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Urbanization has Variable Impacts on Crop Yield and Vegetation Health in the Conterminous Cities
Qiang Zhang
1. Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, Beijing Normal University
2. Faculty of Geographical Science, Academy of Disaster Reduction and Emergency Management, Beijing Normal University
Food security is a high-priority area in the UN Sustainable Development Goals (SDGs). The food security issue has been investigated in the backdrop of climate change impacts related to agricultural yield changes over the last few decades due to direct connection of agriculture to climate. However, direct and indirect impacts of urbanization on agriculture still remain imperfectly understood though fast urbanization has elevated impacts on ambient environment and on agriculture as well. In this study, urban impacts on agriculture involve direct and indirect impacts. Direct impacts indicate urban-induced agricultural variations due to urban encroachment-induced cropland changes; while indirect impacts indicate other urban-related impacts except direct impacts such as impacts from irrigation conditions, air temperature, and aerosol changes and so on because of urbanization. Here, we quantified the impact footprint and explanatory power of the direct and indirect impacts of urbanization on crops in the conterminous areas over 32 major cities across nine Chinese agricultural regions using spatial buffer analysis, geographic detector and pixel decomposition technique. We found that, for most agricultural areas, the agricultural potential productivity (APP) was logarithmically decreasing along the urban-rural direction under the integrated impacts of urbanization. While, in the agricultural regions of northern China, the crop health quantified by vegetation health index (VHI) in the conterminous cities improved along with increased urban intensity under indirect impacts of urbanization, which could offset approximately 44% of the direct negative impacts by urban encroachment-induced cropland loss.