Forests, like most ecological communities, are ever-changing. They grow and develop; even as individual plants die. Small trees grow into large trees whose canopies limit the amount of light reaching the forest floor. Understory plants and shrubs once prospered in the high-light environment between small trees. But now they must compete with other plant species more tolerant of shady conditions. Ecologists call the natural progression of growth and development of plant communities ‘succession’. Succession generally proceeds along a pre-determined path. The local and regional climate, what plant seeds are available, and condition of the soil influence the path. A 'disturbance' is an important point of the successional journey. With disturbance, the successional journey restarts, or is set back to an earlier stage. In forests, disturbances occur on many scales– from a single tree to the entire forest. A single tree dying may ‘disturb’ a small area of forest as it provides an opening in the canopy. The opening allows sunlight to reach the forest floor which supports new plant life. On occasion, many trees of the same size die, as sometimes happens with an insect outbreak or tree disease. This is a large-scale disturbance that may impact forest development for many years. Wildland fire is a disturbance that generally operates at large-scales. It can reshape forests and or any other plant community capable of burning. In the Alaska Arctic, for example, tundra fires are common. Fire can restart the successional journey of a plant community, giving it new life and health. When fire is severe or repeated, it can change the successional path along which that community was developing. Other plant communities may then grow. More Information: |
Last updated: March 27, 2024