干旱区生态环境知识资源中心

Biological soil crusts (BSCs) are extensively developed and commonly regarded as a kind of vegetation in desertification areas around the world. The natural recovery process of BSCs after disturbance and their long-term impacts on the soil water conditions are important but not well understood. In order to provide more insights into this problem, we set up two treatments including BSCs (natural BSCs without disturbance) and disturbed BSCs (the top 30 mm of surface soil, including the BSC layer, was severely disturbed and completely removed) in a semi-arid environment on the Loess Plateau of China. Over the succeeding years, the natural recovery process of BSCs was qualitatively described and the soil water content at 0-90 cm depth of the two treatments was consecutively monitored. The results showed the following: (1) it is possible to recover natural moss-dominated BSCs after severe disturbance under natural conditions, and the recovery process to BSC full-coverage took approximately three years; (2) the BSC disturbance greatly decreased soil water content by up to 18% and the effects gradually weakened with time; (3) the BSC disturbance decreased surface soil water content (0-70 cm) by up to 24% but increased deep soil water content (80-90 cm) by up to 13%; and (4) the BSC disturbance decreased soil water storage at 0-90 cm by 7.8 mm, 4.4 mm, 8.0 mm, and 4.9 mm in the second, third, fourth, and seventh years, respectively. We concluded that the BSC disturbance degraded soil water conditions in the three to four years following the disturbance. Therefore, the artificial destruction of natural moss-dominated BSCs in a semiarid region on the Loess Plateau of China should not be recommended as a land management practice for the improvement of soil water conditions. (C) 2014 Elsevier B.V. All rights reserved.