title: Bacteria increase arid-land soil surface temperature through the production of sunscreens.
abstract: Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming has apparent and immediate consequences for the soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. These results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales.
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Estelle
authors.initials: E
authors.lastname: Couradeau
authors.affiliation: Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Ulas
authors.initials: U
authors.lastname: Karaoz
authors.affiliation: Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Hsiao Chien
authors.initials: HC
authors.lastname: Lim
authors.affiliation: Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Ulisses
authors.initials: U
authors.lastname: Nunes da Rocha
authors.affiliation: Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Trent
authors.initials: T
authors.lastname: Northen
authors.affiliation: Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA.
authors.forename: Eoin
authors.initials: E
authors.lastname: Brodie
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA.|Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Ferran
authors.initials: F
authors.lastname: Garcia-Pichel
mesh_terms: D001419:Bacteria; D000458:Cyanobacteria / Q000502:physiology; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013696:Temperature
chemical_list: D012987:Soil