Comparison of Species Richness and FAD2 Functional Diversity in Order to Estimate the Biomass Production in the Central Zagros

In contrast to the taxonomic biodiversity, based only on the relative abundance of species in the community, functional diversity summarizes various aspects of the biological composition and, hence, the role of populations in the community. Functional diversity may be linked directly to the ecosystem services; the plant biomass encompasses many ecosystem services such as food supply, conservation, tourism, and pollination. In this study, we tested several hypotheses (1) existence of a close relationship between species richness and plant biomass (2) existence of a close relationship between FAD2 (Functional Diversity index) and plant biomass (3) explaining the high percentage of plant biomass variations. The results showed that the species richness in order to predict the plant biomass with a correlation coefficient equal to three does not count as a proper indicator. However, the correlation coefficient of FAD2 Functional Diversity with plant biomass was about 0.4, which is relatively good indicator to estimate the plant biomass because of explaining a significant percentage of the biomass variations. Finally, our results clearly showed that the incorporation of abiotic factors, plant traits and functional diversity (FAD2), containing the parameters of rainfall, leaf length, plant height and FAD2 index, could explain 75% of plant biomass variations and was considered as the most appropriate model predicts plant biomass.