近20年新疆农田生态系统碳足迹时空变化

Temporal and spatial differences in carbon footprint of regional farmland ecosystem in Xinjiang during recent 20 years

利用1994—2013年新疆农田生产投入和农作物产量等数据,采用碳排放系数法估算了新疆农田生态系统的碳排放量、碳吸收量及碳足迹的变化动态以及在各县市的空间分布特征。结果表明:新疆农田生态系统的碳排量从1994年的179.46万t增长到2013年的474.15万t;不同年份农业碳排放均主要源于化肥使用量的增加和不科学的灌溉方式,其最大贡献率分别为40.02%和41.56%;农田生态系统的碳吸收量20年间增加了2185.04万t,棉花对新疆农田生态系统的碳吸收量贡献最大,多年平均贡献率达47%;新疆农田生态系统的碳排放量、碳吸收量区域主要集中在南疆的县市并呈现出沿天山对称的趋势;1994—2013年,农田生态系统碳足迹呈现快速增长态势,从1994年的2 732.63×104C·hm-2·a-1增加至2013年的4 474.89×104C·hm-2·a-1,碳足迹增加了283.59×104C·hm-2·a-1,表明新疆农田生态系统存在碳生态盈余的现象,种植结构生态效益指数大于1的年份为11个,种植结构的调整迫在眉睫。

Statistic data on investment in farmland production and yield in Xinjiang from 1994 to 2013 were collected, and the carbon emissions coefficient method was employed to estimate the carbon emissions and absorptions of farmland ecosystems and carbon footprints in Xinjiang and their distribution in counties and cities. The results showed that the carbon emissions of farmland ecosystem in Xinjiang were increased from 1. 7946 million tons in 1994 to 4. 7415 million tons in 2013. Carbon emissions were mainly derived from increased agriculture fertilizer usage over years and irrational irrigation methods, with biggest contribution rates of 40.02% and 41.56%, respectively. Carbon absorption in farmland ecosystem was increased by 21. 8504 million tons over 20 years, contributing the most to the carbon absorption in farmland ecosystem of Xinjiang, and its annual average contribution rate reached 47 %. Farmland ecosystem carbon emissions and carbon absorption in Xinjiang area presented the obvious spatial agglomeration in some counties and cities in southern Xinjiang and displayed a trend of being symmetrical along the Tianshan mountain. Farmland ecosystem carbon footprints showed a trend of rapid growth, from 2 732.63 ×10^4 C.hm-2.a-1 in 1994 to 4 474.89 × 10^4 C.hm-2.a-1 in 2013. Carbon footprint had increased by 283.59 × 10^4 C. hm-2. a- 1 indicating that carbon ecological surplus was found in farmland eeosystems of Xinjiang. In 11 years, the planting structure ecological indexes were greater than 1. Therefore, adjustment of planting stmeture is imminent.