Increase the layering in a community, and you increase the variety of species, which in turn improves the habitat. Simple environments, say a stand of Torrey Pine trees, can be overtaken by insect species that favor the Torrey Pines as food. These destructive species have plenty of food, no competition and may destroy that plant community.

If you create a stand of trees made up of several different plant species, whose leaves and heights favor a variety of insect species that compete with one another and no one insect species is favored, that stabilizes the community.