Dissertations / Theses on the topic 'Abundance models'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Abundance models.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Jensen, Adam G. "Updated interstellar abundance studies and implications for dust models." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256457.
Full textEnsign, William E. "Multiple-scale habitat models of benthic fish abundance in riffles." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/38204.
Full textPh. D.
Forney, Karin A. "Patterns of variability and environmental models of relative abundance for California cetaceans /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9823699.
Full textBlanchard, Monica R. "Using Network Models to Predict Steelhead Abundance, Middle Fork John Day, OR." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4477.
Full textMomal, Raphaëlle. "Network inference from incomplete abundance data Accounting for missing actors in interaction network inference from abundance data Tree‐based inference of species interaction networks from abundance data." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASM017.
Full textNetworks are tools used to represent species relationships in microbiology and ecology. Gaussian Graphical Models provide with a mathematical framework for the inference of conditional dependency networks, which allow for a clear separation of direct and indirect effects. However observed data are often discrete counts and the inference cannot be directly performed with this model. This work develops a methodology for network inference from species observed abundances. The method relies on specific algebraic properties of spanning tree structures to perform an efficient and complete exploration of the space of spanning trees. The inference takes place in a latent space of the observed counts.Then, observed abundances are likely to depend on unmeasured actors (e.g. species or covariate). This results in spurious edges in the marginal network between the species linked to the latter in the complete network, causing inaccurate further analysis. The second objective of this work is to account for missing actors during network inference. To do so we adopt a variational approach yielding valuable insights about the missing actors
Harris, Danielle V. "Estimating whale abundance using sparse hydrophone arrays." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3463.
Full textRoss, Beth E. "Assessing Changes in the Abundance of the Continental Population of Scaup Using a Hierarchical Spatio-Temporal Model." DigitalCommons@USU, 2012. http://digitalcommons.usu.edu/etd/1147.
Full textHanson, John Mark 1955. "Patterns of animal abundance in lakes : the role of competition in the fish-macroinvertebrate relationship." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71975.
Full textDuFour, Mark R. "Quantification of Variability, Abundance, and Mortality of Maumee River Larval Walleye (Sander vitreus) Using Bayesian Hierarchical Models." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1351976817.
Full textSampson, Mark Robert. "Modelling the distribution and abundance of several demersal fish species on the Agulhas Bank, South Africa." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1006207.
Full textMkango, Sara. "Multi-species models of Antarctic krill predators : do competitive effects influence estimates of pre-exploitation whale abundance and recovery?" Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4911.
Full textMany species of baleen whales and seals in the Southern Hemisphere were subject to intensive overexploitation by commercial harvesting in the last two centuries, and many populations were reduced to very low levels. Krill is the dominant prey item of these species. Harvesting (to near extinction) of the large baleen whales (blue, humpback and fin whales) from the start of the 20th century led to a likely increase in the availability of krill to other krill predators such as the Antarctic minke whales and crabeater seals. This phenomenon is referred to as the “krill surplus” hypothesis and has been a central hypothesis of Antarctic ecosystem studies. This thesis aims to better understand species interactions in the Antarctic through developing and extending multispecies models of the system. The study considered only Region A (IWC Management Areas II, III and IV, 60°W to 130°E) because the numbers of baleen whales harvested in Atlantic/Indian Oceans were far greater than in other Oceans, so that the impacts on the dynamics of these species are likely greater. The simple models of competition between blue and fin whales developed give qualitatively similar results to the Mori-Butterworth Antarctic ecosystem model of an initial number of fin whales before exploitation began that is much lower than single species models suggest. However, there are important features of blue and fin whale CPUE data off Durban over the middle decades of the last century that are not reflected by the model results, and a number of possible reasons for this are advanced. In particular, the introduction of competition in the models predicts a steady fin whale population until 1950, but cannot reproduce the feature in the CPUE data of an increase from the 1920’s to 1950’s. The study then extends the Mori-Butterworth Antarctic ecosystem model by adding squid, which has fast dynamics compared to whales and seals. The model estimates population trends in terms of numbers or biomass. This study indicates that results are particularly sensitive to the density dependence assumed for natural mortality and/or birth rate. The results highlight that the squid biomass trajectory is relatively insensitive to initial squid abundance but depends strongly on the density dependence assumed for squid. Generally, the estimated historical trajectories suggest that the inclusion of squid in the model hardly impacts the maxima reached by other species that benefited from the krill surplus. The model predicts that squid started to increase at about the same time (1920) that the reduction of large baleen whales (blue, humpback and fin whales) commenced under heavy harvesting. This suggests that species with fast dynamics such as squid were possibly the first to benefit from krill surplus, even before minke whales and crabeater seals, which started to increase only about a decade later. The study provides a potential framework for understanding the interplay between species with slow and fast dynamics.
