title: Plant community responses to experimental warming across the tundra biome.
abstract: Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3 degrees C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.
authors.affiliation: Boreal Ecology Cooperative Research Unit, U.S. Department of Agriculture Forest Service Pacific Northwest Research Station, University of Alaska, P.O. Box 756780, Fairbanks, AK 99775-6780, USA.
authors.forename: Marilyn D
authors.initials: MD
authors.lastname: Walker
authors.forename: C Henrik
authors.initials: CH
authors.lastname: Wahren
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hollister
authors.forename: Greg H R
authors.initials: GH
authors.lastname: Henry
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Ahlquist
authors.forename: Juha M
authors.initials: JM
authors.lastname: Alatalo
authors.forename: M Syndonia
authors.initials: MS
authors.lastname: Bret-Harte
authors.forename: Monika P
authors.initials: MP
authors.lastname: Calef
authors.forename: Terry V
authors.initials: TV
authors.lastname: Callaghan
authors.forename: Amy B
authors.initials: AB
authors.lastname: Carroll
authors.forename: Howard E
authors.initials: HE
authors.lastname: Epstein
authors.forename: Ingibjörg S
authors.initials: IS
authors.lastname: Jónsdóttir
authors.forename: Julia A
authors.initials: JA
authors.lastname: Klein
authors.forename: Borgthór
authors.initials: B
authors.lastname: Magnússon
authors.forename: Ulf
authors.initials: U
authors.lastname: Molau
authors.forename: Steven F
authors.initials: SF
authors.lastname: Oberbauer
authors.forename: Steven P
authors.initials: SP
authors.lastname: Rewa
authors.forename: Clare H
authors.initials: CH
authors.lastname: Robinson
authors.forename: Gaius R
authors.initials: GR
authors.lastname: Shaver
authors.forename: Katharine N
authors.initials: KN
authors.lastname: Suding
authors.forename: Catharine C
authors.initials: CC
authors.lastname: Thompson
authors.forename: Anne
authors.initials: A
authors.lastname: Tolvanen
authors.forename: Ørjan
authors.initials: Ø
authors.lastname: Totland
authors.forename: P Lee
authors.initials: PL
authors.lastname: Turner
authors.forename: Craig E
authors.initials: CE
authors.lastname: Tweedie
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Webber
authors.forename: Philip A
authors.initials: PA
authors.lastname: Wookey
mesh_terms: D001110:Arctic Regions; D044822:Biodiversity; D018533:Biomass; D002980:Climate; D003247:Conservation of Natural Resources; D017753:Ecosystem; D004777:Environment; D004784:Environmental Monitoring; D014644:Genetic Variation; D017752:Greenhouse Effect; D006358:Hot Temperature; D008962:Models, Theoretical; D018521:Plant Physiological Phenomena; D010944:Plants / Q000378:metabolism*; D012984:Software; D013696:Temperature