High ecosystem multifunctionality under moderate grazing is associated with high plant but low bacterial diversity in a semi-arid steppe grassland

Current studies on the relationship between biodiversity and ecosystem functioning have mostly focused on plant communities. Less is known about the individual and combined effects of biodiversity components above-and-below-ground on ecosystem multifunctionality. The aim of this study was to explore how different management regimes influence multifunctionality via modification of both plant and soil microbial (bacterial and fungal) diversity. We used a 6-year experiment in Inner Mongolian grassland to compare multifunctionality and separate functions related to the C, N, P cycles and plant productivity under four management regimes and examine relationships between these functions and different components of biodiversity, both above- and belowground. Ecosystem multifunctionality and the rates of nutrient cycling and plant productivity, were greatest under moderate grazing intensity, and lowest under no grazing. Further, across all management regimes, multifunctionality was positively related to plant diversity, and plant and soil microbial diversity combined explained a much greater (62.5%) proportion of variance in multifunctionality than that did either component alone. Different components of biodiversity showed contrasting relationships with individual functions: plant diversity was positively related to C and N cycling, whereas bacterial diversity was negatively related to P cycling and plant productivity. Moderate grazing has better outcomes for biodiversity conservation and ecosystem multifunctionality than mowing and cessation of grazing. Sustainable grazing management is a viable strategy to conserve both above- and belowground biodiversity and enhance the delivery of multiple ecosystem functions.