MONITORING RESULTS OF HERBICIDE TREATMENTS AND OTHER TECHNIQUES TO MANGAGE CAREX KOBOMUGI (ASIATIC SAND SEDGE), AN INVASIVE PLANT SPECIES, IN NEW JERSEY’S COASTAL DUNES

Asiatic sand sedge, Carex kobomugi (Ck), was probably introduced to North America about a century ago when shipwrecks released plants used to pack Oriental porcelain. In New Jersey, Ck expanded in area over 300% at Island Beach State Park (IBSP) and 800% at Sandy Hook Unit of Gateway National Park (SHU) between 1985 and 2002. From 1999 – 2003, managers at IBSP sprayed the herbicide Roundup® on three Ck beds. We monitored densities of both invasive and native species in subsequent years. One and two years after being sprayed three times, one bed showed > 90% decrease in Ck abundance and slight increases in native species densities. However, by three years after cessation of spraying, Ck densities started to recover, although native species densities also continued to increase. Another bed, sprayed only once, showed 70% decreases in Ck one year after spraying, a decrease that was sustained for the subsequent two years. One year post-spray no change in native species densities was seen, but native species densities did increase in following years. In a third bed, sprayed several years after the first two, a 96% reduction in Ck abundances was observed several months after application. However some plants later appear to have regenerated, since densities increased by the following spring. Again, spray application not only spared native plants, but appeared to result in increased densities in these species over time. These data are interesting, but represent monitoring of a pre-established treatment program, rather than a controlled scientific experiment. Thus, in 2004 an experiment was initiated at SHU in which 3 replicate 100 m2 plots were established for each of the following treatments: (1) Control (2) Covered by heavy tarpaulins (3) Removal of the top 6-8 inches of growth using a backhoe (4) Application of Roundup®. A fifth treatment is also planned: application of sand in prescribed depths to test smothering tolerances. Before treatment, species densities in each plot were established using replicate quadrat counts, so effectiveness of these different treatment strategies can be assessed in the future.