The Study Of The Soil Improvement Effect Of Decayed Seabuckthorn Pure Forest In North Shaanxi Loess Area

Sea-buckthorn is an excellent species of ecological restoration in the Loess Plateau, creating a large area of sea buckthorn plantations effectively to improve the ecological environment, but a large area of sea-buckthorn plantation have declined.This paper studies the shaanxi wuqi county sea-buckthorn artificial pure forests, analyzes the influence of site factor,soil moisture dynamic change before and after the recession recession seabuckthorn forests and soil improvement effection to explore whether the sea-buckthorn create conditions as pioneer species for vegetation restoration in the late. We can draw the main conclusions as follows:(1)Decline of seabuckthorn forest and site factors have strong influence,the serious recession condition of seabuckthorn forests on four kinds of slope is the sunny slope is the most,half sunny and half shady slope second,and the most light slope is shady slope.In addition to the sunny slope,the mortality of sea-buckthorn forests is0when less than a certain slope,the mortality of sea-buckthorn forests are increased with the increase of slope.shady slope is20°, half shady slope is10°,half sunny slope is17°.(2)The average soil water storage capacity of decayed sea-buckthorn forests are higher than the grass in growth season,but pre-recession seabuckthorn forestsis in contrastThe soil water storage capacity of decayed sea-buckthorn forests in0-20cm soil layer in May and June are higher than the grass.Soil water storage capacity of decayed sea-buckthorn forest in20-40cm soil layer are higher than the grass each month except in September and October.The water storage capacity of decayed sea-buckthorn forest in40-160cm soil layer are also higher than the grass each month,while that of pre-recession sea-buckthorn forests are less than the gress.in each month.. (3) The Soil available P and available K of three types of recession sea-buckthorn forest on the each layer are improved.The content of organic matter and the contentsof the soil total N and effective N below20cm layer of slightly decayed and moderately decayed sea-buckthornforestsincreased. The soil organic matterand effective N contents of severely decayed sea-buckthorn forests below20cm layers are higher than those under undisturbed slopes,while the improved effection of soil total N only reflect in40to60cm soil layer.(4) The decline of seabuckthorn forests has close contact with site conditions.The decayed seabuckthorn forests can effectively improve soil moisture and nutrients, especially for deep soil,providing favorable conditions for subsequent vegetation restoration. At the same time the soil nutrient conditions of decayed sea-buckthorn forests have improved,so the seabuckthorn can serve as a pioneer tree species, laying a foundation for subsequent vegetation restoration.