Vegetation Index Dynamics And Its Drivers In The Sandy Region Of Western Inner Mongolia

The sandy region of western Inner Mongolia is an ecologically fragile area,sensitive to climate change,and even weak climate change can have an impact on the ecology of the region.Vegetation is an important part of the ecosystem,and is the most basic database for describing the ecosystem.Therefore,an in-depth analysis of the spatial and temporal variation characteristics of vegetation in the sandy region of western Inner Mongolia and its driving factors reveals the patterns of climate and vegetation changes in the sandy region of western Inner Mongolia and the relationships between them,providing a reference for the formulation of policies to cope with climate and its sustainable development in the sandy region of western Inner Mongolia.Therefore,based on NDVI data and meteorological data,this study used one-dimensional linear fitting,Mann-Kendall mutation test,correlation analysis,partial correlation analysis,coefficient of variation,residual analysis and Hurst index analysis to study the dynamic changes of vegetation indices and their drivers in the western Inner Mongolia sand region from 1982 to 2020.The main conclusions drawn are as follows:The growing season NDVI increased significantly at a tendency rate of 0.01·（10a）^-1 in the sandy region of western Inner Mongolia with low vegetation cover from 1982 to 2020.Spatially,NDVI increased significantly in 56.41%of the image elements,and there was spatial heterogeneity in NDVI,with an overall positive development.The mean NDVI values for the four seasons were ranked as winter-1 and 0.005·（10a）^-1 respectively,and a decreasing trend in spring and winter with a tendency of-0.001·（10a）^-1.The mean NDVI coefficient of variation for the study area was 14%,which is stable and dominated by inverse The mean NDVI coefficient of variation in the study area was 14%,which was stable and predominantly inverse.Interannual temperatures in the sandy region of western Inner Mongolia increased at a highly significant rate of 0.3°C·（10a）^-1 between1982 and 2020（p<0.01）.Temperatures trended upwards in all four seasons,with the tendency rate ranked as spring>summer>autumn>winter.Spatially,winter temperatures showed a decreasing trend with a tendency of-0.06°C·（10a）^-1 in some areas of Alxa,while the rest of the regions showed an increasing trend.Interannual precipitation tends to decrease at a rate of-1.99 mm·（10a）^-1（p=0.67）.Among the four seasons,only autumn precipitation increased with a tendency of 2.62 mm·（10a）^-1（p=0.2）,while spring,summer and winter all showed a decreasing trend,with a fast to slow tendency of spring>summer>winter.In terms of spatial distribution,77.27%,56.67%and 94.85%of areas showed decreasing trends in spring,summer and winter precipitation respectively,while 77.88%of areas showed increasing trends in autumn precipitation.NDVI was positively influenced by temperature and precipitation during the 1982-2020 growing season in the sandy region of western Inner Mongolia,with some time lag.NDVI was more influenced by temperature than by precipitation.Spatially,NDVI was mainly positively influenced by changes in temperature,with a significant positive correlation of 46.36%.In the study area,the NDVI in summer was 54.08%positively correlated with air temperature,and the NDVI in summer was mainly positively influenced by air temperature during the same period.NDVI was not significantly influenced by precipitation in all seasons.There is a one-month lag in the effect of temperature and precipitation on NDVI in the study area.The growing season NDVI in the study area was mainly influenced by human activities.Anthropogenic activities dominate the positive influence with 46.44%.Climate factors dominate the negative impact with 14.08%.The combined factors were dominated by positive impacts with 23.8%.