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Simple Approaches to Improve Restoration of Coastal Sage Scrub Habitat inSouthern CaliforniaAuthor(s): Carl E. Bell, Edith B. Allen, Kristin A. Weathers and Milton McGiffen, Jr.,Source: Natural Areas Journal, 36(1):20-28.Published By: Natural Areas AssociationDOI: http://dx.doi.org/10.3375/043.036.0107URL: http://www.bioone.org/doi/full/10.3375/043.036.0107

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20 Natural Areas Journal Volume 36 (1), 2016

ABSTRACT:MuchofthecoastalsagescrubhabitatinSouthernCaliforniathatexistedpriortoEuropeansettlementhasbeendevelopedforhumanuses.Overthepasttwotothreedecades,publicagenciesandlandconservationorganizationshaveworkedtoacquiresomeoftheremaininglandsforpreservation.Manyoftheselandsaredegradedbypastintensivelivestockgrazing,farming,andfrequentfires,andthenativeflorahasbeenreplacedbyweedy,exoticannualgrassesandforbs,mostlyofMediterraneanorigin.Restorationofnativefloraischallengingandtherearefewsuccessfulexamplestoprovideguid-anceoneffectivemethods.Cost isalsoan importantandprohibitivefactor.Competitionfromweedsisoneof themostdifficult impediments toestablishingnativevegetation,whichoftenpersists in theseedbank.Wecomparedannualapplicationsofthenonselectiveherbicideglyphosateovermultipleyears,followedbyafinalyearwiththegrass-specificfluazifop,asasimple,lowcostmethodofreducingtheexoticseedbanksufficientlytoallownativevegetationtoestablish.Thisapproachwascombinedwithseedingnativeforbs,herbaceousperennials,andshrubsinonehalfofeachtreatmentplot.Herbicidetreatmentsweremadeinthespringeachyearfrom2006to2010,andwerecombinedwithweedtrim-mingin2010and2011toremoveexoticforbinflorescences,andrakingtoremovelitter.In2010,nativeplantcoverinherbicide-treatedplotswasabout50%,consistingof43species,comparedto<5%coverinthecontrolplots.Mostofthenativeplantscamefromtheexistingseedbank,andveryfewfromtheseedmix.Acost analysis showed that aonce-yearlyherbicide treatmentwasaseffectiveasoneap-plicationplusspotsprayingorhandinflorescencetrimming,andismorecost-effectivethanhandweedcontrolandrakingforrestoration.

Index terms:coastalsagescrub,fluazifop,glyphosate,herbicide,weeds

INTRODUCTION

Coastal sage scrub (CSS) is a Mediter-ranean-typefloristiccommunityinlowerelevationCaliforniaandnorthernBajaCali-fornia,Mexico(Rundel2007).InsouthernCalifornia,itoccursinacoastalbandfromSantaBarbaraonthenorthtoSanDiegoin the south and inland to the Riversidearea. CSS vegetation is diverse and spe-ciesrich,buttypicallydominatedbyafewshrubspecies,suchasArtemisia californica Less., Eriogonum fasciculatum Benth., Salvia mellifera Greene, S. leucophylla Greene,and Rhus integrifolia (Nutt.)Rothr. (WeaverandClements1938;Rundel2007).Rainfallislimitingthroughoutthisrange,averaging450mminthenorthernextentto250mminthesouthandinlandregions.Rainfallssporadicallyandunpredictablyfrom fall through spring, followed by asummerdrought offiveormoremonths(Dallman1998).Severalofthedominantspeciesaredroughtdeciduous, includingA. californicaandtheSalviaspecies.Otherdominant species exhibit sclerophyllousleaves, small leaves, are succulents, orhaveextensiverootsystems.

