Vascular Plant and Vertebrate Species Richness in National Parks of the Eastern United States
Abstract
Given the estimates that species diversity is diminishing at 50-100 times the
normal rate, it is critical that we be able to evaluate changes in species richness in order
to make informed decisions for conserving species diversity. To contribute to the
ongoing analysis of species richness relationships, I examined the potential of vascular
plant species richness to be used as a surrogate for vertebrate species richness in the
classes of amphibians, reptiles, birds, and mammals. Vascular plants, as primary
producers, represent the biotic starting point for ecological community structure and are a
logical starting point for understanding vertebrate species associations. I used data
collected by the United States National Park Service (NPS) on species presence within
parks in the eastern United States to estimate simple linear regressions between plant
species richness and vertebrate richness. Because environmental factors in addition to
plant species richness influence species diversity, I included simple linear regressions of
total park area, park latitude, mean annual precipitation, mean annual temperature, and
human population density surrounding the parks for estimating species richness
relationships. I then combined plant species richness and the environmental variables in
multiple regressions to determine the variables that remain as significant predictors of
vertebrate species richness. To test whether there are differences in species richness
patterns among Inventory and Monitoring networks of NPS, I used an analysis of
covariance (ANCOVA) which included park area and plant species richness as
covariates. I detected significant relationships between plant species richness and
amphibian, bird, and mammal species richness. In multiple regressions, plant species
richness was predicted by park area alone. Species richness of mammals was related to
plant species richness and weakly to park area. Reptile species richness was related to
park area and latitude, and amphibian species richness was related to plant species
richness, park area, and latitude. Differences among networks were only statistically
detected in the bird species richness ANCOVA, and interaction of park area and the
networks was detected for all taxa species richness except for mammals. Plant species
richness predicts spiecies richness of different vertebrate groups to varying degrees, and
should not be exclusively used as a surrogate for vertebrate species richness. Plant
species richness should be included with other variables such as sample area and climate
when considering strategies to manage and conserve species richness in National Parks in
the eastern United States. Based on the ANCOVA results it is recommended that park
management of biodiversity be approached from the local and site specific criteria rather
than applying management directives derived from different regions of the United States.
Citation
Myrick, K. E. (2008). Vascular plant and vertebrate species richness in national parks of the Eastern United States (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.Download
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