中文摘要：

黄土高原-青藏高原过渡带是我国农业生产方式变化最剧烈、碳平衡效应最敏感的区域之一.本文分析了海拔梯度上通渭-渭源-夏河样带农业系统的碳平衡.结果表明：随海拔增加,单位面积作物的碳排放、碳固定和碳汇能力逐渐降低,户均家畜碳排放与碳固定、碳源能力递增,综合生产系统由碳汇渐变为碳源,户均碳排放上升,碳固定变化趋势与之相反.黄土高原-青藏高原过渡带的农户占比随碳平衡的变化可用Logistic方程拟合,随海拔升高,在通渭、渭源与夏河3个区域农户占比50.0%拐点处,作物系统的碳排放和碳固定分别为1491、857、376 kg CE·household^-1和6187、3872、778 kg CE·household^-1,家畜系统碳排放和碳固定分别为2218、3725、49511 kg CE·household^-1和138、230、2706 kg CE·household^-1,综合系统碳排放和碳固定分别为3615、4583、49918 kg CE·household^-1和6289、4113、3819 kg CE·household^-1,这些是区域碳平衡调控的关键点.

英文摘要：

The transition zone from the Loess Plateau to the Qinghai-Tibet Plateau is one of the regions with most dramatic changes in agricultural production mode and most sensitive response to the carbon balance effect. This paper analyzed the carbon balance of the agriculture system along the altitude gradient in Tongwei,Weiyuan and Xiahe counties. The results showed that with the increase of altitude,the carbon emission,carbon fixation and carbon sink capacity of crops per unit area decreased accordingly,while the average carbon emission,carbon fixation and carbon source capacity of each household in livestock system increased. The integrated crop-livestock production system changed from carbon sink to carbon source. The average carbon emission of each household rose with altitude,but the carbon fixation was the opposite. The change of percentage of household in the transition zone from the Loess Plateau to the Qinghai-Tibet Plateau with carbon balance could be fitted with Logistic equation. In the crop system of Tongwei,Weiyuan and Xiahe with the altitude increase,carbon emission at the inflection point where the household percentage accounted for 50.0%was 1491,857 and 376 kg CE · household^-1,and carbon fixation was 6187,3872 and 778 kg CE·household^-1,respectively. For the livestock system,carbon emission was 2218,3725 and49511 kg CE·household^-1,and carbon fixation was 138,230 and 2706 kg CE·household^-1,respectively. For the integrated crop-livestock system,carbon emission was 3615,4583 and 49918 kg CE·household^-1,and carbon fixation was 6289,4113 and 3819 kg CE·household^-1,respectively,which could be the key point for the regulation of regional carbon balance.