Abstract Detail


Rudolph, Aaron [1], McCarthy, Brian [2], Snell, Rebecca [2].

Long-term changes to oak-hickory forest composition: Revisiting McCarthy and Wistendahl 38 years later.

Long-term studies focusing on changes to forest structure and species composition are challenging due to the inherent length of time required to observe forest turnover. While studies focusing on reproduction, recruitment, and mortality can provide an idea of future forest structure and composition, extended monitoring of sites can demonstrate precisely the ways in which forests have changed. In 1983, research plots were established on opposing North and South slopes at Waterloo Wildlife Area in Athens County, Ohio, USA as part of a study focusing on differences in hickory (Carya spp.) population structure, and future forest structure based on understory species compositions. In summer 2021, these sites were revisited to again document hickory population structure and overall species compositions at multiple forest layers. The encompassing goal of this study was to determine how oak-hickory forest structure has changed compared to predictions made nearly 40 years ago. A census of all living hickories with diameter at breast height (DBH) greater than 10 cm was conducted, along with point-centered quarter sampling of overstory (DBH > 10 cm) and midstory (DBH > 2.5 cm and < 10 cm) individuals around each hickory. Species presence and abundance were also recorded for saplings (DBH < 2.5 cm and height < 30 cm) and seedlings (height < 30 cm) in nested plots both around each hickory and at randomly placed control plots on each slope. The DBH structure of hickory populations were compared with Kolmogorov-Smirnov tests both among species and between sampling dates. Differences in species diversity through time in both the overstory and midstory levels were compared using Shannon’s diversity index. Species presence and abundance at all forest levels were compared between slopes and through time using non-metric multidimensional scaling (NMDS). While hickory population structures have trended expectedly towards larger individuals, approximately 50 percent of individuals censused in 1983 are now deceased. Mortality appears to have impacted each species differently as mortality does not appear equal among the size classes. Changes in species diversity in the overstory appear minimal due to relatively low turnover of large individuals, while midstory diversity has halved since 1983. This appears largely due to decreases in both species richness and evenness. Species compositions at all layers of the forest appear to maintain classical differences based on north-facing versus south-facing topography, yet the severity of this difference appears to be disappearing in the midstory layer and when compared to species compositions in 1983. While predictions from the original study forecasted a similar forest structure in the present, the degree to which certain species have increased in abundance and others have faltered was underestimated. Without intervention via management or climate change, oak-hickory forest in southeast Ohio may continue to experience decreases in species diversity and a homogenization of structure and composition.

1 - 6300 Ervin Rd Apt 64, Athens, OH, 45701, United States
2 - Ohio University, Environmental and Plant Biology, Porter Hall 315 1 Ohio University, Athens, OH, 45701, USA

Forest structure
Community composition
Diversity loss.

Presentation Type: Oral Paper
Number: EC03004
Abstract ID:43
Candidate for Awards:Ecological Section Best Graduate Student Paper

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