关键词: 关天经济区, 土地利用变化, CASA, 净初级生产力

Abstract: Net primary productivity is the key parameter of terrestrial ecological processes，and an important indicator of estimating the Earth's support and sustainable development evaluation of land ecological system. Net primary productivity is influenced by LUCC. Changing land uses and cover types influences the vegetation composition and health，so it is an important tool for monitoring ecosystem responses to environmental change with understanding the effects of these changes on net primary production （NPP）. Guanzhong-Tianshui economic region is one of key construction of economic zone which is proposed in the "Eleven-Five" Plan of development of the western part of the country. Using remote-sensing images and precipitation，temperature，and total solar radiation data from 1980，2000，2005 and 2011，and a light utilization efficiency model，we studied the effects of changes in these parameters and land use and cover types on NPP in China’Guanzhong-Tianshui region. We determined the NDVI of vegetation in the basin，and used these results to estimate the NPP of vegetation in the basin and the influence of land use and cover type changes on NPP under two climate scenarios. Using CASA model to estimate the NPP and get LUCC in Guanzhong-Tianshui Economic region for four years. Based on the analysis，get the effect of land use change which impact on net primary productivity. At last，give a solution for Guanzhong-Tianshui Economic region make the area developing sustainable. Results indicate as follows：（1） the net primary productivity is 2.3×10⁷ gC·m^-2·a^-1 in 1980，1.7×10⁷ gC·m^-2·a^-1 in 2000；2.4×10⁷ gC·m^-2·a^-1 in 2005；2.1×10⁷ gC·m^-2·a^-1 in 2011. returning farmland to regional net primary productivity growth has significant effects，form 2000 to 2005 years，the net primary productivity of forest increased 3.15×10⁷ gC·m^-2·a^-1，accounting for 41.2%.（2） It is obvious that the relationship with spatial distribution of the net primary productivity and land use types，economic development level and terrain. High net primary productivity distributed in Qinling Mountains and Baoji and Tianshui junction of the mountainous area，and low value area distributed in Guanzhong Plain of the economic developed area，Xi’an is representative area.（3） In all types of land use，the woodland of net primary productivity mean maximum，the second is the grass，and cultivated land. The change of land use type of regional net primary productivity is obvious. Cultivated land changed into land for urban and rural residents mining make net primary productivity reduced，and cultivated land changed into the grass make net primary productivity increase，and cultivated land changed into forest land need longer fixed number of year to show its real net primary productivity effect.

Key words: Guanzhong-Tianshui Economic region, LUCC, CASA, NPP