EuropeansettlementofCaliforniaresultedin extensive loss of CSS and conversionto exotic annual grassland (Minnich andDezzani1998;Allenetal.2000;TallutoandSuding2008;Flemingetal.2009).Early

Spanishcolonistsinthelate18thcenturyintroducedextensivelivestockgrazing,andmanagement practices through the early20th century often included intentionalfiretoburnoffscrubandencourageforage(Burcham 1957). Most lands within therange of CSS that were level enough totillwereconvertedtoagricultureorpasturebeforethefirststatewidevegetationsurveyofthe1930s(VegetationTypeMap;Coxet al. 2014). Some of these lands havemorerecentlybeenconverted tohousingdevelopments(Chenetal.2010),asCSSincludesthemostdesirablecoastallandsforurbanexpansion.Theresultisthesignifi-cantlossofCSSvegetation.EstimatesofpresettlementCSSthathasbeenconvertedto agriculture, urban development, andexotic annual grassland vary from 40 to90%(Westman1981;Clelandetal.2016).ThequalityofremainingCSScommunitiesvariesconsiderably;estimatessuggestthat50%oftheremaininghabitatisdegradedbyfrequentwildfires, invasiveplants,airpollution,andothercauses(Freudenbergeretal.1987;Allenetal.2000;Clelandetal.2016).

CSShasoneofthehighestconcentrationsoffederallylistedandrarespeciesintheUnited States, and is considered one ofthe most threatened ecosystems in thecountry(Nossetal.1995).Inanefforttopreserve CSS, government agencies and

Natural Areas Journal 36:20–28

R E S E A R C H A R T I C L E

3Correspondingauthor:carl@socalinvasives.com;(760)815-2777

•

Simple Approaches to Improve

Restoration of Coastal Sage Scrub Habitat in Southern

California

Carl E. Bell1,3

1UniversityofCaliforniaCooperativeExtension

SanDiego,CA

Edith B. Allen2

Kristin A. Weathers2

Milton McGiffen, Jr.2

2UniversityofCaliforniaDepartmentofBotanyand

PlantSciencesRiverside,CA

•

Volume 36 (1), 2016 Natural Areas Journal 21

private conservancies have been acquir-ing land as part of habitat conservationplanstopreventurbandevelopment(Scottetal.2006).Someof thisCSShabitat isundergoingrestorationbecausethenativevegetation has been replaced by exoticannuals. Former cattle ranches are typi-callythelargestcontiguouspropertiesthathaveconservationvalue,butalsoincludedegradedlands.Forexample,theCountyofSanDiegoBarnettRanchReservenearthe city of Ramona, California, whereweconductedour research,wasusedbyMission San Diego for cattle grazing inthe mid-eighteenth century. The Countybought the property in 2002 to becomepartoftheCountyMulti-SpeciesConser-vation Plan, a habitat conservation plandesigned to satisfy mitigation concernsregarding development and endangeredspecies (Helix Environmental Planning2004).The entire 294-ha reserve burnedinawildfireinNovember2003.Althoughthe property was purchased for its na-tive habitat value, approximately 95 hais dominated by weedy exotic grassesandforbs(HelixEnvironmentalPlanning2004). The presettlement habitat of thislandisunknown,butbasedonfragmentsof remnant vegetation it is likely that ithadbeenamixofCSS,nativeperennialgrassland, and native annual forb fields(HelixEnvironmentalPlanning2004).

Theseexoticgrasslandsdonotundergonat-uralsuccessiontoCSS,nativegrassland,orannualforbland(StylinskiandAllen1999;Allenetal.2005),andmustberestored.Removaloftheexoticgrasseswithherbi-cidesorothermethodshasbeenused torestoreCSSandnativegrassland(EliasonandAllen1997;Cioneetal.2002;GillespieandAllen2004;MarushiaandAllen2011;Belletal.2013;Kimballetal.2014),butexoticgrassremovalhasoftenbeentransi-toryorhasresultedinthereplacementoftheexoticgrasswithexoticforbs(Allenetal.2005;Tallutoetal.2006).Oneproblemmightbethedurationoftheweedremovalefforts,whichwasonly2–3yearsinthesestudies.Inadditiontoremovingtheextantexotic vegetation, we hypothesized thatsuccessful restoration also requires seedbankcontrol.Theexoticannualseedbankwas12,000perm2inCSSwithanintactshrubcoverbuthistoricallygrazed,while

