General terms:
* Forest: This is the most common and general term for a large area of trees.
* Woodland: This term suggests a more open and less dense area of trees than a forest.
* Grove: This term refers to a small, usually clustered group of trees.
* Thicket: This term refers to a dense, tangled growth of trees and shrubs.
* Stand: This term is often used for a specific grouping of trees, like a stand of pine trees.
More specific terms:
* Arbor: This term specifically refers to a collection of trees that have been planted for decoration or shade.
* Plantation: This term refers to a large area of trees that have been planted for commercial purposes, like lumber production.
The best collective noun to use will depend on the specific context and the type of trees in the area.