Changes in Fagus grandifolia and Acer saccharum Abundance in an Old-Growth, Beech-Maple Forest at Warren Woods State Park, Berrien County, Michigan, USA


Robert Tatina

Additional Authors:


June 2015


Acer saccharum, Fagus grandifolia, old-growth forest, beech-maple forest, Michigan

ABSTRACT In the beech-maple forest at Warren Woods State Park, the importance values of Fagus grandifolia and Acer saccharum have increased compared with their values from the 1829 Government Land Office survey of the same area—a small increase for F. grandifolia and a large increase for A. saccharum. For F. grandifolia the greatest increase between 1829 and 2014 was in basal area per tree, suggesting that numbers had not increased as much as size; while for A. saccharum the greatest increase was in all relative metrics, but not in basal per tree, indicating that abundance only had increased. From 1933 to the present, all size classes of F. grandifolia, except for the juvenile size class, decreased in density, while only the juvenile size class of A. saccharum decreased. Seedling densities for both species are highly variable from year to year, the highest densities occurring in years with deepest snow cover. For A. saccharum, high densities were probably the result of optimal germination temperatures due to prolonged snow cover. For F. grandifolia, the high seedling density in 2014 may have been due to an abundant seed crop and low seed predation on snow-covered seeds. The relative increase in A. saccharum and the concomitant decrease in F. grandifolia may be due, in part, to higher mortality of larger F. grandifolia trees due to windthrow. This differential mortality may be exacerbated with the increased frequency and severity of storms predicted to occur with global climate change.