Green or grain? Impact of green space expansion on grain production in Chinese cities and its implications for national urban greening schemes

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ContextExpansion of urban green space (UGS) enhances greenery and its benefits in cities. However, the impacts of such expansions on regional landscape sustainability and their spatiotemporal traits across the national scale remain unclear.ObjectivesThis study uncovers a trade-off between agricultural ecosystem services and urban human well-being—the loss of grain production due to UGS expansion consuming cropland—in China from 2000 to 2020. It proposes a safety boundary for UGS expansion to minimize the costs of grain production while addressing the escalating demand for UGS exposure.MethodsUGS expansion and cropland loss are quantified using land cover products, with statistical data contributing to the established relationship between grain loss and UGS coverage. UGS expansion scenarios for 2040 are simulated through bottom-up modeling.ResultsQuadrupled UGS area growth contributed approximately one-third to urban expansion during 2000–2020 in China. Despite improvements in per capita UGS area implying enhanced UGS exposure during rapid urbanization, UGS expansion resulted in a national grain production loss of 4.2 ± 1.4 million t from 2000 to 2020, accelerating post-2010. This loss is equivalent to the annual food intake of 9.3 million Chinese people. We propose a 30.87% UGS coverage target in China by 2040 to preserve UGS access while minimizing grain loss under future urbanization.ConclusionsAcknowledging the critical role of UGS expansion in the issue of cropland loss to urbanization is imperative. Our results offer insights into ensuring human well-being and ecosystem services through landscape and urban planning.