Dissertations / Theses: 'Species richness'

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Norris, Beth J. "Species richness estimation for benthic data." Thesis, University of Kent, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593918.

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This thesis addresses species richness estimation for benthic data by describing the clustering of individuals within a species using a Neyman Type A distribution, and incorporating this into species richness estimates. A review of current species richness estimation methods is included . The maximumlikelihood approach to species richness estimation is extended to incorporate the Neyman Type A model, with a gamma mixing distribution on the mean abundance of individuals within a species. Species richness estimates of this model are compared •1 to those of the simpler negative binomial and Poisson models. The use of a penalisedlikelihood is applied to avoid sp uriously large estimates of species richness that can be associated with the 'boundary problem'. The Bayesian approach to species richness is considered, using uninformative and informative priors. Informative priors are elicited using expert opinion obtained from a number of benthic ecologists at the Centre for Environment, Fisheries and Aquaculture Science. These are iDcorporated into species richness estimation in the form of priors, and also converted into penalties for use in the frequentist approach. Several benthic data sets aTe anaJysed throughout, along with a Lepidoptera data set, and a data set from a common bird census carried out in the USA. In addition, several simulation studies are undertaken to illustrate the performance of the estimators. The research culminates in the application of species richness estimators to estimate species mortality due to dredging carried out off the Norfolk coast. Several estimators can be considered to gain a picture of the effect of dredging, and I recommend that species richness estimators should reflect the underlying distribution of t he data. I also recommend that a precautionary approach should be taken when using these estimators in practical applications.

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Hecnar, Stephen J. "Species richness, species turnover, and spatial dynamics of amphibian communities." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0006/NQ30275.pdf.

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Srivastava, Diane Sheila. "Ecological evolutionary limits of local species richness." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244120.

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Vonlanthen, Corinne Maria. "Alpine plant communities : ecology and species richness /." [S.l.] : [s.n.], 2005. http://www.zb.unibe.ch/download/eldiss/05vonlanthen_c.pdf.

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Hager, Heather Anne. "Conservation of species richness, are all umbrella species of similar quality?" Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ27503.pdf.

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Downer, Monica Ruth. "Plant Species Richness and Species Area Relationships in a Florida Sandhill." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4030.

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Pine sandhill are integral pyrogenic communities in the southeastern United States. Though once widespread, habitat destruction, fire suppression and fragmentation have reduced the population to nearly 3%. It is important to learn as much as possible about these unique areas in order to implement best management practices to conserve and restore the existing populations of these communities. Fire is central to the maintenance of pine sandhill communities and two conceptual hypothesis regarding burn frequency have come to light in maintaining the unique species composition and richness of these areas. The first is the Intermediate Disturbance Hypothesis which suggests that intermediate fire regime maintains species diversity. The second is the Most Frequent Fire Hypothesis suggests that these areas should be burned as frequently as fuels allow. We used species area curves and species area relationships to answer the following questions about a pine sandhill community in the burn plot area of the University of South Florida Ecological Research Area (ERA). What are the patterns of species richness and how do they change with spatial scale? What are the factors contributing to the heterogeneity of this area and how much are they contributing? Do similarly burned areas have similar species composition? Do our results shed some light on the Intermediate Disturbance Hypothesis or Most Frequent Fire Hypothesis? We found that physical distance contributed more to species compositional and spatial patterns than burn regime or elevation, whose effects were small. On this particular scale, the results did not support either the Intermediate Disturbance Hypothesis or Most Frequent Fire Hypothesis, as acquisition rates of species in all burn regimes were quite similar. There was no obvious pattern of increased species richness with frequent or intermediate burning. Our results suggest a need for a dynamic plan for the conservation, preservation and management of pine sandhill communities. One must consider as many factors as possible when managing these lands, as every sandhill is unique. More research should be conducted on these ecologically sensitive and diminished areas in order to formulate best management practices to conserve, protect and restore pine sandhill in the southeastern United States.

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Nyberg, Kruys Åsa. "Phylogenetic relationships and species richness of coprophilous ascomycetes." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-625.

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Coprophilous ascomycetes are a diverse group of saprobes, of which many belong to three families, Delitschiaceae, Phaeotrichaceae and Sporormiaceae, within the large order Pleosporales. The natural relationships and circumscription of these families are unclear, especially within the family Sporormiaceae, where the generic delimitation have been questioned. There is also a need to understand how different ecological processes affect species richness and occurrence of coprophilous ascomycetes in general. The aim of this thesis was therefore to test earlier classifications of coprophilous taxa within Pleosporales, using phylogenetic analyses of DNA sequences; and to study how the habitat, dung type and herbivores´ food choice may affect the species richness and species composition of coprophilous ascomycetes.

A phylogenetic study shows that coprophilous taxa have arisen several times within Pleosporales. Sporormiaceae and Delitschiaceae are separate monophyletic groups and should continue to be recognized as two distinct families within Pleosporales. Phaeotrichaceae forms a monophyletic group, and is, unexpectedly, a strongly supported sister-group to Venturiaceae, but if they belong to Pleosporales or not, remains unresolved. Testudinaceae and Zopfiaceae, which previously had an unclear position in Ascomycota, are shown to be members of Pleosporales and should be treated as two separate families. The genus Eremodothis is, however, not related to Testudinaceae, but is nested within Sporormiaceae and should be transferred to Westerdykella.

