Changes in plant community composition and soil properties under 3-decade grazing exclusion in semiarid grassland

Grazing exclusion is an effective way to restore the degraded grassland, and significantly influences the vegetation compositions and soil properties. Plant–soil interaction plays an important role in the maintenance of both plant community composition and soil properties. However, there is littler information on the changes and feedback plant community and soil properties in the semiarid grassland on the time series of the long-term scale that has been continuous grazing exclusion grassland for thirty years. Using the monitoring data of five reference years from 1982 to 2011, we studied the effects of long-term grazing exclusion on plant community and soil properties, the grazing management treatment was as the control. Our results showed that the coverage, plant density, species richness above- and belowground biomass, and Shannon–Wiener index are higher in the mid- and transitional stage of succession in arid and semiarid grassland and then decreased with increasing restoration time. The plant density, coverage and aboveground biomass of plant functional groups showed similar results. Soil organic matter (SOM), total nitrogen (TN), available potassium (AK), available phosphorus (AP), and available nitrogen (AN) significantly increased with the increase of restoration time. There was an interaction between coverage, species richness, total productivity and some soil properties. For plant functional groups, only perennial bunchgrasses was significant positively related to SOM, TN, AN, and AK. This implies that perennial bunchgrasses may be an indicator of soil properties and improve soil nutrient. Our studies provide new sights into the plant–soil interactions and grassland management in semiarid region.