Abstract:

The processes of terrestrial ecosystem carbon cycle and source change are key scientific problems in global climate change and ecology now. We used statistic data in Jiangxi Province from 2001 to 2010, and the carbon emissions coefficient method to calculate the carbon source/sink of farmland ecosystems and carbon footprints in Jiangxi Province, and analyzed the spatiotemporal differences of carbon source/sink and the changes and reasons of carbon footprints. The results showed as follows. (1) From 2001 to 2010, carbon emissions caused by farmland use in Jiangxi Province increased by 103 times, from 11910 1×106 t in 2001 to 5872 8×106 t in 2010. Agricultural mechanization was the biggest contribution to farmland ecosystem carbon emissions in Jiangxi Province. Carbon intensity of farmland ecosystems in Jiangxi Province showed a trend of increased followed by decreased as a whole. With respect to the regional difference, Ganzhou had the largest farmland ecosystem carbon emissions in Jiangxi Province in 2008; Jingdezhen was the minimum, and its carbon emissions intensity was also the lowest. (2) Carbon uptake of farmland ecosystem in Jiangxi Province during 2001-2010 decreased at first, then increased year by year, and decreased in 2010; the whole carbon uptake from 2001 to 2010 increased by 3209 9×106 t. All kinds of crops, rice had the largest carbon uptake, accounting for more than 75%. From the point of carbon absorption intensity, farmland ecosystem carbon intensity in Jiangxi Province was enhanced followed by weakened. From a regional view, Yichun had the most carbon uptake in various districts of Jiangxi Province in 2009, while Pingxiang had the least. The highest carbon absorption intensity was Fuzhou city, while Jiujiang was the weakest. (3) The carbon footprint of farmland ecosystem in Jiangxi Province rose from 0751 8×106 C〖DK〗·hm-2〖DK〗·a-1, to 1473 4×106 C〖DK〗·hm-2〖DK〗·a-1 in 2009, increased by 0698 1×106 C〖DK〗·hm-2〖DK〗·a-1, and per unit carbon footprint presented an increasing trend year by year. From the perspective of the regional differences, Ganzhou was the most carbon footprint city in Jiangxi Province in 2008, while Pingxiang was the least. The per unit carbon footprint of Ganzhou was the largest, while Jian was the smallest. Nanchang, Jingdezhen and Yichun performed ecological surplus, while other seven regions showed ecological deficit.  Ganzhou  had the largest ecological deficit, while Yingtan city had the least deficit. Conclusion: Jiangxi Province should reduce the use of pesticides, fertilizers, etc., and control the utilization of agricultural mechanization, especially in Ganzhou city, in order to achieve the purpose of reducing carbon emissions