The natural relationships within Sporormiaceae are still not fully resolved and consequently, I suggest a rather conservative generic classification, accepting Preussia, Sporormia, Westerdykella, as well as Sporormiella, despite that the latter is not conclusively well supported as monophyletic. Characters previously used in the taxonomy and classification of Sporormiaceae, as choice of substrate, presence or absence of an ostiole, presence or absence of germ slits, and spore ornamentation, were all homoplastic and not very useful for circumscribing monophyletic groups.

Field-studies of moose (Alces alces), mountain hare (Lepus timidus) and roe deer (Capreolus capreolus) dung resulted in several new species records, which suggests that coprophilous ascomycetes in boreal Sweden are poorly known. Fungal species richness and occurrence on moose dung varied significantly between habitats. Species diversity was negatively associated with amount of insect attack, and insects feeding either on the dung and/or the fungi may be an important factor explaining the observed pattern. Species richness of coprophilous fungi varied also significantly between different dung types. A study of moose, mountain hare, and roe deer dung did not show any consistent patterns in respect to the animals´ digestive system. There was, however, a general strong positive relationship between the total number of ascomycete species and the number of plant species foraged by the three herbivores. Fungal species with large spores (≥ 50 µm) were over-represented on roe deer dung, and under-represented on moose dung, while the reverse was found for species with small spores (<10µm). This suggests that the foraging level of the herbivore, which in turn mirrors species-specific differences in spore dispersal of the fungi, may be an important factor in explaining species richness and diversity of the coprophilous community.

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Dupré, Cecilia. "Regional and local variation in plant species richness." Doctoral thesis, Uppsala universitet, Institutionen för evolutionsbiologi, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-691.

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In this thesis, I examine the variation in plant species richness along gradients of productivity and disturbance in grasslands and forest habitats in southern Sweden, and I compare the documented patterns with theoretical predictions. Moreover, I evaluate the relative importance of habitat quality and habitat configuration for the occurrence of field layer species in deciduous forests. Finally, I present a new method for the determination of the regional species pool. To examine regional and local variation in plant species richness, I gathered data on species composition in plots of different size (0.001 - 1000 m2) in three vegetation types (deciduous forests, dry grasslands and coastal meadows) in four regions of southern Sweden (Öland, Gotland, Småland and Uppland). As predicted by the species pool hypothesis, differences in small-scale species richness of deciduous forests and dry grasslands were correlated with differences in the size of the regional species pool. Moreover, among plots large-scale diversity was predictive of small-scale diversity. Species diversity showed a hump-shaped relationship with productivity in forests, and was related to environmental heterogeneity and the size of the 'habitat-specific' species pool. In the two types of grassland examined, grazed sites were richer in species than abandoned sites. Moreover, both species composition and the representation of plants with different life-history characteristics differed between grazed and abandoned sites. As predicted by the intermediate disturbance hypothesis, species richness was highest at intermediate levels of grazing in coastal meadows. However, all the above patterns were scale-dependent, and not observed at all plot sizes. The occurrence of field layer species in deciduous forests was more strongly related to habitat quality (mainly soil factors) than to habitat configuration (forest area and isolation). Across species, low seed production, clonal reproduction and habitat specificity were negatively associated with isolation.

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Nyberg, Kruys Åsa. "Phylogenetic relationships and species richness of coprophilous ascomycetes /." Umeå : Univ, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-625.

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Dupré, Cecilia. "Regional and local variation in plant species richness /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5064-4/.

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Orme, Christopher David L'Estrange. "Body-size and macroevolutionary patterns of species richness." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398022.

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Harral, Josephine Erica. "Experiments on resource availability and plant species richness." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415053.

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Steinmann, Katharina. "Testing basic assumptions of species richness hypotheses using plant species distribution data /." Zürich, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000254735.

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Giles, Mark. "Patterns of Species Rarity as a Driving Mechanism for Species Richness Gradients." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40587.

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Broad scale geographic variation in species diversity correlates with environmental variables in most taxa, but a mechanistic understanding of this relationship has remained elusive. More than a half-century ago, F.W. Preston observed that the number of individuals per species in species assemblages is log-normally distributed (with two parameters: the total number of individuals, I, and the number of individuals of the rarest species, m). Here, we show that ϕ, a proxy for m, is correlated with environmental variables in several datasets of trees, birds, fish, and invertebrates. Moreover, variation in species richness is more strongly related to this measure of rarity than to environment. In all the datasets we examined, structural equation models are consistent with the hypothesis that environmental variables affect species richness principally by affecting rarity, which in turn affects richness. We propose that geographic variation in the ability of species to persist at low densities provides a possible unifying explanation for global gradients of species richness. Our findings may have important implications regarding Earth’s biodiversity, highlighting the rarest species as those most at-risk but also important indicators for the ongoing consequences of climate change.

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Steck, Claude Eugen. "Conservation of grasshopper species richness in a changing landscape." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29787.

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Nicolakakis, Nektaria. "Innovation rate, brain size and species richness in birds." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31280.

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The number of species varies greatly among taxa. In birds, for example, the parvorder Passerida contains 3556 species while the Odontophorida (New World Quails) contains only six species. This uneven distribution of species among avian taxa is not random and therefore warrants an explanation. The behavioral drive hypothesis stipulates that the capacity for innovation, coupled with the rapid transmission of the behavioral novelty to conspecifics, may expose individuals to new selective pressures and help fix mutations that would otherwise not be expressed. This should lead to accelerated rates of evolution. I test this hypothesis by examining the link between behavioral flexibility and the number of species per taxon. I adopt a comparative approach and seek a general explanation of richness, thereby removing the traditional focus placed on the success of the songbirds and on their complex singing apparatus. I use two measures of flexibility, feeding innovation rate and relative brain size. (Abstract shortened by UMI.)

