Testing biodiversity-ecosystem functioning relationship in the world’s largest grassland: overview of the IMGRE project

Context: The relationship between biodiversity and ecosystem functioning (BEF) is a central topic in ecology on local, regional, and global scales. A powerful approach to BEF studies is large-scale field manipulative experimentation. Objectives: The Inner Mongolian Grassland Removal Experiment (IMGRE) was designed to examine the mechanisms of the BEF relationship in the world’s largest grassland, explicitly considering multiple trophic levels and grazing by grasshoppers and sheep. Methods: IMGRE followed a randomized block design, with a total of 512 plots (6 m × 6 m each). The project involved massive field campaigns and laboratory analyses, and unprecedentedly employed two removal protocols in parallel: complete removal (eradicating all targeted functional types) and partial removal (an equal-disturbance removal scheme). Results: We summarize key findings on aboveground and belowground primary production, functional richness, identity, and composition, compensation at the species, PFT, and community levels, soil water and N retention, net N mineralization, microbial biomass, and grazing by grasshoppers and sheep. Comparing and contrasting results from the two removal protocols, we have found that the responses of ecosystem processes depend on plant functional richness and identity, as well as disturbance characteristics. Conclusions: As part of the special issue on the ecological patterns and processes in the Inner Mongolian Plateau, this article provides an overview of the IMGRE project. The findings of this project shed new light on the BEF relationship in natural grasslands, and have important implications for ecosystem management in the Mongolian Plateau.