Spatial And Temporal Variation Characteristics Of NDVI In The Oasis Transition Zone And Desertification Control Strategies

Desertification is one of the serious ecological and environmental problems facing mankind today.The increasing degree of desertification has a particularly strong impact on oases and their transition zones in arid areas.Oasis transition zone is the ecological buffer zone between desert and oasis,which has a very important role in stopping the forward movement of sand dunes and reducing the wind and sand hazards of oasis.The fragile ecological environment of Minqin Oasis Transition Zone has been strongly influenced by the amount of water coming from the oasis and the social and economic development inside the oasis in recent years,causing the contraction of the transition zone area,which directly affects the ecological environment inside the oasis and poses a serious threat and great challenge to the sustainable development of oasis environmental protection and social economy.In view of this,we study the spatial and temporal variation characteristics of the Normalized Difference Vegetation Index(NDVI)of the Minqin Oasis Transition Zone,analyze the environmental factors affecting the oasis transition zone,and propose corresponding zoning management strategies for the oasis transition zone in Minqin County.This study can provide strong theoretical support for the sustainable socio-economic development of Minqin County and provide a research basis for the management of other oasis transition zones in the arid zone.This paper calculates and extracts NDVI values of the oasis transition zone based on Landsat remote sensing image data of Minqin County from 2000 to 2020,analyzes its spatial and temporal variation characteristics,takes into account the climate and hydrological changes of the watershed,the adjustment of oasis crop cultivation structure and the economic status of the population,uses partial least squares regression analysis and correlation analysis to explore the main influencing factors of NDVI in different regions,and the main findings of the study are as follows:(1)The spatial and temporal variation of NDVI in the transition zone of Minqin Oasis during 2000-2020 was characterized as follows: on the temporal scale,the overall NDVI of the transition zone showed a fluctuating trend of decreasing,with the total mean value decreasing by 0.01 every 10 years on average;on the spatial scale,the overall NDVI of the transition zone decreased with increasing distance towards the desert,with a steep decrease occurring within the distance of 0-240 m from the main body of the oasis,with an average decrease of 0.62 every 100 m.The average decrease was 0.62 per 100 m.(2)The results of the relationship between natural environmental factors and NDVI values in the transition zone show that precipitation has a significant positive influence on NDVI in the transition zone,the temperature has a significant negative influence on NDVI in the transition zone,and runoff has a significant positive influence on NDVI in the transition zone.The relationship between socio-economic environmental factors and NDVI values in the transition zone shows that farmers’ income has a two-sided influence on NDVI in the transition zone,the gross domestic product has a significant positive influence on NDVI in the transition zone,urbanization has a significant positive influence on NDVI in the transition zone,total water use and crop area have a significant negative influence on NDVI in the transition zone as a whole,and NDVI values in the sample points near arable land have a significant positive influence.In recent years,the influence of NDVI in the transition zone has gradually changed from being dominated by natural factors and agricultural factors to being dominated by natural factors,economic factors,population factors and water use,and human activities have influenced the oasis transition zone in a more multifaceted and deeper way.(3)Based on the analysis of NDVI numerical characteristics and influence factors of Minqin Oasis Transition Zone,the transition zone is divided into four regions and the following management strategies are proposed:(1)Area Ⅰ is significantly influenced by precipitation,so this area is under long-term protection and management,with the construction of sand control and sand barrier functional forest belts at the border of the transition zone and regular implementation of artificial rainfall.(2)Area Ⅱ is significantly influenced by population,economy,agriculture and water use,so this area is controlled and managed,sand barriers are established at the outer edge of the area,the agricultural planting structure is adjusted inside the oasis,and the management is monitored annually.(3)Area Ⅲ is significantly influenced by precipitation,runoff,and temperature,so this area is managed by human intervention,planting large areas of protective forests and setting up wind panels at the edge of the transition zone,and monitoring and managing it annually.(4)Area Ⅳ has a strong response to all kinds of factors,and this area is managed comprehensively by planting forest networks and forest belts at the outer edge of the transition zone and setting up windbreaks,and the government strengthens the control of ecological management of the oasis and monitors and manages it monthly.