Long-term study of successional trends in an oak-dominated forest of central Missouri

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Changes in species composition and forest structure were studied over a 36-year period in the Baskett Research and Education Area (BREA) in central Missouri. Permanent plots were established in 1968, the tree ([greater than] 8.75cm) and sapling ( [less than] 8.75 cm) dbh was measured, and species recorded. Plots were classified as dry ridge & slope, mesic slope, glade-like, or bottomland. The plots were resampled in 2004, this time including seedling densities. Quercus alba tree basal area increased but density declined or remained constant. Acer saccharum tree density, basal area and importance value are increased in the dry ridge & slope and mesic slope sites. Quercus spp. regeneration has declined drastically, as shown by an overall reduction in sapling density. A higher density of Quercus spp. seedlings was recorded, indicating that survival and recruitment rather than germination is the issue for the lack of Quercus spp. presence in the sapling class. Larger sapling size classes of A. saccharum showed an increase in density; however, by 2004 A. saccharum density in the smallest sapling size class has declined by almost 90% compared to 1968 in all plot types. Virtually no A. saccharum seedlings were seen. This trend might have resulted from an increase in recent late winter/early spring temperatures and/or an increase in litter layer, both of which could have affected recent germination. At present, A. saccharum is showing an increased presence in the overstory, but Quercus spp. still dominates the overstory. With little to no Quercus spp. in the sapling class and recent A. saccharum regeneration failure, future canopy composition in the long-term remains uncertain.