新疆不同草地类NDVI近20年月际时空动态及其驱动因素OA

Xinjiang was rich in grassland types and had distinct seasons,with grassland productivity fluctuating significantly throughout the year.Conducting long-term and monthly dynamic monitoring was crucial for accurately understanding the patterns of grassland change and for the scientific protection and rational use of grassland resources.This study used MODIS-NDVI data and employed univariate regression analysis,multivariate residual analysis,and the Hurst index to explore the interannual and monthly dynamics of the normalized vegetation index(NDVI)of 11 grassland types in Xinjiang from March to October between 2001 and 2023.It also analyzed the impacts of climate and human activities and predicted future trends.The results showed that:(1)From 2001 to 2023,the NDVI of Xinjiang's grasslands generally showed a fluctuating increasing trend,with the area showing an increasing trend accounting for 75.99％and a decreasing trend accounting for 5.86％.In terms of inter-annual dynamics,the months of April,May,and October stand out with the most significant upward trends,and the NDVI of all types of grasslands shows an increasing pattern.Spatially,there was a distribution pattern of higher NDVI in mountainous areas and lower in plains.In terms of monthly changes,the average NDVI of grasslands first increased and then decreased,reaching a peak in July.(2)From 2001 to 2023,the combined effects of climate change and human activities were the main driving factors behind the increase in NDVI for most grasslands in Xinjiang,accounting for 55.13％.Among these,human activities contributed more to the changes in NDVI than climate change,especially in May,where the area with a contribution rate of 80％—100％was the highest at 62.34％.In alpine and swamp grasslands,the proportion exceeded 90％.(3)In desert steppe grasslands,precipitation and population density have a relatively large positive contribution rate to NDVI,which promotes the growth of grassland NDVI.However,high grazing intensity can lead to a decrease in grassland NDVI.The improvement and implementation of grassland protection policies have provided favorable conditions for the improvement of grassland NDVI.(4)In terms of future trends,the NDVI of Xinjiang's grasslands was mainly expected to increase,accounting for 92.49％.However,from June to September,the area of grasslands expected to show a decreasing trend in the future accounted for about 25％,reaching 34.88％in August.In temperate meadow grasslands and mountain meadow grasslands,more than 10％of grasslands were expected to show a decreasing trend,which required special attention in future grassland use and management.