PARENT SESSION
Contributed Oral Session 163: Forest Ecology: Vegetation Change and Succession
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 520 B, Level 5, Palais des congrès de Montréal
Past, present and future of a suburban old growth forest: Vegetation change and exotic species invasions over 50 years.
Aronson, Myla*,1, Handel, Steven1, 1 Rutgers University, New Brunswick, New Jersey
ABSTRACT- Small urban/suburban forests are often the only natural areas left in highly developed landscapes. The importance of these forest patches for preservation of biodiversity has been well documented, but escalating deer populations and invasion by exotic species may challenge this biodiversity. It is often thought that undisturbed areas are resistant to invasions by exotic plants. This was tested in a 25 ha old growth, uncut forest in central New Jersey in 2003. We surveyed current plant communities and compared these communities to surveys done in this forest over the past 50 years. Data show that over the past 20 years, exotic plant species have gone from uncommon to abundant in this forest. Prunus serotina and Fraxinus americana dominated the sapling layer in 1979, and in 2003 shared dominance with the exotic tree, Ailanthus altissima. The shrub layer was dominated in 1950-1979 by Viburnum acerifolium and by 2003 was completely replaced by a new shrub layer dominated by the exotic shrubs, Ligustrum vulgare and Rosa multiflora. Microstegium vinimeum and Alliaria petiolata, two recent exotic invaders, were dominant species in the herbaceous layer in 2003 but were not present in 1950-1979. The herbaceous layer has lost many native wildflowers typical of eastern mesic forests. Continued heavy invasion by M. vinimeum and A. petiolata may cause further native species losses. Canopy communities have shifted from Quercus-Carya dominated to Quercus-Fraxinus-Acer dominated. Linear regression analysis to predict regeneration potential of the 2003 canopy showed no significant relationships between the canopy and sapling or between the canopy and seedling layers. These results indicate there is little to no regeneration potential of the canopy and the successional trajectory of the old growth may be changing. Although this uncut, old growth forest is relatively undisturbed, it is highly susceptible to invasion by exotic plant species and loss of native species. The future of this forest is unclear, but it is apparent that future communities will be dominated by exotic species without aggressive and continual management.
Key words: old growth, exotic species, New Jersey, invasions