Grazing impacts on ecosystem functions exceed those from mowing

Abstract

Aims Land use change due to the increasing anthropogenic activities is the most important driver leading to alteration of multiple ecosystem functions. Overgrazing is thought to be one of most pervasive and significant degrading processes in grasslands, but direct comparisons with other comparable drivers of land use intensification are lacking. Our results aimed to test how single land use practices (grazing, mowing), and combined land use practices (both grazing and mowing), influence biodiversity, soils and plant function, and the coupling of aboveground and belowground functions and properties in a Eurasian steppe grassland. Methods We examined changes in individual functions associated with aboveground and belowground plant and soil compartments, and multiple combined functions (hereafter ‘multifunctionality’) at 317 sites along an extensive climatic gradient in Northern China. Further, we investigated the correlations (coupling) between aboveground and belowground processes under the three land use scenarios. Results We found a mixture of effects of grazing, mowing and mowing plus grazing. However, values of many aboveground and belowground attributes were lower when sites were grazed. Although grazed sites had lower values of soil carbon and nutrients, there were no grazing-induced changes in root carbon, nitrogen and phosphorus. More importantly, the most intense land use scenario (grazing combined with mowing) decoupled the correlations between belowground and aboveground functions compared with that of single land uses. Conclusions Our study demonstrates that mowing is a better long-term management method than grazing for semi-natural grasslands in the Eurasian steppe are heavily grazed. Our results demonstrate that additional land use pressures imposed when mowing and grazing are applied together can decouple the positive associations between plant richness and functions. This knowledge is critical if we are to adopt strategies to maintain diverse grassland ecosystems and the important services and functions that they provide.