TWENTY-FIVE YEARS OF CHANGE IN A DRY-MESIC FOREST OF SOUTHEASTERN WISCONSIN

摘要

This study assesses successional changes in a southern dry-mesic forest (Curtis 1971) at the Wehr Nature Center in Franklin, Wisconsin, after 25 years of static management. The site was historically maintained by periodic fire. I sampled using techniques that duplicated a 1976 study of the same area. I then calculated importance values as per Curtis (1971) for the 2001 data and compared the results to those from 1976. Among the trees and saplings, I found a decline of importance in oak species, while species of ash and maple increased. I observed a rise in the importance of black cherry within the sapling stratum. Most notably, I found a drastic change in the composition of the shrub layer. Common buckthorn, an invasive exotic, virtually dominates the shrub stratum in 2001 and displaces gray dogwood, which was prevalent in 1976. In the herb layer, I found a rise in importance of jack-in-the pulpit and two of the most common herb species in 1976, enchanter's nightshade and white avens, remained the most prevalent in 2001. Garlic mustard increased in occurrence from 1976 to 2001.1 conjecture the majority of the changes are due to the cessation of fire in the community. If left undisturbed, the dominant overstory may well shift from oak to maple, and the understory community will continue to be dominated by invasive exotic species.