Station 6: Plant Succession
The old roadbed that the trail crosses was built years ago for mineral prospecting and has not been used since the 1920s. Although long abandoned, the road is still easily visible. The trees were removed before road construction. Only grasses grew when the road was first used. Shrubs began growing after the road was abandoned, and now young trees are beginning to grow. The ultimate vegetation that any site can support is known as its “climax plant community,” and the process of change toward climax is known as plant succession. Sub-climax species are known as seral species and occupy different seral stages. Because of different habitat requirements, wildlife changes according to each seral stage. People can influence the rate of change and even reverse its direction to earlier stages of plant succession. In this case, people built a road.
Another example of artificial change is timber harvest. Land managers can simulate a certain stage of succession by cultivating plants of a specific seral stage. For example, browse for deer and elk can be created by promoting brushfields on south-facing slopes after timber is removed. This can be done by burning the area periodically to kill young trees that would eventually shade out the shrubs. Managers may also try to change the rate of succession by planting seral tree species that are less susceptible to insect and disease problems. Through succession, sites always progress to the point that they are populated with climax vegetation. However, climax vegetation is not the same for all sites. It may be a pine forest for one site and a grassland for another site. Each will vary according to the conditions of the surrounding habitat. Still, you will often see many areas with seral plants. Why do you suppose this is true? Think about it as you hike to the next station.