Establishment and growth dynamics of contrasting tree species during 100-years of secondary succession in a Midwestern US deciduous forest

Background/Question/Methods

Most of the deciduous forest in eastern North America is in a state of recovery from intensive harvesting and land use. Understanding the forest response to this disturbance is important for understand the basic ecology of these systems and may inform management, particularly in an era of multiple, oncoming, perturbations (such as those associated with invasive species and climate change). We examined forest dynamics in a second-growth cove forest in Germantown MetroPark (GTM), southwestern Ohio, USA. Our goal was to examine forest dynamics associated with secondary succession. We focused on the following species, which are common to the area, but have contrasting ecologies: Liriodendron tulipifera, Quercus alba, Quercus rubra, and Juglans nigra.  Increment cores were collected at DBH from n = 20 of each species growing within a small watershed, and were cross-dated and measured using standard techniques. We specifically examined i) establishment dates among species and ii) growth dynamics during forest canopy formation.  We expected rapid early growth associated with open conditions following harvesting, followed by decline as the canopy closed.

Results/Conclusions The oldest samples in our collection were L. tulipifera, which established ca. 1880; the most recently establishing species was J. nigra.  We found that trees in GTM established from c. 1880 to 1940 with the majority of regeneration occurring ± 10 years around 1910.  This pattern is generally supportive of an initiating stand following disturbance where L. tulipifera has a dispersal advantage and initiates slightly earlier than a pulse of other species.   Across all years of the study, the four species exhibited similar annual radial growth, with J. nigra slightly slower than the other species.   Based on the mean chronologies, all four species exhibit an initial period of rapid growth, then a decline.  This growth pattern is consistent of initiation in high light conditions followed by canopy closure and competition for light.  In summary, our results suggest that all four species, despite their ecological differences, react to the harvesting in a similar fashion: establishment, rapid growth, and then declining growth associated with light completion.