Betula occidentalis Hook.
Water birch occurs as a deciduous shrub or small tree growing in riparian, wooded communities. Most of these sites have high water tables, and the shallow rooting of the trees on such sites regularly results in windfall. The species grows on a wide variety of soil textures and has high nutritional requirements. Water birch often occurs in dense stands, which provide good cover, forage and nesting opportunities for many wildlife species. Water birch is suitable for revegetating disturbed riparian sites and for stabilizing stream banks, due to its dense root system (Uchytil 1989).
Water birch has a very scattered distribution in the western half of North America. It is found from southern Alaska to southern Manitoba, North Dakota, southern California and New Mexico (Little 1979). It is absent along the Pacific Coastal mountain ranges. Even within British Columbia, its range is markedly scattered, the areas of high occurrence in our survey being clearly separated from each other by areas where it is completely absent.
Distribution and Protected Areas – from Hamann et.al. 2005
Conservation Status Summary – from Chourmouzis et.al. 2009
“Water birch occurs in many zones, but in low numbers. It is most common in the IDF zone. It is under-protected in several zones, but is identified as a species of concern and is recommended for verification only in the IDF and in the northern part of its range in the BWBS zone, where calculated protection levels are near zero.”
Water birch is wind pollinated and its small seeds are wind dispersed. The interval between good seed crops is typically two years (Banerjee et al. 2001). Due to its scattered and wide ranging distribution, populations may be physically isolated and genetically differentiated.
In eastern Washington, northeastern Oregon, western Idaho, and southern British Columbia, water birch hybridizes with paper birch (Betula papyrifera) producing many intermediate forms, which appear to be well established locally (Hitchcock and Cronquist 1964).
Resource management and seed transfer
No information available.