Clark, Emily. "Quantifying the Relative Abundance of the Relaxin Receptor in Cardiac Tissue from Pre-Menopausal and Post-Menopausal Rat Models." Walsh University Honors Theses / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=walshhonors1587410878183115.
Full textGent, John. "Abundance and scarcity : classical theories of money, bank balance sheets and business models, and the British restriction of 1797-1818." Thesis, London School of Economics and Political Science (University of London), 2016. http://etheses.lse.ac.uk/3435/.
Full textBereng, Mosiuoa Walter. "Understanding environmental factors influencing invasion of Lilium formosanum in Mpumalanga Province and models of its potential distribution in South Africa." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/79711.
Full textDissertation (MSc)--University of Pretoria, 2014.
Plant Production and Soil Science
MSc
Unrestricted
Kleisner, Kristin Marie. "A Spatio-Temporal Analysis of Dolphinfish; Coryphaena hippurus, Abundance in the Western Atlantic: Implications for Stock Assessment of a Data-Limited Pelagic Resource." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/137.
Full textKunz, Simon Michael [Verfasser], and W. de [Akademischer Betreuer] Boer. "Constraints on Transport Models for Galactic Cosmic Rays and their Implications for the Anomalous Positron Abundance / Simon Michael Kunz. Betreuer: W. de Boer." Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1064504132/34.
Full textYoung, Alexander L., and Alexander L. Young. "Three Essays on Complex Systems: Self-Sorting in a One-Dimensional Gas, Collective Motion in a Two-Dimensional Ensemble of Disks, and Environment-Driven Seasonality of Mosquito Abundance." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624567.
Full textBouziani, Naceur. "Elaboration d'un modèle thermo-chimique de la matière cométaire : contribution à l'étude physico-chimique des milieux poreux hétérogènes." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10190.
Full textRobin, Geneviève. "Low-rank methods for heterogeneous and multi-source data." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX026/document.
Full textIn modern applications of statistics and machine learning, one often encounters many data imperfections. In particular, data are often heterogeneous, i.e. combine quantitative and qualitative information, incomplete, with missing values caused by machine failure or nonresponse phenomenons, and multi-source, when the data result from the compounding of diverse sources. In this dissertation, we develop several methods for the analysis of multi-source, heterogeneous and incomplete data. We provide a complete framework, and study all the aspects of the different methods, with thorough theoretical studies, open source implementations, and empirical evaluations. We study in details two particular applications from ecology and medical sciences
Sommeria-Klein, Guilhem. "From models to data : understanding biodiversity patterns from environmental DNA data." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30390/document.
Full textIntegrative patterns of biodiversity, such as the distribution of taxa abundances and the spatial turnover of taxonomic composition, have been under scrutiny from ecologists for a long time, as they offer insight into the general rules governing the assembly of organisms into ecological communities. Thank to recent progress in high-throughput DNA sequencing, these patterns can now be measured in a fast and standardized fashion through the sequencing of DNA sampled from the environment (e.g. soil or water), instead of relying on tedious fieldwork and rare naturalist expertise. They can also be measured for the whole tree of life, including the vast and previously unexplored diversity of microorganisms. Taking full advantage of this new type of data is challenging however: DNA-based surveys are indirect, and suffer as such from many potential biases; they also produce large and complex datasets compared to classical censuses. The first goal of this thesis is to investigate how statistical tools and models classically used in ecology or coming from other fields can be adapted to DNA-based data so as to better understand the assembly of ecological communities. The second goal is to apply these approaches to soil DNA data from the Amazonian forest, the Earth's most diverse land ecosystem. Two broad types of mechanisms are classically invoked to explain the assembly of ecological communities: 'neutral' processes, i.e. the random birth, death and dispersal of organisms, and 'niche' processes, i.e. the interaction of the organisms with their environment and with each other according to their phenotype. Disentangling the relative importance of these two types of mechanisms in shaping taxonomic composition is a key ecological question, with many implications from estimating global diversity to conservation issues. In the first chapter, this question is addressed across the tree of life by applying the classical analytic tools of community ecology to soil DNA samples collected from various forest plots in French Guiana. The second chapter focuses on the neutral aspect of community assembly.[...]
Bigaton, Ademir Durrer. "Diversidade de bactérias e arquéias em solos cultivados com cana-de-açúcar: um enfoque biogeográfico." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-10042015-111904/.
