timberline

American  

[tim-ber-lahyn] / ˈtɪm bərˌlaɪn /

noun

1. the altitude above sea level at which timber ceases to grow.

2. the Arctic or Antarctic limit of tree growth.

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timberline British  

/ ˈtɪmbəˌlaɪn /

noun

1. the altitudinal or latitudinal limit of normal tree growth See also tree line

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timberline Scientific  

/ tĭm′bər-līn′ /

1. A geographic boundary beyond which trees cannot grow. On the Earth as a whole, the timberline is the northernmost or southernmost latitude at which trees can survive; in a mountainous region, it is the highest elevation at which trees can survive.

2. Also called tree line

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Etymology

Origin of timberline

An Americanism dating back to 1865–70; timber + line ¹

Explanation

The highest point on a mountain where trees can grow is known as a timberline. Above the timberline, it's much too cold and windy for anything but small, shrubby plants to stay alive. The timberline is sometimes called a "tree line" or "forest line." From far away, this point on a mountain can appear abrupt, but up close it's clear that as the altitude increases, the size and number of trees gradually decreases. Near the timberline, trees become stumpy and more shrub-like. In addition to lower temperatures and gusty winds, there is less air and moisture above the timberline — all factors that make it a hostile environment for trees.

Example Sentences

Found from the coast to the timberline, blueberries are in the same family as the huckleberry.

From Seattle Times • Jul. 1, 2023

Their marriage has “reached the timberline of their affection,” but they don’t notice yet.

From Washington Post • Jan. 27, 2015

Success rates with air bags seem to be higher in places where avalanches slide mostly above timberline, like Alaska and Europe.

From New York Times • Dec. 22, 2012

I’ve stood at timberline on a volcano that seems made of nothing but rubble and hydrothermally altered rock.

From Scientific American • Dec. 6, 2012

Squinting against the gray glare and against the cold and by now steady wind that made his eyes water, he searched the opposite timberline for the gunman, but could see nothing.

From "The Milagro Beanfield War" by John Nichols