基于GEE的大青山国家级自然保护区NDVI变化及影响因素分析

In recent years, China has made great progress in the construction and management of national naturereserves such as the Daqingshan National Nature Reserve in Inner Mongolia. However, the associated ecologicalbenefits have not been effectively assessed. The purpose of this study is to assess whether the establishment ofthe Daqingshan National Nature Reserve has contributed to the ecological recovery and improvement of the area.Examining changes in vegetation dynamics can be an effective tool for regional ecological engineering assessment, and this study analyzes such changes using the normalized difference vegetation index (NDVI). Based onthe Google Earth Engine (GEE) cloud platform, the study uses Landsat remote sensing imagery to extract NDVIdata for the nature reserve for the years 1995 to 2020. Spatial and temporal variation in NDVI and variation drivers before and after the establishment of the reserve were analyzed using Pearson correlation, residual analysisand the Lindeman-Merenda-Gold (LMG) model. A decreasing NDVI trend was identified during the 1995—2008period in 69.04% of the studied area, while an increasing NDVI trend was identified during the 2008—2020 period in 94.98% of the studied area. These results indicate that the quality of vegetation in the study area has improved significantly since it became a national nature reserve. Negative impacts from human activities and climatic warming during the 1995—2008 period led to decreases in NDVI in the studied area, with climate warming being the dominant factor. An increase in precipitation and positive impacts from human activities drove increasesin NDVI in the studied area during the 2008—2020 period, with positive human impacts arising from ecologicalenvironmental protection engineering implementation being the main reasons for vegetation recovery during thisperiod. The selection of Landsat remote sensing images and the use of the GEE integrated computing environment enabled the study to obtain vegetation monitoring data over a long time span and at a high spatial resolution. Spatiotemporal variation in vegetation was also more accurately portrayed using the NDVI measure, therebyenriching the technical means for long time-sequence and small region-scale vegetation monitoring. The resultsof this study provide clear evidence of the ecological benefits brought by the establishment of the Daqingshan National Nature Reserve. At the same time, the study provides basic information and technical support for futureecological-environmental management decisions concerning the protected area.