广东省土地覆盖变化对植被净初级生产力的影响分析

理解土地利用/覆盖变化对植被净初级生产力(Net Primary Productivity,NPP)的影响对于全球碳循环和粮食安全具有重要意义。论文采用优化的CASA(Carnegie-Ames-Stanford Approach)模型估算广东省2000、2005和2010年NPP,分析NPP的空间格局和土地覆盖的时空动态,研究土地覆盖变化对NPP的影响。结果表明:1)广东省NPP空间分布不均,形成一系列高值区和低值区;总体上是粤中区最高,珠三角区最低。2)2000—2010年广东省土地覆盖变化程度增强,城市用地和耕地变化最大,主要集中在珠三角区和粤中区。3)在气候变化条件下,以城市扩张为主导的广东省土地覆盖类型变化整体上造成NPP的损失,损失量主要来自林地和耕地向低生产力土地覆盖类型的转换,尤其是被城市用地占用;不同生态区NPP损失差异显著,珠三角区和粤中区NPP损失较为严重;2005—2010年珠三角区NPP损失量有所降低,其他生态区均有所增加,体现了城市扩张对NPP影响的复杂性。

Analyzing the Effects of Land Cover Change on Vegetation Net Primary Productivity in Guangdong Province

It’s of significant importance to understand the effect of LUCC on vegetation net primary productivity (NPP) in global carbon cycle and food security. This study aimed to investigate how the land cover change caused by urban expansion affects the regional NPP in Guangdong Province. The vegetation type data, land cover data, moderate-resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and meteoro-logical data were combined to simulate the spatial distribution of NPP in the year 2000, 2005 and 2010 in Guangdong Province by using the improved Carnegie-Ames-Stanford Approach (CASA) model. Guangdong Province is divided into four ecological regions: Nanling region, Yuezhong region, the Pearl River Delta and Yuenan region. Then, the spatial pattern of NPP and spatio-temporal dynamics of land cover change were analyzed, and the regional differences of NPP gains/losses caused by land cover change were compared. The results show that: 1) The NPP is heterogeneous in space and forms a series of zones with high value and low value; the Yuezhong region has the highest annual mean NPP, and the lowest NPP value is in the Pearl River Delta. 2) The change of land cover in Guangdong Province increased during 2000-2010, with the maximum changes happening in urban land and cropland, and the Pearl River Delta and Yuezhong region had the most change. 3) Under the condition of climate change, the land cover change resulting from urban expansion caused the overall NPP loss in Guangdong Province; the primary loss is caused by the conversion from croplands and forests to land covers with low productivity, especially the urban land. The NPP losses in different ecological regions are greatly different, the Pearl River Delta and Yuezhong region having more serious NPP loss during 2000-2005, and with a decrease of NPP loss in the Pearl River Delta and increases in other ecological regions during 2005-2010, which indicates that the effects of urban expansion on NPP are complex.