Spatial and temporal variations of forest LAI in China during 2000–2010
Spatial and temporal variations of forest LAI in China during 2000–2010
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DOI：
10.1007/s11434-012-5064-8
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发表时间：
2012-04
影响因子：
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通讯作者：
Yibo Liu;W. Ju;Jingming Chen;G. Zhu;Bailing Xing;Jingfang Zhu;M. He
中科院分区：
文献类型：
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作者：
Yibo Liu;W. Ju;Jingming Chen;G. Zhu;Bailing Xing;Jingfang Zhu;M. He
森林是重要的陆地生态系统。它们的叶面积指数（LAI）是决定大气和地面之间物质和能量交换的关键参数。利用MOD 09 A1和MCD 43 A1数据，建立了基于4尺度几何光学模型的反演模型，反演了2000 - 2010年中国8维500 m叶面积指数产品。使用在6个典型区域中测量的LAI来验证所得到的LAI产品。分析了森林叶面积指数的时空变化及其与气温和降水的关系。结果表明，500 m叶面积指数产品在6个典型区域的精度均在70%以上，说明该产品具有可靠性。2000 - 2010年，东北、华北和中南地区森林叶面积指数呈上升趋势。然而，中国东南部和西南部部分地区的森林叶面积指数呈下降趋势，主要是因为2008 - 2010年期间观察到的显着下降。东北地区年平均森林叶面积指数与年平均气温呈显著正相关，西南地区年平均森林叶面积指数与年平均气温呈显著负相关。与中国中南部和华北地区的年总降水量呈正相关。2001年和2009年的异常气候条件导致秦岭以南和淮河流域的森林叶面积指数明显低于常年。部分地区年平均叶面积指数下降1.0以上。
Forests are crucial terrestrial ecosystems. Their leaf area index (LAI) is a key parameter determining the exchange of matter and energy between the atmosphere and the ground surface. In this study, MOD 09A1 and MCD 43A1 data were input into an inversion model based on the 4-scale geometric optical model to retrieve 8-d 500 m LAI products in China during the period 2000 to 2010. The resulting LAI product was validated using LAI measured in 6 typical areas. The spatial and temporal variations of forest LAI and its relationships with temperature and precipitation were analyzed. The results show that the accuracy of the 500 m LAI product was above 70% in the 6 typical areas, indicating the reliability of this product. From 2000 to 2010, forest LAI in northeast, north, and south central China showed increasing trends. However, forest LAI in southeast and parts of southwest China showed downward trends, mainly because of the significant decrease observed during the period 2008 to 2010. Annual mean forest LAI positively correlated with annual mean temperature (AMT) in northeastern China and negatively correlated with AMT in southwest China. It had positive correlations with annual total precipitation in central south and north China. The abnormal climate conditions in 2001 and 2009 caused forest LAI to be obviously lower than normal in regions south of the Qinling Mountains and Huaihe River. Annual mean LAI decreased by more than 1.0 in some areas.