This rapid zone of transition is called the upper timberline or tree line.

这种快速的过渡地带被称为“上树带线”或“林木线”。

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Above the tree line there is a zone that is generally called alpine tundra.

林木线上方有一个区域，通常被称为高山苔原。

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Even in dense forest, you should be able to spot gaps in the tree line due to roads, train tracks, and other paths people carve through the woods.

即便身处茂密的森林之中，你也应该能够发现人们在树林中开辟道路、铁轨和其他小路而形成的林木线缺口。

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Roger, Strong-arm!Be advised we have incoming from the tree line at point blue plus two!A.K. s and rockets!

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"You see the river is a tree line, and all this is basically fresh-water marsh."

VOA: standard.2010.05.09

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The company is working on restarting them, and he said the focus right now is making line and tree crews available to towns that have requested them.

WSJ: Millions Without Power in New York, New Jersey and Connecticut After Storm

At the edge of his tree line is a forbidding 4-foot hole in the ground.

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