Full textSugarcane is currently the most important culture of the State of São Paulo and has a prominent role among the crops in Brazil. Into the context of a better productivity with greater sustainability, the role of the microbial community present in the soil could have huge importance, aiding a better plant development, supplying it with nutrients or reducing the occurrence of diseases and pests. However, little is known about the microbial community existing in soils cultivated with sugarcane, where a knowledge of the spatial distribution of this community could be helpful to a better understanding of the processes that these organisms are involved. This project aimed to study in a biogeographic approach, the bacteria and archaea diversity in soils of sugarcane in the São Paulo State, focusing on the groups of archaea and bacteria. Analyses of a total of 285 soil samples, obtained in 10 producing distinct regions was performed using independent cultivation techniques such as quantification of total abundance by applying quantitative PCR (qPCR), analysis of the community structure by terminal restriction of length polymorphism (T-RFLP) and determination of its phylogenetic affiliation by high-throughput sequencing of 16S ribosomal genes. The results showed that the main drivers of these communities were the physical and chemical characteristics of the soil (pH, granulometry and organic matter). In addition, the results have shown that archaea community was influenced by management practices (mechanical harvest, vinasse and filter cake adding). Additionally, an unexpected relationship between the structures of these communities with the geographic distribution of the samples was observed. The results demonstrate the complexity of the community of bacteria and archaea along a spatial gradient, suggesting that future studies should consider a broader sampling of the distinct regions. This work supports upcoming studies that aim at developing agricultural practices exploring the soil microbiomes functionality.
Monsarrat, Sophie. "Reconstruction de la distribution et de l'abondance historiques des mammifères marins : établir un niveau de référence pour comprendre le passé, renseigner le présent et planifier l'avenir." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS277/document.
Full textRelevant baselines on the historical distribution and abundance of species are needed to support appropriate conservation targets for depleted species, but the full scale of cumulative human impacts on ecosystems is highly underestimated. In this project, I investigated the challenges and opportunities of combining historical data with analytical methods to improve these historical baselines. Occurrence data from archaeological, historical and industrial sources were reviewed for seven cetacean and three pinniped species, revealing range contractions and population depletions from prehistorical times to today. For five whale species, I used species distribution modelling to combine 19th Century whaling records with environmental data, to estimate pre-whaling distributions. For the highly depleted North Atlantic right whale, (Eubalaena glacialis), I obtained a detailed estimate of pre-whaling distribution and abundance by inferring from the historical distribution and abundance of its congeneric North Pacific right whale (E. japonica). These results suggest that the North Atlantic right whale occupies a small fraction of its historical range and that its current population represents <5% of its historical abundance, with implications for the management, monitoring and conservation targets of this species. More generally, these results emphasize the utility of considering historical data to understand the extent to which species have been impacted by humans, assess their current level of depletion, and inform the options available for their future recovery
Cahen, Sébastien. "Deux enigmes de l'evolution stellaire : les neutrinos solaires et la supernova 1987a." Paris 7, 1987. http://www.theses.fr/1987PA077271.
Full textKoladjo, Babagnidé François. "Estimation non paramétrique du nombre d'espèces : Application à l'étude de la faune ichtyologique du bassin du fleuve Ouëmé." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112153.
Full textThis manuscript is structured in two parts. The #rst part composed of Chapters 2to 4 deals with the problem of estimating the number of classes in a population withan application in ecology. The second part, corresponding to Chapter 5, concernsthe application of statistical methods to analyze fisheries data.In the first part, we consider a heterogeneous population split into several classes.From a sample, the numbers of observed individuals per class, also called abun-dances, are used to estimate the total number of classes in the population. In theliterature devoted to the number of classes estimation, methods based on a mix-ture of Poisson distributions seem to be the most effcient (see for example the workof Chao and Bunge (2002) in the parametric framework and that of Wang and Lind-say (2005) in a non-parametric framework). Applications of these approaches to realdata show that the distribution of abundances can be approximated by a convexdistribution. We propose a non-parametric approach to estimate the distribution ofabundances under the constraint of convexity. This constraint defines a theoreticalframework for estimating a discrete density. The problem of estimating the numberof classes is then tackled in two steps.We show on the one hand the existence and uniqueness of an estimator of adiscrete density under the constraint of convexity. Under this constraint, we provethat a discrete density can be written as a mixture of triangular distributions. Usingthe support reduction algorithm proposed by Groeneboom et al. (2008), we proposean exact algorithm to estimate the proportions in the mixture.On the other hand, the estimation procedure of a discrete convex density is usedto estimate the zero-truncated distribution of the observed abundance data. Thezero-truncated distribution estimate is then extended at zero to derive an estimateof the probability that a class is not observed. This extension is made so as tocancel the first component in the mixture of triangular distributions. An estimateof the total number of classes is obtained through a binomial model assuming thateach class appears in a sample by a Bernoulli trial. We show the convergence inlaw of the proposed estimator. On practical view, an application to real ecologicaldata is presented. The method is then compared to other concurrent methods usingsimulations.The second part presents the analysis of fisheries data collected on the Ouémériver in Benin. We propose a statistical approach for grouping species accordingto their temporal abundance profile, to estimate the stock of a species and theircatchability by artisanal fishing gears
Kada, Sara. "Sources d'hétérogénéité dans la circulation d'agents infectieux transmis par les vecteurs : le cas des tiques et maladies à tiques dans des systèmes d'hôtes structurés spatialement." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT139.
