Ecology: Biocrusts buffer drought

New Phytol. http://doi.org/8c4 (2015)

Biocrusts, comprised of mosses, lichens and cyanobacteria, are common constituents of dryland ecosystems worldwide. An analysis spanning three continents suggests that the conservation of these communities will be key to the maintenance of functional dryland ecosystems under climate change.

Manuel Delgado-Baquerizo and colleagues assessed the ability of moss-dominated biocrusts to regulate soil nutrient and carbon cycling across aridity gradients in the US, Spain and Australia, using measurements of soil carbon, nitrogen and phosphorus levels, together with microbial extracellular enzyme activities. Soils underlying biocrust canopies had greater multifunctionality, that is they stored and cycled more carbon and nutrients, than bare soils in arid and semi-arid regions, but not in more-humid regions. As a result the beneficial effects of biocrusts on soil multifunctionality increased with aridity. Structural equation modelling suggests that the rise in the beneficial effects of biocrusts with aridity can be attributed to an increase in soil microbial abundance, and a reduction in plant cover.

The researchers suggest that biocrusts could prove crucial to the sustainability of dryland ecosystems, which are projected to become increasingly arid over the coming century.