The tree line is the edge of the habitat at which trees are capable of growing. Beyond the tree line, they are unable to grow because of inappropriate environmental conditions (usually cold temperatures or lack of moisture). Some distinguish additionally a deeper timberline or forest line, where trees form a forest with a closed canopy.
At the tree line, tree growth is often very stunted, with the last trees forming low, densely matted bushes. If it is caused by wind, it is known as krummholz formation, from the German for 'twisted wood'.
The tree line, like many other natural lines (lake boundaries, for example), appears well-defined from a distance, but upon sufficiently close inspection, it is a gradual transition in most places. Trees grow shorter towards the inhospitable climate until they simply stop growing.
Famous quotes containing the words tree and/or line:
“Every man is a potential genius until he does something.”
—Herbert Beerbohm, Sir Tree (1853–1917)
“I fear I agree with your friend in not liking all sermons. Some of them, one has to confess, are rubbish: but then I release my attention from the preacher, and go ahead in any line of thought he may have started: and his after-eloquence acts as a kind of accompaniment—like music while one is reading poetry, which often, to me, adds to the effect.”
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)