Paper birch (Ep) - Betula papyrifera
Paper birch is a medium-sized (<40 m tall), deciduous broad-leaved tree, at maturity with a narrowly oval, open crown, ascending branches, slender, often curved, stem, and papery bark, with irregular, rough sections. Its wood is used for veneer, pulp, and many specialty products. It is an important browse tree — its seed, buds, and bark are eaten by wildlife.
|Geographic Range||Geographic element:
North American transcontinental-incomplete
Distribution in Western North America:
(north and central) in the Pacific region; north, central, and (south) in the Cordilleran region
montane boreal - cool temperate - (cool mesothermal)
submontane - montane
Occurrence in biogeoclimatic zones:
(MS), BWBS, SBS, (SBPS), (PP), IDF, ICH, (CDF), (CWH)
Range of soil moisture regimes:
(very dry) - moderately dry - slightly dry - fresh - moist - very moist - (wet)
Range of soil nutrient regimes:
poor - medium - rich - very rich
Paper birch litter contributes to the nutrient status of forest floor by increasing its calcium, magnesium, potassium, phosphorus, and boron concentration, and reducing its aluminum, iron, manganese, and zinc concentration. The presence of birch in coniferous stands will increase decomposition and mineralization rates, thus altering humus form. The shift in humus form from Mors to Mormoders or even Moders results in increased levels of plant-available soil nutrients. This improvement may extend into the top 3 cm of mineral soil.
|Root System Characteristics||Paper birch is generally a shallow-rooted species. The bulk of the roots are in the top 60 cm; tap roots do not develop. Roots are associated with ecto and endo-mycorrhizae.|
|Associated tree species and successional role||In British Columbia, paper birch grows in even-aged, pure stands or mixed with shade-tolerant conifers mainly in second-growth stands. It may be a pioneer (primary succession) on fragmental sites (talus) and is present in early and intermediate (infrequently in late seral) stages of secondary succession on floodplains and upland sites; a minor component in old-growth stands on some montane boreal sites. Paper birch may invade gaps created by windthrow of climax tree species, such as white spruce and hybrid spruce on floodplains, and retain a long-term presence.|
|Genetics||Paper birch has a large, very plastic gene pool. Six varieties are recognized, and hybridization with almost every other native species in the genus is very common.|
|Notes||Paper birch produces moderately high yields of wood in a relatively short time (60 to 80 years) compared to boreal conifers. Considering its productivity, easy regeneration, and low risk of being affected by damaging agents, it is a suitable species for intensive management on some boreal sites. Considering its wildlife and aesthetic values and soil improvement capacity, it is a useful short-term or even a long-term admixture in coniferous stands [e.g., white spruce or hybrid (interior) spruce] throughout the BWBS and SBS zones. More detailed silvics information is given by:
Safford, L.O., J.C. Bjorkbom, and J.C. Zasada. 1990. Betula papyrifera. Pp. 158-171 in R.M. Burns and B.H. Honkala (technical coordinators) Silvics of North America, Vol 2. Agri. Handbook 654, USDA For. Serv., Washington, D.C.