Effects of land cover conversion on soil properties and soil microbial activity in an alpine meadow on the Tibetan Plateau

Land cover conversion intensively occurred in the Tibetan Plateau of China during the past decades. However, responses of soil properties and soil microbial activities to land cover conversion under different land cover types have not been fully understood. The objective was to assess the effects of land cover conversion on soil C and N stocks and soil microbial properties of topsoil of an alpine meadow in the Tibetan Plateau. Soil cores of surface soil (0-20 cm) were collected from three adjacent land cover types: native alpine meadow, artificial grassland and mound-shaped denuded land. Soil microbial metabolic diversity was measured using Biolog EcoPlates. Significant losses of SOC and TN storages were subject to land cover conversion in topsoil, decreasing 14.5 and 10.9 % of alpine meadow to artificial grassland and 52.9 and 51.7 % to denuded land. Alpine meadow soils had the highest soil microbial biomass and microbial metabolic activity of three land cover types. Microbial biomass and microbial metabolic activity decreased markedly after alpine meadow conversion to denuded land. Land use conversion from original alpine meadow to artificial grassland and denuded land caused decline in soil organic carbon density, total nitrogen density and soil microbial activity. Soil carbon emissions from alpine meadow conversion were released to the atmosphere and could influence climatic change.