新疆耕地变化对区域碳平衡的影响

Effects of arable land change on regional carbon balance in Xinjiang

基于"Bookkeeping"模型,对1975-2005年期间新疆耕地变化对区域碳平衡的影响进行了分析。荒漠土地开垦和耕地转移是新疆耕地变化的两种主要方式,1975-2005年这两种耕地变化方式使新疆碳储量增加了20.6 Tg C,其中土地开垦使区域碳储量增加了51.8 Tg C,而耕地转移则向大气排放了31.2 Tg C。在1975-1985年期间,新疆耕地大规模转移,区域碳储量的变化趋势受耕地转移的影响较大;1985年后随新疆土地开垦规模的增加,碳储量变化趋势主要受土地开垦影响。30年间,新疆碳储量增加主要是由草地开垦为耕地引起,而耕地转移为草地是新疆碳储量减少的主要原因。新疆地区进行合理的水土开发活动有利于区域碳固定,且长期的耕作管理活动会进一步增强耕地的碳汇功能。

The potential effect of land use change on global climate change is attracting more and more attention, but in terms of estimation of terrestrial carbon budget, there have been relatively few studies on the effects of land use change on carbon balance in arid region. The large-scale change of arable land has occurred in Xinjiang, and its influences on the regional carbon balance needs to be discussed. First, we analyzed the annual arable land area change of Xinjiang based on the remote-sensing land use/cover data and the statistical arable land area data. Then, we obtained a set of local parameters for Bookkeeping model by exploring published scientific literature, soil census data and field investigation data. Finally, we analyzed the impacts of arable land change on region carbon balance of Xinjiang from 1975 to 2005 by combining mathematical statistics method and Bookkeeping model. The research shows that： land reclamation and arable land transfer were the major forms of arable land change during 1975-2005. The carbon storage of Xinjiang increased by 20.6 Tg C due to these two change forms, while land reclamation and arable land transfer led to the increments of 51.8 Tg C and -31.2 Tg C, respectively. In the period 1975-1985, owing to the large-scale arable land transfer, the changing trend of carbon storage was mainly impacted by the arable land transfer. With the increase of land reclamation scale, the changing trend of carbon storage was mainly impacted by the land reclamation after 1985. Over the past 30 years, the increase of carbon storage in Xinjiang was mainly caused by the grassland reclamation, while the transfer of arable land to grassland was the main reason for the reduction of carbon storage. Generally speaking, proceeding reasonable land and water development is beneficial to the regional carbon sequestration, and long-term management of farming activities will further enhance the carbon sink function of arable land.