Soil forms the foundation of all woodlands, determining what types of plant species can grow well, which in turn determines what type of animals can live in a particular forest. Soil also plays an important role in watershed health. The type of soil in a given location determines how much food and moisture are available for trees and other plants. Some soil types hold water well and provide a good medium for the microorganisms that break down organic matter into nutrients. Others do not. This crucial difference in soils can determine which trees are able to survive and thrive in a particular location.