Changes in biocrust cover drive carbon cycle responses to climate change in drylands

13 páginas.- 5 figuras.- referencias.- Este artículo tiene una corrección en 2014 http://hdl.handle.net/10.1111/gcb.12659

Dryland ecosystems account for ca. 27% of global soil organic carbon (C) reserves, yet it is largely unknown how climate change will impact C cycling and storage in these areas. In drylands, soil C concentrates at the surface, making it particularly sensitive to the activity of organisms inhabiting the soil uppermost levels, such as communities dominated by lichens, mosses, bacteria and fungi (biocrusts). We conducted a full factorial warming and rainfall exclusion experiment at two semiarid sites in Spain to show how an average increase of air temperature of 2–3 °C promoted a drastic reduction in biocrust cover (ca. 44% in 4 years). Warming significantly increased soil CO2 efflux, and reduced soil net CO2 uptake, in biocrust-dominated microsites. Losses of biocrust cover with warming through time were paralleled by increases in recalcitrant C sources, such as aromatic compounds, and in the abundance of fungi relative to bacteria. The dramatic reduction in biocrust cover with warming will lessen the capacity of drylands to sequester atmospheric CO2. This decrease may act synergistically with other warming-induced effects, such as the increase in soil CO2 efflux and the changes in microbial communities to alter C cycling in drylands, and to reduce soil C stocks in the mid to long term.

This researchwas funded by the European Research Council under the European Community’s Seventh Framework Programme(FP7/2007-2013)/ERC Grant agreement 242658 (BIOCOM), by the Spanish Ministry of Economy and Competitiveness (pro-jects CGL2007-63258/BOS and CGL2010-21381/BOS), and by the Junta de Andalucía (COSTRAS project, RNM-3614). C. E.and M.L.G. were supported by graduate fellowships from the British Ecological Society (Studentship 231/1975) and the Spanish National Research Council (CSIC, JAE-Pre 029 Grant),respectively. We would like to thank IMIDRA and Lindy Walsh for allowing us working in their properties, as well asto the Junta de Andalucia for allowing us to work in the Paraje Natural Karst en Yesos de Sorbas

Peer reviewed