Date of Award
Master of Science
Holzmueller, Dr. Eric
Fralish, Dr. James
AN ABSTRACT OF THE THESIS OF Nick E. Zaczek, for the Master of Science degree in Forestry, presented on March 22nd, 2013, at Southern Illinois University Carbondale. TITLE: FOREST COMMUNITY COMPOSITION ON MESIC SITES IN NORTHERN WISCONSIN MAJOR PROFESSOR: Dr. Eric Holzmueller Prior to the passing of strict fire suppression laws in the late 1920s, the forests of Northern Wisconsin had been intensively harvested and burnt, producing a variety of successional forest community types. In this study successional patterns were examined in forest communities on mesic soils across the region. Stands were sampled using 0.4 ha nested plots for mature overstory trees and 0.004 ha for saplings and 0.002 ha for seedlings for the understory immature stems. Forest community types were organized by classification and multivariate analysis. Comparison of overstory, midstory, and understory species were made and stepwise linear regression was used to determine to what degree eleven soil characteristics were responsible for the occurrence/density of any of the species within the different community types. The six forest community types identified on the mesic soils were Balsam Fir, Bigtooth Aspen, Paper Birch, Quaking Aspen, Red Maple, and Sugar Maple. The first four communities were found on soils containing more than 72% sand and have similar understory conditions dominated by Abies balsamea and A. rubrum with little or no regeneration of the dominant overstory species. These four communities are dominated by species that require disturbances such as fire and/or harvesting to maintain their heterogeneity. The Red Maple and Sugar Maple communities are found on soils containing 65% or less sand. The understory of these two community types is dominated by A. rubrum, A. saccharum, and A. balsamea. It appears that endpoint or a steady-state community has developed on the mesic forest stands, given that no major disturbance occurs, is a convergence of a community of A. balsamea, A. rubrum, A. saccharum, and associated species. A convergence to a forest community dominated by these species poses several concerns to forest and ecosystem health and diversity if no management actions are taken. These species have very little wildlife value and more importantly an increasing density of A. balsamea has the potential to out-compete other species as well as increase the risk of a catastrophic and even stand replacing fire.
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