黑河上游植被覆盖时空变化特征及其未来趋势

目的]分析黑河上游近14a来植被覆盖时空变化特征及其未来趋势,为区域生态保护提供决策参考。方法]基于2001—2014年MODIS-NDVI数据,采用线性趋势和Hurst指数等数理方法进行定量分析。结果]研究区植被覆盖整体处于缓慢增加趋势,年际变化呈现"波动—改善"趋势,空间分布呈现自东南向西北逐渐降低的分布特征,且具有明显经向地带性;植被覆盖改善区和退化区的面积分别占47.74%和21.81%,其中改善区主要分布在研究区中部和西北部,以高寒草原改善为主,退化区主要位于研究区东南部,以高寒草甸退化为主;未来的NDVI将向着改善的方向发展。结论]近14a来黑河上游植被覆盖良好,且未来向着改善趋势发展,但对祁连、民乐和山丹县境内的持续退化区需要采取保护措施。

Spatial-temporal Changes and Future Trends of Vegetation Cover in Upper Reaches of Heihe River

Objective] To study the spatial-temporal changes of vegetation cover in the past 14 years and its future trend in the upper reaches of the Heihe river in order to provide a support for the regional ecological protection.Methods] Based on the MODSI-NDVI data from 2001 to 2014, we did the quantitative analysis by linear trend analysis and Hurst index.Results] The vegetation cover in the study area had been improving slowly, showing a "volatility-improvement" trend on year scale, the mean NDVI decreased gradually from southeast to northwest and shows a meridional zonality. The area with increased vegetation cover accounted for 47.74%, whereas the area with deceased vegetation cover accounted for 21.81%. The improved areas are mainly distributed in the central and northwestern parts of study area with alpine steppe significantly improved. The degraded areas are mainly located in the southeast of study area with alpine meadow significantly degenerated. The vegetation cover in the upper reaches of the Heihe river will increase in the future.Conclusion] The vegetation cover in the upper reaches of the Heihe river is high and the future trends of the vegetation cover is toward improving, but we need to take measures to protect areas still degenerating in Qilian, Minle and Shandan County.