Effects of grazing exclusion on soil-vegetation relationships in a semiarid grassland on the Loess Plateau, China

Grazing exclusion (GE) is regarded as an effective practice to restore degraded grasslands. However, the patterns of vegetation recovery and related regulating factors in response to fencing have not been fully recognized. Hence, quantitative analysis of vegetation-soil relationships in response to GE was conducted in a semiarid grassland located on the Loess Plateau, North China. The results revealed that enclosure establishment significantly increased vegetation cover, height, and productivity but reduced plant diversity. Soil bulk density (0-20 cm) and pH (0-50 cm) clearly decreased after GE, whereas soil water (0-20 cm), organic matter (0-10 cm and 30-40 cm), and nutrient concentration (0-20 cm) increased significantly. Redundancy analysis of vegetation and environmental variables suggested that edaphic properties, including soil water, soil pH, total N, bulk density, and organic matter, was associated with plant community composition. Subsequent canonical correlation analysis indicated that soil bulk density, organic matter, and total N played an important role in shaping vegetation patterns in response to fencing whereas variations in soil pH and total N were the major contributors to variations in grazing rangeland. This work emphasized that fencing is a positive grassland management approach and suitable changes in grazing stock and soil variability are required to quantify vegetation recovery in response to grazing exclusion.