RELATIONSHIP BETWEEN SPECIES RELATIVE ABUNDANCE AND PLANT TRAITS FOR AN INFERTILE HABITAT

This study tested whether differences in species abundance at an infer tile site could be explained by differences in the species' plant trai ts. Nine traits were chosen for the analysis based on results of previ ous studies conducted across soil fertility gradients. The traits were measured for each of seven herbaceous species whose abundance ranged from 5% to 100% of locations occupied in a ridgetop habitat. Using lin ear regression, significant relationships were found between species r elative abundance and each of five traits. In these relationships, a t rait explained between 69% and 88% of interspecific variation in abund ance. Relatively abundant species had a slower growth rate, smaller sh oot mass, higher root to shoot ratio, slower loss of leaf tissue to he rbivores and higher infection of roots by mycorrhizal fungi than less abundant species. Using three of these five traits (i.e. shoot mass, m ycorrhizal infection and loss of leaf tissue to herbivores) as indepen dent variables in a multiple regression equation explained 99% of inte rspecific variation in abundance. The latter result indicates that spe cies relative abundance can be explained for a single habitat by choos ing traits found to be related to species abundance in previous gradie nt studies. However, not every trait chosen was significantly related to species abundance. Therefore, a large number of traits may have to be chosen initially to ensure that some subset of these traits can exp lain species relative abundance.