The environment in the canopy or tops of tall trees in the woods is quite different from that of the environment on the ground. And both of these layers are different from the environment in the layers of smaller trees, shrubs and groundcovers that lie between the tops of the tallest trees and the forest floor. Each of these layers serves a purpose and helps determine the variety of wildlife that can exist in a given area. Each vegetative layer has its own microclimate, and in turn, helps determine the microclimate in the layers beneath it. For example, when you remove the larger trees from an area, all the microclimates beneath them also are affected.
Layers help conserve moisture and moderate temperature variations.
Less watering is needed with multiple vegetative layers than in open expanses of grass. There is a large amount of interdependence between layers and the wildlife that live within. For example, numerous insects live within these layers and provide needed protein for the birds to feed their young. In addition, many birds forage on the ground for food, nest in higher trees with sturdy branches, and seek shelter and escape from predators in shrubs and small trees. Maximizing the number of vertical layers in your landscape is not just for the benefit of wildlife.