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过去60a来,长江中下游平原的乡村地区发展迅速,引起土地利用覆被及其土壤有机碳储量明显地变化。通过选取区域代表性样方、基于1942年航片和2002年IKONOS影像研究小尺度土地利用覆被变化、土壤取样和收集1965年前土壤有机碳历史数据,用尺度推绎和蒙特卡洛不确定性分析方法,评价了19402002年长江中下游平原人口密集的乡村景观区域中土地利用覆被的面积及其030cm土壤(或底泥)有机碳储量的变化。结果表明:近60a来,在86×103km2的区域中有47%的面积发生土地利用覆被转化,其中耕地转化为非耕地的面积为21%(18×103km2)。土地利用覆被类型转化及其有机碳密度的变化导致该区域土壤有机碳储量的净增加。该区域稻田和闲置水域面积分别减少了21.5%(18.5×103km2)和6.7%(5.7×103km2),导致其土壤(或底泥)有机碳储量分别减少41.8TgC和12.9TgC;而水产养殖、非渗漏表面为主的建筑用地、种植木本作物和种植1年生作物的水浇地面积分别增加了14.2%(12.2×103km2)、7.7%(6.7×103km2)、3.5%(3.0×103km2)和2.0%(1.7×103km2),使其土壤(或底泥)有机碳储量分别增加32.2TgC、22.2TgC、12.2TgC和6.5TgC。近60a来,整个区域030cm土壤有机碳的储量增加了18.2TgC,其净增加的可能性为75%,形成了弱碳汇。这主要是由于区域稻田土壤有机碳密度增加了17%,使区域土壤有机碳储量增加了22.2TgC(其净增加的可能性为92%);而且,稻田转化为种植木本作物和种植1年生作物的水浇地也使区域土壤有机碳储量分别增加了1.3TgC(净增加的可能性为86%)和0.3TgC(净增加的可能性为70%);此外,闲置水域转化为水产养殖也使区域土壤有机碳储量增加1.3TgC(净增加的可能性为77%)。但是,稻田转化为水产养殖和非渗漏表面为主的建筑用地导致区域土壤有机碳储量损失6.3TgC和0.6TgC。因稻田土壤有机碳密度增加及稻田转化类型的土壤有机碳储量变化的影响,使整个区域形成弱碳汇,但如果稻田继续减少的话,很可能变成碳源。通过选取区域代表性样方、研究小尺度土地利用覆被变化、土壤取样和收集土壤历史数据,采用尺度推绎方法,研究揭示了19402002年长江中下游平原人口密集的乡村景观区域中土地利用覆被的面积及其土壤有机碳储量的变化。
Over the past 60 years, the rapid development of rural areas in the middle and lower reaches of the Yangtze River has caused a significant change in land cover and soil organic carbon storage. Based on the 1942 aerial photographs and the 2002 IKONOS images, the study of small-scale land-use cover change, soil sampling and collection of historical data of soil organic carbon before 1965 were carried out on a scale deduction and Monte-Carlo uncertainty Sex analysis method to evaluate the change of land cover and its 030cm soil (or sediment) organic carbon storage in the densely populated rural landscape area in the middle and lower reaches of the Yangtze River from 1940 to 2002. The results showed that in the past 60 years, 47% of the area of 86 × 103km2 had been converted into land-use cover. The area of cultivated land converted to non-cultivated land was 21% (18 × 103km2). The change of land cover types and their organic carbon density led to a net increase of soil organic carbon storage in this area. The area of paddy field and idle water in this area decreased by 21.5% (18.5 × 103km2) and 6.7% (5.7 × 103km2), respectively, resulting in a decrease of 41.8TgC and 12.9TgC in soil (or sediment) organic carbon storage respectively. However, aquaculture, The area of irrigated land with plots of seepage mainly increased by 14.2% (12.2 × 103km2), 7.7% (6.7 × 103km2), 3.5% (3.0 × 103km2) and 2.0% (1.7 × 103km2), so that the soil (or sediment) organic carbon storage increased 32.2TgC, 22.2TgC, 12.2TgC and 6.5TgC respectively. In the recent 60 years, the reserves of 030cm soil organic carbon in the whole area increased by 18.2TgC, with a net increase possibility of 75%, forming a weak carbon sink. This is mainly due to an increase of 17% in the density of soil organic carbon in paddy fields in the region and an increase of 22.2TgC in soil organic carbon stocks in the region (with a net increase possibility of 92%); furthermore, the conversion of paddy fields to planting woody crops and planting 1 year old Crop irrigations also increased soil organic carbon stocks by 1.3 Tgc (86% net increase) and 0.3 Tgc (70% net increase) respectively; in addition, conversion of idle waters into aquaculture Increased the area’s soil organic carbon stock by 1.3 TgC (77% probability of a net increase). However, the conversion of paddy fields into aquaculture and non-seepage-dominated land for construction led to the loss of 6.3 TgC and 0.6 TgC of soil organic carbon in the area. Due to the increase of organic carbon density in paddy soil and the change of soil organic carbon storage in the paddy field conversion type, weak carbon sinks are formed in the whole area, but if the paddy field continues to decrease, it is likely to become a carbon source. Through the selection of regional representative quadrats, the study of small-scale land-use change, soil sampling and collection of soil history data, the use of standard deduction method, the study revealed the land use cover of the 1940-2002 plain population in the densely populated rural landscape area The area covered and the change of soil organic carbon storage.