Photoautotrophic surface communities forming biological soil crusts (biocrusts) are crucial for soil stability as well as water, nutrient and trace gas cycling at regional and global scales. Quantitative information on their global coverage and the environmental factors driving their distribution patterns, however, are not readily available. We use observations and environmental modelling to estimate the global distribution of biocrusts and their response to global change using future projected scenarios. We find that biocrusts currently covering approximately 12% of Earth’s terrestrial surface will decrease by about 25–40% within 65 years due to anthropogenically caused climate change and land-use intensification, responding far more drastically than vascular plants. Our results illustrate that current biocrust occurrence is mainly driven by a combination of precipitation, temperature and land management, and future changes are expected to be affected by land-use and climate change in similar proportion. The predicted loss of biocrusts may substantially reduce the microbial contribution to nitrogen cycling and enhance the emissions of soil dust, which affects the functioning of ecosystems as well as human health and should be considered in the modelling, mitigation and management of global change.

形成生物土壤结皮（生物结皮）的自养表面群落对于土壤稳定性以及区域和全球规模的水，养分和微量气体循环至关重要。然而，关于它们的全球覆盖范围和驱动其分布方式的环境因素的定量信息尚不容易获得。我们使用观察和环境模型来估计生物结皮的全球分布，并使用未来的预测方案对生物结皮对全球变化的响应进行估算。我们发现，由于人为原因引起的气候变化和土地利用集约化，目前覆盖地球约12％地表的生物结皮在65年内将减少约25-40％，其响应远比维管植物大得多。我们的结果表明，当前生物结皮的发生主要是受降水，温度和土地管理的共同驱动，并且未来的变化预计将以相似的比例受到土地利用和气候变化的影响。预计的生物结皮损失可能会大大减少微生物对氮循环的影响并增加土壤粉尘的排放，这会影响生态系统的功能以及人类健康，应在全球变化的建模，缓解和管理中加以考虑。