The Distribution And Driver Anlysis Of Land Degradation In The Three-North Shelter Forest Region Of China

Land degradation is regarded as one of the most serious and widespread environmentalissues all over the world especially in arid, semi-arid and dry sub-humid areas. And then, theseareas occupy about60%in the Chinese land, which is severely influenced by land degradation.Therefore, It is very important to anlysis of the spatio-temporal changes and driver factors in theland degradation for controlling the status of land degradation and evaluating of the ecologicalmanagemet project benefits.In this paper, we analyze the land degradation trend and spatial change quantificationally andscientifically in the Three-North Shelter Forest region of China from1982to2006, using theremotely-sensed data of NOAA/AVHRR Normalized Difference Vegetation Index on the flat ofGIS, and then assess the effect of the regional land degradation only by human activity on thebasis of a distinction between land degradation in the human and natural actors.The main contents and conclusions of this paper is as follows:(1) The gridded precipitation data is interpolated combined with the latitude, longitude andweather station rainfall data, using the multiple linear regression and residual method, and thenextended to the entire project area by DEM. The results obtained by the method is more accurateand reliable than obtained directly through the interpolation;(2) The long time series characteristics of land degradation is analysed based on thesen+Mann-Kendall trend analysis method in the Three-North Shelter Forest region of China.This method could not only take the significance test for quantitative data on the trend ofchanges in the statistical sense, but also must not obey a certain distribution of sample data andhave a strong ability to avoid the measurement error and outliers. The results indicate that theland degradation have declined as a whole, its significant increase was13.00%, and thesignificant decrease was17.29%. Land degradation of most provinces tend to improvent,especially in Neimeng and Qinghai except Ganshu. And then the human-induced significantvegetation increase is1.93％, by contrary, the degradation is6.19％.(3) The residual method is used to evaluate the climate and human activities in the landdegradation and analyze the the change of long time series land degradation reason in the projectarea. The results showed that: it is11.93%that a significant positive effect of vegetation changeis brought by human activities, and a significant negative effect of6.19%. This shows that the impact of vegetation change is relatively weak due to the changes in rainfall over time in aridand semi-arid areas, and a significant change in vegetation is mainly affected by humanactivities.This estimation method successfully evaluated the land degradation in the Three-NorthShelterbelt Project Area. This indicated that the method has a certain scientific used on a largescale, verified by the medium-resolution Landsat satellite images, and then the verifying resultsare significant consistency with it. The following conclusions can be drawn: the natural climaticconditions are beneficial for the ecological improve and restoration as a whole, and humanfactors play an active role in ecological restoration, indicating that the Three-North ShelterbeltProject played a certain effect in it.