the native seed density was only 400seeds/m2(CoxandAllen2008a).Ifseedinputs to the soil are stopped, the weedseed bank declines rapidly (Radosevichetal.2007).OurrestorationresearchwasdesignedtodeterminehowdifferentlevelsofinvasiveweedcontrolwouldinfluenceestablishmentfromthenativeseedbankofCSS(Allenetal.2001).Forcomparison,weincludedasubplottreatmentofseed-ingnativeforbsandshrubstoenhancethenativeseedbank(Allenetal.2001).Weedcontrolwasdoneannuallyusingherbicidestoreduceadditionstotheweedseedbankwhile allowing depletion of the existingseed.Anadaptivemanagementapproachwas used to control different weed lifeforms as the community developed overtime. To encourage establishment of thenative community of forbs and shrubs,the broad-spectrum herbicide used ini-tially was substituted by a grass-specificherbicideafter threeyears.At thispoint,inflorescencesofexoticforbsweretrimmedmanually to reduce their contribution tothe seedbank. If successful, this wouldbeasimple,relativelylowcostapproachthat could be adopted by land managersinSouthernCalifornia.

METHODS

Research plots were established on twosites approximately 100 m distant fromeach other within exotic grass and forb-dominated areas in the Barnett RanchReserve. The vegetation adjacent to theresearch site is a subassociation of CSSknown as inland, or Riversidean, sagescrub (Westman 1981). Our preliminaryvegetation survey showed ~1% cover ofnative shrubs and forbs in a matrix ofdenseexoticgrassesandforbs,suggestingthereisstillanativeseedbankthatmightgerminateuponreductionofexoticseeds.Site1was locatedonasouth-facinghillwitha30%slopeandwasdominatedbyexoticforbs.ThesoilatSite1isaCienabaveryrockycoarsesandyloam—ashallowsoil10to50cmdeepoverbedrockwithavery lowwater availability capacityofless than2cm.Site2was120m to thesoutheastofSite1,onflatterground(5to9%slope)withanorth-facingaspect.Site2wasdominatedbyexoticgrasses,withsoilcharacterizedasaFallbrookRockySandy

Loam—adeepersoil,50to100cmabovebedrock,andawateravailabilitycapacityof18cm.Elevationatbothsitesisabout450m.Meanprecipitationis414mmperseason (July 1 to June 30), but seasonalvariationovertheyearsofthisresearchwas152mmin the2006/07season,371mmin2007/08,285mmin2008/09,and441mmin2009/10,accompaniedbyconsid-erablein-seasonvariation(CIMIS2014).Thesitehasrelativelylowanthropogenicnitrogen deposition (~6 kg N ha-1 yr-1,Fennetal.2010).

Our research utilized a split-plot designwith three treatments at each of the twosites. Herbicide was the main plot treat-ment,appliedtoplots6×18mwithfivereplications per treatment. Treatmentswere; (1) herbicide applied once eachspringbroadcastoverthewholeplot(here-afterHerbicide1X),(2)herbicideappliedbroadcast once in the spring followedby spot spraying weeds as needed thatemergedafter the initial treatment(here-afterHerbicide2X),and(3)anunsprayedcontrolplot(hereaftercontrol).BroadcastherbicideapplicationsweremadeinFebru-ary or March each year depending uponexotic plant emergence following winterrains. Broadcast herbicide applicationsweremadewithahose-endsprayerwithaboomlessnozzle(Boominator1250)pres-sured by an electric diaphragm pump at275kPaandasprayvolumeof280Lha-1.Asurfactantwaspresent inallherbicideapplicationstoimproveherbicideabsorp-tion into theplant foliage.Spotsprayinginthesecondherbicidetreatmentwasdonetwoweeksafterthebroadcastapplicationwithahand-pressuredbackpack sprayer,usinga2%solutionofglyphosateinwater.Broadcastapplicationsweremadeoverthewholeplotonemergedweedsandnativeforbs,butcarewas taken toavoidappli-cationtothefewnativeshrubs(typicallyone or less per plot) that had survivedthewildfire.Theherbicideusedannuallyin 2006 through 2009 was glyphosate, anonselectiveherbicideappliedatarateof4.7L(0.28kgae)ha-1.