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Williams, Brandon M. "The influence of soil heterogeneity on plant species richness." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/10650.

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Environmental heterogeneity is often cited as one of the driving mechanisms behind community species composition and diversity. However, its contribution to species composition in plant communities remains unclear because few experiments demonstrate a causal link between environmental heterogeneity and plant diversity. This is particularly true for soil manipulations despite that fact that soil is expected to provide the key resources necessary for plant growth. Here, I utilize a unique manipulation of the soil profile to create communities with spatially heterogeneous and homogeneous soil arrangements and examine the influence of soil heterogeneity on community structure, through species composition and flowering patterns, during community assembly. I employed an annual census of the assembling communities and recorded the identity and density of all species within the patches. After two years, I found that species richness was significantly higher in heterogeneous than in homogeneous plots. In the heterogeneous plots, thirteen species had higher greater establishment rates in a specific patch type representing one of the three soil strata. However, no species had greater association with the mixed stratum, comprising the homogeneous plots, than one of the heterogeneous strata. This pattern of species sorting between soil types suggests that the increased richness in heterogeneous plots is due to the increased variety of soil types comprising those communities. Alternatively, species richness in homogeneous plots, where species did not sort to distinct soils, was strongly associated with total plant density. This experiment is one of the first to provide clear, experimental evidence that fine-scale soil heterogeneity increases species richness through species sorting during community assembly.
Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences

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Cardillo, Marcel. "The evolution of the latitudinal gradient in species richness /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16383.pdf.

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Boucher-Lalonde, Véronique. "Predicting Broad-scale Patterns in Species Distributions." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34306.

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Species richness of virtually all high-level taxonomic groups is strongly statistically related to climatic variables such as temperature and precipitation, and consistently so across space and time. These observations are consistent with a causal link between the number of species that occur in a given region and its climate. Although dozens of hypotheses have been proposed, the main mechanisms underlying this pattern remain largely unresolved. And, few ecological studies have attempted to identify regularities in the individual species distributions that make up the richness–climate relationship. Despite the complexities of species’ biologies, I found that, to a first approximation, species’ probability of occupancy at continental scales were generally well statistically explained by a Gaussian function of temperature and precipitation. This simple model appeared general among species, taxa and regions. However, although individual species’ ranges are strongly statistically related to climate, spatial variations in richness cannot be explained by systematic variations in species’ climatic niches. And, individual species track changes in climatic variables through time much more weakly than species richness tracks these changes, suggesting that richness is at least partly constrained by mechanisms independent of species identities. Moreover, at macro-scales, species richness was also not strongly predictable from the temperature at which clades have originated, from historical variability in climatic variables nor from local short-term extirpation rates. In sum, I rejected several prominent hypotheses aiming to explain richness–climate relationship and found several lines of evidence inconsistent with the common idea that climatic constraints on individual species, by themselves, can explain richness–climate relationship. I propose a mechanism to explain, as a first approximation, the continental biogeography of species distributions that relies on neutral processes of dispersal and local extinctions within species’ broad deterministic thermal tolerances.

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Wells, Emma Claire. "Seaweed species biodiversity on intertidal rocky seashores in the British Isles." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/1178.

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Karns, Rachael Cassandra. "Microbial Community Richness Distinguishes Shark Species Microbiomes in South Florida." NSUWorks, 2017. http://nsuworks.nova.edu/occ_stuetd/453.

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The microbiome (microbial community) of individuals is crucial when characterizing and understanding processes that are required for organism function and survival. Microbial organisms, which make up an individual’s microbiome, can be linked to disease or function of the host organism. In humans, individuals differ substantially in their microbiome compositions in various areas of the body. The cause of much of the composition diversity is yet unexplained, however, it is speculated that habitat, diet, and early exposure to microbes could be altering the microbiomes of individuals (Human Microbiome Project Consortium, 2012b, 2012a). To date, only one study has reported on microbiome characterization in a shark (Doane et al., 2017; skin microbiome of the common thresher shark). A comparative characterization of microbiomes sampled from different shark species and anatomical locations will allow an understanding of the differences in microbiomes that may be explained by variance in shark habitat and diet. Florida leads as shark bite capitol of the world, with 778 unprovoked bites recorded since 1837, or 4-5 average bites per year. With only a few bites a year, there is not a lot of opportunities to study these bites. What can be studied, however, is how the microbial environment in shark’s teeth is composed. To understand overall microbiome composition, and if microbiomes are distinct from the environment, or specific by species or anatomical location (henceforth location), we characterized microbiomes from the teeth, gill, skin, and cloacal microbiomes of 8 shark species in south Florida (nurse, lemon, sandbar, Caribbean reef, Atlantic sharpnose, blacktip, bull, and tiger) using high throughput DNA sequencing of the 16S rRNA gene V4 region. There was a significant difference in microbial community richness among species, sample location, but not the interaction between species and location. Microbial diversity by location was significantly different for both the Shannon index and Inverse Simpson index. Samples examined by species had no significant difference in microbial community diversity overall for both Shannon and Inverse Simpson indexes. Microbial community diversity of samples by location and species combined significantly differed when submitted to an analysis of variance with the Shannon index, but not the Inverse Simpson index. Teeth microbial communities showed the most diversity based on both Shannon and Inverse Simpson indices. Teeth microbiomes are distinct but also share taxa with the water they inhabit, including potentially pathogenic genera such as Streptococcus (8.0% ± 9.0%) and Haemophilus (2.9% ± 3.3%) in the Caribbean reef shark. The lemon shark teeth hosted Vibrio (10.8% ± 26.0%) and the Corynebacterium genus (1.6%±5.1%). The Vibrio genus (2.8% ± 6.34%), Salmonella enterica (2.6% ± 6.4%), and the genus Kordia (3.1% ± 6.0%) are found in the nurse shark teeth microbial community. Strikingly, the Vibrio genus was represented in the sandbar shark (54.0% ± 46.0%) and tiger shark (5.8% ±12.3%) teeth microbiomes. One OTU related to traditionally non-pathogenic family Phyllobacteriaceae appear to be driving up to 32% of variance in teeth microbiome diversity. We conclude that south Florida sharks host distinct microbiomes from the surrounding environment and vary among species due to differences in microbial community richness. Future work should focus on bacteria found in shark teeth to determine if those present are pathogenic and could provide insights to bite treatment.

