Central Ohio ravine forests are being subjected to increasing levels of disturbance due to residential and commercial development. This development has led to increased fragmentation of these urban forests, allowing non-native species to invade, e.g., Lonicera maackii (Rupr.) Herder. L. maackii is detrimental in forest ecosystems due to its allelopathic effects, fast growth rates, and leaf phenology. In central Ohio, community groups have conducted removal efforts aimed at eradicating this species from two urban ravines, Adena Brook and Rush Run.
Stand composition, and L. maackii abundance, height, and response to treatment were determined following sampling in the summer of 2008. Fifteen 200-m2 plots were established in three ravines in Franklin County, Ohio. Flint Run was the reference for this study, and three plots were established in this relatively undisturbed ravine. In both Rush Run and Adena Brook, three plots were established where no treatment had occurred and three plots were established where treatment had occurred. It was anticipated that the urban ravines had higher densities of L. maackii and decreased woody plant species diversity. It was also expected that after removal efforts were completed seed bank regeneration would result in lower densities of L. maackii compared with planting of woody species.
There was a significant difference between density of L. maackii in the disturbed areas compared with the reference study location, as well as treated areas compared with untreated areas (p < 0.001 for both). There were differences in the density, height, and height distributions. The morality percentage was significantly different between treated plots in Rush Run and Adena Brook (p = 0.001).
In untreated plots across all locations, there were significant differences in the Shannon-Weiner Diversity Index between the reference study area and the disturbed, untreated areas at the 1- by 1- m level (p < 0.001). There was lower woody plant diversity in the reference area compared with the untreated, disturbed areas.
Finally, there was a significant difference in woody plant density in treated Adena Brook plots compared with treated Rush Run plots (p = 0.03). The L. maackii reproduction rate was lower at Rush Run compared with Adena Brook, however, this difference was not statistically significant (p = 0.905). Treated Rush Run plots had higher density of L. maackii individuals per square meter compared with both Flint Run and treated Adena Brook plots, however, the difference was also not significant (p = 0.5).
An understanding of the effectiveness of L. maackii removal efforts in urban ravine forests will provide beneficial information to Central Ohio community groups, allowing them to better restore these urban ravine forests.