The transition from forest to treeless tundra on a mountain slope is often a dramatic one.

从森林到山坡上没有树木的苔原的过渡通常会十分突然和明显。

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In the far north, it is tundra, which gives way to forest as you move southward.

最北面是苔原地区，接下来往南是森林带。

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The line between tundra and forest runs through this image.

冻土带与森林之间在照片上呈现出一条分界线。

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Then it was tundra, then birch forest, then pine forest, then alder, linden, elm and ash, then most recently oak, but beech was coming.

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The episode is known as the Younger Dryas, because in Scandinavia abundant pollen from a tundra flower called the mountain avens, Dryas octopetala, reappears in soil from this date, indicating that the forest had once more given way to tundra.

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And then move up into Ponderosa pines, then in upper elevations spruce and fir forest, and then finally to some sort of alpine tundra up at the top.

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