title: Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands.
abstract: Drylands occur worldwide and are particularly vulnerable to climate change because dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability and change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation. Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change-induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, that is, leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water-limited ecosystems.
authors.affiliation: Institute of Biology, Biodiversity and Ecological Modeling, Freie Universität Berlin, Altensteinstr. 34, D-14195, Berlin, Germany.|Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), D-14195, Berlin, Germany.
authors.forename: Britta
authors.identifier: 0000-0003-4767-6406
authors.initials: B
authors.lastname: Tietjen
authors.affiliation: Department of Botany, University of Wyoming, Laramie, WY, 82071, USA.|Section of Conservation Biology, Department of Environmental Sciences, University of Basel, 4056, Basel, Switzerland.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Schlaepfer
authors.affiliation: US Geological Survey, Southwest Biological Science Center, Flagstaff, AZ, 86004, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Bradford
authors.affiliation: Department of Botany, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: William K
authors.initials: WK
authors.lastname: Lauenroth
authors.affiliation: Center for Sustaining Agriculture and Natural Resources, Washington State University, Wenatchee, WA, 98801, USA.|SAH Ecologia LLC, Wenatchee, WA, 98801, USA.
authors.forename: Sonia A
authors.initials: SA
authors.lastname: Hall
authors.affiliation: US Geological Survey, Southwest Biological Science Center, Moab, UT, 84532, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Duniway
authors.affiliation: School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Tamara
authors.initials: T
authors.lastname: Hochstrasser
authors.affiliation: CAS Institute of Atmospheric Physics, Beijing, 100029, China.
authors.forename: Gensuo
authors.initials: G
authors.lastname: Jia
authors.affiliation: US Geological Survey, Southwest Biological Science Center, Flagstaff, AZ, 86004, USA.
authors.forename: Seth M
authors.initials: SM
authors.lastname: Munson
authors.affiliation: US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, 97331, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Pyke
authors.affiliation: Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada.|Department of Ecology and Environmental Science, Climate Impacts Research Centre, Umeå University, 981 07, Abisko, Sweden.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Wilson
mesh_terms: D057231:Climate Change; D055864:Droughts; D004463:Ecology; D017753:Ecosystem; D011891:Rain; D012987:Soil / Q000737:chemistry; D014867:Water
chemical_list: D012987:Soil; D014867:Water
keywords: direct and indirect effects; drought risk; ecohydrological model; shrub encroachment; soil water availability; vegetation impacts