Studying On Vegetation Quick Recovering In Sand Zone Large Region

Taking the different enclosed period pasture of Yanchi County as the research object, The research time lasted from 2002 to 2006, the vegetation recovered quickly since the enclosed measures done in 2002, the biomass, coverage, biodiversity index value is getting higher, forming the Sophora alopecuroides and Artemisia capillaries Thunb community, the stabilization of the community is increasing. The pasture enclosed since 2002 is better than long-time enclosed (the combating desertification demonstration project carried out in the typical county on the end of last century). At the same time, Based on NDVI and quantificational remote sensing model on vegetation fraction, extract the grade map of vegetation fraction. Based on the analysing of the grade map of vegetation fraction in 1989 1999 2003,the results show that the vegetation fraction is increasing in this two period. The annual average change in later period (1999-2003) is more than that in early period (1989-1999), it attributes to the enclosed measured. It declarates that the enclosed measure could make the vegetation recover quickly.As the enclosed time increasing, the pasture enclosed since 2002, the growth is getting decline after enclosed 4-5 years, specially the long-time enclosed pasture, the growth is also getting decline, this all note that the enclosed time effect the growth of the vegetation huge.The paper analyzing the reasons of the vegetation variation, the climate (including rainfall and wind), artificial factors, microbiotic soil crust, external disturbance effect the growth of the vegetation. The microbiotic soil crust has a course inhibited to the growth of the vegetation after promoting it, applying the redundancy impact on vegetation stabilization, disturbance impact on the vegetation, it is considered that the management of the pasture should be adjusted, not just enclosed, but using properly, then the ecological and economic benefit could all win.