| 1982年至2003年藏北高原草地生态系统NDVI与气候因子的相关分析 |
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| 引用本文： | 赵玉萍,张宪洲,王景升,沈振西.1982年至2003年藏北高原草地生态系统NDVI与气候因子的相关分析[J].资源科学,2009,31(11):1988-1998. |
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| 作者姓名： | 赵玉萍 张宪洲 王景升 沈振西 |
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| 作者单位： | 1. 中国科学院地理科学与资源研究所,北京,100101;中国科学院研究生院,北京,100049
2. 中国科学院地理科学与资源研究所,北京,100101 |
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| 摘 要： | 本文利用1982年～2003年GIMMS每15d合成的归一化植被指数(Normalized Difference VegetationIndex,NDVI)数据集和藏北高原8个气象站1981年～2003年逐月气象资料,用相关分析研究了NDVI与6个气候因子的相关性及其时气候因子的时滞响应情况,同时计算了气温、降水和风速3个气候因子与NDVI的偏相关系数.结果表明:①除噶尔和改则之外,6个站的NDVI与同期月均气温、月均最高气温、月均最低气温、月均相对湿度和月降水量都呈高度正相关(P<0.001),其中与月均最低气温的相关性最好,NDVI与当月降水量的相关系数为那曲>索县>安多>当雄>班戈>申扎;月均风速与藏北高原草地NDVI呈高度负相关(P<0.001;当雄除外,为D<0.05);②NDVI对气温和降水的响应有滞后效应:改则和噶尔NDVI对气温滞后3个月,其它6个站滞后1个月;噶尔NDVI对降水的滞后期为2个月,其它7个站均滞后1个月;申扎和改则(噶尔)NDVI对空气湿度分别滞后1和2个月,其它5个站无滞后;那曲、安多、班戈和申扎NDVI对降水的累积滞后期为1个月,当雄和索县为2个月,改则和噶尔为4个月,NDVI对降水响应的累积滞后相关系数从东到西呈降低趋势;③除改则和噶尔之外的6个站NDVI变化受气温的影响大于降水;在气温-降水-风速组合下,除改则和噶尔之外的6个站NDVI第一相关因子仍是气温,但索县、那曲、班戈和申扎属于气温-风速-降水驱动型,安多和当雄属于气温-降水-风速驱动型.藏北草地NDVI与气候因子的相关性受植被类型、海拔、年降水量和年平均风速的影响.
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| 关 键 词： | 藏北高原 草地生态系统 气候因子 相关分析 |
Correlation Analysis between NDVI and Climatic Factors of Grassland Ecosystems in the Northern Tibetan Plateau from 1982 to 2003 |
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| ZHAO Yuping,ZHANG Xianzhou,WANG Jingsheng and SHEN Zhenxi.Correlation Analysis between NDVI and Climatic Factors of Grassland Ecosystems in the Northern Tibetan Plateau from 1982 to 2003[J].Resources Science,2009,31(11):1988-1998. |
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| Authors: | ZHAO Yuping ZHANG Xianzhou WANG Jingsheng and SHEN Zhenxi |
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| Abstract: | Normalized difference vegetation index (NDVI), which is closely related to plant absorbability of photosynthetically active radiation (PAR), is generally taken to be a good indicator of terrestrial vegetation. We used time series (1982-2003) NDVI from the Global Inventory Modeling and Mapping Studies (GIMMS) in combination with climatic data from eight meteorological stations to examine the relationships between climatic factors and NDVI for grasslands of different types across the Northern Tibetan Plateau. Also, we discussed contributors affecting the correlation between NDVI and climatic factors. A bivariate correlation analysis was performed to examine the linear correlations and lag-linear correlations between monthly maximized NDVI and 6 monthly climatic factors, including mean monthly air temperature, mean minimum air temperature, mean maximum air temperature, relative humidity, mean wind velocity and cumulative precipitation. The partial correlations between temperature/precipitation, temperature/precipitation/wind velocity and NDVI were investigated by a partial correlation analysis in order to remove errors resulting from interactions among these climatic factors. Except the Gerze and Gaer stations, there were significant positive linear correlations between NDVI and temperature, precipitation and air moisture of the current month (P<0.001) in other six stations. The climatic factor having the highest correlation with NDVI was mean monthly minimum temperature. Correlation coefficients between NDVI and mean monthly minimum air temperature for the Suoxian, Nagqu, Amdo, Damxung, Baingion and Xainza stations decreased in sequence. Alpine meadow showed the highest positive correlation with monthly cumulative precipitation than did grasslands of other types. Mean monthly wind velocity was negatively correlated to NDVI (i.e. Damxung, P<0.05; other stations, P<0.001). NDVI of the Gerze station showed the highest correlation with wind velocity compared with other climatic factors of the current month. Regarding grasslands of all types across the Northern Tibetan Plateau, the response of NDVI to temperature and precipitation showed a time lag effect. Except the Gaer station, the time lag as to responses of NDVI to precipitation and temperature for grasslands of different types was around one month and one to two months or so, respectively. The accumulated time lag periods of NDVI and corresponding precipitation was two months for the Suoxian and DamXung stations, four months for the Gerze and Gaer stations, and one month for the other four stations. The results of partial correlation analysis showed that temperature was the most important factor affecting NDVI of grasslands, and wind was another key factor affecting NDVI of grasslands. In general, changes in NDVI for the Suoxian, Nagqu, Baingion and Xainza stations were primarily driven by temperature-wind velocity-precipitation, but for the Amdo and Damxung stations, that relation was changed to temperature-precipitation-wind velocity. It was concluded that vegetation type, altitude, mean annual wind velocity and mean annual precipitation have significant influences on the correlation between NDVI and climatic factors. |
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| Keywords: | NDVI Northern Tibetan Plateau Grassland ecosystems NDVI Climatic factors Correlation analysis |
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