2000 BES Abstracts

Native and Exotic Vines Competition During Urban and Rural Forest Gap Regeneration

Helen T. Dijkstra, Steward T.A. Pickett

Exotic plant species are abundant in urban and suburban forests. Forest gaps are the principal sites of regeneration in mesic forests, which in turn determine the composition of the future forest stand. In a pilot survey we found 50 % of the vine species in urban and suburban forest gaps were exotic.

Our goals are 1) To determine whether exotic vines compete with saplings more intensely than native vines in forest gaps. 2) To test whether root competition between vines and saplings is stronger than shoot competition. 3) To identify the distribution and abundance of exotic plant species in forest gaps along an urban to rural gradient in Baltimore.

Exotic competition with native saplings in forest gaps may determine the composition of forest stands affected by urbanization. Vines seem to exhibit both strong root and strong shoot competition. Using plant competition theory we will identify the mode of competition, root or shoot, most significant in exotic vine- sapling competition. We use a set of native and exotic vines, and saplings of one tree species, common in Baltimore. We have experimentally planted these species into Baltimore's urban forest gaps to quantify root and shoot competition exhibited by exotic vines with a native sapling species. We have initiated a survey in Baltimore to identify the distribution and abundance of exotic plants in urban and rural forest gaps. Our data will be integrated with BES databases to identify forests in Baltimore most at risk due to exotic plants.