资源环境硬约束下中国耕地休耕优先区识别

为厘清全国耕地资源环境本底并识别中国休耕优先区，该研究从生态保护红线、土壤污染状况、地下水超采和耕地质量等级等4个维度，运用生态保护红线划定、内梅罗综合污染指数、地下水水位变幅等方法系统分析中国耕地资源环境胁迫因子空间格局及分异特征，并构建多准则休耕规则识别不同情景下中国休耕规模及优先区的空间分布。结果表明：1）中国北方划入生态保护红线范围内耕地面积远高于南方，划入一级生态保护红线范围内耕地占3.57%；2）中国耕地重、中度污染面积分别占1.23%和2.31%，南方整体污染高于北方且南方呈局部分散、北方呈点状集聚格局；3）地下水超采区集中于河北、河南、吉林和江苏，重度超采区仅占0.68%；4）耕地质量总体一般，劣等、低等耕地面积分别占3.69%和14.0%，北方明显高于南方且大范围分散分布。依据多准则休耕规则综合评判，划入休耕优先区占全部耕地的23.70%，比食品安全优先、产能损失最小和生态保护优先3种情景分别高8.40%、4.18%和3.12%，其中禁植必休区、限植休耕区和重点轮休区分别为1.95%、4.71%和6.18%。因此，必须从源头治理视角厘清耕地资源环境本底，权衡休耕的迫切性，为国家层面上休耕规划有效落地、污染休耕治理和耕地保护创新提供技术支撑。

Identifying the fallow priority areas of cultivated land under resources and environmental constraints in China

Abstract: This study aims to identify the priority areas of fallow under the resources and environmental background of cultivated land in China. The spatial pattern and differentiation characteristics of ecological stress factors were systematically determined using the Nemerow integrated pollution index, the variation of groundwater level, the service function of the ecosystem, and the sensitivity of the ecological environment. Four dimensions were also considered, including ecological protection red line, soil pollution, over-exploited groundwater, and arable land quality. Subsequently, a multi-criteria and multi-objective optimization of fallow was constructed to identify the scale of fallow, and the spatial distribution of priority areas. Three scenarios were also selected, including the priority to food safety (PFS), the minimum production capacity loss (MCL), and the priority to ecological security (PES). Especially, each scenario was set as the low, medium, and high level for better prioritizing fallow units. A spatial weighing of all factors was also carried out to delineate the fallow priority areas of cultivated land under resources and environmental constraints. As such, an optimal matching was achieved for the correlation between ecological security, food production, and quality. The results showed that: 1) There were much larger areas of arable land within the delineation of ecological protection red line in northern China than those in the south. Specifically, the area of arable land within the first- and the second-class ecological protection red line delineation accounted for 3.57%, and 10.95%, respectively. 2) The area ratios of farmland with slight, moderate, and severe pollution were 18.56%, 2.31%, and 1.23%, respectively. The overall pollution in the south was higher than that in the north. There was a partially scattered distribution of pollution in the south, whereas, the north showed a pattern of spot-like agglomeration. 3) The areas of over-exploited groundwater were mainly concentrated in the provinces of Hebei, Henan, Jilin, and Jiangsu, where the severe over-exploited areas accounted for only 0.68% of the whole of China. The severe over-exploited areas with the large-scale contiguous patterns were 4670km2 and 3950km2 in Hebei and Henan, respectively. 4) The total proportions of arable land quality accounted for 3.69% and 14.0%, respectively, for the grade of the inferior and poor grade in northern China, particularly with the widely dispersed pattern, compared with the south. The priority fallow areas accounted for 23.70% of the total study area, according to the comprehensive evaluation of cultivated land and multi-criteria fallow. Specifically, the proportions of the prohibited-planting-fallow area (I), restricted-planting-fallow area (II), key-rotation area (III), and general-rotation area (IV) were 1.95%, 4.71%, 6.18%, and 10.86%, respectively. Furthermore, the priority fallow areas were 8.40%, 4.18%, and 3.12% higher than those of the PFS, MCL, and PES, respectively. Consequently, this finding can provide strong technical support to effectively implement the fallow planning, thereby protecting the cultivated land from soil pollution in modern agriculture.