title: Climatic warming strengthens a positive feedback between alpine shrubs and fire.
abstract: Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems.
authors.affiliation: The Centre of Excellence for Environmental Decisions, School of BioSciences, The University of Melbourne, Parkville, Vic., 3010, Australia.|Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., 3086, Australia.
authors.forename: James S
authors.identifier: 0000-0003-4785-0742
authors.initials: JS
authors.lastname: Camac
authors.affiliation: Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., 3086, Australia.|Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, 0909, Australia.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Williams
authors.affiliation: Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., 3086, Australia.
authors.forename: Carl-Henrik
authors.initials: CH
authors.lastname: Wahren
authors.affiliation: Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., 3086, Australia.|Bio21 Institute, School of BioSciences, The University of Melbourne, Melbourne, Vic., 3010, Australia.
authors.forename: Ary A
authors.initials: AA
authors.lastname: Hoffmann
authors.affiliation: The Centre of Excellence for Environmental Decisions, School of BioSciences, The University of Melbourne, Parkville, Vic., 3010, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Vesk
mesh_terms: D001110:Arctic Regions; D001315:Australia; D057231:Climate Change; D017753:Ecosystem; D005390:Fires; D065929:Tundra
keywords: Bayesian models; biotic interactions; gap dynamics; growth; mortality; recruitment