Coastal Zone 2003

Georgian Court University

Effectiveness of low-impact management strategies for the removal of C. kobomugi (ASIATIC sand sedge) from dune communities within New Jersey’s Coastal Parks

Audrey McGough, Department of Biology, Georgian Court University
Katy Bevaart, Department of Biology, Georgian Court University
Jason Ondreika Department of Biology, Georgian Court University
Purvi Patel Department of Biology, Georgian Court University
Louise Wootton* Department of Biology, Georgian Court University

Keywords: Asiatic sand sedge, Carex kobomugi, invasive, non-indigenous, management, eradication methods, Roundup®

Citation: McGough A, Bevaart K, Ondreika J, Patel P, Wootton L. 2003. Effectiveness of low-impact management strategies for eradication of Carex kobomugi (Asian sand sedge) from dune communities within New Jersey’s coastal parks. 5-page Extended Abstract. In Coastal Zone 2003 Conference Proceedings.

INTRODUCTION

Carex kobomugi (Asiatic sand sedge) is a perennial plant of the family Cyperaceae native to coastal Japan, China and Korea. Used as a packing material for fine china imported from Asia, surviving shoots and/or viable seeds of Carex kobomugi are believed to have been released into North America as the result of shipwrecks carrying such cargo in the early 1900s (Halsey 2002). Recognized as an effective sand binder (Lea and McLaughlin 2002), C. kobomugi was later deliberately planted as a dune stabilizer in erosion-prone areas in several states on the U.S. Eastern Seaboard, including New Jersey. Although listed at one time on the endangered species list for New Jersey (Fairbrothers and Hough 1973), perceptions of C. kobomugi in recent years have changed. The species is now listed as one of the ten most unwanted plant species in New Jersey (Bennett-Chase 2001) and has been targeted for elimination. Research by our group at Island Beach State Park (IBSP) and Gateway National Parks Sandy Hook Unit (SHU) supports the classification of this species as invasive as, relative to a similar survey in 1985 (Shisler et al. 1987) there was an increase of about 300% in number of beds present and about a 400% increase in bed size by 2002 (Wootton, this conference).

Eradication of Carex kobomugi in North America has proven difficult. Mechanical means of removal using backhoes and sifters have met with partial success in small stands only. Care must be taken to remove all parts of the root system when digging, as any remaining rhizome parts are likely to grow into new plants (Lea and McLaughlin 2002). Removal of larger stands via application of chemicals (Roundupā) to individual plants has been reported to be more successful. However, careful application is necessary in order to avoid spraying native fauna because Roundup® works indiscriminately on all vegetation. A minimum of two applications, along with spot treatments, are prescribed for complete eradication of the species (Lea and McLaughlin 2002). Careful monitoring of the treated beds is also suggested, in order to spot any newly emergent plants.

An eradication program for Carex kobomugi was implemented at IBSP, beginning in 1999. However, previous to our study, no formal monitoring had been carried out to assess the effectiveness of this program. Our study had two main objectives: first to assess the effectiveness of the Roundupā applications in the removal of C. kobomugi from the treated sites, and secondly to assess the effectiveness of the application methods used in sparing native species within the sprayed beds.

MATERIALS AND METHODS

The eradication program implemented at IBSP utilized narrowly focused spray applications of Roundupā to individual Carex kobomugi plants. The purpose of this program was to eliminate the sedge, while sparing the native plants growing in the same area. This study focused on two of the four beds sprayed. The first stand of C. kobomugi that we monitored was treated twice in 1999 and again in 2000. This was a relatively small and isolated bed located on the seaward side of IBSP at approximately the midway point of the park. The second bed that we studied was a much larger and less isolated bed of C. kobomugi, located at the south end of the park, also on the seaward side. This bed has been treated only once to date, in the fall of 2001.

To evaluate the effectiveness of the spray regime in eliminating C. kobomugi, and to assess the success of that spray program in sparing non-targeted plants, surviving plants within two of the treated beds were surveyed. Surveying was accomplished by selecting 1m² plots within the bed using a systematic sampling design, supplemented by randomly selected plots until at least 1% of the bed area had been surveyed. Numbers of each type of plants within each 1m² survey plot were counted and recorded. To assess the species composition of similar areas of the dune to that colonized by C. kobomugi, a systematic sampling design was used to select a series of survey plots ringing the bed at a distance of 5m outside the bed’s perimeter. The numbers and types of plants within each of these plots were also recorded. Since the numbers and species of plants within the beds had not been determined prior to the implementation of the spray program we surveyed several untreated C. kobomugi beds near each of the treated beds using the same procedures as mentioned above. We used the data so obtained to represent what the treated beds had presumably been like before treatment (i.e. as “controls”), in terms of the abundance and diversity of plants within the beds.

