Abstract: Biodiversity has significant impacts on ecosystem function. As important aspects of biodiversity, species diversity and functional group diversity have caused wide concern of ecologists. However, comprehensive and systematic studies are lacking on Songnen grassland biodiversity. In this study, we investigated 42 communities (including 427 species) and studied biodiversity of herbaceous plants in Songnen grassland. The species in Songnen grassland were dominated by families of Gramineae, Asteraceae, and Leguminosae. The aboveground biomass of the dominant species had absolute advantage, and was significantly positively related with the aboveground biomass of the community (R²=0.904). The species diversity indexes had significant differences between different communities in Songnen grassland. Among all the 42 communities, species richness index of Leymus chinensis dominated community (the most important community) was the lowest (2.6). The diversity indexes of different functional groups also had obvious differences. The functional group diversity of C₄ grasses dominated community was higher than that of C₃ grasses dominated community. There was a significant positive relationship between functional group diversity and species diversity (P<0.01), indicating that functional group diversity may be able to denote the biodiversity of ecosystem to some extent in Songnen grassland.

Key words: Salix psammophila branch, branching exponent, allometry relationship., metabolic exponent