Effects of Vegetation Patchy Distribution on Runoff, Erosion and Nutrients Loss in Desertified Steppe Area
Updatetime:2011-11-25From:
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Runoff is the dominant pathway of water, nutrients and soil materials transfer and redistribution in arid land, which is strongly affected by vegetation pattern. The influences of the mosaic distribution of biological soil crust patches and spot-structured shrub patches in desertified steppe area in southeast fringe of Tengger desert on runoff, soil erosion, sedimentation and related resources redistribution were investigated. The results show that vegetation patches could obstruct the runoff and sediment, which inevitably leads to the reduction of resources losses. There is a source-sink relationship for resource (water, sediments and nutrients) redistribution between the biological soil crust patch and shrub patch. Under the simulated rainfall condition, the time of ponding and runoff commencement in the plots consisting of both crust and shrub patches is significantly longer than those in the plot consisting of only crust patches; the volume of rainfall for runoff commencement of the former was remarkably greater than that of the latter. In simulated and natural rainfall events, the shrub patches effectively obstructed and captured the runoff and carried sediments, organic matter and nitrogen, etc, which are generated from the biological soil crust patch. The water penetration depth in shrub patches was significantly greater than that in crust patches. The resource capture of shrub patches effectively decreases resource leakage, which is beneficial to desertification prevention.
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