AN OLD GROWTH OAK FOREST AT LEONARD WILDLIFE PRESERVE IN BERRIEN COUNTY, MICHIGAN

摘要

In the past, much of the eastern United States was covered by old growth oak and oak-hickorj forests in which white oak was a dominant species. Periodic low severity fires were thought to maintain these forests by eliminating competition from shade tolerant species and increasing light transmission to the forest floor. After European settlement, much of these forests were logged, and firt was suppressed in those that remained, causing a decline in white oaks. A 15-ha forest at Leonarc Wildlife Preserve near Lakeside, Michigan, was found to have numerous very large diameter whitt and red oaks. The tree species composition and demography were described from samples taken ai the preserve in 2020. In addition, canopy cover and light measurements were taken to determine il sufficient light existed at the forest floor to support the survival of oak seedlings and their recruitment. The forest canopy was found to be dominated by white oak and red oak, some of which exceeded 150 years of age, with a subcanopy of sugar and red maple and American beech. Size class frequency distributions showed that red and white oaks had gaps in smaller size classes indicative ol populations that may be in decline. The same was not true for the maples and beech, which seemec poised to replace the aging oaks. Light intensity was found to be below that conducive for oak survival.