Crop diversification is increasingly recognized as a strategy to stabilize national food production, yet the benefits of this approach may vary across nations due to the scale dependence of crop diversity and stability. Here we use crop production data from 131 nations from 1961 to 2020 to explore the spatial scale dependence of the crop diversity–stability relationship. Drawing on ecological theory and complementary analytical approaches, we find that as the total national harvested area increases, yield stability increases. Crop diversity stabilizes national yield stability, as does an increase in the number of farms, but these stabilizing effects are weaker in smaller countries. Our findings suggest that enhancing crop diversity at the national level may not provide a de facto universal strategy for increasing yield stability across all countries—with implications for national strategies promoting crop diversification to protect against food system shocks.

作物多样化越来越被认为是稳定国家粮食生产的一项战略，但由于作物多样性和稳定性的规模依赖性，这种方法的好处可能因国家而异。在这里，我们使用 1961 年至 2020 年 131 个国家的农作物生产数据来探讨农作物多样性与稳定性关系的空间尺度依赖性。借鉴生态理论和补充分析方法，我们发现随着全国总收获面积的增加，产量稳定性也随之增加。作物多样性可以稳定国家产量的稳定性，农场数量的增加也可以稳定国家产量，但这些稳定作用在较小的国家较弱。我们的研究结果表明，在国家层面增强作物多样性可能并不能提供事实上的普遍战略来提高所有国家的产量稳定性，这对促进作物多样化以防止粮食系统冲击的国家战略具有影响。