Results

We found that the mean number of Carex kobomugi in both treated beds was significantly reduced relative to the untreated controls. However in neither bed was C. kobomugi completely eliminated. The mean number of C. kobomugi stems in nearby untreated beds was about 120-150 stems/m² (Figures 1 and 2). Number of C. kobomugi stems in the bed treated only once averaged about 31 stems/m² (Figure 1). Mean number of C. kobomugi stems in the bed receiving multiple treatments was about 10 stems/m² (Figure 2). American beach grass (Ammophila breviligulata) and seaside goldenrod (Solidago sempervirens) were the two most abundant native species both inside and outside C. kobomugi beds. Numbers of these species were statistically similar in treated and untreated beds (Figures 3 and 4). In the bed treated in 2001 only, the mean number of Ammophila stems/m² was approximately 15, while the numbers in nearby untreated beds averaged between 4 and 26 stems/m² (Figure 3). The mean number of goldenrod /m² in the single-treatment bed was approximately 4, compared to an average of about 2-4 plants/m² in nearby untreated beds. Inside the bed that received multiple treatments of Roundup® the average number of Ammophila was again approximately 15 stems/m² compared to 7-10 stems/m² in the nearby untreated beds. The mean number of goldenrod in the multiple treatment bed was approximately 2 stems/m², compared to averages of about 2-5 stems/m² in nearby untreated beds.

Figure 1. Comparison of mean number of C. kobomugi stems/m² in untreated versus treated beds for the large bed, treated once in 2001 only. Error bars are 1 S.D.

Figure 2. Comparison of mean number of C. kobomugi stems/m² in untreated versus treated beds for the small bed treated twice in 1999 and 2000. Error bars are 1 S.D.

Figure 3. Comparison of abundances of Ammophila breviligulata and Solidago sempervirens inside versus outside untreated C. kobomugi beds for the large bed, treated once in 2001 only. Error bars are 1 S.D.

Figure 4. Comparison of abundances of Ammophila breviligulata and Solidago sempervirens inside versus outside untreated C. kobomugi beds for the small bed treated twice in 1999 and again in 2000. Error bars are 1 S.D.

Discussion

Even with repeated applications, the current program Roundup® application at IBSP has not been completely successful in eradicating C. kobomugi, perhaps because of the low-impact application method used. This application method does, however, seem to be effectively sparing the native species within the beds. Unfortunately, effective eradication of C. kobomugi would probably involve more aggressive, broadband applications of herbicide that would preclude the beneficial ecological and geomorphologic effects of the current strategy. Moreover, it is likely that even such an aggressive strategy would require multiple chemical applications over time to be effective. In the interim, the defoliated dunes would be vulnerable to erosion. In light of these observations, control rather than eradication may be a more realistic goal for management of this species in coastal dune systems, at least in the immediate future. This proviso notwithstanding, given the current exponential expansion rate of this species and its impact on native species (Wootton this issue), it is clear that the longer managers wait to employ some form of control for this species, the more difficult will be the task of removal. This in turn will make the removal itself increasingly damaging to the dunes and the communities that they support. It is thus our recommendation that continued, careful application of Roundup® or similar herbicides be continued at IBSP.

ACKNOWLEDGEMENTS

This study was supported by the National Sea Grant College Program of the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration under NOAA grant #A/S-1 SGEP-1. The views expressed herein do not necessarily reflect the views of any of those organizations. NJSG-03-514.

Literature Cited

Bennett-Chase D. 2001. Japanese sedge. http://www.savebarnegatbay.org/herbarium/japanesesedge.shtml

Fairbrothers DE, Hough MY. 1973, Rare or Endangered Vascular Plants of NewJersey, Department of Botany, Rutgers University, New Brunswick, NJ

Halsey S. 2002 Carex kobomugi (Japanese Sedge) an introduced dune plant now genus non grata: Management issues in State and Federal Parks. Geol. Soc. America, Abstracts with Programs (Northeastern Section, Springfield), Vol. 34, No. 2 http://gsa.confex.com/gsa/2002NE/finalprogram/abstract_31998.htm

Lea C, McLaughlin G. 2002. Asiatic sand sedge http://www.nps.gov/plants/alien/fact/cako1.htm

Shisler JK, Wargo RN, Jordan RA. 1987. Evaluation of Japanese sedge, Carex kobomugi, for use in coastal dune planting and stabilization. New Jersey Agriculture Experiment Station Publication number P-40502-03-87

Wootton, LS. (This issue) Spread rate and changes in species diversity associated with the introduced Asiatic sand sedge, Carex kobomugi, in New Jersey coastal dune communities.

Corresponding Author: Louise Wootton, Ph.D.
Department of Biology, Georgian Court University, Lakewood, NJ 08701
Phone (732) 364 2200 x 2349 E:mail: woottonL@georgian.edu