The 30m-NDVI-based Alpine Grassland Changes and Climate Impacts in the Three-River Headwaters Region on the Qinghai-Tibet Plateau from 1990 to 2018  

基于30m归一化植被指数的近30年三江源高寒草地植被时空变化及气候影响研究

作　　者：SUN Ziyu WANG Junbang 孙梓煜;王军邦(中国科学院地理科学与资源研究所生态系统网络观测与模拟院重点实验室国家生态科学数据中心,北京100101;中国科学院大学,北京100049)

机构地区：[1]National Ecosystem Science Data Center,Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Resources and Ecology》2022年第2期186-195,共10页资源与生态学报（英文版）

基　　金：The Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0302);The Joint Research Project of the People’s Government of Qinghai Province and Chinese Academy of Sciences(LHZX-2020-07);The National Natural Science Foundation of China(31971507)。

摘　　要：The response of long-term vegetation changes and climate change has been a hot topic in recent research.Previously,a Landsat-based fusion model was developed and used to produce a dataset of normalized vegetation index(NDVI)for the Three-River Headwater region on the Qinghai-Tibet Plateau with a spatial resolution of 30 m and the time spanning the nearly 30 years from 1990 to 2018.In this study,the NDVI was applied to an analysis of the spatial and temporal changes in the alpine grassland and the impacts from climate change using the Theil-Sen Median method and linear regression.The results showed that:(1)The regional mean NDVI was 0.39and showed a spatial pattern of decreasing from the southeast to the northwest in the recent three decades.Among the three parks,the Lancang River Park had the highest NDVI(0.43),followed by the Yellow River Park(0.38)and Yangtze River Park(0.23).(2)An upward trending was found in the NDVI time series at a rate of 0.0031 yr^(-1)(R^(2)=0.62,P<0.01)over the whole period of 1990–2018.The increasing rate(0.00649 yr^(-1),R^(2)=0.71,P<0.01)in the latter period of 2005–2018 was nearly 2.3 times of that(0.00284 yr^(-1),R^(2)=0.31,P<0.01)in the previous period of1990–2005.In the latest periods,the three parks experienced rates that were 2.3 to 63 times the corresponding values in the early period.(3)The NDVI is correlated more positively with temperature than precipitation.The impacts of climate change decreased along with the coverage fraction from the higher,median and then lower levels.The climate change can explain 34%of the variability in the NDVI time series of the areas with a higher fraction of grassland coverage,while it was 31%for the median fraction and 20%for the lower fraction.This study is the first to use the 30 m NDVI dataset spanning nearly 30 years to analyze the spatial and temporal variability and climate impacts in the alpine grasslands of the Three-River Headwater region of the Qinghai-Tibet Plateau.The results provide a basis for assessments on the ecological ma植被长期变化及其对气候变化的响应一直是生态学研究的热点。本研究应用前期基于Landsat数据融合得到的青藏高原三江源区1990–2018年近30年30 m空间分辨率归一化植被指数(NDVI),以Theil-Sen中值法和线性回归,分析了近30年高寒草地时空变化及气候变化影响。结果表明:(1)研究区NDVI呈从东南到西北逐渐降低的空间格局,全区平均NDVI为0.39,其中澜沧江源NDVI最高(0.43),其次是黄河源(0.38)和长江源(0.23)。(2)研究期间,全区NDVI以0.0031yr^(-1)的速率呈上升趋势(R^(2)=0.62,P<0.01),后期(2005–2018年)增长速度为0.00649 yr^(-1)(R^(2)=0.71,P<0.01),是前期(1990–2005年间)速率0.00284 yr^(-1)(R^(2)=0.31,P<0.01)的近2.3倍,说明后期(2005–2018年)植被变绿加速,且不同流域间增速在2.3至63倍间。(3)NDVI与温度的相关性高于与降水的相关性,气候变化可解释高、中、低覆盖度草地NDVI年际变化的34%、31%和20%,从高覆盖到低覆盖草地气候变化的影响依次减小。本研究首次分析了近30年青藏高原三江源地区高寒草地时空变化及气候影响,为基于长时间序列数据为基准进行生态管理成效评价和草地生态质量评价,提供了较高空间分辨率和较长时间序列的数据基础,研究结果也为青藏高原高寒草地保护和恢复提供科学依据。

关 键 词：Normalized Difference Vegetation Index(NDVI) the Three-River Headwater region alpine grassland climate change 

分 类 号：Q948.112[生物学—植物学]