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 Managementhours) where <strong>the</strong> plant is nei<strong>the</strong>r inundated at high tide norrained on, low amounts <strong>of</strong> silt and salt on <strong>the</strong> treated plants,and complete coverage <strong>of</strong> <strong>the</strong> treated plant (“spray-to-wet”).Where Spartina grows in <strong>the</strong> San Francisco Estuary, <strong>the</strong>serequirements can be difficult to meet. Tidal fluctuations precludemost low and mid-elevation sites from adequate drytime for glyphosate most <strong>of</strong> <strong>the</strong> year. Siltation is a constantproblem in <strong>the</strong> highly turbid waters <strong>of</strong> <strong>the</strong> estuary, <strong>of</strong>ten resultingin much <strong>of</strong> <strong>the</strong> herbicide binding to <strong>the</strong> accumulatedsilt on <strong>the</strong> plant’s leaves ra<strong>the</strong>r than entering <strong>the</strong> plant’s tissuesand translocating properly. Finally, complete coverage<strong>of</strong> <strong>the</strong> targeted Spartina can be difficult to achieve over largestands or in areas difficult to access. Given all <strong>of</strong> <strong>the</strong>se constraints,very few days are available in a given growing season(late May through mid-October) with <strong>the</strong> convergence <strong>of</strong>conditions necessary for efficacious treatment using thisherbicide.The San Francisco Estuary is also <strong>the</strong> habitat <strong>of</strong> <strong>the</strong>Federal and State endangered California clapper rail (Ralluslongirostris obsoletus), whose breeding season extends fromFebruary 1 through August 31 <strong>of</strong> each year. Many <strong>of</strong> <strong>the</strong>marshes where larger populations <strong>of</strong> clapper rail breed havebeen invaded by non-native Spartina, and represent <strong>the</strong> majority<strong>of</strong> <strong>the</strong> infestation in <strong>the</strong> estuary. No Spartina controlwork can occur during <strong>the</strong> clapper rail breeding season in<strong>the</strong>se marshes. Therefore, <strong>the</strong> larger infestations <strong>of</strong> nonnativeSpartina may only be treated between September 1and roughly <strong>the</strong> end <strong>of</strong> October every year. During this time,tidal windows <strong>of</strong> opportunity that allow for <strong>the</strong> required drytime for glyphosate are limited. Finally, in most sites in <strong>the</strong>estuary, late-morning or early-afternoon winds develop thatexceed spray drift reduction criteria for herbicide application(10 mph sustained winds). As a result, in <strong>the</strong> 2004 treatmentseason, Spartina control work within clapper rail occupiedmarsh was restricted to roughly 6-10 days where all necessaryconditions were met.2004 TREATMENTAt <strong>the</strong> outset <strong>of</strong> <strong>the</strong> 2004 treatment season, <strong>the</strong> SSPscalled for treatment <strong>of</strong> 45 individual sub-areas within <strong>the</strong>selected 16 sites. The total area targeted was 181 ha (447ac), which roughly coincided with <strong>the</strong> initial estimates <strong>of</strong>population size determined in 2001, just after <strong>the</strong> ISP’s inceptionand initial inventory mapping <strong>of</strong> <strong>the</strong> non-nativeSpartina in <strong>the</strong> estuary. Figure 1 shows <strong>the</strong> locations <strong>of</strong> <strong>the</strong>various control sites within <strong>the</strong> estuary.As <strong>of</strong> December 2004, 176 ha (435 ac) <strong>of</strong> targeted nonnativeSpartina had been treated, with roughly 0.8 ha (2 ac)slated for manual control work in January 2005. Herbicidetreatment <strong>of</strong> several sub-areas with large infestations wascancelled as a result <strong>of</strong> heavy October rains, which preventedvehicle travel on bay-mud levees. Planned use <strong>of</strong> anamphibious excavator (Aquamog) was also postponed because<strong>of</strong> rain.RATE OF SPREADIn <strong>the</strong> fall <strong>of</strong> 2004 <strong>the</strong> ISP Inventory Monitoring Programproduced a Monitoring Report based on selected sitessurveyed during 2003 (California Coastal Conservancy2004(a)). This report analyzed <strong>the</strong> change in area <strong>of</strong> nonnativeSpartina at 28 monitoring sites stratified across <strong>the</strong>estuary by subregion (latitude), site type and marsh type.Based on sample surveys, <strong>the</strong> report extrapolated an average244% increase in area between 2001 and 2003 from all nonnativeSpartina species in <strong>the</strong> estuary. Spartina alterniflorahybrids were found to be spreading at <strong>the</strong> fastest rate, by asmuch as 317% over that time period. In 2001, an estuarywideinventory mapped approximately 195 ha (470 acres) <strong>of</strong>non-native Spartina, with hybrids comprising all but five <strong>of</strong><strong>the</strong>se hectares. Applying <strong>the</strong> 317% rate <strong>of</strong> increase results inan estimate <strong>of</strong> as much as 793 ha (1960 acres) <strong>of</strong> S. alterniflorahybrids in <strong>the</strong> estuary in 2003.Based on <strong>the</strong>se numbers, 2004 treatment efforts resultedin some 20% <strong>of</strong> <strong>the</strong> estuary’s Spartina population receivingtreatment during <strong>the</strong> year, leaving 80% untreated. If <strong>the</strong> untreatedarea doubles by <strong>the</strong> 2005 treatment season, <strong>the</strong>recould be as much as 1,294 ha (3,200 ac) <strong>of</strong> non-nativeSpartina requiring treatment during that year. This numberbecomes even larger if efficacy rates (40-80%) <strong>of</strong> <strong>the</strong> varioustreatment methods are factored into <strong>the</strong> calculation.OUTLOOK FOR 2005 AND BEYONDGiven <strong>the</strong> “supra-exponential” expansion <strong>of</strong> <strong>the</strong>Spartina hybrid swarm in <strong>the</strong> estuary, <strong>the</strong> ISP has determinedthat only an aggressive, comprehensive strategyaimed at treating all <strong>of</strong> <strong>the</strong> Spartina during <strong>the</strong> 2005 controlseason has a realistic chance <strong>of</strong> eradicating <strong>the</strong> invader from<strong>the</strong> estuary. Building upon <strong>the</strong> partnerships and experiencedeveloped during <strong>the</strong> 2004 treatment season, <strong>the</strong> ISP willaim to put in place each <strong>of</strong> <strong>the</strong> four main components <strong>of</strong>Spartina treatment for each site or sub-area in <strong>the</strong> estuary.The components, broadly defined are:• Partner identification and buy-in. Identification <strong>of</strong><strong>the</strong> specific agency, landowner or land manager for<strong>the</strong> estimated 130 sub-areas requiring treatmentduring 2005 can be difficult given overlappingjurisdictional boundaries, property lines that bisectSpartina infestations, and o<strong>the</strong>r issues. Much <strong>of</strong> thiswork for public property has been accomplishedduring <strong>the</strong> 2004 treatment season; however,extensive public outreach will be necessary for <strong>the</strong>large number <strong>of</strong> individual private property ownerswhose properties are infested with non-nativeSpartina.• Development <strong>of</strong> Site-Specific Treatment Plans. Foreach sub-area or site a site-specific treatment planwill be produced following <strong>the</strong> model <strong>of</strong> <strong>the</strong> 2004SSPs, and incorporating elements <strong>of</strong> <strong>the</strong> FWS BOand EA. These plans will be developed in close- 221 -