基于CASA模型的甘南地区草地净初级生产力时空动态遥感模拟

植被净初级生产力(net primary productivity,NPP)及其对气候变化的响应研究是全球变化的核心内容之一。基于地理信息系统和卫星遥感应用技术,利用CASA模型估算了2001-2008年甘南草地NPP,在模型验证的基础上,分析了甘南草地NPP空间分布格局和时间分布特征。结果表明,1)2001-2008年甘南草地多年平均NPP为483.41 g C/(m²·a),大体呈现由西南向东北逐渐减少的趋势,单位面积多年平均NPP在海拔3 000~3 500 m最高,达到497.07 g C/(m²·a);2)甘南草地植被生长季节变化明显,主要生长期集中在第177~240天;3)甘南草地NPP呈现增加趋势,增长趋势最明显的草地类型是低平地草甸类,而沼泽的变幅最小,通过与8年间温度和降水的分析可以看出,影响甘南草地NPP变化的主要驱动力是降水量。

Spatial-temporal dynamics simulation of grassland net primary productivity using a satellite data-driven CASA model in Gannan prefecture

Net primary productivity (NPP) and its responses to global change are one of the focuses of global change research. Based on GIS technology and remote sensing imagery, the grassland NPP and its spatial-temporal dynamics in Gannan prefecture during 2001 to 2008 were estimated with the Carnegie-Ames-Stanford Approach (CASA) model. Average annual NPP from 2001 to 2008 was 483.41 g C/(m²·a) in the study area. There was obvious seasonal change in the grasslands of Gannan, and the main growth period lasts from 177 to 240 days. There was a rising trend in the grassland NPP of the eight years. Between different grassland types, the trend of rising NPP on lowland meadow was the largest while that on marsh was smallest. Analysis of the temperature and precipitation of the eight years showed that the temporal variation of NPP was mainly influenced by changes of annual precipitation.