基于MODIS植被指数的甘南草地生物量

利用2006-2008年MODIS植被指数和同期野外调查数据,建立草地地上部分干物质产量遥感监测模型.根据七种草地类型多年平均根冠比对2006-2008年甘南草地生物量(地上+地下部分)进行了估算,比较了不同时间尺度下的模拟效果,绘制了甘南草地生物量空间分布图,分析了不同地区、海拔高度和草地类型的草地生物量特征,探讨了甘南地区草地生物量的年际变化.结果表明:2006-2008年甘南草地生物量分别为3.784×1013,3.527×1013,3.26×1013g,其空间分布具有白西向东逐渐减少的趋势;在没有消除噪音的情况下,用月作为时间尺度的模拟效果较好;甘南草地生物量在3000～4000m处的产量最高,占草地总产量的84.69%;2006-2008年甘南草地生物量呈减少趋势,年均减少速率为97.91 g/(m2·a).

Grassland biomass based on MODIS vegetation index in Gannan Prefecture

A remote sensing model for grass aboveground dry matter biomass monitoring was constructed from the MODIS vegetation indices in 2006-2008 and with dry matter information from field survey during the same time, to estimate the grassland biomass (both aboveground and underground) during 2006-2008 in Gannan Prefecture based on the average root-shoot ratio of seven types of grassland in several years. The simulation was performed and compared under various temporal scale; the map of spatial distribution of grassland biomass in Gannan Prefecture was mapped; the characteristics of grassland biomass in different regions, altitudes and grassland types were analyzed; and the annual change of grassland biomass in Gannan Prefecture was discussed. The result shows that grassland biomass during 2006-2008 were 3.784 ×10~(13), 3.527×10~(13) and 3.26×10~(13) g, respectively; there is a trend in the spatial pattern of grassland biomass, which is a decreasing from west to east; if the contamination from noise is not eliminated, the result of simulation under month-based temporal scale is better; the maximum yield occurrs between the altitude of 3 000～4 000 m in Gannan Prefecture, accounting for 84.69% of the total grassland; grass biomass in Gannan Prefecture was decreasing from 2006 to 2008, with an average annual reduction rate of 97.91 g/(m~2·a).