Botanizing in Alaska: Dwarf Birch

I found this tree trunk on a rocky outcrop at the top of a mountain just outside Fairbanks, Alaska. The wood was spread over a foot or so, though I didn't have a measuring-tape handy to get a precise measure. The cold and exposed environment suggests that the tree would have grown very slowly and may be anywhere from decades to hundreds of years old.

In this environment, strong winter winds quickly abrade away overly-exposed living material. Dead material doesn't last very long either. Yet this tree remains alive, with vital growth attached to the dead wood at the lower-right and upper-left.

It was only by comparing the above tree to something more youthful (at right) that I was able to identify it as the Dwarf Birch (Betula nana). Forests of this tree can be ancient, but only inches tall.


References:

• https://en.wikipedia.org/wiki/Betula_nana
• http://www.fs.fed.us/database/feis/plants/shrub/betnan/all.html
• http://plants.usda.gov/core/profile?symbol=BENA