Invasive species have the potential to establish themselves as an ecosystem dominant. In this study, we characterized the current forest composition of an old growth forest in an urban park in Rochester, NY. This park is composed of a variety of different species of trees, shrubs, and herbaceous cover. It has a series of intermingled trails, variable changes in relief, and is heavily used by the community. Proximity to the neighborhood exposes the park to propagule pressure of the mature street trees. Within the park, the nonnative but commonly planted landscape tree Norway maple (Acer platanoides) is present, and previous research has found that this species can have a significant impact on the areas it inhabits. The Norway maple has been described as a prolific seed producer, shade tolerant, and a strong competitor for limiting resources. We hypothesized that the forest trajectory is shifting to a non-native species dominated forest. In order to test this expectation, the forest was surveyed at random points along four parallel transects. At each point we measured canopy and subcanopy trees, seedlings and saplings, herbaceous cover, and shrub cover. In addition to this a soil seed bank study was performed to observe germination of seed in open canopy/greenhouse conditions.
Results/Conclusions
Discovered upon analysis of the collected data was that the current canopy trees were dominated by native species including 31.5% Red Oak (Quercus rubra), 18.2% White Oak (Quercus alba), 17.7% Black Oak (Quercus velutina), 11.1% Black Cherry (Prunus serotina), and 7.0% Sugar Maple (Acer saccharum). However, the Norway maple was the most dominant (31.3%) in the subcanopy of the forest. Also found was that of the seedlings and saplings, this species was also the most dense (41.4%). The seed bank analysis found successful germination of approximately 300 individual plants including, tree seedlings, and various types of herbaceous cover. Furthermore, the seed bank information showed the presence of another invasive tree species, Tree of Heaven (Alianthus altissima). These findings provide an understanding of what we can expect of the forest composition in future generations. If this current trajectory continues, one of our local forests will be dominated by non-native, invasive species, which may have additional ecological consequences than just lost species diversity.