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White, Peter. "The effects of biotic and abiotic forces on species richness." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104714.

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One central question in ecology is why some areas have many species and others have few. Many explanations have been proposed and often the forces that drive species richness are context-dependent. These forces are divided into two general categories: biotic drivers and abiotic drivers. Biotic drivers are most commonly described in terms as top-down and bottom-up effects while abiotic drivers are commonly described in terms of climate and habitat disturbance. The objective of this thesis is to determine how these drivers affect species richness in terrestrial ecosystems. To test this I examine an insect herbivore assemblage in a disturbed forest fragment landscape in southern Canada. I use geographic information systems techniques to determine the impact of a natural episodic disturbance (i.e. an abiotic natural driver) and a chronic human disturbance (i.e. an abiotic human driver) on forest habitat quality (Chapter 1) and on a forest-dwelling caterpillar assemblage (Chapter 2). I show that ice storms result in a heterogeneous pattern of spatial damage across a forest landscape, differing depending on the type of coarse woody debris examined. These different types of coarse woody debris provide habitat for a diversity of taxa. In contrast with natural disturbance, I found that human-based disturbance do not have a positive impact on caterpillar assemblages. Pursuant to this, I explore the concept of habitat quality from the perspective of host plant identity (Chapter 3) and host plant quality (Chapter 4). I found that caterpillar assemblages have strong host plant preferences and that these preferences may depend on quadrat-scale foliar qualities (i.e. a biotic bottom-up driver) and parasitoid densities (i.e. a biotic top-down driver) at different times in the growing season. This thesis adds to a growing body of literature aimed to better understand the drivers of insect species richness across disturbed landscapes. In addition, this thesis develops several management-specific tools for measuring forest disturbance and provides valuable insight into how the selection of different tree species for planting initiatives can have important impacts on forest communities.
Les communautés forestières qui habitent les parcelles de forêts qui subsistent aujourd'hui sont affectées par les perturbations ainsi que par la qualité de l'habitat que leur procure les plantes-hôtes. Ces deux phénomènes ont un impact particulièrement important dans les paysages modifiés par l'activité humaine. Développer une meilleure compréhension de ces phénomènes va faciliter la prise de décision et les efforts de conservations visant à préserver et protéger la biodiversité des forêts. L'objectif global de cette thèse est d'étudier les divers aspects reliés à la qualité de l'habitat dans les parcelles forestières des collines montérégiennes du sud-est du Québec, Canada. J'utilise des techniques en système d'information géographique pour déterminer l'impact d'une perturbation naturelle épisodique (tempête de verglas) ainsi qu'une perturbation anthropogénique chronique (sentiers récréationnels) sur la qualité des habitats forestiers (Chapitre 1) et un assemblage de chenilles vivant en forêt (Chapitre 2). J'ai démontré que les dégâts engendrés par les tempêtes de verglas sont distribués de façon hétérogène à travers le paysage forestier, différant selon le type de débris ligneux grossiers examiné. Ces différents types de débris ligneux grossiers servent d'habitat à divers groupes taxonomiques. J'ai découvert que les perturbations anthropogéniques, au contraire des perturbations naturelles, n'ont pas eu d'impacts positifs sur les assemblages de chenilles vivants en forêt. J'ai également exploré le concept de qualité d'habitat en considérant l'identité de la plante hôte (Chapitre 3) et la qualité foliaire à l'échelle du quadrat (Chapitre 4). J'ai découvert que l'assemblage de chenille démontre des préférences marquées pour certaines plantes hôtes et que ces préférences peuvent dépendre de différentes qualités foliaires à l'échelle du quadrat à différentes périodes durant la saison de croissance. Cette thèse contribue à la documentation croissante sur les facteurs qui affectent la richesse spécifique des communautés d'insectes vivant dans les forêts des paysages perturbés. De plus, cette thèse propose plusieurs outils spécifiques à la gestion pour évaluer les perturbations en milieu forestier et donne un aperçu de l'impact que peut avoir la sélection de différentes espèces d'arbres sur les communautés forestières lors de l'élaboration d'initiatives de plantation d'arbres.

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Castellano, Jorge Aurora. "Species richness in riparian vegetation, a pilot study in Halmstad." Thesis, Högskolan i Halmstad, Miljövetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-27952.

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The riparian forests are hotspots of biodiversity and serve important roles in maintainingthe water quality. The study and understanding of this ecosystem is basic to know how theriparian zones respond to the threat and the changes produced by the urbanization. Theobjective of this pilot study was to know the species richness and check the status of theriparian vegetation along two different rivers in Halmstad, Nissan and Fylleån. The studywas focus on the status of trees at both rivers to see if the proximity of the city has anyimpact on the biodiversity. In total 9 different species were found, nevertheless only 3 ofthese species were founded on both localizations: Quercus robur, Betula pendula and Pinussylvestris. The Shannon Index showed a higher biodiversity on Nissan riparian zones, whichis the river that present the urban component. The urban area is the one that presentshigher level of biodiversity, tree species and number of individuals but there are notenough to be in a good standard. The result just show that the urban area is in a bettercondition that the natural one. The institutional efforts should be focusing on preserveboth environments with special attention to the natural environment.

