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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Local and regional influences on the structure of freshwater zooplankton communities /

Shurin, Jonathan Bane. January 2000 (has links)
Thesis (Ph. D.)--University of Chicago, Dept. of Ecology and Evolution, August 2000. / Includes bibliographical references. Also available on the Internet.

Biotic soil crusts of Oregon's shrub steppe /

Ponzetti, Jeanne M. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references (leaves 62-74). Also available via the World Wide Web.

Influence of native bunchgrass and invasive forb litter on plant growth in a semi-arid bunchgrass prairie

Hoopes, Carla. January 2006 (has links) (PDF)
Thesis (M.S.)--Montana State University--Bozeman, 2006. / Typescript. Chairperson, Graduate Committee: Cliff Montagne. Includes bibliographical references (leaves 63-70).

Emergent models in hierarchical and distributed simulation of complex systems : with applications to ecosystem and genetic network modelling /

Stolk, Henk. January 2005 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Biology of acid-sulfate-chloride springs in Yellowstone National Park, Wyoming, United States of America

Boyd, Eric Stephen. January 2007 (has links) (PDF)
Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Gill G. Geesey. Includes bibliographical references.

The development of landscape design principles based upon ecosystem aesthetics, and their application in rehabilitating Diablo Lake Overlook, Ross Lake National Recreation Area, Washington

Degerman, Traci Michelle, January 2007 (has links) (PDF)
Thesis (M.S. in landscape architecture)--Washington State University, May 2007. / Includes bibliographical references (p. 58-62).

The role of functional traits and phylogeny in assembly of tropical forest communities in Danum Valley, Sabah

Kaye, Maria Ellen January 2016 (has links)
Tropical forests have been studied by community ecologists since the earliest days of the field because of their diversity and complexity and much of the theory behind community assembly has been developed in the tropics. However, the processes that act to assemble species in tropical forest across a very fine scale are still poorly understood. This study investigates community structure in 20ha area of hyper diverse tropical rainforest in Sabah, Malaysia. In order to examine community phylogenetic structure, I reconstructed a molecular phylogeny for all species in the study site using DNA barcoding loci. From this, I calculated phylogenetic diversity metrics for each community and then used a null model to compare observed phylogenetic diversity with that which would be expected if communities were randomly assembled with respect to phylogeny. The analyses showed that communities are more closely related than predicted by the null model. I also collected species functional trait data and showed that species assemblages and community weighted mean trait values correlate with environmental gradients on the plot. I also compared functional diversity to data simulated from null models. This showed that communities are on average more functionally similar than predicted at random. Finally, I performed a multivariate analysis with environmental, spatial, phylogenetic and trait data from communities across the plot. The analyses recovered an elevational and soil gradient that correlated strongly with community composition. Species occupying different ranges along this gradient had differing trait values and were phylogenetically distinct. These analyses demonstrate that even fine scale environmental variation is influential in assembling communities over a small area of forest. A soil nutrient gradient is consistently recovered that correlates with topography, suggesting that soil nutrient distribution is mediated by the downslope movement of water leaching soils on ridge tops and leading to accumulation of nutrients in valleys. This gradient is associated with species compositional variation and also with community weighted mean functional traits, indicating that the environment is influencing species distributions even over very small areas. Communities were both functionally and phylogenetically clustered, adding further support to this conclusion.

Disturbance, grazing and succession : an experimental approach to community analysis

Peer, Rebecca Lynn January 1983 (has links)
xi, 98 leaves ; 28 cm Notes Typescript Thesis (Ph. D.)--University of Oregon, 1983 Includes vita and abstract Bibliography: leaves 92-98 Another copy on microfilm is located in Archives

Invasive species impacts on ecosystem structure and function

Jaeger, Andrea L. January 2006 (has links)
Thesis (M.S.)--Michigan State University. Dept. of Fisheries and Wildlife, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references. Also issued in print.


BROWN, JOEL STEVEN. January 1986 (has links)
Variability is a universal, but poorly understood, property of ecosystems. A common belief that environmental variability has a destabilizing effect on species coexistence is being challenged by a growing body of theoretical research; variance in resource abundances may actually promote species coexistence. Here, I develop three models which give ecological conditions for coexistence on a single resource. The first considers a resource whose abundance varies seasonally. Coexistence may be possible if there is a tradeoff between foraging efficiency and maintenance efficiency. The first species can forage profitably on low resource abundances while the second uses dormancy to "travel" inexpensively between temporal periods of high resource abundance. The second considers a resource whose abundance varies spatially. Coexistence may be possible if there is a tradeoff between foraging efficiency and the cost of travel. The first species forages patches to a lower giving up density while the second can inexpensively travel between patches with high resource abundances. The third considers an environment in which foraging costs change seasonally. Coexistence may be possible if there is a tradeoff between the cost of foraging during different seasons. The species which is the most efficient forager changes seasonally. Because coexisting species often exhibit little apparent diet or habitat separation, seed-eating desert rodents offer a promising community for testing the three aforementioned mechanisms of coexistence. In a community of four granivorous rodents, (Perognathus amplus, Dipodomys merriami, Spermophilus tereticaudus, and Ammospermophilus harrisii), I used artificial seed patches to measure species and habitat specific foraging efficiencies. The third mechanism of coexistence appears to explain the presence of P. amplus, D. merriami, and S. tereticaudus in the community. Each enjoys a season during which it is the most efficient forager. The second mechanism of coexistence explains the presence of A. harrisii in the community. This species preferred to forage a large number of widely spaced patches to a high giving up density rather than foraging a few patches to a low giving up density.

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