基于夜间灯光数据的太湖流域城镇扩张对净初级生产力的影响研究

理解人类活动变化对生态环境的影响,识别生态环境变化区域及其成因,对制定差异化的区域生态保护政策具有重要意义。基于MODIS17A3和DMSP/OLS稳定夜间灯光数据,结合RS与GIS技术,构建城镇开发程度指数,采用一元线性趋势分析法对城镇开发程度进行分区,利用Pearson相关系数计算城镇开发程度与NPP的作用关系,并运用热点分析模型探讨土地利用转型对NPP变化的影响。结果表明:(1)2000—2010年,太湖流域年均NPP变化范围是388.79—452.54 gC m~(-2)a~(-1),NPP变化呈波动下降趋势;(2)城镇开发程度缓慢增加区对NPP变化影响较小,增加区与快速增加区对NPP变化影响较大;(3)太湖流域土地转型主要发生在耕地转建设用地、林地转建设用地和水域转建设用地,建设用地面积的快速扩张及由此导致的城镇开发程度的增加,是流域NPP降低的主要原因。

The impact of urban expansion on net primary productivity in the Taihu Lake basin based on nighttime light images

Understanding the relationship between human activities and ecological environment and identifying the changing areas of the ecological environment and their causes is of great significance to the formation of ecological protection policies for differentiated regions. The Taihu Lake basin is the core of the Yangtze River Delta, which has experienced rapid economic growth (GDP +15.7%/year), population growth (+3.0%/year on average), urbanization (+ 9.2%/year on average) from 1985 to 2010. Rapid industrialization and urbanization have significantly changed the pattern of land use, which has posed a threat to the region''s ecological security and sustainable development. Based on the MODIS 17A3 and DMSP/OLS nighttime light images, we determined the urban development level index, and a linear trend analysis was used to partition the urban development levels. We used the Pearson correlation coefficient to calculate the relationship between the urban development level and net primary productivity (NPP). Finally, a spatial correlation model was used to analyze the impact of urban expansion on the NPP in the Taihu Lake basin, combined with geographic information system (GIS) and remote sensing (RS) techniques. The results showed that the average NPP in the Taihu Lake basin varied from 388.79 gC m^-2·a^-1 to 452.54 gC m^-2·a^-1 from 2000 to 2010. The average NPP over 11 years was 422.65 gC m^-2·a^-1. The changes in average annual NPP were fluctuating and declining. The urban development level slow-increased zone had little effect on the change in NPP, while the increased zone and rapid-increased zone had great influence on the NPP. Along with the increase in the urban development level, land transformation mainly occurred from farmland to construction, forest to construction, and water to construction. The rapid expansion of urban areas has led to increase in construction land and the urban development level, which are the main reasons for the decrease in NPP.