Often a single stage may be prolonged by continued disturbances. It is any relatively discrete event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability or the physical environment. The kind, frequency and magnitude of disturbances determine the composition and successional stage of stands of trees. Whereas, catastrophic disturbances in mature forests induce reversion to pioneer stages of succession, very mild disturbances tend to keep a mature forest in a relatively steady state. These are forests that have survived for a long period of time without a catastrophic disturbance.
Climaxes can be climatic or related to other disturbances like fire, pests or windthrow.
Climax communities ultimately succumb to rarely occurring and catastrophic disturbances. Black spruce gets dwarf mistletoe which ultimately leads to wildfire. White cedar gets windthrown and if patches are large enough leads to wildfire. Maple-basswood is same scenario as cedar. Balsam fir gets spruce budworm which can lead to wildfire.