While "forest" is a common term for a large area of trees, it doesn't specifically refer to the trees themselves as a group.
Here are some other options, depending on the specific type of trees and the context:
* Stand: A stand of trees refers to a specific group of trees, often of the same species, growing together.
* Copse: A copse is a small, dense group of trees, often used to describe a thicket or a grove of small trees.
* Wood: This term can be used to describe a small forest or a group of trees, often managed for timber.
Ultimately, the best collective noun for a forest of trees depends on the specific context and the desired tone.