Biocrust research in North America with a focus on drylands: history, insights and opportunities

Abstract The last half of the previous century has seen an explosion in publications on biocrusts, communities of eukaryotic and prokaryotic organisms inhabiting the uppermost surface of predominantly dryland soils. Much of the early work emanated from the western United States, yet there have been few attempts to document the breadth of this work and its contribution to our understanding of the ecosystem roles of biocrusts. We used a structured literature search to extract the 868 publications on biocrusts published between January 1900 and July 2024, and explored the trends in publications in 12 subject areas over that time. We found that almost half of the 868 publications focussed on the ecological and physiological effects of biocrusts and that more recent research explored emerging fields such as restoration, monitoring and climate change impacts. Five authors comprised about 10% of all authors on these publications, and 5.5% of publications had 10 or more authors. The number of authors per publication tended to increase over time. We identified three main periods of research ranging from basic ecology and exploration of ecological mechanisms pre-2000 to biocrust function, physiology and climatic drivers up to 2020. The post-2020 period was characterized by a greater emphasis on molecular approaches, restoration and climate change impacts. Our literature review identifies knowledge gaps associated with the need for more trained taxonomists, and greater education on biocrust ecology and function. Potential developments in biocrust research include a greater use and recognition of biocrust species traits, the establishment of a dedicated international biocrust society, and the development of a global research and monitoring network to coordinate methods and provide a framework to answer critical knowledge gaps.