| The understory vegetation layer, although composing the majority of plant diversity in most forests, is not well understood in terms of spatial and temporal dynamics. Specifically, the role of factors such as disturbance, climate, and underlying environmental heterogeneity are not understood either singly on in concert. The dissertation sought to address the above issues by asking the following questions: (1) What is the role of treefall-related mound and pit microrelief in determining pattern in the understory community? (2) At forest stand and sub-stand spatial scales, which environmental factors have an effect on pattern in the understory vegetation community? (3) How does pattern in the understory community vary over time?; Field work for this study took place over a four-year period (1999–2002) at the Edmund Niles Huyck Preserve in east central New York state. Methods included estimation of understory vegetation cover using fine scale grids (20m by 20m extent, 0.25m2 cell size) and coarse scale belt transects (20m length, 0.25m2 cell size, located over a larger area of the forest). Data were also collected on age and composition of the canopy trees, leaf litter depth, and microtopographic elevation of the forest floor in areas sampled at both fine and coarse scales.; Results of the analyses showed that (1) role of treefall mound and pit complexes varies depending on location and the particular species examined, (2) similar factors, including leaf litter depth, canopy tree species, microtopographic elevation and spatial position, were influencing species composition patterns at both the fine and coarse scales and (3) species richness and composition patterns vary depending on climatic conditions from year to year with variability taking the form of local extinctions/(re)colonizations or alteration of the spatial pattern of individuals. The significance of this research lies in its ability to inform conservation managers of factors important to the preservation of biodiversity. |
