Patch- and regional-level population biology, with particular reference to Gleditsia triacanthos (Fabaceae): Landscape and plant ecology across the geographic range

Ecological analyses at large spatial scales have emerged over the past decade in response to increasing awareness of the importance of landscape- and regional-scale processes in structuring fragmented terrestrial communities. Even relatively large-scale ecological studies, however, are usually not large enough to observe the variation in conditions that a species experiences across its entire geographic range. The geographic ranges of tree species often encompass great latitudinal and altitudinal scope, and all the associated climatic and geological variability which subsequently affects a suite of ecological, physical and physiological factors. In this thesis I examine the applicability of classic theories and current frameworks for understanding regional-scale population dynamics of plants across their geographic range. I have reviewed several literature bases from the general 'tree' perspective, including metapopulation- and landscape ecology, patch-matrix models, connectivity and species ranges. I analyze population performance parameters at 22 populations of the dioecious tree Gleditsia triacanthos in relation to position in the range, population size and density, and measures of the surrounding landscape structure at various spatial scales. I examine the distribution of abundance across the geographic range of G. triacanthos with particular attention to the predictions of the central-peripheral model. I used GIS datasets of landcover to extract measures of the spatial structure of landscapes across the range, and determine whether variation in abundance can be explained by landscape spatial structure, and whether this is consistent across the range. Finally, I used GARP (Genetic Algorithm for Rule-Set Production) to develop habitat suitability models based on known occurrences in particular regional conditions, as well as conditions across the geographic range as a whole, and interpret the models in terms of niche breadth and overlap between central and peripheral populations. Many factors influence the distribution of abundance and population performance across the range in Honey Locust, and effects of these factors appear to differ regionally and latitudinally. Abundance and performance of G. triacanthos populations were not simply related to position in the range as predicted by the central-peripheral model. Populations at the western periphery of the species' range have a broad niche, show active recruitment and high density and abundance, but high levels of developmental instability and low survivorship. Populations in the southern part of the range have a narrower niche breadth and show low recruitment, density, abundance and developmental instability, but high survivorship. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .M87. Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 5782. Thesis (Ph.D.)--University of Windsor (Canada), 2005.