三峡库区“耕—果”转换时空变化特征及其启示——以草堂溪流域为例

三峡库区坡耕地如何实现功能转型,及其转型过程的作用机制对库区未来的粮食安全、生态安全等问题意义重大。本文利用0.51 m高清遥感影像数据,以草堂溪流域为研究区,结合野外实地考察,通过分析坡耕地向经果林的农地用途转换过程来揭示三峡库区坡耕地功能转型的内在机制。研究表明：（1）草堂溪流域的耕—果转换重心在2012年后,以高程800 m为拐点由西南部低海拔平坝地区向东北部高海拔、坡耕地覆盖地区转移,变化发生点均在坡度 15°~30°范围内;（2）研究区耕—果转换的集聚特征一般发生在8.5 km左右的特征尺度上,且空间分布随时间推移愈发均匀;（3）耕—果转换现象与人为活动关系密切,多发生在河流、道路及农村居民点附近;（4）耕—果转换可在微观与宏观尺度上总结为六种变化模式,受社会经济与自然因素驱动,库区耕—果转换的本质为坡耕地功能转型,且转型重点倾向于经济效益与生态效益的共赢。

Spatio-temporal variation of farmland-fruit forest conversion and its enlightenment in Three Gorges Reservoir area: A case study on Caotangxi watershed

The transformation of the function of sloping farmland, and the mechanism of this process are of great significance to studies on the future food security and ecological security in the Three Gorges Reservoir area (TGRA). This study, based on 0.51 m high resolution remote sensing image data, took the Caotangxi watershed as the study area. Combined with field investigation, we visualized the spatial shape of sloping farmland function transformation by analyzing the conversion of sloping farmland into economic fruit forest. Then we discussed the conversion of agricultural land use in the study area and revealed the internal mechanism of sloping farmland function transformation in the TGRA. Research showed that: (1) Around 2012, the focus of farmland-fruit forest conversion in Caotangxi watershed transferred from low altitude plain in the southwest to high altitude and sloping farmland covered areas in the northeast, with the 800-m elevation as the inflection point. And the change points are within the slope of 15°-30°. (2) The aggregation of the farmland-fruit forest conversion in the study area generally occurred at about 8.5 km characteristic scale, and the spatial distribution was more balanced with time. (3) The phenomenon of farmland-fruit forest conversion was closely related to human activities, and occurred mostly in the vicinity of rivers, roads and rural settlements. (4) The farmland-fruit forest conversion could be summed up as 6 change patterns on the micro and macro scales. Driven by social, economic and natural factors, the farmland-fruit forest conversion in the TGRA is essentially the sloping farmland function transformation, and the focus tended to be a win-win situation of economic and ecological benefits.