Full textDifferent hosts may not contribute equally to parasite transmission. For instance, some individuals or species may be more heavily infected than others, an observation that lead to the `20/80' rule, stating that in many cases 20% of individuals are responsible for 80% of the transmission. However, studies on heterogeneity in transmission have primarily focused on intrinsic factors of transmission, such as susceptibility and infectivity, while the impact of extrinsic factors, such as connectivity network among individuals or species of the host community and the role of various host movements has been relatively neglected. This thesis investigates the role of extrinsic transmission heterogeneities on the spread of infectious disease in multi-host systems, using tick-seabird-microparasite system as empirical models for theoretical investigations. Four main causes of heterogeneity in transmission of vector-borne diseases were considered : (i) heterogeneity in vector abundance, distribution, and estimation thereof (ii) heterogeneity in contact among species in a multi-host, multi-vector community, (iii) heterogeneity in infection spread caused by different host mouvement behaviors (notably the potential role of ‘prospecting’ by host individual among host groups), and (iv) heterogeneity in dispersal ability and transmission competence among vectors with different life-history traits (stage-dependent dispersal). First, we highlight the need to accurately estimate ectoparasite abundances with hierarchical modeling approaches that can take into account both heterogeneity in their detection probability and their aggregated distribution among hosts. Next, using network theory to examine the impact of community context on disease transmission and maintenance, we found that network structure (modularity, nestedness) and node-based measures (e.g., centrality) both shape the emergence of ‘super-spreader’ species (i.e., species that contribute disproportionally to disease transmission) and keystone species (i.e., species that contribute disproportionally to disease maintenance) in multi-host, multi-vector pathogens communities. Finally, we explored the contribution of host behavior and vector life-history traits to the spread of infectious agents. By reviewing the recent literature, we highlight the fact that prospecting, relative to various other types of host movement, may be of key importance to disease transmission among host groups, notably in social species. We also show how vector life history characteristics (e.g. length of bloodmeals) and demographic constraints (Allee effects) affect their colonization potential. Soft ticks, which take a single, long bloodmeal at only the larval stage, should have much lower colonization rates than hard ticks, which take a single, long bloodmeal at every life stage. These stage-dependent dispersal discrepancies may have direct consequences for the genetic structure of their populations and the spread of vector-borne infectious agents. Overall, these findings highlight the importance of studying the causes and consequences of transmission heterogeneity in multi-host, multi-vector systems. A series of potentially important sources of heterogeneity in parasite transmission are outlined, together with perspectives of empirical and theoretical studies to further explore their implications for understanding ecology and evolution of host-parasite interactions and for disease management purposes
Nishioka, Shuichiro. "Technology, productivity and knowledge in the factor abundance model." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273684.
Full textMortara, Sara Ribeiro. "Abundância de samambaias em metacomunidades: relacionando padrões e processos com modelos estatísticos." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-17082016-141523/.
Full textUnderstanding how communities are assembled from a species pool is a central question in community ecology. Different approaches to link pattern and processes in community ecology were proposed. Some examples are assembly rules and the community phylogenetic approach. However, one aspect not accounted in those approaches is how neutral processes affect community patterns. There is a consensus that both niche and neutral processes affect community assembly and that the goal should be assess the relative importance of each process. The general idea if this thesis was to use statistical models to represent how niche and neutral generate community patterns. In Chapter 3, I proposed a framework based on hierarchical models to express niche and neutral processes. I used this approach to represent hypothesis in which only niche processes affect community structure, only neutral processes or a hierarchical combination of both explains species abundance. By using model selection, I identifyied which combination of processes better predicts observed abundances on local communities. I showed that fern communities across altitudinal gradients at Serra do Mar in Paraná, Brazil are structured by a mixture of environmental filtering, ecological drift and limited dispersal. Environmental filtering defines species abundance, selecting the best ecological strategies of species depending on altitude. Variation on species abundance sharing the same ecological strategies is explained in part by drift and limited dispersal, and in part by habitat filtering independent of species traits considered in the models. Hence, I refined how niche and neutral processes affect fern abundance on altitudinal gradients. In Chapter 3, I used a case study to explore the idea from community phylogenetics of inferring processes affecting communities based on patterns of phylogenetic structure. I used the modeling framework from Chapter 3 to simulate communities built by niche, neutral and combination of both processes. I found that communities based on niche processes are likely to generate a random phylogenetic structure. The detection of random phylogenetic strucure was even more common on communities built solely by neutral processes and combination of both niche and neutral processes. Therefore, the case study showed that a non random phylogenetic strucure is unlikely and that neutral processes strongly affect the outcome of phylogenetic patterns. Based on the framework proposed on this thesis it is possible to delimit the influence of niche and neutral processes on community assembly and to understand what are the consequences in terms of community patterns. Translating different processes into mixed models can be a powerful tool to quantify patterns and built explanations on how the processes operate together
Whiting, Michael Lawrence. "Soil moisture model to improve mineral abundance estimates from hyperspectral data /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
Full textPereira, Caroline. "A multiwavelength abundance analysis of sdB stars using new model atmospheres." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557885.
