| This study focused on fifteen species endangered in Illinois, five threatened and three classified as forest sensitive species. Biological and ecological attributes of these and 24 common congeneric species were compared through univariate and multivariate analysis. For all but four attributes, common and rare species had distributions that were very different from one another. The observed value exceeded the tabled value at the 95% confidence level (p < 0.05) for fourteen attributes with eleven of those significant at the 99% confidence level. Distributions for all the climatic attributes, average annual precipitation, biotemperature, and aridity index, were significantly different between common and rare species. Percent sand and silt are both significantly different (p < 0.0001 and p < 0.0006, respectively) between common and rare species sites, but not percent clay. The percent organic carbon was also significantly different (p < 0.0012) with several rare species occurring in soil high in organic matter. Ground cover beneath rare versus common tree species was significantly different for both percent herbaceous and woody ground cover (p < 0.0001), as was percent herbaceous plants growing in close association with common and rare herbaceous plants.; Inorganic carbon was significant and had the highest loading on axis one of a principle components analysis for the all species and rare groups, while no attribute was found to be significant among the common species group. Texture was also significant and had the highest loading on axis two for the all species group (silt and clay) and the rare species group (silt). In the ordinations, species that occur in a specific mesohabitat, e.g. prairie, aligned with other species of the same mesohabitat. The aligning of species in the ordinations shows that there is a suite of attributes within a specific range that characterize the individual mesohabitats. |
