基于MODIS的陕西省叶面积指数时空变化特征分析

Analyses of Spatial-temporal Changes of Leaf Area Index in Shaanxi Province Based on MODIS

叶面积指数(LAI)作为表征植被冠层的重要参数,在定量分析陆地生态系统能量交换中具重要意义。利用MODIS叶面积指数产品,结合地表覆盖分类数据,对2001-2014年陕西省LAI进行了监测。结果表明:1)陕西省LAI最大值平均总体呈波动中上升趋势,年内变化呈现明显的季节差异。2)陕北地区LAI上升趋势明显,年际波动较大,渭北塬区以及陕南东部部分区域LAI呈上升趋势,但年际间变化不大,其他区域LAI年际间变化趋势和波动均不明显。3)陕西省范围内典型植被类型LAI最大值平均年际变化均呈现上升趋势,但年内变化曲线各不相同。退耕还林、植树造林等生态工程是陕西省LAI上升的主要原因,气候因素是LAI产生波动的直接原因。反映了陕西省植被群体结构空间分布以及变化特征,为进一步陆地生态系统研究提供了重要参数。

As a crucial parameter to characterize the canopy structure,leaf area index（LAI）exhibited significance in analyzing energy exchanges within terrestrial ecosystem.In this study,a spatial-temporal changes of LAI analysis in Shaanxi Province from 2001 to 2014was conducted.The MODIS products were applied to generate LAIseries in Shaanxi Province during the period of 2001 to 2014.By employing the land cover map,the LAIseries of four typical vegetation types were also derived.The results indicated that：1）The spatial pattern of LAIshowed obviously distinct spatial and seasonal variations.The inter-annual mean of maximumLAIshowed an increasing trend during 2001-2014.2）The annual LAIin Northern Shaanxi from 2001 to 2014increased and interannual fluctuation changed significantly.The annual LAIin Weibei dry highland and the east of Southern Shaanxi increased with small interannual fluctuation change.The annual LAIin regions had unconspicuous trend and interannual fluctuation.3）The inter-annual mean of maxiumLAI among different vegetation types in Shaanxi Province increased from 2001 to 2014.It was pointed out that the monthly LAI variations of four vegetation types were in single peak pattern with variations.The increasing trend was primarily reflecting afforestation and reforestation and the fluctuation was directly linked to climatic factors.The research results reflected the spatial distribution and variation characteristics of the vegetation in Shaanxi Provance and had important significance for the further study of terrestrial ecosystem.