Full textSakr, Ziad. "Cosmology beyond ΛCDM model in the light of cluster abundance tension." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30346.
Full textThe ΛCDM model has proved successful in describing to a high precision most of nowadays cosmological observations. However, one of its parameters, σ 8, measuring the present matter amplitude fluctuations, constrained from CMB angular power spectrum, the Cls, was found by the Planck mission, in significant tension with value constrained by SZ galaxy cluster counts in the near universe. In the present work we investigate extensions to ΛCDM model as possible origins behind this discrepancy. To test these extensions, we performed a Monte Carlo analysis to compare constraints on σ 8 in ΛCDM with constraints under these extensions, using mainly CMB Cls combined with cluster counts sample. The later were based on different mass observables relations and covered different redshift ranges: X-ray cluster in the local universe, SZ Planck mission clusters from the near universe or photometric richness estimated detected clusters from future high redshift upcoming Euclid alike mission. Because an improper determination of the calibration of cluster mass function could also be behind this discrepancy, our approach was, when combined with CMB, to leave the calibration factor free to vary and be constrained by data. Introducing three degenerate massive neutrinos, we found that they have no significant effect on fixing the discrepancy between CMB and Xray or SZ cluster counts. We then allowed the growth index ƴ to vary. We find a correlation in the confidence space between ƴ and the X-ray mass observable factor not affected by the presence of massive neutrinos, indicating that a modifying gravity is favored over massive neutrinos as a way to alleviate the tension. However, when a SZ cluster sample covering a larger redshift range was used, we found that the correlation between ƴ and the calibration factor, is constrained by the evolution of the growth through redshift and limited to a region where it cannot fix the discrepancy. [...]
Pereira, Tiago Mendes Domingos, and tiago@mso anu edu au. "Confronting the new generation of stellar model atmospheres with observations." The Australian National University. Research School of Astronomy and Astrophysics, 2009. http://thesis.anu.edu.au./public/adt-ANU20100701.165106.
Full textCampbell, S. W., T. N. Constantino, V. D'Orazi, C. Meakin, D. Stello, J. Christensen-Dalsgaard, C. Kuehn, et al. "Towards 21st century stellar models: Star clusters, supercomputing and asteroseismology." WILEY-V C H VERLAG GMBH, 2016. http://hdl.handle.net/10150/621500.
Full textJorge, Marcelo Haidar. "Assessing the Influence of Prescribed Fire on Faunal Communities in a Pyric Landscape." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/104395.
Full textMaster of Science
Understanding the link between environmental factors such as fire, land cover and soil productivity is essential for wildlife managers to maintain healthy wildlife populations. The Longleaf pine (Pinus palustris) ecosystem requires frequent fire and has seen drastic reductions in land area due to fire suppression. Current restoration utilizes prescribed fire, controlled burning of an area, and hardwood removal, logging hardwood trees such as oaks, but more research is needed to understand how this restoration influences the wildlife in the longleaf pine ecosystem. As such, we collected data collected from Camp Blanding Joint Training Center and Wildlife Management Area to understand how fire influences the relative numbers of mammalian predators, the distribution and species richness (i.e. number of unique species) of avian species, guilds and communities, and vital rates (i.e. births, survival to a certain age) of white-tailed deer fawns. Our results indicated that mammalian predator distributions, and avian species richness were influenced by fire and land cover. Mammalian predator space use was altered by fire conditions and landcover, which supports a predator management strategy that utilizes prescribed burning and hardwood removal used in restoration and conservation of the LLP ecosystem to indirectly alter predator distributions. Some mammalian mesocarnivores (i.e. foxes, skunks, weasels, etc.) historically common throughout the southeastern United States were rarely detected, suggesting more research is needed to identify the cause of the potential decline of cryptic mesocarnivores in the Southeastern United States. Avian species richness, number of unique species, at the community level was positively influenced by pyrodiversity, the number of unique burn years in an area. This supports and further extends the 'pyrodiversity begets biodiversity' hypothesis for avian species, which states that greater pyrodiversity increases the diversity of bird species in that area. Avian species richness of cavity nesting birds decreased with increasing time since fire. Our results suggest that managers can promote avian community diversity by reducing the size of burn units to create areas with multiple adjacent burn units, with unique fire histories and a mosaic of post-fire conditions. Lastly, fawn recruitment was greater on the higher productivity site than the low productivity site, however, within sites soil productivity did not seem to influence birth and recruitment. Although we did not statistically test the factors influencing our parameters between sites, we hypothesize that the variation in coyote activity rates as well as soil productivity and its subsequent effects (i.e. forage availability, concealment cover, and land cover type) likely drove the differences we saw between sites. These results are relevant to local managers and provide support for managing deer differently across both sites. In conclusion, understanding the influence of fire in a frequently burned landscape allows us to better inform management of predators and avian communities using prescribed burns, and the differences in deer populations between areas allowed us to better in inform managers on harvest quotas so that the magnitude of the effect of harvest can better match the population vital rates of each area.
