基于气候带与农业区划的农田生态系统服务权衡及驱动机制

农田生态系统作为重要的陆地生态系统之一，不同气候带与农业区的农田生态系统服务权衡关系与机理尚不明确。该研究定量分析了1990-2019年典型区域淮河流域农田生态系统关键服务食物供给与土壤保持的权衡强度，运用地理探测器方法揭示了不同气候带与农业区划下农田生态系统服务权衡关系的驱动机制，完善与细化了农田生态系统服务权衡机理，为推进淮河流域不同气候区和农业区的粮食安全和生态安全协同和精准施策提供科学依据。结果表明：1）淮河流域食物供给服务总体呈现增长趋势，黄淮海平原食物供给增长幅度显著高于长江中下游。土壤保持服务分区差异较大，在气候带上表现为亚热带增长趋势快于暖温带，在农业区划上表现为长江中下游增长趋势快于黄淮海平原，但黄淮海平原土壤保持平均值高于长江中下游。2）淮河流域农田食物供给与土壤保持两种服务间的权衡关系存在时空分异性，总体呈现加剧态势，权衡强度表现为暖温带长江中下游农业区>亚热带农业区>暖温带黄淮海平原农业区。3）淮河流域农田生态系统食物供给与土壤保持间的权衡关系受自然因素和人为因素共同作用，人为因素尤其是化肥施用量显著增强了食物供给与土壤保持间的权衡；在不同气候带与农业区，气候因素和地形因素对权衡关系的影响差异显著，其中，暖温带黄淮海平原农业区受地形因素和年均温的影响显著，而其他农业区年降水量的作用更明显。4）粮食主产区耕地利用与保护政策制定应充分考虑农田生态系统供给服务（粮食生产）和支持服务（土壤保持）的权衡关系在不同气候带和农业区划作用机制的时空差异性，同时要考虑驱动因素的普遍性与差异性，减少人为因素的普遍影响，并结合不同区域自然因素及与人为因素的交互影响分区施策。

Trade-off and driving mechanisms for farmland ecosystem services based on climatic zones and agricultural regionalization

Abstract: Farmland is one of the important terrestrial ecosystems that related to the national food security. There are some trade-offs among the farmland ecosystem services during sustainable development. But, it is still unclear on the trade-off relationship and driving mechanisms of farmland ecosystem services in the different climatic and agricultural zones. Among them, the Huaihe River Basin under the subtropical and warm temperate zones can be divided into the Middle-lower Yangtze Plain and the Huang-Huai-Hai Plain, in terms of agricultural zoning. Taking the Huaihe River Basin farmland ecosystem as the research object, this study aims to refine the trade-off mechanism of farmland ecosystem service using climate and agricultural zones. The core service functions were quantitatively analyzed (such as the food supply and soil conservation) from 1990 to 2019. Root Mean Square Error (RMSE) was then selected to evaluate the trade-off degree between them. GeoDetector was also used to reveal the natural and human drivers of changes in the trade-off relationship. The results showed that: 1) An overall growth trend was found in the food supply services of the study area. Specifically, the growth of food supply in the Huang-Huai-Hai Plain was significantly higher than that in the Middle-lower Yangtze Plain. Soil conservation services varied greatly in the different districts. A faster growth trend of climate zones was observed in the subtropical zone than in the warm temperate zone. A faster growth trend of agricultural zones was in the Middle-lower Yangtze Plain than that in the Huang-Huai-Hai Plain. By contrast, the average soil conservation value in the Huang-Huai-Hai Plain was higher than that in the Middle-lower Yangtze Plain. 2) There was an increasing trend with the significant spatial divergence in the trade-off between the farmland food supply and soil conservation services. The trade-off relationship was the most significant in the warm temperate Middle-lower Yangtze Plain agricultural zone, followed by the subtropical agricultural zone, and the warm temperate Huang-Huai-Hai Plain agricultural zone. 3) Both natural and human factors were dominated in the trade-off relationship between the food supply and soil conservation in the study area. There were only a few variations in the relative contributions of human factors and soil texture factors to the trade-off relationship between the two services in different zones. A significant variation was found in the contributions of climatic and topographic factors to the trade-off relationship between the two services in the different subdivisions. The contribution of topographic factors to the trade-off relationship was higher in the warm temperate Huang-Huai-Hai Plain agricultural zone than that in the rest two regions. There was also the great difference in the relative contribution of climatic factors. Therefore, the annual average temperature posed a higher influence on the trade-off relationship in the warm temperate Huang-Huai-Hai Plain agricultural zone, whereas, the annual precipitation was a higher influence in the other two regions. 4) Some recommendations were given for the decision making on the use and conservation of farmland in major food-producing regions. The spatial and temporal variability can also be fully considered for the trade-off between supply services (food production) and support services (soil conservation) of farmland ecosystems in different climatic and agricultural zones. At the same time, the universality of driving factors can also be critical to reduce the negative impact of human factors. The natural factors of different regions and the interaction mechanisms can be expected to combine with the human factors for the zoned policies, in order to improve the targeting policies in different climate and agricultural zones. The finding can also provide a scientific basis to promote the precise policy-making and synergistic development for the food and ecological security in different climatic and agricultural zones of the Huaihe River Basin.