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Payan, Garrido C. E. "Hunting sustainability, species richness and carnivore conservation in Colombian Amazonia." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18773/.

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Colombia embraces 7% of the Amazon basin, a worldwide conservation priority ecosystem, and most of it overlaps with indigenous territories. Some indigenous communities live inside protected areas and the impact of people in parks on biodiversity is uncertain. This work compares harvests measures hunting sustainability from indigenous people, prey species richness and carnivore density in a protected area and an unprotected area in Amazonia. Field data collection was collected for 14 months by recording hunting harvests from indigenous groups inside and outside Amacayacu National Park and camera trapping in their respective hunting catchment areas. Hunting harvests, catchment areas sizes and hunters effort where comparable between sites, Catch Per Unit (CPU) effort was slightly here in the unprotected site, nevertheless hunters harvested equal biomass to those in the park. Hunting of the largest mammal species at both sites showed evidence of unsustainable extraction rates and were taken more often than expected from availability. The majority of hunting occurred within 15 km from towns and hunting within the first 5 km was higher in the unprotected area. Relative abundance indexes of game species presented no strong difference between sites. Edge effect from hunting towns was evident at a large scale and the probability of detecting game species and carnivores farther from town was significantly higher. Jaguar (Panthera onca) and ocelot (Leopardus pardalis), densities did not vary significantly outside or inside the park. These densities are reported for the first time in Colombia. Prey base of indigenous communities showed decreased abundance outside the park, and the continuing hunting pressure could drive large game species to local extinction, unless limits to human increase and sustainable hunting is achieved, particularly in the unprotected area.

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Muller, Michael René. "Environmental correlates of avian species richness over southern Ontario, Canada." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10250.

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Species richness is an ecologically important descriptor of ecosystems and, as a component of biodiversity, may be useful for conservation planning. Global and local patterns of richness have been related, with moderate success, to climatic and habitat parameters respectively. However our ability to predict species richness breaks down at intermediate scales (quadrats 10$\sp0$-10$\sp3$ km$\sp2$ in size extending over regions of 10$\sp3$-10$\sp6$ km$\sp2$). We examined the spatial variation in breeding bird species richness in 100 km$\sp2$ squares, across 200,000 km$\sp2$ of southern Ontario, and tested for relationships with a suite of environmental variables that included, climate, human population, land cover, a heterogeneity index, soil fertility and parkland. We conclude that at this spatial scale, the variation in total avian species richness over southern Ontario is not sufficiently well related to either temperature or habitat to warrant further investigation of possible mechanistic links. The richness of certain guilds, however, shows some promise as a possible measure for conservation planning and management. (Abstract shortened by UMI.)

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Stuart-Fox, Devi M. "Evolution of colour variation and species richness in agamid lizards /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16809.pdf.

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Yu, Zequn [Verfasser], Jürgen [Akademischer Betreuer] Bauhus, and Michael [Akademischer Betreuer] Scherer-Lorenzen. "The influence of tree species richness on tree nutrition in a subtropical mixed-species experiment." Freiburg : Universität, 2019. http://d-nb.info/119003137X/34.

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Brüsin, Martin. "Influence of landscape scale and habitat distribution on individual bat species and bat species richness." Thesis, Linköpings universitet, Biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111400.

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Habitat fragmentation is one of the most important factors affecting species extinction and biodiversity loss, Species habitat response expects to differ with habitat feature at different spatial scales and this study was to identify how bat diversity and individual bat species respond to different habitat amounts. The local bat species richness was observed in 156 different locations in Östergötland and the proportion of different habitats were calculated for circular areas with diameters ranging from 400 m. to 12 km. from each location. Although we found that the individual bat species responded differently to the amount of each habitat at different spatial scales, the bat species richness showed a decreasing response with increasing spatial scale. The strongest response of bat species richness to habitat characteristics was at a scale of 939 m.

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Bogardus, David C. "Comparison of tree species richness and species diversity in public landscapes of Broward County, Florida." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024623.

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De, Camargo Rafael Xavier. "Effects of Habitat Change on Bird Species Richness in Ontario, Canada." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26258.

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It is generally assumed that when natural habitat is converted to human-dominated cover such area is “lost” to its native species. Extinctions will ensue. The literature generally assumes that species are extirpated as natural area is reduced, following the well-known species-area relationship (SAR). However, SARs have consistently over-estimated species losses resulting from conversion of natural habitat to human-dominated land covers. We hypothesize that the overestimation occurs because these area-based models assume that converted habitat is “lost”, eliminating all species. However, in the real world, conversion of natural land cover to human-dominated cover frequently produces new land covers, different from the original habitat, but not necessarily completely inhospitable to biodiversity. We evaluated the responses of total avian richness, forest bird richness and open habitat bird richness to remaining natural area within 991 quadrats, each 100 km2, across southern Ontario. Total bird species richness does not follow SAR predictions; rather, the number of bird species peaks at roughly 50% natural land cover. The richness of forest birds does follow the usual SAR power-law as a function of forested area. In contrast, richness of birds that prefer open-habitat does not increase monotonically with either natural- or human-dominated land cover. However, we can partition human-dominated land cover into an “available human-dominated” component and “lost” habitat. Richness of open-habitat species relates to the amount of available human-dominated cover. Distinguishing three habitat types (natural, available human-dominated, and lost) permits accurate predictions of species losses in response to natural habitat conversion.

