苏南地区净第一性生产力对土地利用变化的响应

通过CASA模型对苏南地区1999年和2008年净第一性生产力(NPP)进行估算,分析NPP时空变化及其对土地利用变化的响应,结果显示:①1999-2008年,苏南地区NPP时空变化显著,19个市县的NPP均为减少:昆山减少量最大(以C计)242.04 g/m2,扬中最小(以C计)70.94 g/m2; NPP减少量高值区位于太湖流域,低值区位于苏南西北部.②与1999年相比,2008年6种地类的平均NPP都在下降:建设用地和耕地减幅最大,分别为55.69％、45.74％; NPP减少量高值区耕地和建设用地转化斑块最为突出,低值区减少量主要源于林地和草地的转化.这与太湖流域城市群迅速扩张下农用地转换为建设用地趋势明显的土地利用方式在空间上吻合.③NPP变化与耕地变化的相关性最强,相关系数为0.523.林地-水域、耕地-水域、林地-草地、耕地-草地这4种转换方式下NPP损益较大.

Net Primary Productivity of South Jiangsu in Response to Land Use Cover/Change

Net primary productivity (NPP) of South Jiangsu in 1999 and 2008 was estimated through CASA model, the spatial and temporal variations of NPP and its response to land use cover/change (LUCC) was also analyzed. The result showed: 1) from 1999 to 2008, NPP of South Jiangsu changed greatly both in space and time. 2) On regional scale, NPP of all 19 counties decreased: NPP of Kunshan reduced to the maximum of 242.04 g/m2, while Yangzhong reduced the minimum of 70.94 g/m2. High value area of NPP reduction was in Taihu basin and the low value zone was located in the northwest of South Jiangsu. 3) On land use scale, the average NPPs of six types were in decline: construction land and farmland decreased greatly with decline rates 55.69% and 45.74% respectively. In the high value area of NPP reduction, the conversion between farmland and construction land was most prominent while the NPP reduction in low value area was mainly due to the transformation between forest and grass land. This phenomenon was inconsistent to land use in city group of Taihu basin. The correlation between NPP change and farmland change was highest to 0.523. NPP loss and gain were great in four conversion modes: forest-water, farmland-water, forest-grassland and farmland-grassland.