Subplotswereeitherseededwithamixofseven native CSS species or nonseeded.Subplotswereassigned randomly toonehalf of the main plots divided on the

22 Natural Areas Journal Volume 36 (1), 2016

axis,6×9m.SeedingoccurredinFebru-ary2007,thesecondseasonoftreatment.Before seeding, all unsprayed controlplotsweremowedto2–6cmheightwithstring trimmers to improve seed contactwithsoil.Themowedduffwasrakedofftheplots to buffer areas, taking care notto rake duff across different treatments.Theherbicidetreatedplotshadscantlitteror living plants so de-thatching was notneeded. Commercial seed (S&S SeedsInc.) thathadbeenimbibedfor24hourswere hand sown following duff removaland in anticipation of rainfall. SpeciessownincludedEriophyllum confertiflorum (DC)A. Gray, Eriogonum fasciculatum, Acmispon glaber (Vogel) Brouillet, A. strigosus (Nutt.) Brouillet, Marah mac-rocarpa (Greene)Greene, Crocanthemum aldersonii (Greene)Janch., and Cryptantha intermedia (A.Gray)Greene.Allseedhadbeen collected from naturally occurringplantsinthearea.Rainfallwas49mmthetwoweeksfollowingsowingandthetotalaccumulationwas78mmthe restof theseason until 1 July 2007 (CIMIS 2014).SpeciesnomenclaturefollowsBaldwinetal.(2012).

Becauseofincreasingnativespeciescoverin2010,fluazifop-P-butyl(FusiladeDX)herbicidewasbroadcasted23March2010at1.3Lha-1in theherbicide treatments.This herbicide, which generally is onlytoxictoPoaceae,canalsoinjureorinhibitseedproductionofsomeErodium species (ChristopherandHoltum2000;SteersandAllen 2010;Weathers 2013). Since Ero-diumwasthedominantgenusinthetreatedplots,theuseoffluazifop-P-butylofferedanopportunitytoreduceseedproductionbyErodiumspp. whileavoidinginjurytoabundantnativeflora.Theglyphosatespotspray treatments were also suspended in2010 and no herbicides were applied in2011.Toassist incontinueddepletionoftheweedseedbank,theinflorescencesofweedy species, principally Erodium spp.andHirschfeldia incana (L.)Lagr.-Fossat,were cut off with a string trimmer.ThisoperationcommencedinMarch2010andwasrepeatedfourtimesthroughtheseasonuntillateMay2010.

Data collected included plant cover andspeciesrichnessinone0.5by1.0-mfixed

quadratpersubplotinMayof2006,2007,and2008.In2009,datawerenotcollectedbecause of fiscal limitations. Data wereagaincollectedin2010.Foranalysis,coverdataforspecieswerecombinedintothreefunctional groups: native forbs, exoticforbs, and exotic grasses. Pretreatmentcover and richness data were collectedpriortothe2006herbicideapplication.Aone-wayANOVAofplotswithineachsiteshowednosignificantdifferencesincoverandrichnessoffunctionalgroupspriortotreatment application. The 2006 through2008 main plot cover data for May ofeachyearwereanalyzedwitharepeatedmeasuresANOVAforeachsiteandeachplantfunctionalgroup,wheretherepeatedmeasureiscoveroffunctionalgroupsoverthethreeyears(JMP2012).Subplotdatawere combined to have one sample permain plot (i.e., there were five replica-tions). The repeated measures analysisshowedsignificantyear(repeatedmeasure)by treatment interactions in most cases,sodatawerealsoanalyzedseparatelybyyearusingone-wayANOVAtocompareamongthethreetreatments.Arcsintrans-formationswereusedpriortoanalysistoimprovenormalityofthedata.Coverdataintablesandfiguresareback-transformedforpresentation(SteeleandTorre1980).Becauseoftheunknownimpactofalackofglyphosatetreatmentin2010,theeffectofthefluazifoptreatment,the2009gapindatacollection,andtheweedinflorescenceremovaleffect,the2010datawereanalyzedseparatelywith treatmentandreplicationasfactors.Whensignificantdifferences(P< 0.05) existed among treatment meanswithinayear, theywere separatedusingtheTukey-KramerHighlySignificantDif-ferenceTest(T-KHSD),P=0.05.

In 2011, an inventory of native shrubswastakencountingallindividualsoffivespecies (A. glaber, E. confertiflorum, E. fasciculatum, A. californica, and Salvia apiana Jeps.) in each of the 6 × 9-msubplots (total of 30 subplots). FactorialANOVAwasperformedoncountdataonthesefivespeciesandthecombineddataofthethreeseededspecies(A. glaber, E. confertiflorum and E. fasciculatum) inSite 1. There was low shrub emergenceinSite2,andmanyplotshadnoseededplants emerge at all, so these data were

notanalyzedstatistically. Site1dataweresubjected to square root transformationbeforeanalysistoimprovethehomogeneityofvariances(SteeleandTorre1980).