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Tognelli, Marcelo Fabio. "Patterns of species richness and conservation of South American terrestrial mammals /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

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Entling, Wiebke. "Macroecology of European spiders : habitat specialization, body size and species richness /." [S.l.] : [s.n.], 2008. http://www.zb.unibe.ch/download/eldiss/08entling_w.pdf.

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Beccaloni, George William. "Studies on the ecology and evolution of Neotropical ithomiine butterflies (Nymphalidae: Ithomiinae)." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307456.

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Dower, Katherine Mary. "Sand inundation on rocky shores : its effects on species richness and the structure of species assemblages." Thesis, Rhodes University, 1990. http://hdl.handle.net/10962/d1007183.

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Although sand deposits are present on many intertidal rocky shores, their effects on species richness, zonation and trophic structure have often been overlooked. This study is the first to recognise sand as an important abiotic factor on South African rocky shores. Rocky shores in the eastern Cape Province of South Africa are subject to extensive sand inundation and are composed of two hard substrata of differing topographies. Four sites on one substratum and six on the other were sampled quantitatively using quadrats. The biota were identified, counted and/ or weighed to provide a matrix of species biomass and numbers in separate zones. This matrix was then analysed using ordination and classification. A total of 321 species were identified which is more than local rocky or sandy shores. While the intermediate disturbance hypothesis would predict high species richness on these shores, it does not fully explain this richness nor the distribution of species assemblages. Habitat heterogeneity, including the dynamics of sand deposits, is strongly influenced by substratum topography and is the most important factor generating species richness. Abrasion by sand (sand scour) causes local reductions in richness but the presence of semi-permanent sand deposits allows habitation by psammophilic and sand-dependent species. As a result the biota of a sand inundated rocky shore includes both a full rocky shore and a large sandy beach component. Substratum topography controls patterns of sand deposition and retention and community analysis showed that samples were clustered primarily according to species richness and secondarily according to substratum type. Ordination of species identified an arc of species assemblages of decreasing levels of sand tolerance. These corresponded to sample groupings so that th assemblages found in various habitats were characterised by particular levels of sand tolerance. The presence of sand has a negative effect on the biomass of primary producers and filter feeders but a positive effect on the biomass of deposit feeders. Because sand is retained to different degrees in different zones, trophic structure varies between zones and to a lesser extent, between rock types. In general, however, the trophic structure of sand inundated rocky shores is similar to that of non-inundated shores.

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Jezkova, Tereza, and John J. Wiens. "What Explains Patterns of Diversification and Richness among Animal Phyla?" UNIV CHICAGO PRESS, 2017. http://hdl.handle.net/10150/623200.

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Animal phyla vary dramatically in species richness (from one species to >1.2 million), but the causes of this variation remain largely unknown. Animals have also evolved striking variation in morphology and ecology, including sessile marine taxa lacking heads, eyes, limbs, and complex organs (e.g., sponges), parasitic worms (e.g., nematodes, platyhelminths), and taxa with eyes, skeletons, limbs, and complex organs that dominate terrestrial ecosystems (arthropods, chordates). Relating this remarkable variation in traits to the diversification and richness of animal phyla is a fundamental yet unresolved problem in biology. Here, we test the impacts of 18 traits (including morphology, ecology, reproduction, and development) on diversification and richness of extant animal phyla. Using phylogenetic multiple regression, the best-fitting model includes five traits that explain approximate to 74% of the variation in diversification rates (dioecy, parasitism, eyes/photoreceptors, a skeleton, nonmarine habitat). However, a model including just three (skeleton, parasitism, habitat) explains nearly as much variation (approximate to 67%). Diversification rates then largely explain richness patterns. Our results also identify many striking traits that have surprisingly little impact on diversification (e.g., head, limbs, and complex circulatory and digestive systems). Overall, our results reveal the key factors that shape large-scale patterns of diversification and richness across >80% of all extant, described species.

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Kretz, Lena. "The role of adjacent vegetation on the recovery of riparian flora : Effect of upstream and upland vascular vegetation after stream restoration in a boreal catchment." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-108082.

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Restoration of streams that were formerly channelized for timber-floating has become increasingly common. Generally, this restoration returns boulders from riparian zones to streams, leading to wider, more heterogeneous channels with slower flows. The primary goal is to enhance fish populations, but riparian vegetation is also expected to be favoured. However, increases in floristic diversity have not been observed and reasons for this slow response are still unknown. One possible explanation might be the lack of colonist pools. I therefore investigated how surrounding plant compositions influence riparian recovery. The vascular plant flora was identified in riparian sites and in adjacent upstream riparian and upland sites. Four reach types were included: unchannelized, channelized, restored and demonstration restored. Species richness and floristic similarities among types of sites and reaches were compared. Correlations with upland and upstream channel slopes were made and the importance of variation in seed floating ability was tested. The results show that unchannelized reaches were floristically similar to their adjacent upstream riparian and upland sites, whereas channelized reaches showed more different floras. Restoration created a somewhat more homogeneous flora among the three site types and demonstration restored reaches were most similar to upstream sites. Soil moisture conditions (i.e. wetland vs. forest) in the uplands had stronger impacts on species similarities than upland or upstream channel slopes. I conclude that adjacent sites are important for floristic recovery of riparian reaches and that demonstration restoration is most advantageous for riparian recovery. I recommend protection of upland sites from forestry to facilitate recovery.
Local- and landscape-scale effects on biodiversity after stream restoration

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37

Ödeen, Anders. "Effects of Post-Glacial Range Expansions and Population Bottlenecks on Species Richness." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1426.

