How might the making of moai have led to the collapse of the forests on easter island?

The Islanders cut down trees to transport the moai. Easter Island was settled by Polynesians between A.D. 800 and 1200. Some facts indicate that the island might have had human inhabitants as early at A.D. 400. When Europeans arrived in 1722, the native population was dying off. Evidence indicates, however, that the inhabitants once had a large, thriving civilization. Archaeological research provides evidence of ancient forests that disappeared and a society that collapsed.

Ithink it is 4. making colonies.