干旱区生态环境知识资源中心

Livestock grazing is recognised as one of the main causes of vegetation and soil degradation/desertification in the semi-arid Horqin sandy steppe of northern China. In this paper, soil-plant system carbon (C) in a representative degraded sandy grassland in the Horqin sandy steppe (42degrees58’ N, 120degrees42’E altitude c. 360 m a.s.l.) was measured. Three situations: long-term continuous grazing (CG), exclosure for 5 years (5EX), and exclosure for 10 years (10EX), were compared to assess the effect of grazing management on C sequestration. Ground cover increased from the CG (35%) to the 5EX (63%) and to the 10EX (81%), and accordingly soil organic C at 0-15 cm depth and total plant components C increased from the CG (492 and 98 g m(-2)) to the 5EX (524 and 134 g m(-2)) and to the 10EX (584 and 317 g m(-2)). The results suggested that continuous grazing in the erosion-prone sandy grassland is very detrimental to vegetation and soil. Under exclosure conditions, vegetation restoration and litter accumulation significantly increased plant-soil system C storage, and thus sequestration of atmospheric C. It was concluded that the degraded sandy grassland could contribute to significant C sequestration with the implementation of protective practices.