THE INFLUENCE OF VINES ON AN OLIGOHALINE MARSH COMMUNITY - RESULTS OFA REMOVAL AND FERTILIZATION STUDY

The effects of competitive suppression by vines on the non-vine plant community have received little attention in temperate habitats. This s tudy investigated the impact vines have on their herbaceous hosts in a wetland community at two soil fertility levels. Plots in an oligohali ne marsh were treated in a 2 x 2 factorial design with vine removal an d fertilization over two growing seasons. There was no significant int eraction between removal and fertilization treatments on any of the me asured variables. Vine removal initially caused an increase in light p enetration through the canopy, but by the end of the study, plots with vines removed had less light due to a 25% increase in biomass by the plants released from competition with vines. For plots with vines remo ved, species richness was higher during a brief period in the spring o f the second year, but by the end of the study, richness in removal pl ots decreased relative to controls. Fertilization caused a 40% increas e in biomass overall, although only two species, Sagittaria lancifolia L. and Polygonum punctatum Ell., showed dramatic increases. Despite f ertilization causing a 40% decrease in light penetration to the ground , no change in species richness was observed. Overall, these results s how that vine cover in this wetland suppresses non-vine species and re duces community biomass. Removal of vines increased biomass of non-vin e dominants but resulted in only an ephemeral change in species richne ss. Fertilization did not increase the effects of vines on the non-vin e community.