title: Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome.
abstract: According to some treatises, arctic and alpine sub-biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long-standing and far-reaching problem. We studied broad-scale patterns in climate and vegetation along the gradient from Siberian tundra via northernmost Fennoscandia to the alpine habitats of European middle-latitude mountains, as well as explored those patterns within Fennoscandian tundra based on climate-vegetation patterns obtained from a fine-scale vegetation map. Our analyses reveal that ecologically meaningful January-February snow and thermal conditions differ between different types of tundra. High precipitation and mild winter temperatures prevail on middle-latitude mountains, low precipitation and usually cold winters prevail on high-latitude tundra, and Scandinavian mountains show intermediate conditions. Similarly, heath-like plant communities differ clearly between middle latitude mountains (alpine) and high-latitude tundra vegetation, including its altitudinal extension on Scandinavian mountains. Conversely, high abundance of snowbeds and large differences in the composition of dwarf shrub heaths distinguish the Scandinavian mountain tundra from its counterparts in Russia and the north Fennoscandian inland. The European tundra areas fall into three ecologically rather homogeneous categories: the arctic tundra, the oroarctic tundra of northern heights and mountains, and the genuinely alpine tundra of middle-latitude mountains. Attempts to divide the tundra into two sub-biomes have resulted in major discrepancies and confusions, as the oroarctic areas are included in the arctic tundra in some biogeographic maps and in the alpine tundra in others. Our analyses based on climate and vegetation criteria thus seem to resolve the long-standing biome delimitation problem, help in consistent characterization of research sites, and create a basis for further biogeographic and ecological research in global tundra environments.
authors.affiliation: Department of Ecology University of Oulu FI-90014 Oulu Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Virtanen
authors.affiliation: Department of Arctic and Marine Biology University of Tromsø - The Arctic University of Norway Campus Alta NO-9509 Alta Norway; Section of Ecology Department of Biology University of Turku FI-20014 Turku Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Oksanen
authors.affiliation: Department of Arctic and Marine Biology University of Tromsø - The Arctic University of Norway Campus Alta NO-9509 Alta Norway; Section of Ecology Department of Biology University of Turku FI-20014 Turku Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Oksanen
authors.affiliation: Finnish Meteorological Institute PL 503 00101 Helsinki Finland.
authors.forename: Juval
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Arctic Centre University of Lapland P.O. Box 122 FI-96101 Rovaniemi Finland.
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Forbes
authors.affiliation: Northern Research Institute Box 6434, Forskningsparken NO-9294 Tromsø Norway.
authors.forename: Bernt
authors.initials: B
authors.lastname: Johansen
authors.affiliation: Department of Geography and Geology Division of Geography University of Turku FI-20014 Turku Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Käyhkö
authors.affiliation: Department of Ecology and Environmental Science Umeå University SE-901 87 Umeå Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Olofsson
authors.affiliation: Finnish Meteorological Institute PL 503 00101 Helsinki Finland.
authors.forename: Jouni
authors.initials: J
authors.lastname: Pulliainen
authors.affiliation: The Norwegian Institute for Nature Research (NINA) Framsenteret NO-9296 Tromsø Norway.
authors.forename: Hans
authors.initials: H
authors.lastname: Tømmervik
keywords: Alpine; arctic; biome delimitation; ecoregion; mountains; tundra ecosystems; vegetation pattern; winter climate
references.citation: Tree Physiol. 1999 Sep;19(11):725-732
references.pmid: 12651311
references.citation: New Phytol. 2013 Nov;200(3):898-910
references.pmid: 23869846
references.citation: Oecologia. 2005 Sep;145(2):288-97
references.pmid: 15959819
references.citation: Ann Bot. 2014 Jul;114(1):1-16
references.pmid: 24793697
references.citation: New Phytol. 1989 Nov;113(3):377-389
references.pmid: 33874201
references.citation: Ambio. 2006 Jun;35(4):190-7
references.pmid: 16944644