| Nowadays desertification is one of the ecological environmental problems that all countries in the world need to face together.It is a phenomenon of vegetation destruction,soil productivity decline or even loss under the influence of various natural and human factors.It will not only affect the current human production and living environment and reduce people's quality of life,but also pose a serious threat to the future sustainable development of the world.Paying attention to and accurately grasping the dynamic changes of desertification land in the region as well as studying its driving force mechanism can provide scientific theoretical support for the prevention and control of regional desertification,and it can not be ignored for safeguarding people's production and living standards.China's research on desertification is mostly concentrated in the northwest region.However,in recent years,the study of desertification in the south has received more and more attention from researchers.Aba Prefecture in western Sichuan is a typical plateau ecological fragile district and one of the most severe and typical southern regions affected by desertification.With the change of climate and the further development of socio-economic and regional tourism activities in the region,the fragile ecological environment may be further affected.Therefore,the research on desertification monitoring and driving mechanism for the region is of great significance for the sustainable development of the Aba region.Taking Aba as the research area prefecture in western Sichuan,the paper uses the multi-source remote sensing data of the area between 2000 and 2018 to discuss the degree of desertification land evolution in Aba prefecture from the aspects of desertification information reversed from several indexes such as vegetation coverage,MSAVI,GSI and other indicators,as well as area change,spatio-temporal change and desertification land evolution in Aba prefecture through the temperature and precipitation of the area.Based on the analysis of climatic factors such as wind speed,humidity and socio-economic factors,the driving force mechanism of spatio-temporal change of desertification is discussed qualitatively and quantitatively from both natural and man-made aspects.The main findings are as follows:(1)The desertified land in the Aba area is mainly distributed in the southeast part of Aba Prefecture,mostly in Wenchuan County,Xiaojin County,Li County and Songpan County.In the past two decades,the change of desertification area in the region has showed a fluctuating trend.The desertified land area fluctuated back and forth in 20 years,and the total area basically stabilized.The dominant type of desertification was mild desertification.(2)The altitude has a significant impact on the desertification distribution in the Aba area.The area more than 4,500 meters above sea level has maintained at least 70% of desertification rate in the last 20 years,in the meantime the degree of desertification development is also dominated by extremely severe desertification;the area with the most serious development of desertification is concentrated at altitudes of 3,500 meters to 4,500 meters.Accounting for 60% of the desertification area in the whole region,which is a place that needs to be paid attention to in the future.(3)Desertification changes are influenced by both natural and human factors,but the dominant factors affecting desertification in different regions are also different.In the area above 4,500 meters above sea-level,the desertification is mainly affected by natural factors.AS the temperature rises and the precipitation increase,the desertification area in the area also increases,and the overall trend shows a positive correlation.In the region between 3,500 and 4,500 meters above sea-level,natural and human factors act simultaneously on desertification changes in the area,and the contribution rate is equivalent.In the area below 3500 meters above sea-level,it is mainly affected by human factors.With increase of the government investment in desertification control,desertification has reversed,but at the same time the rapid development of the secondary industry and the increase of population have caused a tendency to worsen desertification in the region.So,reversal and deterioration have basically reached a state of mutual balance,that is to say the desertification area has not continued to increase,and the overall trend is relatively gentle.(4)After the principal component analysis of the driving force factors for the change of total desertification area,it was found that the human factor is the main driving force of desertification change in the region,and its contribution rate reached 64%;Natural factors have laid the overall pattern of desertification distribution,but in areas with high human activities,desertification is increasingly affected by human factors,especially in short-term scales,which are basically due to human activities.Therefore,the prevention and control of desertification requires the government to further increase investment and improve the quality of the population and environmental awareness. |
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