Artists are often clever painters able to bring emotion from their own mind and into the minds and hearts of others. Their specialty could be fear and menace, or it could be a sense of calm and harmony. Painting a forest as part of the story they are telling is where much of the underlying emotional content may be coming from, and it all depends upon how they represent the trees and underbrush in the background. It can make people shiver or relax, and a true professional can feel good about their work when they see the reactions of others.
For those who do not paint for a living, it could seem almost impossible to choose one section of a painting to hold that much emotion for the viewer, yet it can be the perfect way to convey emotional content. For paintings where fear is part of what is being shown, trees that lean in a menacing manner towards a viewer can be interpreted subconsciously as menacing. Dark leaves, pale trunks, and even a few glimpses of clouds in the treetops can all work together to produce just the right atmosphere.
A single branch or root in the path of the subject of the painting can be used to show feeling. If a person is depicted running down a forest path, the viewer knows they may be snagged by that low branch, or they could see the person tripping over a root conveniently placed. All of these add to the emotional content of a painting. Even if the person in the painting is shown as happy and relaxed, the thought of their next step being dangerous can change how the viewer interprets the painting.
Not all paintings with forests are dark and frightening, and some of them show the beauty, harmony, and the happiness people may feel when they are in a forest. Fewer trees, bright underbrush, and blue sky in the treetops can all portray a feeling of lightness and happiness in those viewing the scene. While it might be much more striking to see a frightening forest, not all artists want viewers to wonder if they should ever commune with nature.