Biocrusts cover ~30% of global drylands with a prominent role in the biogeochemical cycles. Theoretically, biocrusts, vascular plants, and bare soil can represent multiple stable states in drylands. However, no empirical evidence for the existence of a biocrust stable state has been reported. Here, using a global drylands dataset, we found that biocrusts form an alternative stable state (biocrust cover, ~80%; vascular cover, ≤10%) besides bare soil (both biocrust and vascular cover, ≤10%) and vascular plants (vascular cover, >50%; biocrust cover, ~5%). The pattern of multiple stable states associated with biocrusts differs from the classic fold bifurcation, and values of the aridity index in the range of 0 to 0.6 define a bistable region where multiple stable states coexist. This study empirically demonstrates the existence and thresholds of multiple stable states associated with biocrusts along climatic gradients and thus may greatly contribute to conservation and restoration of global drylands.

生物结皮覆盖约 30% 的全球旱地，在生物地球化学循环中发挥着重要作用。从理论上讲，生物结皮、维管植物和裸土可以代表旱地的多种稳定状态。然而，没有关于生物结壳稳定状态存在的经验证据的报道。在这里，使用全球旱地数据集，我们发现除了裸土（生物结皮和维管盖覆盖，≤10%）和维管植物（血管覆盖，>50%；生物结皮覆盖，~5%）。与生物结皮相关的多个稳定状态的模式不同于经典的折叠分岔，干燥指数在 0 到 0.6 范围内的值定义了多个稳定状态共存的双稳态区域。