caa a22 4500 605517290 CHVBK 20210128100719.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s10533-015-0163-7 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0163-7 Observations of net soil exchange of CO2 in a dryland show experimental warming increases carbon losses in biocrust soils [Elektronische Daten] [Anthony Darrouzet-Nardi, Sasha Reed, Edmund Grote, Jayne Belnap] Many arid and semiarid ecosystems have soils covered with well-developed biological soil crust communities (biocrusts) made up of mosses, lichens, cyanobacteria, and heterotrophs living at the soil surface. These communities are a fundamental component of dryland ecosystems, and are critical to dryland carbon (C) cycling. To examine the effects of warming temperatures on soil C balance in a dryland ecosystem, we used infrared heaters to warm biocrust-dominated soils to 2°C above control conditions at a field site on the Colorado Plateau, USA. We monitored net soil exchange (NSE) of CO2 every hour for 21months using automated flux chambers (5 control and 5 warmed chambers), which included the CO2 fluxes of the biocrusts and the soil beneath them. We observed measurable photosynthesis in biocrust soils on 12% of measurement days, which correlated well with precipitation events and soil wet-up. These days included several snow events, providing what we believe to be the first evidence of substantial photosynthesis underneath snow by biocrust organisms in drylands. Overall, biocrust soils in both control and warmed plots were net CO2 sources to the atmosphere, with control plots losing 62±8g C m−2 (mean±SE) over the first year of measurement and warmed plots losing 74±9g C m−2. Between control and warmed plots, the difference in soil C loss was uncertain over the course of the entire year due to large and variable rates in spring, but on days during which soils were wet and crusts were actively photosynthesizing, biocrusts that were warmed by 2°C had a substantially more negative C balance (i.e., biocrust soils took up less C and/or lost more C in warmed plots). Taken together, our data suggest a substantial risk of increased C loss from biocrust soils with higher future temperatures, and highlight a robust capacity to predict CO2 exchange in biocrust soils using easily measured environmental parameters. US Government, 2015 Autochamber nationallicence Biological soil crusts nationallicence Castle valley nationallicence Utah nationallicence Soil respiration nationallicence Gap filling nationallicence Global climate change nationallicence Net soil exchange nationallicence NSE nationallicence Net ecosystem exchange nationallicence NEE nationallicence Darrouzet-Nardi Anthony U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut Reed Sasha U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut Grote Edmund U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut Belnap Jayne U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut Biogeochemistry Springer International Publishing 126/3(2015-12-01), 363-378 0168-2563 126:3<363 2015 126 10533 https://doi.org/10.1007/s10533-015-0163-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0163-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Darrouzet-Nardi Anthony U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut NATIONALLICENCE 700 1- Reed Sasha U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut NATIONALLICENCE 700 1- Grote Edmund U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut NATIONALLICENCE 700 1- Belnap Jayne U.S. Geological Survey, Southwest Biological Science Center, 84532, Moab, UT, USA aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 126/3(2015-12-01), 363-378 0168-2563 126:3<363 2015 126 10533