What is the tree line?

(Image credit: Nathan Anderson)

Question from Ahmed Ali

The tree line is the highest point in a habitat where trees can grow. The low temperatures and dry conditions at high altitude make it difficult for seeds to germinate, and young trees can struggle to take hold. Wind and snow can snap their fragile branches, and cold conditions can make photosynthesis more difficult. 

The exact altitude of the tree line varies depending on the habitat, but they are easy to spot. The trees quickly start to become thin on the ground and then disappear altogether.

Answered by Laura Mears for Brain Dump in How It Works issue 123.

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