Recordswerekeptforalloperationsrel-evant to treatments. These included: theamountofherbicideused;thetimerequiredtospraytreatedplots,bothbroadcastandspot spray; and time required to trimweed inflorescences. This informationwasusedtocalculatecostsofrestorationtreatments.

RESULTS

Pretreatment cover at both sites wasdominated by a small number of mostlyexotic species, largely Erodium botrys (Cav.) Bertol. and exotic grasses (Table1).Thenativeplantcommunitycomprisedoffivespecieswhosecombinedcoverwaslessthan1%ineithersite(Table1).Post-treatmentcoverforeachfunctionalgroupwas affected significantly by herbicidetreatment compared to controls over thethreeyears2006–2008,withasignificantinteraction of the repeated measure bytreatment for native forbs in Site 2, butnotSite1(Table2).

Herbicide Treatment Effects on Plant Cover by Functional Group

Exotic grass cover was significantly de-creasedbyboththe1Xand2Xherbicidetreatments compared to controls in bothsites, and there were significant interac-tionsoftherepeatedmeasure(coveroverthree years) by treatment in both sites(Table2).Nineexoticgrassspecieswerepresent,nineinSite1andeightinSite2.Themost commonspecieswereBromus diandrus Roth, Hordeum murinum L. and Avena fatua L.Whiletherepeatedmeasuresanalysis showed an overall response bygrass over the three years in both sites,univariate analyses in 2006 showed thatpost-treatmentexoticgrasscoverdidnotdiffer between herbicide treatments ateithersite(F=3.777,P=0.07atSite1andF=0.504,P=0.620atSite2,Figures1a and 1d). However, the treatment waseffective by the second year of applica-tion,asbothherbicidetreatmentsgreatly

Volume 36 (1), 2016 Natural Areas Journal 23

reducedexoticgrasscovercomparedtotheunsprayedcontrolatbothsitesin2007(F=8.667,P=0.01atSite1andF=203.44,P<0.0001atSite2),2008(F=21.349,P=0.001atSite1andF=18.541,P=0.001atSite2),and2010(F=64.237,P< 0.0001 at Site 1 and F = 80.003, P <0.0001atSite2,Figures1aand1d).ExoticgrasscoverwasconsistentlyhigherinSite2(28.43±4.7%)thanSite1(5.67±1.3%).Exoticgrass cover increased annually inboth sites in the unsprayed control plots(F=27.706,P<0.0001forSite1andF=28.558,P<0.0001forSite2).

Exotic forb cover comprised 24 species,

18 in Site 1 and 22 in Site 2.The mostcommonspecieswereE. botrys, Lysima-chia arvensis (L.)U.Manns&Anderb. , H.incana and Silene gallica L.Exoticforbcoverwasalsosignificantlydecreasedbyboth the herbicide treatments comparedtotheunsprayedcontrolinbothsites,butthere were significant interactions of therepeatedmeasurebytreatment(Table2).The univariate analyses showed no sig-nificant differences in exotic forb coveramong herbicide treatments in the firstyear(F=2.235,P=0.169Site1andF=1.04,P=0.396inSite2,Figures1band1e). In the secondand thirdyears (2007and 2008), herbicide treatments greatly

reducedexoticforbcovercomparedtothecontrol(F=36.323,P<0.0001in2007and F = 11.839, P = 0.004 in 2008) inSite1(Figure1b).InSite2,Herbicide2Xexoticforbcoverwasnotdifferentfromthecontrolin2007(Figure1e).Conversely,in2008,theHerbicide2Xtreatmentreducedcovercomparedto thecontrol,while theHerbicide 1X treatment did not (Figure1e).ExoticforbcoverdataforHerbicide2X are not different from the control orHerbicide1XinSite1(Figure1b)in2010.In2010,however,Site2exoticforbcoverdataforbothHerbicide1XandHerbicide2Xaresignificantlygreaterthanthecontrol(Figure1e).

