TESTING MANAGEMENT STRATEGIES FOR THE INVASIVE ASIATIC SAND SEDGE, CAREX KOBOMUGI, IN NEW JERSEY'S COASTAL DUNES

Since its accidental introduction to New Jersey about a century ago, Asiatic sand sedge (Carex kobomugi) has spread along the East Coast. While its range now extends from Massachusetts to the Carolinas, the species is particularly abundant in New Jersey, where it has expanded into many of the State's remaining coastal dune systems. Carex is expanding rapidly in NJ, with most stands expanding by several meters in diameter every year. This expansion has well-documented negative effects on the abundance and diversity of native species and threatens many rare or endangered species, including piping plovers, seabeach amaranth and tiger beach beetles. As a result, removal of Carex from New Jersey's coastal dunes has become a major goal for environmental managers. However, the species is a highly effective dune-stabilizer, so removal has to be carried out with care to avoid significant dune erosion.

We tested a variety of potential management strategies for this species in one of the larger stands within the Sandy Hook Unit of the Gateway National Recreation Area. 18 replicate 10 x 10 m plots were set up within this stand and the effectiveness of 1) herbicide (Roundup^®) application, 2) removal via excavation with a backhoe and sand-sifting and 3) use of a tarpaulin was compared. We had also hoped to test the effectiveness of sand-burial in removing this species. However, we were unable to obtain sufficient sand to bury even the relatively small test plots, suggesting that, even if effective, this strategy would be unlikely to be adopted by park managers. 1 year after the plots were treated, all three methods had resulted in an order-of-magnitude reduction in Carex abundance. Mean Carex stem densities m^-2 were as follows: Control: 228 +/- 22, Roundup^®: 19 +/- 6, Removal: 41 +/-17, Tarpaulin: 44 +/-16). There was no significant difference in effectiveness between the three treatments. Abundance and diversity of native species in control and treatment plots were not significantly different for any species encountered, so removal of Carex had not yet resulted in any significant recovery of these species. However, the real test will be these treatments' effectiveness in controlling Carex and enabling recovery of native species over the longer term. Consequently, we plan to continue to monitor the recovery of these plots, as well as plots previously studied at Island Beach State Park, in future years.