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:
“If you believe in the soul, do not clutch at sensual sweetness before it is ripe on the slow tree of cause and effect.”
—Ralph Waldo Emerson (1803–1882)
“A route differs from a road not only because it is solely intended for vehicles, but also because it is merely a line that connects one point with another. A route has no meaning in itself; its meaning derives entirely from the two points that it connects. A road is a tribute to space. Every stretch of road has meaning in itself and invites us to stop. A route is the triumphant devaluation of space, which thanks to it has been reduced to a mere obstacle to human movement and a waste of time.”
—Milan Kundera (b. 1929)