三峡库区山区传统农业生态系统转型

三峡库区是集农村、山区、移民区为一体的典型生态脆弱区,研究其传统农业生态系统的变化对于库区的农村发展与乡村振兴具有重要意义。通过“理论分析—实证研究—趋势预测”的研究框架,以草堂溪流域为例,利用2012-2017年的Quick Bird高分遥感影像结合自然资源要素与农户行为从空间尺度上人地关系变化角度出发对三峡库区山区传统农业生态系统的转型及趋势进行解析。研究发现：① 利用100 m间隔范围的缓冲环将三峡库区的农业生态系统模式分为高低低、高低高、低高低与低低高4种类型,不同模式分别代表三峡库区不同的农业发展阶段,揭示了库区传统农业生态系统由传统耕作方式向现代农业转型的趋势。② 库区的农业生态系统正逐步由传统的耕作区域内粗放利用的纯农生计方式,通过坡耕地撂荒、经果林种植等生态恢复方式,向聚落周边300 m范围内种植结构合理化、物种多样化的集约利用方式转型。③ 以农户与坡耕地等系统要素为代表的三峡库区传统农业生态系统正在发生转型。其中坡耕地多由生产功能主导向生态与经济功能并重转变,农户生计方式趋于多样化,聚落系统生态活力逐渐增强,且农业生态系统转型的变化范围基本由高海拔山地区域向河谷平坝区迁移。此外,尽管在数据时限方面存在不足,但研究结果对于库区乡村土地利用、山区水土流失治理及农村人居环境改善均有启示意义。

Traditional agroecosystem transition in mountainous area of Three Gorges Reservoir Area

The Three Gorges Reservoir Area (TGRA) is a typical ecological vulnerable area with a characteristic of rural, mountainous and immigrant areas, therefore, it is of great significance to study the traditional agroecosystem changes in the TGRA for rural development and revitalization. According to the framework of "theoretical analysis - empirical study - trend prediction", this paper, taking the Caotangxi watershed as an example, analyzes the transition and trend of the traditional agroecosystem in the mountainous area of TGRA from the spatial change of man-land relationship by combining the Quick Bird high-resolution remote sensing images from 2012 to 2017, the natural resources and the farmers' behavior. The results show that: (1) the agroecosystem in the TGRA can be divided into four models by using buffer rings of 100 m interval, namely, the high-low-low, high-low-high, low-high-low and low-low-high. Different models, which represent the agricultural development stages in the TGRA, can reveal the trend of traditional agroecosystem transition from traditional way to modernization. (2) The agroecosystem in the TGRA is gradually transforming from the extensive agricultural land use to the intensive utilization way characterized by the rationalization of planting structure and species diversity within a range of 300 m around the settlements, through the ecological restoration way such as the abandonment of sloping farmland and the planting of economic fruit forest in the traditional farming area. (3) The traditional agroecosystem in the TGRA, represented by system elements such as farmers and sloping farmland, is undergoing transformation. Among them, the sloping farmland has mostly transformed from the type dominated by production function to the type with an equal emphasis on ecological and economic functions, the way of farmers' livelihood has tended to diversify, the ecosystem vitality of settlements system has gradually increased, and the change range of agroecosystem transition has basically migrated from high mountain area to valley flat area. Additionally, although there is a deficiency in study time limit, the results still have enlightenment for the rural land use, the control of soil and water loss and the improvement of rural living environment of the mountainous areas in the TGRA.