Dussán-Duque, Beatriz Salomé. "Ecology of the Guiana dolphin (Sotalia guianensis) in the Southern area of the Gulf of Morrosquillo, Colombia : implications for conservation." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4153.
Full textWessling, William T. "Institutional quality, economic development, and natural resource abundance| Towards and interactive model of development." Thesis, Webster University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1525314.
Full textThe study of institutions (i.e., "the rules of the game" in a society) has grown from a small fringe subject in the late 1980s to a massive pillar in the current study of International Political Economy. Two thing has become clear during the course of this growth and the involved research it entails: (1) institutional Quality (especially quality of governance and rule of law) has a determinant effect on the GDP development of a given countries economy and (2) institutional quality has a determinant effect on whether a country is either "cursed" or "blessed" with natural resource abundance (i.e., whether they are growth "winners" or "losers" in terms of GDP development. The purpose of this study is to determine whether the presence of abundant natural resources amplifies this determinant effect when controlled for nonresource abundant states, and if so to what extent. The study ultimately finds amplification of the effect of institutional quality on GDP per capita when controlling for natural resource abundance, ultimately suggesting that resource abundance can be either a "blessing" or a "curse" depending on preexisting institutional quality. Secondary findings indicate the existence of a "slippage" effect in institutional quality once natural resources are introduced to a given state's economy.
Zahid, Saman. "Comparing Resource Abundance And Intake At The Reda And Wisla River Estuaries." Thesis, Linköpings universitet, Statistik och maskininlärning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-172770.
Full textWatson, L. Scott. "Solar models including revised abundances and dark matter : constraints from helioseismology and neutrino observations." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491613.
Full textVasilyev, Valeriy [Verfasser], and Norbert [Akademischer Betreuer] Christlieb. "Dynamical model atmospheres for the abundance analysis of pulsating stars / Valeriy Vasilyev ; Betreuer: Norbert Christlieb." Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/117769171X/34.
Full textRethwisch, Michael D., Charles McDaniel, and Manuel Peralia. "Seasonal Abundance and Field Testing of a Citrus Thrips Temperature Development Model in Arizona Citrus." College of Agriculture, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/220568.
Full textCondé, Paula Alves. "Modelos teóricos de distribuição de abundância das espécies para caracterização da diversidade biológica e a utilização de diferentes medidas de abundância." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-17122012-145930/.
Full textThe species abundance distributions (SADs) are considered an informative way to describe the biological diversity revealling one of the most wellestablished patterns in ecology: the predominance of rare species in biological communities. The generality of such pattern made it relevant to the analysis of other biodiversity parameters an to induce the development of theoretical models of SAD. On the other hand statistical models of SAD occupied a central role in biology as an empirical principle that underlies many ecological theories. Preston suggested in 1948 that SADs follow an approximately lognormal distribution, but that may appear truncated by the effect of sample size, being completely revealed only in large samples. This idea is associated with the statistical property of consistency, which implies that the accumulation of evidence - represented by the increase in sample size - approaches the samples distribution to the true model, as well as the estimates of the parameters to their real values. Beyond the effect of sample size, the SADs may differ depending on the measure of abundance adopted. Studies suggest that biomass could be a more efficient measure of abundance to reveal the underlying distribution of biological communities in smaller samples or scales (differential veiling). In this context, our aim in this study was to investigate and discuss the advantage of considering biomass in theoretical models of SAD. Thus we evaluated the effect of sample size on the quality of models fitness under two different measures of species abundance: biomass and number of individuals. We simulated samples of different sizes taken from an empirical database of Scarabaeinae beetles - recognized as a potential and relevant indicator in ecological studies. Further we adjusted the simulated samples to different SAD models and evaluated the efficiency of each kind of abundance index to reveal the correct model, as well as the accuracy and precision of the parameters estimates. Our results show that the efficiency of biomass to reveal the underlying distribution is not as general as suggested by previous works. According to our analysis criteria, biomass was not consistently as far more efficient in revealing the correct model or in providing greater accuracy and precision in parameters estimates than the number of individuals. Thus, the statement that the SAD biomass is not veiled on small scales or samples does not seem to be general. Moreover our results also indicate that the effect of differential veiling on SADs using biomass and number of individuals depends on the choice of the evaluated model and data set. However, if the cause of the differential veiling - between the biomass and number of individuals SADs - is mainly due to scale effects. An alternative explanation is that the scale of this study was not wide enough to show it. Considering the sampling effects studied here in biodiversity evaluation we highlight the lack of studies investigating the use of biomass as a measure of abundance in SADs which the implications of different effects on this measure indicate the urgent call by further studies on this subject, enablying us to isolate the effect of scale from the sample size
anderson, kaylee. "Using Linear Mixed Models to Analyze Native and Non-Native Species Abundances in Coastal Sage Scrub." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/807.
