Distinguishing the impacts of land use and arid process on natural potential productivity of cultivated land in the North Farming - Pastoral Zone of China

摘要

The paper distinguished the impacts of land use and arid process on the Natural Potential Productivity of Cultivated Land (NPPCL) in the North Farming - Pastoral Zone of China (NFPZC) from 1990 to 2000 with the integration of remote sensing technique and Geographical Information System (GIS). The arid processes in NFPZC from 1970 to 2006 were analyzed. The land use processes from 1990 to 2000 were investigated. The NPPCL in NFPZC from 1990 to 2000 were calculated by using the Thornthwaite-Memorial model. And finally the influences of land use and arid process on the NPPCL in NFPZC from 1995 to 2007 were distinguished by using the powerful spatial analysis function of GIS. The main results were as follows:(1) In spite of some climate variation, it still had an obvious arid process in the NFPZC during the past three decades. Such arid process made the NPPCL in the NFPZC decrease 16.61 million tons from 1990 to 1995 and 19.55 million tons from 1995 to 2000.(2) From 1990 to 2000, cultivated land in NFPZC changed intensively. It expanded from 231907 km~2 in 1990 to 238032 km~2 in 1995 and 244109 km~2 in 2000. Such land use process caused the NPPCL in the NFPZC increase 5.36 million tons from 1990 to 1995 and 4.48 million tons from 1995 to 2000.(3) Influenced simultaneously by land use and arid process, NPPCL also changed obviously in NFPZC from 1990 to 2000 with 11.24 million tons decrease during 1990 and 1995 and 15.08 million tons decrease during 1995 and 2000 respectively. Spatially, the NPPCL is sensitive to arid process in the Northwest area of NFPZC, governed by Shanxi province, Gansu province and Ningxia autonomous region. While in the Northeast area of NFPZC governed by Hebei province and Shanxi provinces, land use play the dominate role to influence NPPCL. It suggested that the impacts of both the cultivated land loss and the climate change on cultivated land productivity should be simultaneously concerned to avoid food problems in China.