干旱区生态环境知识资源中心

Since the Chinese government initiated its economic reform in 1978, rapid economic development has spurred land use and land cover change (LULCC) in China, which resulted in many ecological problems such as land degradation and desertification. To address these serious ecological crises, the government launched a series of ecological restoration programs which have caused significant LULCC and a profound impact on the terrestrial ecosystem. This study used net primary productivity (NPP) as an important indicator of the arid and semi-arid ecosystem’s productivity to estimate the impacts of the LULCC driven by ecological restoration programs in Xinjiang from 2001 to 2009. The modeling method was based upon the Carnegie-Ames-Stanford Approach (CASA) terrestrial carbon model and Moderate-resolution Imaging Spectroradiometer (MODIS) remote sensing data and meteorological data for modeling simulation. The results demonstrated that the forest area of Xinjiang had the most net increase of 9093 km(2) in the study period, compared to other land cover types. The most dominant land cover changes during 2001-2009 were from grassland to forest and mutual transformation between grassland and desert. Total NPP of whole area increased by 252.51 Gg C during the study period. The increase of total NPP in forest was the most obvious among all vegetation types, with a net increase of 1782.88 GgCyr(-1). It can be concluded that the increase of regional NPP mainly resulted from forest expansion. During 2001-2009, the mean NPP in forest, grassland and desert had a slight decrease, whereas the cropland and crop/natural vegetation mosaic land mean NPP increased fractionally. By using the climate in 2001 to simulate the NPP of Xinjiang in 2009, we explored the influences of land use and cover changes and climate change on regional NPP. Compared to climate change, human activities produced an obvious positive effect in the increase of total NPP, especially for forest land. As a result, ecological restoration programs produced positive impacts on forest expansion and carbon sequestration in Xinjiang. (C) 2013 Elsevier B.V. All rights reserved.