Full textFlesch, Aaron D., Philip C. Rosen, and Peter Holm. "Long-term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation." Wiley, 2017. http://hdl.handle.net/10150/626024.
Full textDuFour, Mark R. "Hydroacoustic Quantification of Lake Erie Walleye (Sander vitreus)Distribution and Abundance." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1483715286731694.
Full textReynolds, Julia Mae. "Effects of Model Design and Environmental Variables on Juvenile U.S. South Atlantic King Mackerel (Scomberomorus cavalla) Abundance." Thesis, College of Charleston, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10746023.
Full textAs growing human populations put an increasing demand on finite ocean resources, fisheries management tools rely ever more on high quality inputs and a comprehensive understanding of model factors. Stock assessment modeling for South Atlantic (SA) King Mackerel, Scomberomorus cavalla , uses inputs such as abundance indices, growth parameters, and fisheries landings. However, one underlying assumption in this modeling system is there are measurable connections among life stages. A juvenile abundance index developed from the SEAMAP-SA Coastal Trawl Survey (CTS) is presumed to represent ecological recruitment. Very weak correlations to other life stage proxies suggested a deficiency with the juvenile abundance index accuracy and indicated data exploration into the index formulation was needed. Examination of CTS juvenile length frequencies support that the smallest juveniles appear in the summer and spring juveniles are from overwintering of the previous year class. Juvenile abundance indices developed using year class (year in which a fish is spawned) rather than year of sampling (as done for previous assessments) showed substantial differences, in particular lowering AIC values indicating an improvement in model accuracy. Evidence of seasonal and regional variation with CTS juveniles prompted the development of separate age 0 and age 1 indices. Correlations of these indices to fisheries-derived year class strength suggested the age 0 index to be the best indicator of initial juvenile king mackerel abundance while the age 1 index reflects abundance after high early life stage mortality. Data exploration also was conducted for potential environmental variables impacting age 0 and age 1 abundance. Relationships were found between age 0 abundance and freshwater input, the Gulf Stream, hurricane activity, and predator abundance and between age 1 abundance and freshwater input and hurricane activity. This research provides not only valuable baseline knowledge for SA king mackerel juveniles, but also findings pertinent for their management.
Fässler, Sascha M. M. "Target strength variability in Atlantic herring (Clupea harengus) and its effect on acoustic abundance estimates." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1703.
Full textChen, Wei-Ching. "Selective Oxidation of Lignin Models and Extracts with Earth-Abundant Transition Metals and Hypervalent Iodine." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32181.
Full textGosse, John W. "Relative abundances of birds of prey in different forest habitats in the Western Newfoundland Model Forest /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq25845.pdf.
Full textFalcao, de Jesus Manuel Jose Romao Xavier. "Civil war and natural resources : a quantitative approach." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1140.
Full textMarchetto, Camila. "Estimativas de abundância do boto-cinza (sotalia guianensis) (cetacea, delphinidae) no complexo estuarino de paranaguá utilizando modelos de captura-recaptura." Universidade do Vale do Rio dos Sinos, 2011. http://www.repositorio.jesuita.org.br/handle/UNISINOS/3970.
Full textMade available in DSpace on 2015-06-23T15:46:03Z (GMT). No. of bitstreams: 1 CamilaMarchetto.pdf: 6103936 bytes, checksum: 36dc3b26c7388f19f25645a5d91132af (MD5) Previous issue date: 2010
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
FAPESP - Fundação de Amparo à Pesquisa do Estado de São Paulo
Estimativas de abundância populacional são consideradas importantes parâmetros ecológicos. Estudos envolvendo estes parâmetros são escassos e concentrados em regiões específicas da distribuição do boto-cinza (Sotalia guianensis). O objetivo deste estudo foi obter a estimativa da abundância populacional desta espécie em um setor do Complexo Estuarino de Paranaguá (PR) (25º22’S – 25º27’S; 48º12’W – 48º40’W). Foram realizadas saídas a campo para aplicação da técnica de fotoidentificação no período compreendido entre o inverno de 2006 e o inverno de 2008. Uma área total de 110 km² foi dividida em três subáreas menores para que cada parte selecionada fosse amostrada em um dia. Para as saídas a campo utilizou-se uma embarcação de alumínio realizando um deslocamento em zig-zag pelo estuário a fim de aumentar a chance de encontro com os grupos de botos. A fotoidentificação foi realizada com uma câmera digital reflex 35 mm, acoplada a lentes zoom de 400 mm. As fotos tomadas foram classificadas em categorias de acordo com o foco, contraste e tamanho da nadadeira dorsal em relação à distância do fotógrafo. Para a estimativa de abundância da população utilizaram-se modelos de captura-recaptura para populações fechadas. Durante o período de estudo foram realizadas 39 saídas a campo com 227 grupos de botos que variaram de dois a 100 indivíduos (média ± DP: 12,7 ± 16,6 indivíduos). Um total de 40.340 fotografias foi tomado, sendo 13.522 (33,5%) consideradas de qualidade suficiente para serem analisadas. Dentre as fotografias de excelente qualidade, 3.114 ou 23,03% foram de indivíduos que possuíam marcas conspícuas nas nadadeiras dorsais e que permitiram uma identificação individual, totalizando 109 indivíduos diferentes identificados ao longo das temporadas de estudo. A estimativa do tamanho da população variou de 200 a 441 indivíduos dependendo do modelo utilizado. Esta pode ser considerada uma estimativa mínima, visto que somente uma parte do Complexo Estuarino de Paranaguá foi amostrada neste estudo. Em vista disso, recomenda-se amostrar toda a extensão do CEP para obter a estimativa total da população local. Do mesmo modo, este dado é importante para compor o banco de informações da Área de Proteção Ambiental de Guaraqueçaba, contribuindo para o desenvolvimento de estratégias de conservação do boto-cinza e de outros recursos biológicos locais.