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This thesis relates modern speciation theory to the effects of sudden changes in the range and size of populations. Special reference is made to the climatic oscillations during the Quaternary ice ages. A meta-analysis of laboratory experiments showed that support for allopatric speciation is weak, especially for the peripatric type of allopatric speciation. Furthermore, factors traditionally believed to increase the likelihood of speciation have had little effect on the generation of reproductive isolation in speciation experiments. However, the method of testing reproductive isolation appeared important, in the sense that experimentally derived sister populations were likely to demonstrate reproductive isolation from each other but not from the unaffected mother population. Raw data from mating tests showed that the poor isolation between mother and daughter populations was an effect of asymmetric mate preferences towards males from the mother population. This suggests that peripatric speciation can be effective in generating reproductive isolation between sister populations. The proposed mechanism is that males become less attractive to females by losing certain secondary sexual traits during population bottlenecks, and that females shift their preferences towards other male traits. Support for this mode of speciation is found in the widespread bird genus Motacilla (wagtails). This genus is characterised by extensive plumage variation and contains a large number of widely distributed taxa in the northern parts of its distribution. This thesis shows that taxonomic diversity of wagtails is inversely related to complexity in song and to diversity in molecular and mitochondrial markers. The northern taxa seem to be descendants of southern populations, which were subjected to bottlenecks during expansions into re-opened habitats after the last ice age. The bottlenecks would not only reduce genetic diversity but also inhibit cultural transmission of song to the leading edge of colonisers, allowing sexual selection on other traits, such as plumage. Rapid plumage differentiation among wagtail taxa appears to be a recurrent process and has lead to convergent evolution, making the currently recognised species Motacilla flava (Yellow Wagtail) polyphyletic.

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Wesheu, Irene Catherine. "Species richness - standing crop relationships on an infertile shoreline in Nova Scotia." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5200.

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Blocksome, Carolyn E. "Sericea lespedeza (Lespedeza cuneata) : seed dispersal, monitoring, and effect on species richness." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/192.

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40

Ödeen, Anders. "Effects of post-glacial range expansions and population bottlenecks on species richness /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5140-3/.

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Hopton, Matthew E. "Relationship Between Environmental Heterogeneity and Patterns of Species Richness of Terrestrial Vertebrates." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1139689520.

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42

Dyer, E. "A global study of the distribution and richness of alien bird species." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1475851/.

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Alien species are a major component of human-induced environmental change, yet spatial and temporal variation in the drivers of their introduction, and their subsequent distribution and richness, are poorly understood. Here, I present a global analysis of the drivers of this variation for a major animal group, birds (Class Aves), using the newly-created Global Avian Invasions Atlas (GAVIA) database. GAVIA includes information on introduction successes and failures, enabling me to examine the effect of colonisation pressure (the number of species introduced) on alien bird distributions. A description of the GAVIA database is given in Chapter 2, with details on its scope and sources, data collation and validation, and the production of alien range maps. Chapter 3 focuses on the early stages of the invasion pathway, and shows that historical introductions tend to originate in Europe, were driven by the global movements of British colonialism, and involved species deemed useful. Modern introductions, in contrast, tend to originate in Southeast Asia and Africa, are driven by factors associated with wealth, and involve species found in the pet trade. Chapter 4 identifies colonisation pressure as the principal determinant of alien bird species richness at a global scale. Additional anthropogenic factors (residence time, distance to historic port) and environmental variables (temperature range, precipitation) also influence richness. Chapter 5 analyses the factors influencing alien geographic range size, with species achieving a larger alien range if they have been introduced more often, have a larger native range and a shorter residence time. Chapter 6 examines latitudinal patterns of alien species richness and range size, and the likelihood of failure relative to latitude and native range limits. Overall, I demonstrate that alien bird distributions are primarily driven by anthropogenic influences, and highlight in particular the importance of incorporating a measure of colonisation pressure into studies of invasion.

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Pender, Jocelyn E. "Climatic Niche Estimation, Trait Evolution and Species Richness in North American Carex (Cyperaceae)." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34334.

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With close to 2100 species, the flowering plant genus Carex (Cyperaceae; sedges) is an example of an evolutionary radiation. Despite its potential for use as a model taxon in evolutionary studies, the diversification of sedges remains largely unexplored. This thesis realizes the potential of Carex as an evolutionary model group by using it to ask questions about species richness patterns. More specifically, it seeks to determine the relationship, if any, between rates of trait evolution and species richness. This tests the hypothesis that organisms with increased abilities to evolve new traits, speciate more rapidly. Morphological and ecological (habitat and climatic niche) traits are modelled on a nearly complete regional (North America north of Mexico) phylogeny and rates of trait evolution are compared among non-nested sister groups. However, before trait evolution is modelled, this work evaluates the sensitivity of climatic niche estimates to underlying distribution datasets. It tests the agreement of niche estimates derived from the commonly used online repository GBIF (the Global Biodiversity Information Facility) and county-level distributions via BONAP (the Biota of North America Program). Results showed that in the context of phylogenetic comparative analyses, it is not vital to obtain highly accurate climatic niche estimates. The second study found significant positive correlations between the rates of climatic niche, habitat and reproductive morphological evolution and species richness. This result supports the role of high trait lability in generating species richness and more generally, the idea that high trait disparity through evolutionary time leads to species success.

