Variation Of Vegetation EVI And Its Driving Factors In Anhui Province During 2000-2020

Vegetation cover is important to the stability of regional ecosystems and is a focus of research on the relationship between natural and human environments.Although some studies have investigated the association between changes in vegetation cover and various influencing factors,these have shortcomings in quantifying direct and indirect effects.In this study,we first used ESTARFM（Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model）to produce a high spatial and temporal resolution EVI dataset and cross-validate MOD13Q1 EVI data.The MOD13Q1 EVI data of Anhui Province from 2000 to 2020 were then used as the data source,and the univariate linear regression,coefficient of variation and Hurst index methods were used to analyze spatial and temporal trends and fluctuations in the EVI between 2000and 2020 and predict future trends.Further partial correlation analysis method were used to explore the time-lag effect of EVI changes on climate change in Anhui Province.Finally structural equation model（SEM）was used to quantify the effects of topography,annual average temperature,annual precipitation and human activity changes on EVI variation in Anhui Province.The main findings are as follows.（1）The cross-validation results of MOD13Q1 EVI data in Huainan mining area show that it is in good agreement with ESTARFM EVI in both interannual and inter-monthly trends,and also has good spatial consistency.（2）From 2000 to 2020,the overall EVI in Anhui Province showed a fluctuating trend that increased at a rate of 0.0181·10a^-1,and the EVI variation has obvious seasonal characteristics,with the highest EVI values in summer and the lowest EVI values in winter.The EVI showed a spatial distribution pattern of high in the north-south and low in the middle,and 67.1%of the study area showed a greening trend.The EVI was relatively stable in most regions,with regions of fluctuating EVI being mostly affected by urbanization.The overall EVI change exhibit anti-sustainability that indicates for a period after 2020,EVI will likely decrease.（3）From 2000 to 2020,the average partial correlation coefficients of monthly precipitation,monthly mean temperature and monthly EVI in Anhui Province were0.19 and 0.60,respectively,and the significantly correlated areas accounted for 76.01%and 95.36%of the study area,respectively.There was a significant lag effect in the response of monthly EVI to monthly precipitation in Anhui Province,and the areas with a lag time of 1,2 and 3 months accounted for 40.6%,22.8%and 10.7%of the study area,respectively.There was no significant lag effect（99.4%）in the response of monthly EVI to monthly mean temperature in Anhui Province.The bias correlation coefficients of grassland,shrubland and forested land with precipitation were larger,followed by paddy land and the smallest in dry land.In terms of lag time,there were mainly 0-1 month,0-2 month,0/2-3 month,0/2-3 month,and 0/2-3 month lags in response to precipitation for dryland,paddy,grassland,shrubland,and forested land,accounting for 95%,98%,90%,90%,and 87%of the area of the corresponding land use types,respectively.（4）Among the regions of EVI increase,72.2%had no change in land-use type,while 10.8%and 6.6%changed to farmland and woodland land uses,respectively.Among the regions where EVI decreased,69.9%had no change in land-use type,while13.7%changed from farmland to construction land.Overall,human activity change was the main influence on EVI change,which was mainly reflected in the negative impacts of accelerated urbanization.Topography had direct and indirect effects on EVI variations in Central and Southern Anhui.Annual precipitation change had a stronger impact on EVI variation in Northern and Central Anhui than in Southern Anhui,while annual average temperature change had a small impact in the entire province.Compared with other study methods,SEM provides a new approach to quantifying the influences of vegetation cover dynamics.In addition,the results of this study have important implications for ecological environmental protection and sustainable development in Anhui Province.Figure 40 Table 7 Reference 108...