title: Impacts of different climate change regimes and extreme climatic events on an alpine meadow community.
abstract: Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversity.
authors.affiliation: Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar.
authors.forename: Juha M
authors.initials: JM
authors.lastname: Alatalo
authors.affiliation: VTI, Swedish National Road and Transport Research Institute, Box 55685, 102 15 Stockholm, Sweden.
authors.forename: Annika K
authors.initials: AK
authors.lastname: Jägerbrand
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 461, SE-405 30 Gothenburg, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Molau
mesh_terms: D000220:Adaptation, Biological; D057231:Climate Change; D065948:Grassland; D063245:Plant Development