Date of Award

12-2009

Degree Name

Master of Science

Department

Zoology

First Advisor

Nielsen, Clayton

Abstract

I studied the ecological factors related to declining forest forb communities in the Lower Peninsula of Michigan during 2007 and 2008. Data on forb demography, fecundity, and deer herbivory rates were collected for endemic forbs given deer density and site-specific environmental factors. Investigations into endemic forbs were conducted at the population-, community-, and landscape-levels to detect overarching trends. Diverse and abundant forb communities were principally found in areas with available water and rich soil organic matter and were not affected by sympatric vegetation competition, canopy density, or deer densities. Deer densities were highest in lowland conifer stands, vegetated open lands, and heterogeneous landscapes, but herbivory was driven by population-level processes including the selection of specific forb species at the time of seed production. At the landscape level, soil conditions and human influence were major factors affecting the distribution of endemic forb communities. Soil conditions exhibited a non-linear, but generally positive relationship with forb diversity, and human influence negatively affected site diversity. Soil conditions and road densities were used to develop a spatial model identifying a gradient of priority-conservation areas across the study area. Conservation agencies interested in similar vegetation communities should consider anthropogenic factors, nutrient cycling, and local environmental conditions when conducting ecological research and identifying forb conservation areas.

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