Population abundance estimates can be considered one of the most important ecological parameters. Studies on Guiana dolphin (Sotalia guianensis) estimates are scarce and concentrated in specific areas of its distribution. The objective of the present study was to estimate the population size of this species in a sector of the Paranaguá Estuarine Complex (PEC) (25º22’S – 25º27’S; 48º12’W – 48º40’W), state of Paraná, Brazil. Surveys were conducted to apply the technique of photo-identification from winter 2006 to winter 2008. An area of 110 km² was divided into three smaller subareas to allow each selected portion of the estuary to be surveyed in a day. Boat-based surveys followed a random zig-zag pattern in the estuary in order to maximize the chance of encountering groups of dolphins. The photoidentification was performed using a 35 mm reflex digital camera with a 400 mm zoom lens. Photographs were classified into categories according to the focus, contrast and size of the dorsal fin in relation to distance from the photographer. Capture-recapture models for closed populations were used. A total of 39 surveys was conducted and 227 groups of dolphins were recorded, ranging from two to 100 individuals (mean ± SD: 12.7 ± 16.6 individuals). A total of 40.340 photographs was taken, from which 13.522 (33.5%) were considered useful for identification purposes. A total of 3.114 (23.03%) photographs allowed individual identification, resulting in 109 individuals identified through different seasons. The estimates gathered ranged from 200 to 441 individuals depending on the selected model. This is a minimum estimate, since only a part of the Paranaguá Estuarine Complex was sampled. It is recommended to survey the whole estuarine area where dolphins can be found in order to reach an accurate estimate of the total population size. This study adds another information to the database of the Environmental Protection Area of Guaraqueçaba, contributing to the development of conservation strategies of estuarine dolphins and other local biological resources.
Dénes, Francisco Voeroes. "Abundância de aves de rapina no Cerrado e Pantanal do Mato Grosso do Sul e os efeitos da degradação de hábitat: perspectivas com métodos baseados na detectabilidade." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-15012015-152016/.
Full textUrbanization and the expansion of agricultural frontiers are among the main forces driving the degradation of natural habitats in Neotropical open habitats. Inference and estimates of abundance are critical for quantifying population dynamics and the impacts of environmental change. Yet imperfect detection and other phenomena that cause zero inflation can induce estimation error and obscure ecological patterns. We examine how detection error and zero-inflation in count data of unmarked individuals inform the choice of analytical method for estimating population size. We review established (GLMs and distance sampling) and emerging methods that use N-mixture models (Royle-Nichols model, and basic, zero-inflated, temporary emigration, beta-binomial, generalized open-population, spatially explicit, single-visit and multispecies) to estimate abundance of unmarked populations. As a case study, we employed a single visit N-mixture approach to model roadside raptor count data and investigate how land-use transformations in the Cerrado and Pantanal domains in Brazil have affected the populations of 12 species on a regional scale (>300,000 km2). Methods differ in sampling design requirements, and their suitability will depend on the study species, scale and objectives of the study, and financial and logistical considerations, which should be evaluated to use funds, time and effort efficiently. In the case study, detection of all species was influenced by time of day, with effects that follow expectations based on foraging and flying behavior. Closed vegetation on and carcasses found during surveys also influenced detection of some species. Abundance of most species was negatively influenced by conversion of natural Cerrado and Pantanal habitats to anthropogenic uses, particularly pastures, soybean and sugar cane plantations, even for generalist species usually considered poor habitat-quality indicators. Protection of the remaining natural habitats is essential to prevent further decline of raptor populations in the study area, especially in the Cerrado domain