linked to the biodiversity crisis. This thesis proposal was to investigate the effects that landscape structure (including anthropogenic disturbance) and habitat quality have in the spatial distribution, in the movement patterns and in the habitat selection of the white-lipped peccary - Tayassu pecari (WLP). This species is the only Neotropical forest ungulate that forms large herds, and it is a keystone species in forest ecosystems because its local extinction may cause additional biodiversity losses through cascading effects. Still, little is known about WLPs space use and fine-scale movement. For that aim we studied the species distribution and movements in different scales and biomes of Brazil, investigating which landscape variables would influence the species in different scales and orders of selection. Our findings show strong negative effects of landscape modification and habitat fragmentation on white-lipped peccary distribution, with only 47% of the Brazilian territory with suitable areas for the species. We also found that less than half of all protected areas in the Cerrado and the Atlantic Forest biomes have suitable habitat for WLP. For the movement analysis we tracked 30 individuals with GPS collars from July 2013 to October of 2016 in the Pantanal and in the Cerrado of Mato Grosso do Sul state. Our main results showed a positive selection of WLP for fore... (Complete abstract click electronic access below)
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Carvalho, Carolina da Silva. "O papel da estrutura da paisagem na variabilidade genética da palmeira Euterpe edulis na Mata Atlântica". Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/3770.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Não consta resumo em outro idioma.
Essa dissertação está estruturada em dois capítulos cujo objetivo geral foi entender como características da paisagem influenciam a variação e a estruturação genética, usando a abordagem de genética da paisagem e a palmeira Euterpe edulis (Arecaceae) como modelo de estudo. A genética da paisagem surgiu a partir da junção de três grandes áreas da ciência: ecologia da paisagem, ecologia espacial e genética de populações (Manel et al. 2003). Difere-se de disciplinas clássicas como genética de populações e filogeografia, pois incorpora testes explícitos de heterogeneidade ambiental a fim de entender a distribuição da variabilidade genética no espaço (Storfer et al. 2007). Dentre as abordagens frequentemente realizadas na genética da paisagem podemos: identificar características da paisagem que influenciam a conectividade e diversidade genética, realizar design de corredores ecológicos e reservas, e predizer impactos de futuras mudanças ambientais na conectividade e permanência da espécie (Spear et al. 2010). No entanto, a primeira abordagem é a mais utilizada nos estudos, onde são testados o efeito do relevo, da hidrografia, das estradas (Spear et al. 2005), dos corredores, do tamanho e do isolamento dos fragmentos, e da proporção de habitat (Coulon et al. 2004, Dixo et al. 2009) sobre o fluxo gênico e variação genética. Além disso, a genética da paisagem pode ser particularmente importante para explicar padrões originados a partir de processos micro-evolutivos (Manel et al. 2003), principalmente em paisagens extremamente fragmentadas. Como é uma área relativamente nova, estudiosos da genética da paisagem vem colocando esforços para testar uma grande variedade de métodos estatísticos (e.g. Cushman et al. 2006, Cushman & Landguth 2010, Wagner & Fortin 2012), técnicas de tratamento espaciais de dados, e favorecendo-se da alta tecnologia do desenvolvimento de marcadores genéticos (Spear et al. 2005, Storfer et al. 2007). No entanto, apesar do crescente número de publicações, Storfer e colaboradores (2010) encontraram que a maioria dos estudos em genética da paisagem ainda está concentrada na América do Norte e Europa, sendo que 90% dos estudos incluem apenas uma espécie e apenas 14,5% desses é realizado com plantas. Portanto, no primeiro capítulo dessa dissertação intitulado “Linking genetics to landscape: large scale study of an Atlantic Rainforest palm species Euterpe edulis” foi realizada uma metanálise com o objetivo de avaliar a contribuição relativa da heterogeneidade ambiental, da adequabilidade ambiental para o estabelecimento da espécie, e dos efeitos antrópicos para explicar a variação da diversidade genética e do grau de endocruzamento em populações de Euterpe edulis ao longo do bioma Mata Atlântica. O segundo capítulo intitulado: “Matrix resistance and habitat loss determines patterns of genetic differentiation in a Rainforest palm species”, avaliou se a perda de habitat e a fragmentação afetam a variabilidade e diferenciação genética do E. edulis. Para responder a nossa pergunta, sete paisagens de 2 km foram analisadas no estado de São Paulo, sudeste do Brasil, totalizando 22 áreas. Para acessar a variabilidade e diferenciação genética dessas áreas, utilizamos 8 locos de microssatélites e usamos comparação de modelos com múltiplas hipóteses concorrentes baseado no critério de informação de Akaike (AIC).

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