他们正在砍伐树木。

Tāmen zhèngzài kǎnfá shùmù.

They are cutting down trees.

砍伐导致生态失衡。

Kǎnfá dǎozhì shēngtài shīhéng.

Logging has led to ecological imbalance.

他参与了非法砍伐行动。

Tā cānyùle fēifǎ kǎnfá xíngdòng.

He participated in illegal logging activities.