Dynamics and disturbance in an old-growth forest remnant in western Ohio

Background/Question/Methods

Non-equilibrium processes, such as disturbance and climate, vary through time and can lead to changes in the community structure of forests. A widespread community shift has been witnessed across eastern North America where oak (Quercus spp.) populations are decreasing while maple (Acer spp.) populations are increasing. Altered fire regimes over the last century are thought to be the primary driver of oak to maple community shifts; however, the influence of other non-equilibrium processes on this community shift remains under-explored. Our study sought to determine the community structure and disturbance history of an old-growth forest remnant in an area of western Ohio where fires were historically uncommon. To determine community structure, abundance of woody species was measured within 32 plots at 4 canopy strata and dendrochronology was used to determine the relative age-structure of the forest. Dendroecological techniques were used to determine the disturbance history of the site.

Results/Conclusions

We found that early and mid-successional genera like oaks and hickories (Carya spp.), while common in the overstory, are significantly underrepresented at lower canopy strata while maples are increasing in abundance. A shift in disturbance regime ca. 1890 is believed to be the primary reason for the observed change in community structure. We believe a suite of ‘multiple-interacting drivers’ including anthropogenic land use changes to the areas surrounding the site and alterations in food web dynamics are responsible for the dominance shift that is occurring in this old-growth forest remnant. Future studies are needed to further chronicle shifts in community structure and advance our understanding of disturbance dynamics in eastern deciduous forests.