Tree Thinning
Thinning, Periodic Thinning
noun, verbal noun
Fell trees in intervals, instead of all at once, and it's called tree thinning. That way there's still some forest there, but you get your wood to use for other things too.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
間伐を行うことで、残った木は幹が太く枝葉がしっかりとした健全な木に育ちます。
Periodic thinning of forests makes the rest of trees grow thick trunks and tough, healthy branches and leaves.