Proceedings of the Third International Conference on Invasive ...

<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 4: Spartina Control and ManagementCOVERING THE SPARTINA THREAT: AN ALTERNATIVE CONTROL METHOD FOR NON-NATIVE SPARTINA PATENS IN A WEST COAST SALT MARSHD.L. PICKERING2499 North Bank Rd., Otis, Oregon 97368; dpickering@tnc.orgOn Oregon’s central coast, <strong>the</strong> Nature Conservancy’s Cox Island Preserve harbors <strong>the</strong> introducedsalt marsh grass Spartina patens (saltmeadow cordgrass), <strong>the</strong> only known infestation in <strong>the</strong> state.The 187-acre preserve lies in <strong>the</strong> Siuslaw River, seven miles inland from <strong>the</strong> Pacific Coast. Spartinapatens is native to <strong>the</strong> east coast <strong>of</strong> <strong>the</strong> United States, found from Newfoundland to Texas. It wasprobably introduced to <strong>the</strong> west coast in <strong>the</strong> early 1900s. Spartina. patens invades mid-marshcommunities at elevations ranging from 1.83 to 2.05 meters (m) above mean low water (Frenkel andBoss 1988). Initially, it spreads primarily by rhizomes and forms circular, monotypic stands whichcrowd out native plants and eliminate wildlife habitat. These Spartina patches accumulate sedimentand litter at a faster rate than <strong>the</strong> surrounding marsh vegetation, thus altering <strong>the</strong> natural succession<strong>of</strong> <strong>the</strong> site. To restore Cox Island and prevent S. patens from spreading to o<strong>the</strong>r estuaries, we fieldtestedmethods that have shown promise at controlling S. patens elsewhere. Covering with heavydutylandscaping fabric anchored by spikes was <strong>the</strong> most effective control method <strong>of</strong> those we tried.Leaving <strong>the</strong> fabric on for two years kills <strong>the</strong> Spartina. After removal, native salt-marsh vegetationre-colonizes on its own. To date, 0.81 hectares (ha) (2 acres [ac]) have been restored and ano<strong>the</strong>r1.62 ha (4 ac) are now covered. This methodology may not be feasible for large-scale control effortson well-established infestations, but it is a very viable option for control efforts at <strong>the</strong> most effectivetime to eliminate invasive non-native species, during <strong>the</strong> early stages <strong>of</strong> an infestation.Keywords: Spartina patens, non-chemical control, salt marsh management, geotextile coveringTHE SPARTINA THREATThe only known Oregon occurrence <strong>of</strong> <strong>the</strong> introducedsalt marsh grass Spartina patens (saltmeadow cordgrass)occurs on <strong>the</strong> Nature Conservancy’s 187-acre Cox IslandPreserve located in <strong>the</strong> Siuslaw River. Spartina patens isnative to <strong>the</strong> east coast <strong>of</strong> <strong>the</strong> United States, found fromNewfoundland to Texas. It was probably introduced to <strong>the</strong>west coast around <strong>the</strong> turn <strong>of</strong> <strong>the</strong> 20 th century.Spartina. patens invades mid-marsh communities atelevations ranging from 1.83 to 2.05 meters (m) above meanlow water (Frenkel and Boss 1988). Initially, it spreadsprimarily by rhizomes and forms circular, monotypic standswhich crowd out native plants and eliminate wildlife habitat.These Spartina patches accumulate sediment and litter at afaster rate than <strong>the</strong> surrounding marsh vegetation, thusaltering <strong>the</strong> natural succession <strong>of</strong> <strong>the</strong> site.At Cox Island, S. patens apparently established inundisturbed vegetation before 1939. Since <strong>the</strong>n, it spread tocover approximately 1.1 hectares (ha) (2.7 acres [ac]) by1996. If uncontrolled, it could continue to spread until allavailable habitat is occupied (Frenkel and Boss 1988).EARLY DETECTION PARTNERSHIPO<strong>the</strong>r invasive species <strong>of</strong> Spartina from <strong>the</strong> east coasthave become established in Washington and California. Forexample, S. alterniflora has infested Willapa Bay inWashington where it is eliminating an important feedingarea for migratory waterfowl by invading mudflats andforming a Spartina monoculture (Aberle 1993).Studies indicate that 13 Oregon estuaries are at risk <strong>of</strong>invasion by non-native Spartina species (Daehler and Strong1996). Seeds or o<strong>the</strong>r propagules could be dispersed to newareas by migratory waterfowl, dredging operations, shellfishharvesting or movement <strong>of</strong> materials between oysterproducingareas. Early detection is essential to prevent newinfestations in Oregon (Pfauth et al. 2003).The Nature Conservancy has partnered with <strong>the</strong> OregonDepartment <strong>of</strong> Agriculture (ODA) and <strong>the</strong> SiuslawWatershed Council to control Spartina on <strong>the</strong> Cox IslandPreserve and to detect any new infestations in <strong>the</strong> state. In2003, ODA developed a Spartina Response Plan to protectOregon estuaries from Spartina invasions (Pfauth et al.2003). Nature Conservancy and Watershed Councilmembers have volunteered to survey salt marsh areas in twoestuaries for invasive Spartina species. Two patches <strong>of</strong> S.patens were found in <strong>the</strong> Siuslaw Estuary on propertyadjacent to Cox Island and were controlled. No o<strong>the</strong>rSpartina was found.RESTORING COX ISLANDTo restore Cox Island and prevent S. patens fromspreading to o<strong>the</strong>r estuaries in Oregon, <strong>the</strong> NatureConservancy field-tested several control methods from 1996- 263 -