title: Phenological response of tundra plants to background climate variation tested using the International Tundra Experiment.
abstract: The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms.
authors.affiliation: Department of Biological Sciences, Florida International University, Miami, FL, USA. oberbaue@fiu.edu
authors.forename: S F
authors.initials: SF
authors.lastname: Oberbauer
authors.forename: S C
authors.initials: SC
authors.lastname: Elmendorf
authors.forename: T G
authors.initials: TG
authors.lastname: Troxler
authors.forename: R D
authors.initials: RD
authors.lastname: Hollister
authors.forename: A V
authors.initials: AV
authors.lastname: Rocha
authors.forename: M S
authors.initials: MS
authors.lastname: Bret-Harte
authors.forename: M A
authors.initials: MA
authors.lastname: Dawes
authors.forename: A M
authors.initials: AM
authors.lastname: Fosaa
authors.forename: G H R
authors.initials: GH
authors.lastname: Henry
authors.forename: T T
authors.initials: TT
authors.lastname: Høye
authors.forename: F C
authors.initials: FC
authors.lastname: Jarrad
authors.forename: I S
authors.initials: IS
authors.lastname: Jónsdóttir
authors.forename: K
authors.initials: K
authors.lastname: Klanderud
authors.forename: J A
authors.initials: JA
authors.lastname: Klein
authors.forename: U
authors.initials: U
authors.lastname: Molau
authors.forename: C
authors.initials: C
authors.lastname: Rixen
authors.forename: N M
authors.initials: NM
authors.lastname: Schmidt
authors.forename: G R
authors.initials: GR
authors.lastname: Shaver
authors.forename: R T
authors.initials: RT
authors.lastname: Slider
authors.forename: Ø
authors.initials: Ø
authors.lastname: Totland
authors.forename: C-H
authors.initials: CH
authors.lastname: Wahren
authors.forename: J M
authors.initials: JM
authors.lastname: Welker
mesh_terms: D001110:Arctic Regions; D057231:Climate Change; D017753:Ecosystem; D035264:Flowers / Q000254:growth & development; D038622:Internationality; D008954:Models, Biological; D063245:Plant Development; D018515:Plant Leaves; D010944:Plants / Q000145:classification*; D012621:Seasons; D013997:Time Factors
keywords: growth form; season length; snowmelt; thaw degree days