Habitat

Global change

Ecology

Biology

Agroforestry

Nutrient cycle

Precipitation

Archaeology

Earth science

Environmental change

Geology

Soil water

Oceanography

Biosphere model

Greenhouse gas

Climate change

Land use, land-use change and forestry

Geography

Biological soil crust

Terrestrial ecosystem

Environmental science

Soil science

Land use

Cycling

Lichen

Meteorology

Endangered species

Biosphere

Ecosystem

Nature Geoscience

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. Biocrust coverage of soils could decrease by 25–40% within 65 years, due to climate and land-use changes. Biocrusts, such as lichens and algae, cover 12% of Earth’s land surface but environmental modelling suggests that they are vulnerable to change.

Dryland photoautotrophic soil surface communities endangered by global change