Spatial patterns of soil nutrients, plant diversity, and aboveground biomass in the Inner Mongolia grassland: before and after a biodiversity removal experiment

Context: Spatial heterogeneity is ubiquitous in ecological systems, and has important effects on biological diversity and ecological processes. Objectives: Does spatial heterogeneity affect the relationship between biodiversity and ecosystem functioning (BEF)? To help address this question, this study investigated how the spatial patterns of key BEF variables changed before and after the biodiversity removal during a BEF experiment in China. Methods: Our analysis was based on data from the Inner Mongolia grassland removal experiment (IMGRE) which was conducted in the Xilingol Steppe, Inner Mongolia, China. We quantified the spatial patterns of key variables of BEF, and examined the spatial relationships among these variables, using biodiversity indices and spatial statistical methods (autocorrelation and semivariance analysis). Results: Our results show that the variables of BEF in the Inner Mongolian grassland had various spatial patterns, most of which were spatially correlated to each other. Removal treatments had significant effects on these spatial structures and correlations. These effects were diverse in terms of both their kinds and magnitudes because of different removal protocols and treatments. Conclusions: The differences in spatial patterns of plant and soil variables and their correlations before and after the biodiversity manipulation do not necessarily imply that the results from BEF experiments like IMGRE are invalid, but they do suggest that the possible effects of spatial heterogeneity on the BEF relationship should be further scrutinized in future studies.