1982—2022年黄土高原归一化植被指数变化的时空特征

长时间地表植被指数变化序列构建与分析是生态环境监测领域的重要内容。以我国生态工程建设重点地区——黄土高原为研究区,采用时间序列的方差匹配方法,融合了2套卫星遥感的归一化植被指数(NDVI)数据产品(GIMMS 3g和MODIS),建立了覆盖1982—2022年的黄土高原暖季(5—9月)NDVI数据集,揭示了其间黄土高原植被覆盖变化的时空特征。研究发现：黄土高原暖季NDVI呈现“先慢后快”的增加趋势,转折点大致出现在2002年,1982—2002年暖季NDVI增速仅为0.01/(10 a),2003—2022年增速高达0.06/(10 a),其中十八大以来增速尤为显著;暖季NDVI快速增加区域主要位于黄土高原中部,并向东北、西南方向延展,与“退耕还林(草)”重点区域范围基本一致;在黄土高原南部、东部和青海省东部一带,暖季NDVI呈缓慢下降趋势。过去40年间黄土高原NDVI增加与生态工程建设关系密切。

Temporal and Spatial Characteristics of Normalized Difference Vegetation Index (NDVI) Changes in the Loess Plateau from 1982 to 2022

The construction and analysis of long-term change series of surface vegetation index is an important content of ecological environment monitoring.China''s key area of ecological engineering construction,the Loess Plateau,is taken as the research area,and two sets of satellite remote sensing NDVI data products (GIMMS 3g and MODIS) are fused by using the variance matching method of time series.As the result,a NDVI data set covering the warm season (May-September) of the Loess Plateau from 1982 to 2022 is established,revealing the temporal and spatial characteristics of vegetation cover changes in the Loess Plateau during this period.Research has found that:In the warm season of the Loess Plateau,NDVI shows a increasing trend of "slow first and then fast",with a turning point around 2002.From 1982 to 2002,the NDVI growth rate was only 0.01/(10 a) in the warm season,and from 2003 to 2022,the growth rate was as high as 0.06/(10 a),with the growth rate particularly high since the 18th National Congress of the Communist Party of China.The rapidly increasing area of NDVI in the warm season mostly occurs in the central part of the Loess Plateau and extends towards the northeast and southwest,which is highly consistent with the key area of grain for green.In the southern and the eastern parts of the Loess Plateau and the eastern part of Qinghai Province,NDVI of the warm season shows a slow downward trend.In summary,these findings suggest that over the past 40 years,the increase of NDVI of the Loess Plateau''s warm season was deeply related to ecological engineering.