Short-term grazing exclusion has no impact on soil properties and nutrients of degraded alpine grassland in Tibet, China

Abstract. Since the 1980s, alpine grasslands have been seriously degraded on the Tibetan Plateau. Grazing exclusion by fencing has been widely adopted to restore degraded grasslands. To clarify the effect of grazing exclusion on soil quality, we investigated soil properties and nutrients by comparing free grazing (FG) and grazing exclusion (GE) grasslands in Tibet. Soil properties, including soil bulk density, pH, particle size distributions, and proportion of aggregates, were not significant different between FG and GE plots. Soil organic carbon, soil available nitrogen, available phosphorus contents did not differ with grazing exclusion treatments in both 0–15 and 15–30 cm layer. However, soil total nitrogen and total phosphorus contents were remarkably reduced due to grazing exclusion at the 0–15 cm depth. Furthermore, growing season temperature and/or growing season precipitation had significant effects on almost all soil properties and nutrients indicators. This study demonstrates that grazing exclusion had no impact on most soil properties and nutrients in Tibet. Additionally, the potential shift of climate conditions should be considered when recommend any policies designed for alpine grasslands degraded soil restoration in the future. Nevertheless, because the results of the present study come from short term (6–8 years) grazing exclusion, the assessments of the ecological effects of the grazing exclusion management strategy on soil quality of degraded alpine grasslands in Tibet still need long term continued research.