Discovering a hidden ecological treasure: Biological soil crusts of Argentina

Biological soil crusts (biocrusts) are topsoil, diverse communities of micro- and macro-organisms that contribute to soil stability, fertility, nutrient cycling and water dynamics in drylands. Although the number of studies on the ecology and biology of biocrusts in Argentina has increased over the last two decades, works are still scarce compared to other parts of the world. Despite the surface area occupied by drylands in our territory (~ 75 %), which also present a remarkable bioclimatic and phytogeographic diversity, biocrusts are an ecological actor that remains poorly studied. Therefore, we find it valuable to review our current understanding of biocrusts in Argentina to identify knowledge gaps and establish future priority lines of research. Here, we synthesize what we know about biocrusts in Argentina, focusing on their taxonomic composition, biological interactions within the community, distribution patterns, responses to natural and human-induced stress factors, ecosystem multifunctionality and restoration techniques. We have identified several critical aspects of biocrust biology and ecology that should be prioritized in future works. For example, it is essential to advance taxonomic studies, incorporating molecular tools to accurately classify biocrust components, which will help us deepen our understanding of biological community interactions and allow us to improve the use of biocrusts in restoration of degraded soils. We also need to expand our understanding of how biocrusts respond to environmental factors across different spatial and temporal scales, to model their responses to future scenarios of global change. While biocrust restoration efforts are showing promising results, works are primarily focused on greenhouse or laboratory cultivation techniques, and all these efforts must be validated in the field. We consider that the diversity of Argentinean drylands offers a good natural laboratory for studying biocrusts and can serve as a model for testing hypotheses on their biology and ecology.