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基于植被降水利用效率和NDVI的黄河上游地区生态退化研究
引用本文:杜加强,舒俭民,张林波.基于植被降水利用效率和NDVI的黄河上游地区生态退化研究[J].生态学报,2012,32(11):3404-3413.
作者姓名:杜加强  舒俭民  张林波
作者单位:中国环境科学研究院,北京100012;国家环境保护区域生态过程与功能评估重点实验室,北京100012
基金项目:国家自然科学(41001055)和中国环境科学研究院中央级公益性科研院所基本科研业务专项资助项目(2009KYYW10)
摘    要:提出了一种植被降水利用效率和NDVI变化趋势分析相结合识别生态退化、生态恢复区域的方法。利用黄河上游地区1982—2006年的AVHRR NDVI数据及同期16个气象站的降水量数据为基础数据源,计算每个像元的降水利用效率及其变化趋势,结合NDVI变化辨识生态退化和生态恢复的区域范围。结果表明,研究区域80%处于生态恢复阶段,恢复现象较为明显的区域主要位于东南部;生态退化显著的区域主要集中在玛多县县城,扎陵湖、鄂陵湖附近和龙羊峡库区周边。该结果与黄河上游地区草地退化的现状基本吻合,表明该方法可靠性较强,可以作为评估区域生态退化或生态恢复的方法。植被降水利用效率与NDVI变化趋势相结合的方法可以避免仅使用降水利用效率可能产生的误判。研究可为黄河上游地区开展生态恢复工程,合理规划和调整生态建设布局提供科学依据。

关 键 词:降水利用效率  归一化植被指数(NDVI)  生态退化  生态恢复  识别  黄河上游地区
收稿时间:5/24/2011 4:07:57 PM
修稿时间:2011/10/31 0:00:00

Analysis of ecosystem degradation and recovery using precipitation use efficiency and NDVI in the headwater catchment of the Yellow River basin
DU Jiaqiang,SHU Jianmin and ZHANG Linbo.Analysis of ecosystem degradation and recovery using precipitation use efficiency and NDVI in the headwater catchment of the Yellow River basin[J].Acta Ecologica Sinica,2012,32(11):3404-3413.
Authors:DU Jiaqiang  SHU Jianmin and ZHANG Linbo
Affiliation:Chinese Research Academy of Environmental Sciences,Beijing,Chinese Research Academy of Environmental Sciences,Beijing,Chinese Research Academy of Environmental Sciences,Beijing
Abstract:The accurate identification of areas of ecosystem degradation and an objective evaluation of the effects of ecological restoration projects is necessary for ecological management and planning at the landscape scale. Ecological degradation and ecological restoration are dynamic equilibrium processes, while degradation must be considered relative to the pristine state of the ecosystem, and need to be analyzed from a time series perspective. Satellite remote sensing is widely used in ecological monitoring and assessment, as it provides extensive coverage, good spatial and temporal continuity and a long time-series dataset. This paper proposes a method for the identification of areas of ecosystem degradation and ecosystem recovery using long time-series satellite remote sensing and precipitation data, which are integrated into trend analyses of the precipitation use efficiency (PUE) and a normalized difference vegetation index (NDVI). The PUE is calculated as the ratio of cumulative NDVI to precipitation. Significantly reduced PUE and NDVI values indicate that ecological degradation is occurring, while increasing PUE and NDVI values indicate ecological recovery. This method was applied to the headwater catchment of the Yellow River basin in China using Advanced Very High Resolution Radiometer NDVI data from 1982 to 2006 and meteorological data from the same time period. The annual PUE value was calculated using the cumulative NDVI and precipitation in the growing season for each pixel. A comparative analysis of the trends in PUE and NDVI was undertaken to detect areas of ecosystem degradation and restoration. The results show that: (i) The average PUE and NDVI values across the region increased slightly, and the area undergoing ecosystem rehabilitation during 1982-2006 comprised more than 80% of the study area. (ii) The degraded area, with significantly negative trends in the PUE and NDVI values, mainly occurred in the region surrounding Maduo County, Zaling and Eling lakes and Longyangxia Reservoir. Significant ecosystem recovery was found in southeast part of the study area, where strong positive trends were identified in the PUE and NDVI values. (iii) The areas with ecosystem degradation and restoration detected in this study were consistent with the current grassland degradation situation in the headwater catchment of the Yellow River basin, indicating that this method is reliable and could be applied to the evaluation of the regional ecosystem. (iv) The PUE value is partially dependent on changes in the precipitation, so false ecosystem degradation or ecosystem recovery trends may be identified caused by rapid increases and decreases, respectively, in the precipitation rate. For example, a decrease PUE in Xining City was partly caused by increased precipitation. Evaluating the trends in both PUE and NDVI may avoid the errors caused by using PUE as the only factor when evaluating ecosystem degradation and recovery. This method is simple, feasible, usable and practical, and the required data are easily accessible. This method allows ecosystem changes to be studied at the landscape scale, and can be used for a preliminary investigation prior to a large scale survey of ecological degradation or restoration. The results of this study suggest that evaluating the temporal change in PUE and NDVI may provide a useful large-scale indicator of landscape degradation or recovery at decadal time intervals. We recommend the broad-scale application of this method, using temporal trends in the PUE and NDVI. This study provides a scientific basis for the planning and regulation of ecological reconstruction in the headwater catchment of the Yellow River basin, China.
Keywords:precipitation use efficiency  NDVI  ecosystem degradation  ecosystem recovery  identify  the headwater catchment of the Yellow River basin
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