Forest health has become a major problem in much of the west and is closely linked to forest succession. Disturbances such as fire, flood, or windstorm periodically interrupt forest succession and recreate earlier seral conditions. The frequency and intensity of disturbance controls the extent of succession or the number of seral stages that may occur on a site. When the frequency of these disturbances is interrupted such as with fire control, succession can carry species composition and density beyond the historical range of seral stages. Historically, sites which were frequently disturbed are the first to get beyond their historical range and experience forest health problems when these disturbances are interrupted. Whereas, sites which, historically were less frequently disturbed may experience more complex successions that include outbreaks of insects and disease as part of the historical range of conditions.