Arctic Moor Birch - Betula pubescens subspecies tortuosa
The Arctic Moor Birch occurs as a shrub or small tree, to 20 feet. It is native to Iceland, Greenland, Scandinavia and Northern Europe.
Also commonly called "Mountain Birch", this tree extends farther into the arctic than any other broadleaf tree.
Trees - Table of Contents
 
Leaves and Catkins

The Arctic Moor Birch is a shrub or small tree, growing to 20 feet. It is native to Greenland, Scandinavia and protected inland valleys of Northern Europe. It is usually multi-trunked, with often interlacing, ascending branches. Twigs have numerous small resin glands. Leaf blade is ovate, rhombic-ovate, or suborbiculate-rhombic, 1-2 inches long, base cuneate to truncate, margins coarsely serrate or dentate, apex acute; surfaces abaxially moderately pubescent. Infructescences 1/2 inch; scales pubescent to glabrous, often ciliate, central lobe oblong or narrowly triangular, apex acute to obtuse, lateral lobes divergent and ascending, about equal in length but somewhat broader. Samaras with wings about equal in diameter to body, broadest near summit, usually extended beyond body apically.


 

Animals dependant on Birch
  • Moose: Important browse throughout most of range. Nutritional quality is poor in winter, but is important to wintering moose because of its sheer abundance in young stands.
  • White-tailed Deer: though considered a "secondary-choice food", it is an important dietary component. In Minnesota, white-tailed deer eat considerable amounts of birch leaves in the fall.
  • Snowshoe hare browse birch seedlings and saplings.
  • Porcupines feed on the inner bark
  • Beaver also eat it though generally prefer aspen, while willow and paper birch are second choice foods.
  • Voles and shrews eat the seeds.
  • Numerous birds and small mammals eat paper birch buds, catkins and seeds.
  • Young paper birch stands provide prime deer and moose cover.

Birds:

  • Numerous cavity-nesting birds nest in birch, including woodpeckers, chickadees, nuthatches, and swallows.
  • A favorite feeding tree of yellow-bellied sapsuckers, which peck holes in the bark to feed on the sap. Hummingbirds and red squirrels also feed at sap wells in paper birch created by sapsuckers.
  • Ruffed grouse eat the catkins and buds.
  • Redpolls, siskins, and chickadees obtain a considerable portion of their annual diet from birch seeds
 
 


 

Abstract - (excerpt from The Journal of Vegetation Science)
The tree limit of Betula pubescens ssp. tortuosa (mountain birch) in the southern Swedish Scandes was monitored during 1972-1992. The study included various aspects of growth, vigour and reproduction of Betula. The main focus was on the character and mechanics of the tree limit/climate equilibrium system. The tree limit, which changed in response to a temperature rise early this century, remained constant in position and tree physiognomy did not change, although the past 50 yr or so have been colder. Indeed, growth and reproductive effort and capacity decreased in this period. Obviously, most resources in Betula were used to resist stress in the mature phase, resulting in delayed recession of trees. Unless drastic warming occurs, stem dieback is predicted for the near future. Even a minorclimatic disturbance would have an effect, because resources are gradually being depleted. Radial growth correlated most closely with the mean temperature in July. Particularly at the present-day tree limit, the variance in annual growth could be largely explained by climatic factors. The hypothesis is that long-term tree limit dynamics during the late Holocene is merely a matter of fluctuations in vegetative vigour and stature of old individuals. At the population level, response to climatic variability appears to be greatly delayed.
 

 
 

              
 
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