Abstract Detail


Leonard, Hanna [1], Gorchov, David [2].

Long-term effects of an invasive shrub, Amur honeysuckle (Lonicera maackii), and white-tailed deer (Odocoileus virginianus) on forest floor plant composition.

The negative impacts of overabundant white-tailed deer (Odocoileus virginianus) and invasive species in deciduous forests have been well documented. However, their combined impacts are less understood. We tested the impacts of 11 years of exclusion of deer and removal of the invasive shrub Amur honeysuckle (Lonicera maackii (Rupr.) Herder, Caprifoliaceae) on forest floor plant composition in deciduous forests in Ohio. We used five paired deer exclosure and access plots that were established in 2010 in the Miami University Natural Area forests in southwest Ohio. One half of each plot had honeysuckle removed and the other half had honeysuckle present. In each half-plot we recorded percent cover of each species in 18 1000 cm2 subplots. These plots were sampled May 27-Jun 17 (spring survey) and July 20-Aug 6 (summer survey). Data were pooled by half plot for analysis. Species were classified as either native or nonnative and were also classified by growth forms. Species richness and percent cover were analyzed using two-way split-plot ANOVA in R 4.1.1. Richness of native species in summer, but not spring, was significantly affected by honeysuckle treatment and the deer * honeysuckle interaction. Native species richness was lower where honeysuckle was present; this effect was greatest in the deer exclosure plots. Cover of native species in both seasons was significantly impacted by both the deer treatment and the deer * honeysuckle interaction. Native cover was highest where both honeysuckle and deer were absent. The exclusion of deer also impacted cover of several growth forms. Tree cover and vine cover were significantly affected by the deer treatment and interaction during both seasons. For both of these growth forms, cover was highest where both stressors were absent. Shrub cover in spring was significantly greater in deer exclosures. Graminoid cover in both seasons was significantly greater where deer had access and in summer was also greater where honeysuckle was removed. Annual cover in summer was significantly greater in deer access plots. This higher cover of annuals could be a consequence of the significantly higher cover of bare ground in both seasons where deer had access. We compared these findings to surveys of the same plots in 2015, five years after initiation of the experiment. In 2021 more growth forms were significantly affected by deer treatment, and more with deer * honeysuckle interaction effects, than in 2015. Few parameters were affected by honeysuckle in either survey. These findings indicate that overabundant deer have more impacts on forest floor vegetation than do invasive shrubs. However, the exclusion of deer combined with removal of this invasive shrub resulted in the greatest values of native cover. tree cover, and vine cover. These impacts of deer, and of combined deer exclusion and invasive shrub removal, have become more important over time.

1 - 12084 Paulmeadows Dr, 12084 Paulmeadows Dr, Cincinnati, OH, 45249, United States
2 - Miami University, Department Of Biology, Pearson Hall, Oxford, OH, 45056, United States

non-native species
deciduous forest

Presentation Type: Oral Paper
Number: EC09007
Abstract ID:225
Candidate for Awards:None

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