Scale effects of vegetation restoration on soil and water conservation in a semi-arid region in China: Resources conservation and sustainable for management

The scale effect of vegetation restoration on soil and water conservation has received little attention, despite numerous studies on the assessments of vegetation restoration at different spatial scales. This study investigated the scale effect of vegetation restoration on soil erosion and water yield at Yanhe watershed, Chinese Loess Plateau. It provides the site-based temporal and spatial varying relationships among vegetation restoration, soil erosion, and water yield. Spatial modeling and mapping methods were used to analyze the scale effect at regional and sub-watershed scales. Our results indicated vegetation restoration has generated positive impacts on soil erosion reduction and negative impacts on water provision in the whole watershed. Croplands, sparse grasslands, and moderate grasslands were the land types which contributed the most to soil erosion. The decrease of cropland was the major contribution to soil erosion reduction. Moreover, the trade-off relationship between soil erosion and water yield existed in the whole watershed, but the degree of trade-off varied from one sub-watershed to another. High-risk soil erosion regions were concentrated in the central watershed. But in this region, the impacts of vegetation restoration on soil erosion control varied with different sub-watersheds. A simple increase of vegetation might not help reduce soil erosion in sub-watersheds where are characterized by low vegetation coverage and scattered vegetation restoration. Vegetation restoration should be based on past spatial LULC patterns. Soil erosion control should focus on the current level of cropland management and areas of vegetation maintenance than new afforestation in the high-risk soil erosion regions.