Multifactor classification and analysis of upland hardwood forest ecosystems of the Kickapoo River watershed, southwestern Wisconsin

An ecological multifactor approach was used to develop a hierarchical classification of upland hardwood forest ecosystems of the Kickapoo River watershed, southwestern Wisconsin. This method was chosen from among the variety available because of its utility in this area of heavily disturbed forests. Eleven major ecosystem units were distinguished for the 67 plot areas sampled. Each ecosystem unit is characterized by a distinct combination of physiography (aspect and slope position and steepness), soil (parent material depth and type), and vegetation (canopy tree species and groups of ground cover species), and occurs in a unique position in the landscape. The canopies of most units are dominated by combinations of northern red oak (Quercusrubra L.), white oak (Q. alba L.), and sugar maple (Acersaccharum Marsh.). The results of several discriminant analyses indicate a high level of association between plots within some units. A combination of physiographic, soil, and vegetational variables resulted in the highest overall percentage of correct classification of the plots. These 11 ecosystem units ranged in estimated productivity (average site index for northern red oak) from 12 to 21 m, with the two extremes significantly different at the 5% level.