Trees grow at various locations throughout the map. Some islands have more trees than others.
A tree can be chopped down with an axe or a chipped stone (starting weapon/tool) to get wood which is used in many craftable and build items. The total amount of wood yielded depends on the size of the tree with bigger trees giving more wood than smaller ones.
Once chopped down the tree will appear as a stump and regrow after approximately 24 game hours.
Note: a falling tree does not damage the player.