PARENT SESSION
Oral Session #1: Invasive Species Control.
Presiding: S. Smith
Monday, August 5. 8:00 AM to 11:30 AM. Mohave Meeting Room, TCC.
The effects of biological control agents on Lythrum salicaria in a restored urban freshwater wetland.
PEHEK, ELLEN*,1, ANZELONE, MARIELLE1, 1 New York City Department of Parks, New York, NY
ABSTRACT- Less than 1% of New York City's freshwater wetlands have survived urbanization. This stark fact underscores the importance of maintaining the fragments that remain. Invasive plants are arguably the biggest threat to restoring ecological function in these compromised wetlands. In this study, we examined the effects of biological control agents on Lythrum salicaria fitness in a restored freshwater wetland in New York City. Over the past three years, we recorded changes in individual plant fitness with respect to three treatment species: Hylobius transversovittatus, a root-mining weevil, Galerucella calmariensis and Galerucella pusilla, two leaf-eating beetles. Plant characteristics measured in individual plots included: percent cover, number of stems, plant height, number of inflorescences, length of inflorescences and number of flowers per inflorescence. After analyzing three years worth of data, certain trends became apparent. From 1999 (year 1) to 2000, nearly all indices of L. salicaria fitness increased except the number of buds per 5cm of inflorescence, which decreased. This may be because of a drought in the first monitoring year, which probably supressed the number and vigor of L.salicaria plants. In 2001, almost all indices decreased except for the number of L. salicaria stems per plot, which increased. This may be due to the rising frequency of insect damage we observed during the study. We also compared species richness among plots, which remained constant over the three year period, but percent cover and frequency of Phragmites australis increased within individual plots for years 2 and 3. Here lies the dilemma; will the site be rid of L. salicaria only to make way for P. australis?
KEY WORDS: Lythrum salicaria, restored, urban , wetland