PARENT SESSION
Thursday, August 10, 5:00-6:30 pm
Poster Session 20 - Biodiversity
Exhibit Hall, Ballroom Level, Cook Convention Center

An index of biochemical diversity: from strategies of the living to afterlife effects.

Epps, Kimberly^*,1, Comerford, Nicholas¹, ¹ University of Florida, Gainesville, FL

ABSTRACT- The lack of predictability of decomposition or mineralization behavior in litter mixture experiments may arise from the fact that the traditionally used descriptors of diversity – species- and functional group-richness – poorly characterize the traits that drive the processes under observation. We introduce a multivariate index of biochemical diversity based on Rao's Quadratic Entropy (Rao 1982) which incorporates both species character and relative abundance to describe the heterogeneity of chemical composition of collections of plant material. Using published data sets from natural and managed forest systems from temperate and tropical zones we demonstrate how chemical diversity as calculated from litter nutrient profiles varies widely within a given number of species or functional group and that the relationship of biochemical diversity versus species richness provides a unique snapshot of resource packaging as viewed by decomposers. When based on live foliage, the biochemical diversity index is a distillation of the resource capture and defense strategies of a plant community and may present a tool for monitoring shifts in community composition or responses to environmental conditions. We show the versatility of the index as a means to illustrate the resorption patterns of plant communities, as well as the variation in chemical expression of species under different environmental conditions and over time. We propose litter biochemical diversity to be a more relevant and comprehensive independent variable against which to gauge microbially dependent processes. Moreover, the potential for such an index to simultaneously represent foliar defense, nutrient allocation, and decomposability has implications for linking aboveground diversity and belowground processes.

Key words: multivariate diversity index, tropical and temperate forests, ecosystem functions