Proceedings of the Third International Conference on Invasive ...

Chapter 4: Spartina Control and Management<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaFrequency60504030202.47.5a% survivalSan Francisco1008060402000 30 60 90 120days post-planting100plants were exposed to ambient light and temperatureconditions for 132 days after planting. Survival, culm lengthand <strong>the</strong> number <strong>of</strong> culms were recorded at 30, 51, 74, 95,116 and 132 days after planting. Survival was defined as <strong>the</strong>presence <strong>of</strong> at least one green culm. Roots, rhizomes, culmsand inflorescences were separated 132 days after plantingand <strong>the</strong>ir fresh weight (fw) recorded. Dry weight (dw) wasobtained after drying <strong>the</strong> roots, culms and inflorescences to aconstant weight in <strong>the</strong> greenhouse and oven drying <strong>the</strong>rhizomes at 65-70°C for 48 hours.Propagule Dispersal StudyMonthly releases <strong>of</strong> buoyant, biodegradable woodendrift cards began in September 2004 from <strong>the</strong> mouths <strong>of</strong>Willapa Bay in Washington and Humboldt and SanFrancisco bays in California. A total <strong>of</strong> 600 cards arereleased each month—200 each per bay. Releases occurredwithin two hours after high tide to ensure an outgoingcurrent. Each batch <strong>of</strong> cards was printed with a unique codedenoting <strong>the</strong> location, month and year <strong>of</strong> <strong>the</strong> release as wellas reporting instructions and contact information. Velocityestimates were made under <strong>the</strong> assumption that <strong>the</strong> recoverydate was <strong>the</strong> same as date <strong>the</strong> card washed ashore and that<strong>the</strong> card followed a straight line <strong>of</strong> travel.RESULTS36Field Study <strong>of</strong> Rototilling EffectsThe mean fragment density was 310 (± 54.8)/m 2 within10 cm <strong>of</strong> <strong>the</strong> surface. Of <strong>the</strong>se, 87.7% had at least one culmattached (Table 1). No plant material o<strong>the</strong>r than S.alterniflora was present in any <strong>of</strong> <strong>the</strong> plots.One-way Analysis <strong>of</strong> Variance (ANOVA) (α=0.05)comparing quadrats were performed on rhizome length andculm length (log(x+1) transformed) and rhizome diameter91215Rhizome Length (cm)Fig. 2 Rhizome sizes found immediately following single-pass winterrototilling in Willapa Bay, WA.b% survivalWillapa Bay1008060402000 30 60 90 120days post-plantingFig. 3. Percent S. alterniflora fragment survival over time for (a) SanFrancisco and (b) Willapa Bay plants. Treatment groups are delineated bysalinity (- - - - - for 0 ppt, ––––– for 15 ppt, and –– - - –– for 35 ppt), andrhizome size (plain line = small, = large).((x+1) 1/2 transformed) and number <strong>of</strong> culms per fragment.The quadrats did not vary significantly in rhizome length(p=0.240) or <strong>the</strong> number <strong>of</strong> culms per rhizome fragment(p=0.322). There were significant differences betweenquadrats with regard to culm length (p