基于MODIS数据的内蒙古草地光能利用率时空变化分析

Spatiotemporal Variations Analysis of Grassland's Light Use Efficiency in Inner Mongolia Based on MODIS Data

光能利用率(常以ε表示)直接影响草地植被的能量分配和光合速率,是影响NPP形成的重要参数之一。论文以MODIS数据及地面气象数据为数据源,在GIS和RS的支持下,研究了2003年内蒙古地区生长季草地的光能利用率(ε)及时空变化。结果表明,内蒙古地区生长季草地光能利用率(ε)在0～0·292 9 gC·MJ-1之间,平均值为0·220 4 gC·MJ-1。该地区草地生长季光能利用率空间分布规律明显,总体上呈由高纬度的东北部地区向低纬度的西南部地区逐渐降低的趋势,与该地区降雨空间分布相同。内蒙古地区生长季所有草地类型的平均光能利用率(ε)季节变化呈明显的单峰变化,其增长速率从5月开始为单调递减。

Light use efficiency （LUE, ε is often used to express LUE） impacts on the energy distribution of grassland vegetation and photosynthetic rate directly, and it＇ s one of the key essential parameters that monitors grassland NPP using remote sensing model. In this article, with the aid of GIS and RS processing software, based on MODIS and in situ meteorological data, we studied the spatial distribution of ε and its spatiotemporal variations in growing season in Inner Mongolia in 2003. The results show that ε varied between 0 - 0.2929 gC · M J^- 1, and the average ε was 0.2204 gC · MJ ^-1 in growing season in Inner Mongolia. The ε spatial distribution rule was gradually declining from northeast to southwest, which is the same as the rainfall spatial distribution. The seasonal variation of average ε was obviously in a single peak, the growth rate of ε declined from May.