Site Native Species Exotic Forbs Exotic Grasses

Artemisia californica (0.3%) Hirschfeldia incana (0.3%) Avena sp. (0.2%)

Daucus pusillus (0.08%) Brassica nigra (0.1%) Bromus sp. (4.4%)

Acmispon glaber (.02%) Erodium botrys (60.1%) Hordeum sp. (0.03%)

E. ciculatarium (0.5%)

Logfia gallica (0.01%)

Hypochaeris glabra (0.1%)

Silene gallica (0.5%)

Total Cover: <1% Total Cover: 61.2% Total Cover: 5.3%

Ambrosia confertiflora (0.1%) Lysimachia arvensis (0.1%) Avena sp. (0.9%)

Pseudognaphalium californicum

(0.4%)

Convolvulus arvensis (0.1%) Bromus sp. (31.5%)

(0.4%) E. botrys (6.7%) Hordeum sp. (18.1%)

Rumex crispus (0.1%)

Total Cover: <1% Total Cover: 7.0% Total Cover: 49.8%

1

2

Table 1. Pretreatment percent cover estimates (n = 30) by experimental site. Barnett Ranch Reserve, Ramona, California, March 2006.

Factor

Site 1 df F P F P F P

Treatment 2 30.1 <0.0001 16.8 0.0003 11.6 0.0016

RM (cover over 3 years) 2 5.37 0.0118 10.1 0.0007 4.03 0.0309

RM X treatment 4 0.29 0.8795 9.4 <0.0001 10.5 <0.0001

Site 2

Treatment 2 15.7 0.0004 6.98 0.0098 56.8 <0.0001

RM (cover over 3 years) 2 40.4 <0.0001 65.3 <0.0001 16.9 <0.0001

RM X treatment 4 5.6 0.0024 7 0.0007 12.5 <0.0001

Native Forbs Exotic Forbs Exotic Grasses

Table 2. Statistics (df, F, and P values) for repeated measures ANOVA and interactions for percent cover at Site 1 (forb site) and Site 2 (grass site). The repeated measure (RM) is cover over three years (2006–2008) with three treatments (herbicide 1X, herbicide 2X, and control) and five replications. Analysis conducted on arcsin transformed data. Data collected June 2006 through June 2010 at Barnett Ranch Reserve, Ramona, California.

2� Natural Areas Journal Volume 36 (1), 2016

Figure 1. Exotic grass, exotic forb, and native forb percent cover ± SEM by experimental site as affected by treatment, Barnett Ranch Reserve, Ramona, California, 2006 through 2010. Plots were treated with herbicides annually in spring prior to vegetation sampling each May, and were seeded with native species in February 2007. Figure 1a is exotic grass cover in Site 1; 1b is exotic forb cover in Site 1; 1c is native forb cover in Site 1. Figure 1d is exotic grass cover in Site 2; 1e is exotic forb cover in Site 2; 1f is native forb cover in Site 2. Treatment means within a year that share the same letter above the bars are not different according to the Tukey-kramer Highly Significant Difference Test, P = 0.05. Lack of letters above the means indicate that there were no significant differences among treatments.

Volume 36 (1), 2016 Natural Areas Journal 2�

Native forb cover increased significantlyafter herbicide treatments in both sitesoverthreeyearsusingrepeatedmeasuresANOVA,andtherewasasignificantinter-actionoftherepeatedmeasurebytreatmentinSite2,butnotSite1(Table2).Herbicidetreatments improvednativeforbcover inall three years in Site 1 (F = 5.37 P =0.012;Figure1c).InSite2therewasnosignificanteffect in2006(F=0.93,P=0.435),butherbicidetreatmentsimprovednativeforbcover in2007and2008(F=15.30, P = 0.0018 and F = 18.53, P =0.001, respectively;Figure1f).Similarlyin 2010, the univariate analyses showedthat native forbs had greater cover witheitherherbicidetreatment(F=17.006,P=0.0013forSite1andF=14.435,P=0.0022forSite2).Therewerenosignifi-cantdifferencesbetweenthetwoherbicidetreatmentsinanyyearfornativeforbcoverateithersite,onlybetweentheherbicidetreatmentsandthecontrol.

Seeded Native Species

Seeded native species cover was lowthroughouttheexperiment.Twoofsevenseeded species, M. macrocarpa and C. aldersonii,werenotdetectedinanyoftheplotsinanyyear.Coverneverexceeded2%for the other five seeded species for thedurationof theexperiment.Thoseplantsthatdidemerge,however,were,withoneexception,inherbicidetreatedplots.

