南方红壤丘陵区耕地生态问题识别与修复分区

农业空间生态修复是国土空间生态修复的重要内容之一，耕地作为农业空间的重要载体，精准识别耕地生态问题并对其系统分区，是新时期耕地高质量发展与科学高效开展国土空间生态修复的重要前提。该研究以南方红壤低山丘陵区耕地生态修复为研究对象，以江西省为例，针对国土空间规划中耕地生态修复的景观连通性、矿山生态负面影响，恢复退化土地生态功能和农业开发对生态空间胁迫程度四大方面，识别了江西省耕地的破碎化、矿山损毁、水土流失以及与生态用地冲突四大生态问题，采用基于修正的通用水土流失方程（RUSLE）模型、景观指数、土地利用转移矩阵和GIS空间分析等方法对各生态问题的指标程度进行定量化分析；基于组合权重构建了生态修复综合指数，依据流域、主要生态问题与修复程度分区方法，对全省耕地生态修复进行了综合分区。结果表明：1）2000-2018年间，江西省耕地水土流失主要以轻度侵蚀为主，水土流失总面积减少50.98%，赣江上游流域和鄱阳湖环湖区等水土流失现象加重；耕地斑块密度、破碎度趋于增加，聚集度趋于离散；耕地占用林地、水域与湿地等生态用地面积共计739.15 km2；建材及砖瓦黏土类和稀有稀土金属等废弃矿山累计破坏耕地的面积为13.18 km2。2）江西省耕地生态修复综合指数空间差异化明显，按照划分标准，将江西省共划分为8个流域大区，38个小区，包括水土保持重点修复、矿山生态重点修复、生态用地重点修复和耕地连通重点提升四个方向的修复内容。研究可为国土空间规划中农业空间的耕地高质量发展提供方法支撑，为江西省农业空间生态修复布局提供科学依据。

Identification of ecological problems and restoration zoning in the hilly red soil region of southern China

Abstract: Ecological restoration of land space is one of the most important contents to promote agricultural production in recent years. The cultivated land is also one of the major carriers in agricultural space. A better tradeoff between cultivated land and forest can greatly contribute to the ecological protection and restoration. However, the agricultural land has been fragmented by rapid urbanization, particularly by the transfer of cultivated to marginal land, and the unreasonable land use. Therefore, it is very necessary to accurately identify the ecological patterns of cultivated land for the decision-making on the high-quality development and the scientific restoration of land space. Taking Jiangxi Province of China as the research area, this study aims to improve the scientific and reasonable zoning of the spatial layout during ecological restoration. The identification angles of cultivated land were set as the key points of agricultural spatial ecological diagnosis, according to the standard on Compilation of Provincial Land Spatial Ecological Restoration Planning (Draft for Comment). Some aspects were considered, including the ecological restoration functions of degraded land, the distribution scope and degree of ecological space stress caused by agricultural development, the landscape connectivity, and the negative impact on the mine ecology. The ecological cultivated land was closely related to the spatial restoration of agricultural production. Four indicators were then identified for the fragmentation of cultivated land, mine damage, soil erosion, and the conflict with ecological land. The index degree was also calculated using Revised Universal Soil Loss Equation (RUSLE), landscape index, land use transfer matrix, and GIS spatial analysis on each ecological restoration. Furthermore, the comprehensive index of ecological restoration was constructed using the combination weight. The ecological restoration of cultivated land was divided systematically, according to the division method of watershed, main ecological challenges, and restoration degree. The results show that: 1) The mild erosion of cultivated land was found in the study area during 2000-2018. The total area of soil erosion decreased by 50.98%. But the worse erosion was observed in the upper reaches of Ganjiang River, and the area around Poyang Lake. There was a great increase in the patch density and fragmentation of cultivated land, indicating the discrete aggregation tends. Specifically, the cultivated land was occupied 739.15 km2 of ecological land, such as forest land, water area, and wetland. The cumulative area (13.18 km2) of cultivated land was destroyed by the abandoned mines, such as the building materials, brick clay, and rare earth metals. 2) There was the outstanding spatial differentiation in the comprehensive index of the cultivated land during ecological restoration. Eight river basins and nine types of secondary areas were then subdivided into 38 sub-districts, according to the key restoration of soil and water conservation, the mine ecology, ecological land, and cultivated land connectivity. Two recommendations were given: 1) The Xinjiang and Xiushui basins need to strengthen the soil and water conservation, as well as the mine ecological restoration. 2) The ecological conflict remediation of cultivated land and the mine ecological restoration can be focused on the central areas of Poyang Lake, Raohe River basin, and the upper reaches of Ganjiang River. The finding can provide a strong support to the high-quality development of cultivated land in agricultural space in national land spatial planning. A scientific basis can also be offered to the ecological restoration layout of agricultural space in Jiangxi Province of China.