Comparison of Oak and Sugar Maple Distribution and Regeneration in Central Illinois Upland Oak Forests

Although white oak (Quercus alba) dominated much of the mid-west and eastern US hardwood forests prior to European settlement, changes in disturbance frequencies and habitat fragmentation, coupled with other biotic pressures, are allowing sugar maple (Acer saccharum Marshall) to displace oak in the upland forest understory. Since our understanding of how disturbance mechanisms influence oak regeneration is not fully clear, there is lack of consensus on how to employ management practices. We collected seedling microhabitat data from 5 upland oak forest sites in central Illinois, each differing in age class and/or silvicultural treatment to determine: 1) Whether species of tree seedlings are selectively recruiting into specific microhabitats, 2) Whether silvicultural treatment results in changes in microhabitat at the stand scale, and 3) Whether silvicultural treatments alter seedling-environment relationships. Despite different management histories, oak and maple seedling densities were not significantly different among sites. Results of a MANOVA showed significant relationship between understory oak and maple distributions with slope position (\u3c0.0001) and a slope x aspect interaction (0.0189). Maples were more prevalent in mesic slope and aspect positions. A PCA for environmental variables followed with MANOVA by site showed the environmental relationships among species was consistent across sites. At each site, oaks typically separated from sugar maples suggesting environmental variables influence distribution regardless of site history. Results suggest that management intensity for oak in upland forests could be based on landscape position. Maple expansion may be reduced by concentrating mechanical treatments in expected areas of maple colonization, while continually using fire throughout stands to promote oak regeneration