Abstract:

The land system is a complex ecosystem of multidimensional interactions among human activities, socio-economics, and natural ecology, playing a key role in promoting ecological stability and sustaining human life. It provides extensive ecosystem services (ES) to humanity across the production, living, and ecological dimensions, including provisioning, regulation, and cultural services. In the land system, different ES functions exhibit a complex interdependence or trade-off relationship with human social systems. The Yangtze River Economic Belt (YREB) is one of China’s most important grain production areas. The rapid urbanization process has led to the expansion of urban areas, which has encroached upon existing farmland resources. According to the third national land survey, China's farmland area has decreased by 113 million acres, facing intensified pressures on natural resources and environmental degradation, as well as challenges such as farmland-based pollution, with the potential for developing reserve farmland resources being undermined. Therefore, this study adopts the perspective of ES to explore the spatiotemporal evolution patterns and the trade-off and synergy effects of the farmland production-living-ecology functions. Based on this, it proposes differentiated and refined management zoning and control pathways, which have profound practical significance for ensuring China’s farmland security and food security. In this context, this study selects eight indicators, including food supply (FS), cultivated land carrying capacity, agricultural economic density, density of agricultural labor force, water yield (WY), soil and water conservation (SR), carbon sequestration (CS), and habitat quality (HQ), using the land use transfer matrix, the InVEST model, and the trade-off and synergy model. It constructs the 2000‒2020 farmland “production-living-ecology” evaluation system for the YREB, exploring the trade-offs and synergies between farmland’s multifunctionality, identifying farmland function zoning in the YREB, and proposing differentiated land zoning optimization pathways. The main conclusions are as follows: Overall, between 2000 and 2020, there was a significant transfer effect between farmland and other land use types in the YREB. Specifically, from 2000 to 2020, the total area of farmland transfer and out of the YREB was 235146 km², accounting for 11.5% of the total farmland area. From the perspective of farmland transfer out, the total area of farmland transferred to other land use types was 105061 km². Among them, paddy fields and dry land were primarily transferred to forest land and built-up land, with transfer areas of 53248 km² and 51813 km², respectively. From the perspective of farmland transfer in, the total area of land types converted into farmland was 74505 km². Among them, the newly added paddy fields were transferred from forest land, with a total inflow area of 31486 km². In contrast, the newly added dry land was mainly converted from forest land, with a total inflow area of 43019 km². From the perspective of production function, the high-value areas of farmland the production function are mainly distributed in regions such as the northern Anhui Plain and Jiangsu Plain in the downstream YREB. The medium-value areas for production function are mainly distributed in regions such as the Sichuan Basin and the middle and lower reaches of the Yangtze River Plain. From the perspective of living function, the cultivated land's living function index exhibited a trend of first increasing and then decreasing between 2000 and 2020. In 2000, high-value areas of living function were concentrated in western Anhui, Shanghai, and northeastern Zhejiang Province. Medium-value areas were located in Hubei, Yunnan, and the Sichuan Basin. Low-value areas were mostly distributed in Guizhou Province and southern Jiangsu. Between 2010 and 2020, high-value areas of living function were primarily concentrated in Shanghai, Jiangsu Province, southern Hunan Province, and the Sichuan Basin. Medium-value areas were mainly concentrated in Anhui, Zhejiang, and the Poyang Lake Plain. Low-value areas were mainly distributed in the upstream regions of the Yangtze River Economic Belt, including Yunnan, Guizhou, and Chongqing. From the perspective of ecological function, the ecological function of the YREB farmland system remained at a relatively low level between 2000 and 2020. The high-value areas are mainly distributed in the upstream YREB regions such as Yunnan, Guizhou, and Chongqing. The medium-value and low-value areas span across the middle and lower reaches of YREB, including regions such as Sichuan, Hunan, Hubei, Jiangsu, Shanghai, and Anhui. Between 2000 and 2010, the ecological function of the region declined sharply. By 2020, the ecological function had gradually increased and stabilized. From the perspective of the integrated “production-living-ecology” function of farmland, the threefold function of YREB farmland showed an evolution pattern of initial increase followed by a decrease between 2000 and 2020. From the perspective of the trade-off and synergy effects between production function and living function, overall, the production function and living function of the YREB farmland system mainly show a slight trade-off. Among them, 39.97% of the counties show varying degrees of synergy, 50.78% exhibit trade-off relationships, and 9.52% of the counties show no correlation or insignificant relationships. From the perspective of the trade-off and synergy effects between production function and ecological function, overall, a slight synergy is observed. Among them, 51.38% of the counties show varying degrees of synergy, 42.73% display varying degrees of trade-off relationships, and 5.89% show no correlation or insignificant relationships. From the perspective of the trade-off and synergy effects between the living function and ecological function, overall, the production function and living function of the YREB farmland system mainly show a slight trade-off. Among them, 46.15% of the counties show varying degrees of synergy, 46.06% exhibit varying degrees of trade-off relationships, and 7.79% of the counties show no correlation or insignificant relationships. Finally, this study categorizes the cultivated land in the YREB into three functional zones: elastic development zones, production protection zones, and key development zones. For elastic development zones, the study sets management goals aimed at promoting coordinated urban-rural development, alleviating regional ecological pressure, and enhancing the sustainable use of cultivated land. For production protection zones, the goals focus on safeguarding cultivated land security, advancing green and efficient agricultural practices, and jointly strengthening ecological barriers. For key development zones, the proposed goals include integrating urban and rural spatial planning, facilitating industrial integration, and promoting the functional transformation and upgrading of cultivated land. The research results can provide a scientific basis for the “in-out balance” of farmland and food security in YREB.

Key words: multifunctional farmland, ecosystem services, trade-offs and synergies, functional zoning, Yangtze River Economic Belt

摘要： 从生态系统服务的视角出发，探索耕地“生产-生活-生态”功能的时空演化规律及其权衡协同效应，对保障中国的耕地安全红线和粮食安全具有深远的现实意义。以长江经济带的耕地为研究对象，基于InVEST模型（Integrated Valuation of Ecosystem Services and Tradeoffs）、权衡协同模型、熵权法等方法，对2000－2020年长江经济带耕地的“生产-生活-生态”功能进行量化，揭示了长江经济带耕地多功能的时空演变特征，在县域尺度下进一步分析耕地三生功能间的权衡协同效应，并识别耕地的功能分区，提出了差异化的优化路径。结果表明，1）2000－2020年间水田和旱地主要转移为林地和建设用地，转出面积分别为53248 km²和51813 km²；其他地类向水田与旱地的转入面积分别为31486 km²和43019 km²。2）2000－2020年耕地的“生产-生活-生态”功能综合指数分别为0.47、0.52、0.45，呈先升后降的演变趋势；20.4%的县域耕地三生功能有所提升，45.5%的县域呈现不同程度的下降态势。3）耕地的“生产-生活-生态”功能间的权衡协同效应呈显著的空间异质性。4）将耕地划分为弹性发展区（58.7%）、生产保护区（23.3%）以及关键发展区（17.8%）三类，并提出差异化、精细化的耕地优化路径与管理策略。

关键词: 耕地多功能, 生态系统服务, 权衡协同效应, 功能分区, 长江经济带