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Henriksson, Anna. "Biotic resistance in freshwater fish communities." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110251.

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Invasions of non-native species cause problems in ecosystems worldwide, and despite the extensive effort that has been put into research about invasions, we still lack a good understanding for why some, but not other, communities resist these invasions. In this doctoral thesis I test hypotheses on biotic resistance using a large dataset of more than 1000 both failed and successful introductions of freshwater fish into Swedish lakes. We have found that the classic species richness hypothesis is a poor descriptor of introduction success because it fails to acknowledge that resident species contribute to the resistance in different ways. We developed a new measure of biotic resistance, the weighted species richness, which takes into account that the resident species contributes to the resistance with different strength and sign. Further, we correlated performance traits of species in their role as an invader and as a resident species to predict how the biotic resistance of these communities would develop over time. We found a positive correlation between performance traits: Some species have high introduction success, they make a large contribution to the resistance, and they cause extinctions when introduced but do not go extinct themselves when other species establishes, whereas other species are weak performers in these respects. Thus, the biotic resistance of these communities should grow stronger as non-native species accumulates. These results give us clues about what type of communities that should be most sensitive to further invasions, i.e., communities harboring species weak performers. My results show that the biotic resistance of communities is an important factor in determining invasibility of a community. They also show that methods for quantifying resistance must take into account how interactions are structured in nature. What determine the biotic resistance of a community is the type of interactions that the resident species have with the invader and not the species richness of the community.

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Nielsen, Uffe Nygaard. "Influences on species richness and composition of belowground communities at multiple spatial scales." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24811.

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46

Hoare, David Barry. "Patterns and determinants of species richness in mesic temparate grasslands of South Africa." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1275.

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The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.

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Van, Tonder Carlo. "Factors influencing species richness, cover and composition of vegetation on Namaqualand quartz fields." Thesis, Nelson Mandela Metropolitan University, 2006. http://hdl.handle.net/10948/630.

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Quartz fields contribute significantly to plant diversity in the Succulent Karoo biome. They are distinctly different from surrounding habitats and have high levels of plant endemism. Biological soil crusts are features of quartz field soils and fulfill a vital function in that they stabilize soils. It is important for managers of nature reserves and agricultural rangelands to know what factors influence quartz field soils and vegetation. Both stakeholders could benefit from new information that would allow for informed decision-making regarding land-use on quartz fields. The present study took place in the Namaqua National Park that contains a significant proportion of the Riethuis-Wallekraal quartz fields phytochorion. The first part of the study aimed to understand whether certain land-use activities potentially destabilize quartz field soils, which might have possible ramifications for associated biological soil crusts and vegetation. It was followed by relating variation in soil stability with species richness, cover and species composition of quartz field vegetation. Overall, positions assumed to be impacted by land-use activities had less stable soils compared to positions assumed not be impacted. Soil stability had a significant influence on species richness and cover but to a lesser degree on species composition. Quartz field vegetation was significantly influenced by soil physical and chemical properties as well as location in the quartz fields landscape. The second part of the study aimed at understanding how species richness of isolated quartz outcrops is related to their size compared to that of a mainland body of quartz outcrops. No clear species-area relationships emerged from the study. There were significant differences between isolated outcrops and mainland outcrops in substrate and vegetation composition. Findings are discussed in relation to Island Biogeography Theory.

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Jobe, R. Todd White P. S. "Biodiversity and scale determinants of species richness in Great Smoky Mountains National Park /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,398.

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Curriculum of Ecology." Discipline: Ecology; Department/School: Ecology.

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Boag, Angela Elaine. "Spatial models of plant species richness for British Columbia's Garry oak meadow ecosystem." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46920.

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Garry oak meadow ecosystems in British Columbia are fragmented, increasingly degraded, and have been prioritized for conservation. While distribution maps of remnant meadow patches have been developed, the ecological integrity of plant communities in many of these remnants remains unknown. Modeling and mapping ecological integrity could inform conservation prioritization exercises in the region. The primary goal of this thesis was to develop distribution models of native and exotic plant species richness in Garry oak meadow remnants. Secondly, multiple independent datasets were used to analyze the effects of sample size and sampling bias on the accuracy and reliability of resulting predictive maps, which is an active area of research in species distribution modeling. Finally, I investigated whether Terrestrial Ecosystem Mapping (TEM) – a publicly available GIS layer of plant community associations – provided a valid geographical extent over which to map predictions. In Chapter 2, different datasets were found to produce different models of species richness. However, different native richness models produced similar distribution maps, while exotic richness maps based on different datasets were less similar. The incorporation of spatial variables into models did not improve model fit, however significant residual spatial autocorrelation at a broad scale was detected in some cases, suggesting that an important environmental covariate is missing from these models. Examples of potential missing covariates include deer density and disturbance history. Overall, this research demonstrates that multiple independent datasets are very important iii for validating species distribution models, especially in heterogeneous landscapes. Additionally, large sample sizes and sampling broadly across of the area of prediction result in more robust models. The results presented in Chapter 3 suggest that mapping predictions exclusively over Garry oak ecosystem-classified TEM polygons is potentially overly conservative, as species richness of native meadow species was found to be high in other TEM classifications as well. This suggests that Garry oak meadow plant communities do not exist solely in discreet meadow patches, and that they are dispersed throughout other habitat types including Douglas-fir – salal forests.

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Scholes, Lianna. "The response of species richness to manipulations of energy supply in protist microcosms." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421224.

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Dissertations / Theses on the topic 'Species richness'

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