Grazing induced changes in plant diversity is a critical factor controlling grassland productivity in the Desert Steppe, Northern China

The desert steppe is a large component of the semi-arid grassland ecosystem in northern China, and provides significant resources for livestock production. However, overgrazing is regarded as one of main causes of its degradation and desertification over recent decades. Quantifying the direct and indirect effects of grazing disturbance on plant community productivity in the desert steppe ecosystem can provide insights into appropriate measures for the restoration of degraded grassland and biodiversity conservation. Here, we examine the effects of four grazing intensity treatments: no grazing (control), light grazing (LG), moderate grazing (MG) and heavy grazing (HG) on the plant community and soil nutrients with sheep grazing over 12 years in a desert steppe in Inner Mongolia, northern China. The results showed that increasing grazing intensity resulted in decreased species richness, Shannon-Wiener and Pielou's index, as well as above- and belowground biomass. Soil moisture, nitrogen, available potassium and soil organic carbon were not affected (P > 0.05) by grazing disturbance. In addition, grazing disturbance had a greater indirect effect on aboveground biomass via plant diversity. Consequently, plant diversity is a key indirect factor that determines community productivity in response to grazing disturbance. Reducing grazing pressure can contribute to maintaining relatively high species diversity and productivity in the desert steppe of northern China.