内蒙古草地生态系统近10年NPP时空变化及其与气候的关系

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。通过改进的光能利用率模型(CASA模型),利用MODIS NDVI数据、土地覆盖分类数据、气象数据等,逐像元模拟2001-2010 年内蒙古草地生态系统NPP的时空变化,分析其对气候因子变化的响应关系。结果表明,1)2001-2010年内蒙古草地多年平均NPP为281.3 g C/(m²·a),空间分布呈由西南向东北递增的趋势,草甸草原、典型草原和荒漠草原平均NPP分别为431.8,288.7和123.5 g C/(m²·a);2) 2001-2010年间内蒙古草地NPP总体上呈上升趋势。NPP上升趋势最明显的草地主要分布在毛乌素沙地、浑善达克沙地、科尔沁沙地、呼伦贝尔盟和大兴安岭南麓地区,而下降趋势最明显的草地主要分布在阴山山脉和锡林郭勒盟中部的典型草原区;3) 总体而言,降水量是内蒙古草地净初级生产力的主要影响因素。草甸草原NPP与降水量、温度的关系均很密切,而且与温度的相关性更强;典型草原和荒漠草原NPP则主要受降水量控制,其中荒漠草原NPP与降水量的关系更密切。

Spatio-temporal variation analysis of grassland net primary productivity and its relationship with climate over the past 10 years in Inner Mongolia

Net primary productivity (NPP) and its response to global change are two of the focuses in global change research. Based on MODIS NDVI data, land use classification data, and meteorological data, the spatio-temporal change in NPP of Inner Mongolia grassland was simulated using an improved light use efficiency model (CASA model). The relationships between NPP and climate factors were analysed based on partial correlation coefficients of the two-group elements. The average annual NPP from 2001 to 2010 was 281.3 g C/(m²·a) in the study area, with an obvious increasing trend from southwest to northeast. The mean NPP in the unit area of meadow steppe was 431.8 g C/(m²·a), in typical steppe it was 288.7 g C/(m²·a) and in desert steppe was 123.5 g C/(m²·a). There was a rising trend in the grassland NPP during the past ten years. Grassland NPP in Mu Us sandy land, Hunshandak sandy land, Horqing sandy, HulunBuir league and the southern slope of the Greater Hinggan Mountain exhibited the most obvious increasing trend, while in the Yin mountain region and the centre of Xilin gol league it showed the most obvious decreasing trend. As a whole, precipitation was the dominant driving force of NPP of Inner Mongolia grassland, while the NPP of meadow steppe correlated with both precipitation and temperature, but with more dependence on temperature. Compared with temperature, precipitation influenced NPP of typical steppe and more seriously, desert steppe.