Boreal ForestsBoreal Forests Coniferous forests are mainly found in broad circumpolar belt across thenorthern hemisphere and on mountain ranges where low temperatures limitthe growing season to a few months each year - thus too unfavorable formost hardwoodsTaiga, SiberiaBoreal, Canadian Rockies, AlbertaBoreal Forests Average daily temperature of 10°C is found in fewer than 120 days andcold seasons last 6 months. Tundra will form at the northern edge whenthere are 30 days only of average daily temperature of 10°C and coldseason lasts up to 8 monthsTaiga, SiberiaBoreal, Canadian Rockies, AlbertaBoreal Forests The terms boreal and taiga are also used in more specialized sense -species diversity gradient from boreal to taiga to tundraBoreal Forests Extends from Alaska to New Foundland. Furthest north extension at69° in NW Canada. Extends from easternScandinavia across northernAsia to the Pacific Ocean.Furthest north extension at72° in Siberia.Boreal Forests The distribution of the biome (and thus individual species) is oftencalled circumboreal The placement of southerncontinents precludes borealformations in the southernhemisphereBoreal Forests Almost all the gymnosperms are evergreen, except Larix (larch)Deciduousforest!Boreal Forests The circumboreal biome is closely linked (vegetation and flora) totemperate montane forestsBoreal ForestsPonderosa pine,Mammoth, CABristlecone pine, GreatBasin Natl Park, Nevada The circumboreal biome is closely linked (vegetation and flora) totemperate montane forestsBoreal Forests Gymnosperm evergreen leaves areheavily protected by tannins, terpenes,and other acids Soil is 'spodosol' [podzol], heavily leached and acidic - infertile!Boreal Forests Soil is 'spodosol' [podzol], heavily leached and acidic - infertile! A horizon is largely leached and ash-colored due to quartz sand (fromglacial scouring)Boreal Forests Landscape is young due to Pleistoceneglacial activity which is reflected in poorlydrained water systems - forms complexinteractions of forests and various wetlandsof fens and bogsCanadian Shield fensBoreal Forests Boreal forests and fire are closely linkedNorthwest Territories, CanadaHiawatha Natl Forest,U.P. MichiganBoreal Forests Boreal forests and fire are closely linked - fire frequency is high!Fire history in North American borealforestsBoreal Forests Jack pine (serotinous cones), jack pine budworm, hymenopteran parasites,and fire - complex interactionsFairbanks, AlaskaBoreal Forests North American floristics: gymnosperms and few angiosperm hardwoodsBoreal Forests North American floristics: white spruce most widespread N Am treeBoreal Forests North American floristics: black spruce more specialized on poor soilBoreal Forests North American floristics: balsam firBoreal Forests North American floristics: lodgepole pineBoreal Forests North American floristics: jack pineBoreal Forests North American floristics: tamarack, larchBoreal Forests North American floristics: white cedar, arbor vitaeBoreal Forests North American floristics: white birch - widespread angiospermBoreal Forests North American floristics: trembling aspen - widespread angiospermBoreal Forests North American floristics: ferns diversePteridium aquilinum - bracken fernVaccinium vitis-idaea (Ericaceae) -mountain cranberryLinnaea borealis (Caprifoliaceae) -twin flowerBoreal Forests North American floristics: subshrubs - woody plants low to ground, oftenwith mycorrhizal relationships (e.g., Ericaceae)Maianthemum canadense - Canada mayflowerTrientalis borealis - starflowerBoreal Forests North American floristics: herbsLycopodium obscurum - ground pinePyrola (shinleaf)EricaceaeCorallorhiza (coral root)OrchidaceaeBoreal Forests North American floristics: mycorrhizal parasitesMonotropa (Indian-pipe)EricaceaeLarix decidua (larch)Picea abies (Norwayspruce)Boreal Forests Eurasian floristics: significantly less diverse, three dominant treesPinus sylvestris(Scot’s
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