Distribution characteristics and boundary effects of soil nutrient in silvopastoral system in the loess region of western Shanxi Province, northern China

Taking locust-natural grass model in the Loess Plateau of western Shanxi Province, northern China as research object, soil nutrient distribution characteristics and boundary effects of organic matters, total nitrogen, available P and available K of soil were studied to provide scientific basis for vegetation restoration, land rational use and sustainable management of silvopastoral system in this region. The results showed that 1) soil nutrient content was unevenly distributed, and it showed differences at varied patches in the silvopastoral system, especially in surface soil layer(0-20 cm). 2) There were obvious hierarchical characteristics in soil profile in the silvopastoral system, the soil nutrient content was higher in 0-20 cm soil layer than that in 20-40 cm; in horizontal direction, variation of soil nutrient was relatively steady and soil nutrient content increased with increasing distance from forest edge to grass area. Variation of soil nutrient was relatively complicated and was similar to wave curve. 3) Moving split-window approach showed that boundary soil nutrient in the silvopastoral system had relatively obvious boundary effects. The location of the edge effect of soil nutrient lied in 4 m in grass exterior to 3 m in forest by comprehensive consideration of four types of soil nutrient indices, and then the common width of edge influence to soil nutrient was 7 m.