经济发达区耕地边际化特征、过程及其驱动机制研究——以江苏省为例

Farmland marginalization is a common phenomenon in the process of industrialization and urbanization. In economically developed areas, agricultural infrastructure is constantly improved, agricultural mechanization level is continuously improved, and the proportion of agricultural scale operation is increasing. However, farmers' enthusiasm for grain production, labor force and cost input has been reduced, cultivated land use types have been changed, cultivated land structure has been adjusted, and sown area of grain crops has been reduced, which leads to the reduction of multiple cropping index and grain output. A theoretical framework and analytical system of farmland marginalization in economically developed areas are constructed, and its types and diagnostic criteria are clarified. Taking Jiangsu Province as an example, this project uses multi-source remote sensing images and land use data, combining with rural household survey data and climate data, to identify marginalized farmland information from 2001 to 2017 by applying a refined classification method of farmland, and quantitatively depicts the spatial and temporal changes of farmland marginalization. Coupled with natural, social, economic and policy factors, this project will systematically analyze the influencing factors and driving mechanism of different types of farmland marginalization in the study area at multiple scales. This project is of great importance to deepen the understanding of regional land use transformation, promote the sustainable use of regional agricultural land, optimize the land space layout, and formulate land space control rules.

耕地边际化是工业化与城镇化过程中的普遍现象。针对经济发达区在农业基础设施不断完善、农业机械化水平不断提升、农业规模化经营比例不断提高的背景下，农户种粮积极性降低、劳动力和成本投入减少，耕地利用类型改变、耕地种植结构调整、粮食作物播种面积缩小而导致复种指数降低、粮食产量下降的耕地边际化利用现象，构建经济发达区耕地边际化理论框架和解析体系，明确其类型及诊断标准。本项目以江苏省为例，利用土地利用数据和多源遥感影像，结合农户调查数据和气候数据，采用耕地精细化分类方法提取2001-2017年江苏省边际化耕地信息，定量刻画该地区耕地边际化利用的时空过程与变化特征。耦合自然、社会、经济及政策因素，系统解析不同类型耕地边际化的影响因素与驱动机制，多尺度探讨该地区的耕地边际化现象。本项目对深化认识区域土地利用转型、促进区域耕地可持续利用、优化区域国土空间布局、制定国土空间管制规则等具有重要意义。

经济发达区耕地边际化是经济发达区由于机会成本影响耕地利用方式改变、强度降低或产出效益减少的过程。本项目选取江苏省为研究区，基于多源遥感数据，采用集成学习算法识别部分区域边际化耕地图斑，结合统计数据和问卷调查数据分析耕地边际化利用的时空过程与变化特征，从投入-产出视角构建耕地边际化指数揭示江苏省耕地边际化影响因素及趋势。研究结果表明：（1）江苏省耕地边际化现象出现于种植结构、投入强度和利用程度发生变化的地块，全域耕地都有不同程度的边际化。（2）集成学习算法可以提高识别边际化耕地图斑的精度，但受到影像数量、影像分辨率和样本精度影响，获得江苏省耕地边际化地块时间序列数据集比较困难。（3）随着社会经济发展，江苏省耕地边际化水平变化趋势呈现逐步下降的规律，且不同经济梯度下的区域边际化趋势与省域尺度整体趋势不同。（4）江苏耕地边际化现象具有显著的区域差异性，反映机会成本的社会经济类因素是影响省域耕地边际化趋势的重要因素，苏北地区还受到自然环境类因素影响而苏中和苏南地区还受到农业生产条件影响。本项目可为当前乡村振兴背景下的区域耕地可持续集约化利用模式探索提供指导，并对经济发达区的耕地利用管理、种植模式调整、轮作休耕开展及粮食政策制定提供科学参考。