Abstract

Theory predicts that greater biodiversity is expected to enhance stability of ecosystem. In field experiment, we created some diversity-level assemblages by removing functional groups across two grassland ecosystems and evaluated the responses of spatial stability of aboveground net primary productivity (ANPP) to varying functional trait diversity. The results revealed that higher diversity promoted greater spatial stability in the semi-shrub grassland ecosystem except SGB, whereas the similar pattern in diversity-stability relationship had been scarcely found in the typical steppe ecosystem. Additionally, we found that factors-influencing spatial stability varied across different grassland types. In the typical steppe ecosystem, spatial stability was only accounted for by positive sampling effect induced by high dispersal rate of rhizomatous grass. By contrast, in the semi-shrub grassland ecosystem, diversity level together with positive sampling effect commonly contributed to spatial stability, moreover, effect of particular trait overshadowed that of diversity. We also found that the positive diversity-stability relationship did not exist when compared with two grassland types. Research provides new insights into understanding the relationship between biodiversity and ecosystem functioning in varying environments. This relationship is not consistent across different ecosystems and is often system-dependent. Critical trait of species is particularly an important determinant for ecosystem functioning.

Key words: Biodiversity experiment, spatial variability, functional trait diversity, ecosystem type.

Abbreviation

ANPP, Aboveground net primary productivity; SSS, semi-shrub only; SFL, semi-shrub + forbs + legume; SGB, semi-shrub + rhizomatous grass + bunchgrass; NATS, an untrimmed natural community containing semi-shrub + rhizomatous grass + bunchgrass; FLB, forbs + legume + bunchgrass; NATR, non-trimmed natural community containing forbs + legume + bunchgrass + rhizomatous grass; RRR, only rhizomatous grass.