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

State Parks and Recreation Director Cody Schulz said the campground will be built on former agricultural land on the gorge’s timberline.

From Seattle Times • May 22, 2023

The portrait of Sessions is of a man for whom merely ordering lunch seems to be above the timberline of his intellect and curiosity.

From New York Times • Feb. 16, 2019

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

From Washington Post • Jan. 27, 2015

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

I walked in the direction from which we had come, and when I reached the timberline, I collected wood broken from the cherry tree, the peony, and the walnut, which is the tree of life.

From "The Woman Warrior" by Maxine Hong Kingston