Impacts of land use and climate change on agricultural productivity in Shanghai
气候和土地利用变化对上海市农田生态系统净初级生产力的影响

The impacts of land use and climate change on the agricultural productivity of Shanghai were studied by using simulated cropland net primary productivity (NPP) data from 1961 to 2006. The data were based on the Atmosphere\| Vegetation Interaction Model (AVIM2), and Landsat TM satellite images from 1987, 1997 and 2004. The results indicated that the annual agricultural NPP, driven by climate change, increased 64.37 g·m-2·a-1 with a growth rate of 1.43 g·m-2·a-1 during 1961~2006. Both annual mean temperature and precipitation had significant positive correlations with cropland NPP. For cropland area, its proportion of the total area of Shanghai decreased from 76% in 1987 to 43% in 2004. Considering both land use and climate change factors, the total NPP of the early 21st century decreased by 42% compared with that of the 1980s. However, the land use change had greater impact than climate change on total cropland NPP in Shanghai. From the 1980s to the 1990s, the decrease of land use contributed 78% to the change of total NPP, and it increased to 92% from the 1990s in the early period of 21st century.