Habitat Assessment of Two Narrowly Endemic Plant Species, Ozark Spiderwort (Tradescantia ozarkana) E. S. Anderson and Woods. And Newton's Larkspur (Delphinium newtonianum) D. M. Moore.

摘要

The threat of biodiversity loss is upon us with the onset of climate change and our ever-demanding needs of the Earth's resources for a rapidly growing human population. Species highly vulnerable to loss are those limited in abundance and distribution, or those with reduced genetic diversity. Efforts to actively conserve a sensitive species require effectual data on the probable causes of their vulnerability. Two species of concern, Delphinium newtonianum and Tradescantia ozarkana, are globally rare endemic vascular plant species found only in the Interior Highlands of North America. In an attempt to understand the causes for their endemism, habitat characterization of eight sites for each species was carried out by means of plant community assessments, soil characterizations, natural history investigations, and Geographic Information Systems (GIS) modeling. Ordination methods were utilized both to examine patterns among the sites and to assess stem density as a function of soil chemistry and physical site characters. Stem density for T. ozarkana was found to be significantly correlated with magnesium, copper, zinc, and phosphorus soil content. In contrast, ordination methods identified few factors that were clearly important for D. newtonianum habitat. GIS was used both as tool for habitat data collection on scales not possible by field measurements and for basic habitat modeling to test the predictability of delineating habitat area using easily accessable GIS layers without prior knowledge of habitat parameter importance levels. Although projected habitat modeling was unreliable using these methods, progress was made toward understanding habitat limitations.