基于NPP与EVI的三江源生态状况评估

Using NPP and EVI to assess the ecological status of the Sanjiangyuan area

摘要:

为了探究2001-2019年三江源生态状况在时空上的变化特征,基于Mann-Kendall检验法从时空角度对2001-2019年生长季累计增强型植被指数(Enhanced Vegetation Index,EVI),植被净初级生产力(Net Primary Productivity,NPP)进行趋势变化分析,对三江源生态状况进行评估;通过土地利用类型转移情况对趋势分析研究结果展开进一步验证;最后对NPP与EVI、气候因子(温度和降水)进行相关性分析,探讨NPP变化的主要限制因素。结果表明:时间尺度上,2001-2019年研究区内NPP和EVI总体呈波动上升趋势;空间尺度上,区域内NPP和EVI明显改善面积占比分别为86.06%和34.26%,大部分区域生态状况得到明显改善。2001-2019年研究区草地面积增加了645.89 km2,植被覆盖度增加,这与EVI趋势分析结果一致。NPP与EVI、温度、降水量均成正相关,其中EVI与NPP相关性最强。

Abstract:

This study explored the temporal and spatial variation in the ecological conditions in the Three-River Headwaters Region.Based on the Mann-Kendall test method,the trend change in the cumulative Enhanced Vegetation Index (EVI) and Net Primary Productivity (NPP) of the growing season from 2001 to 2019 was analyzed to assess the ecological status of the source area of the Three Rivers.The results of trend analysis were further verified through the transfer of land use types.The correlation analysis between NPP and EVI,climatic factors (temperature and precipitation) was undertaken,and the main limiting factors of NPP changes were discussed.Our results showed that the NPP and EVI in the study area showed a fluctuating upward trend from 2001 to 2019.On the spatial scale,the areas where NPP and EVI were significantly improved accounted for 86.06% and 34.26%,respectively,and the ecological conditions in most areas were significantly improved.From 2001 to 2019,the grassland area in the study area increased by 645.89 km2,and the vegetation coverage increased,which was consistent with the results of EVI trend analysis.NPP was positively correlated with EVI,temperature,and precipitation,among which EVI had the strongest correlation with NPP.