title: Plants reverse warming effect on ecosystem water balance.
abstract: Models predict that global warming may increase aridity in water-limited ecosystems by accelerating evapotranspiration. We show that interactions between warming and the dominant biota in a grassland ecosystem produced the reverse effect. In a 2-year field experiment, simulated warming increased spring soil moisture by 5-10% under both ambient and elevated CO2. Warming also accelerated the decline of canopy greenness (normalized difference vegetation index) each spring by 11-17% by inducing earlier plant senescence. Lower transpirational water losses resulting from this earlier senescence provide a mechanism for the unexpected rise in soil moisture. Our findings illustrate the potential for organism-environment interactions to modify the direction as well as the magnitude of global change effects on ecosystem functioning.
authors.affiliation: Department of Biological Sciences and Jasper Ridge Biological Preserve, Stanford University, Stanford, CA 94305, USA. zavaleta@ucsc.edu
authors.forename: Erika S
authors.initials: ES
authors.lastname: Zavaleta
authors.forename: Brian D
authors.initials: BD
authors.lastname: Thomas
authors.forename: Nona R
authors.initials: NR
authors.lastname: Chiariello
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Asner
authors.forename: M Rebecca
authors.initials: MR
authors.lastname: Shaw
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Field
mesh_terms: D002245:Carbon Dioxide; D017753:Ecosystem; D017752:Greenhouse Effect; D010944:Plants / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D013696:Temperature; D014867:Water / Q000032:analysis / Q000378:metabolism; D014881:Water Supply
chemical_list: D012987:Soil; D014867:Water; D002245:Carbon Dioxide