Long-term Legacies of Invasive Shrubs on Forest Ecosystems
Thursday, August 8, 2013: 1:30 PM-5:00 PM
101B, Minneapolis Convention Center
Richard L. Boyce
Richard L. Boyce
Invasive plants have major impacts on the structure and function of forest ecosystems. Invasive shrubs, because of their size and longevity, can produce effects not caused by invasive herbaceous plants. They are relatively tall and long-lived, so they can suppress tree seedlings for longer than herbaceous vegetation. Many invasive shrubs take advantage of disturbance to initially become established. They are often prolific seed and fruit producers, and their seed is spread by animals, wind, and water, where they often remain viable in the seed bank for many years. Invasive shrubs often can quickly spread and dominate a stand via the production of root sprouts, stem sprouts, and other forms of vegetative reproduction. Because they often form monotypic stands, invasive shrubs reduce plant biodiversity and hinder forest tree regeneration; these effects have been known for some time. More recently, it has been recognized that these shrubs can destroy habitat for other organisms and disrupt important ecological processes, such as fire frequency and intensity, nitrogen cycling, and soil pH. All of these effects can leave a legacy of alteration that remains even if invasive shrubs are removed.
The purpose of this OOS is to bring together findings on the variety of legacies left by invasive shrubs. One of their most important legacies is the alteration of soils and microbial communities. Therefore, the OOS will begin with studies that examine how invasive shrubs alter belowground ecosystems. Some of these changes are due to altered decomposition dynamics, which will be addressed by looking at decomposition of mixtures of native leaves and leaves from invasive woody plants. Some of these effects can carry over into the aquatic systems embedded within forests, which will be the next topic addressed. Arthropods and the birds that feed upon them can also be affected by invasive shrubs, showing how invasive shrub effects can propagate to other trophic levels. The session will end with an outline of the structures and physiologies these shrubs possess that allow them to invade forests in the first place.