A global meta-analysis led by UNSW scientists shows tiny organisms that cover desert soils — so-called biocrusts — are critically important for supporting the world’s shrinking water supplies. Biocrusts are a rich assortment of mosses, lichens, cyanobacteria, and microscopic organisms such as bacteria and fungi that live on the surface of dryland soils. Drylands, collectively, are the world’s largest biome. “Biocrusts are critically important because they fix large amounts of nitrogen and carbon, stabilise surface soils, and provide a home for soil organisms,” said lead author Professor David Eldridge from UNSW Science.
For the study, the team assembled and then analysed the largest ever global database of evidence on the effects of biocrusts on water movement, storage and erosion, focussing on drylands. “Our emphasis was on dryland soils because biocrusts are often the dominant surface covering on these soils, particularly during dry times,” Prof. Eldridge said. A huge increase in the number of publications on biocrusts over the past decade had prompted the group to critically assess the links between water capture and storage, and landscape stability in drylands.
Importantly, the researchers showed that globally, the presence of biocrusts on the soil surface reduced water erosion by an average of 68%. Prof. Eldridge and his team have been studying the role of biocrusts on Australia’s soils for more than 30 years. The focus of the team’s research is on drylands because they occupy almost half of Earth’s land surface and support almost 40% of the global human population. “The results of this work will be incorporated into global water balance and soil loss models so that managers and governments have a better understanding of the implications of losing biocrusts on the world’s dwindling water supplies,” Prof. Eldridge said.
Source: Science Daily
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