title: Warming-induced upslope advance of subalpine forest is severely limited by geomorphic processes.
abstract: Forests are expected to expand into alpine areas because of climate warming, causing land-cover change and fragmentation of alpine habitats. However, this expansion will only occur if the present upper treeline is limited by low-growing season temperatures that reduce plant growth. This temperature limitation has not been quantified at a landscape scale. Here, we show that temperature alone cannot realistically explain high-elevation tree cover over a >100-km(2) area in the Canadian Rockies and that geologic/geomorphic processes are fundamental to understanding the heterogeneous landscape distribution of trees. Furthermore, upslope tree advance in a warmer scenario will be severely limited by availability of sites with adequate geomorphic/topographic characteristics. Our results imply that landscape-to-regional scale projections of warming-induced, high-elevation forest advance into alpine areas should not be based solely on temperature-sensitive, site-specific upper-treeline studies but also on geomorphic processes that control tree occurrence at long (centuries/millennia) timescales.
authors.affiliation: Long-term Ecology Laboratory, Biodiversity Institute, Oxford Martin School, Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom. marc.maciasfauria@zoo.ox.ac.uk
authors.forename: Marc
authors.initials: M
authors.lastname: Macias-Fauria
authors.forename: Edward A
authors.initials: EA
authors.lastname: Johnson
mesh_terms: D002170:Canada; D002980:Climate; D057231:Climate Change; D004463:Ecology; D017753:Ecosystem; D005843:Geography; D005844:Geology; D008962:Models, Theoretical; D012621:Seasons; D013696:Temperature; D014197:Trees / Q000254:growth & development*
keywords: biogeoscience; climate change; forest ecology; niche modeling; remote sensing