西北典型生态脆弱区植被覆盖度时空变化及其生态安全评价:以宁夏贺兰山为例

Fractional Vegetation Cover Change and Its Evaluation of Ecological Security in the Typical Vulnerable Ecological Region of Northwest China:Helan Mountains in Ningxia

人类生存质量与生态环境密切相关,利用遥感技术可以快速、定量地评价生态环境变化,为区域生态环境治理、改善以及发展规划提供重要参考。以宁夏贺兰山为研究区域,基于1987—2020年5景Landsat 5/8遥感影像,采用植被覆盖度(FVC)和遥感生态指数(RSEI),探究其生态环境时空变化规律,分析2017年贺兰山生态保卫战实施后该区域植被状况和生态恢复效果。结果表明:(1)1987—2020年宁夏贺兰山生态环境得到持续改善,植被覆盖整体提高,年均FVC从保卫战实施前(1987年)的31.03%增长至保卫战实施后(2020年)的43.35%,RSEI指数由32.71%上升至50.45%,生态恢复治理效果显著。(2)研究区FVC和RSEI指数总体偏低,生态质量一般。研究区西部海拔较高地区和中南部旅游密集区FVC和RSEI指数明显退化,退化面积占比分别为12.11%和8.30%,其生态恢复治理仍需高度重视。(3)FVC与RSEI指数的空间分布和变化趋于一致,两者相关系数大于0.80,且绿度指标在主成分分析中所占权重最高,表明FVC指数增加对贺兰山生态环境产生积极影响。研究结果对于贺兰山生态脆弱区及类似保护区生态环境恢复治理评价具有借鉴意义。

The well-being of the human race is closely related to the ecological environment.In the past few decades,indicators retrieved from remote sensing data have been increasingly more widely applied to ecological environment evaluation for their advantages of spatial visualization,and remote sensing technology offers important reference to regional ecological environment governance,improvement,and development planning by quickly assessing regional ecological environment quality.Based on Landsat 5/8 images from 1987,2000,2007,2017 and 2020,vegetation coverage(FVC)and remote sensing ecological index(RSEI)were selected to explore the spatial-temporal changes of ecological environment in Helan Mountains,Ningxia,and to analyze the vegetation status and ecological restoration effect before and after the implementation of ecological protection action in Helan Mountains in 2017.The results show that:(1)In general,the vegetation coverage and ecological environment of Helan Mountains in Ningxia had been continuously improved during 1987-2020.The annual average FVC had increased from 31.03%(1987)before the ecological battle to 43.35%(2020)recently,and the RSEI had increased from 32.71%to 50.45%,indicating a significant effect of ecological restoration.(2)The FVC and RSEI were still at low level,and the overall ecological quality in the research area was in ordinary status.The FVC and RSEI of the higher altitude areas in the west and the tourist-intensive areas in the central and southern regions had been obviously degraded,with degradation rates of 12.11%and 8.30%,respectively.(3)The spatial distribution and variation trend of FVC was highly consistent with those of RSEI,and the correlation coefficients are all greater than 0.80.Greenness index has the highest weight in principal component analysis,indicating that the increase of FVC has a positive impact on the ecological environment of Helan Mountains in Ningxia.The results in the present study have important reference significance for the restoration and management of the ecological environment in the area of ecologically fragile area such as Helan Mountains and other similar protected areas.