thin-out

The barber thinned out his customer's thick hair.

理发师把顾客的浓密头发削薄了些。

Towards the city limits the houses begin to thin out.

靠近城市尽头的地方房屋渐渐稀少起来。

They thinned out a stand to create a lush forest tomorrow.

他们去了林场中多余的树木, 以利来日森林长得更茂密。