Shrub Establishment

The 2011 shrub inventory had enough

germinated shrubs to meet the standardsofnormallydistributeddata forANOVAin Site 1 for four species, but not for S. apiana (Table3).Site2didnothavesuf-ficient shrub data for statistical analysis.In the caseofA. californica,whichwasnot seeded, small plants (mature plantsthatsurvivedthe2003wildfirewerenotcounted)werefoundinthemainplotandsubplotsregardlessoftreatment.Althoughnumbers were higher in the herbicidetreatedsubplots(1.9plantsperplot)thanthecontrols(0.4plantsperplot),noneofthefactorsinthemodel(mainplotherbicidetreatment, subplot seeding treatment, orthe interactionofmainplotandsubplot)werestatisticallydifferent.Withthethreeseededspecies,mainplottreatmentwasasignificantfactorintheANOVAmodelforE. fasciculatum (F=17.059,P=0.0004)and thecombined inventory forall threespecies(F=15.254,P=0.001),butnotforE. confertiflorum(F=2.595,P=0.120)or A. glaber (F=3.055,P=0.093).Seedingwasasignificantfactorforall threespe-cies(A. glaber,F=11.001,P=0.003; E. confertiflorum, F=9.133,P=0.006; and E. fasciculatum, F=37.588,P<0.0001)andthecombinedtotals(F=42.253,P<0.0001).AlloftheS. apianaplantswereinherbicidetreatedplots.

DISCUSSION AND CONCLUSIONS

Nativeforbandshrubspecies,bothextantand introduced as seed, benefitted fromannual herbicide treatments for severalyears (Figures 1c and 1f, Table 3). Theimprovementinnativespeciescoverseems

tobemostlyrelatedtocontrollingexoticannual grasses (Figure 1a vs. 1c and 1dvs.1f)aswasobservedinotherCSSres-torationstudies(Cioneetal.2002;Allenetal.2005;Tallutoetal.2006;CoxandAllen2008b;Kimballetal.2014).Atotalof43nativespeciesemergedonthesetwositeswithcoverupto50%intheabsenceofseeding.Thisishopefulforrestorationefforts that rely entirely on the remnantnative seedbank, especially consideringthat this was a ranch used continuouslyformorethantwocenturies.

This also suggests that concentrating onexoticannualgrasscontrolcanbeause-ful,simple,low-costrestorationtechnique(Table 4).The cost of 1X herbicide wasestimated at $604/ha total for fouryearsofapplication.Thisprovidedweedcontrolequaltoothermorecostlytreatments,andnative cover establishment as effectivelyasmorecostlyseeding.Themultiyearap-proachcanalsoberecommendedinorderto exhaust exotic seed banks, especiallyof grass species. However, there is littlesupportinthedataforthefollow-upher-bicidetreatment(Herbicide2X)intermsofweedcontrolandcostcomparedtojustonebroadcastapplication(Herbicide1X)inthespring(Figure1,Table4).Rakinglitterinthecontrolplotstoimproveseedcontactwithsoilandhandweedtrimmingaddedconsiderablecost.Plotstreatedwithglyphosate were sparse in litter, provid-ingsoilcontactforseeds.Handtrimminginflorescencesfollowingfluazifopin2010did not reduce exotic forbs compared totheherbicidetreatmentsalone(Figure1b,1e),sothispracticewasalsonotcost-ef-

Species

Seeded Not Seeded Seeded Not Seeded Seeded Not Seeded

Acmispon glaber 4.6 (1–9) 2 (0–5) 5.2 (1–13) 1 (0–3) 2.8 (0–8) 0.4 (0–2)

Eriogonum fasciculatum 14.2 (8–25) 1.6 (0–8) 16.2 (12–26) 2.2 (0–6) 0.8 (0–2) 0.2 (0–1)

Eriophyllum confertiflorum 5.2 (0–15) 0 8 (0–19) 0.2 (0–1) 0 0

Combined seeded species 24 3.6 29.4 3.4 3.6 0.6

Artemisia californica

(Unseeded)

Herbicide 2X ControlHerbicide 1X

5.6 (0–16) 2.0 (0–5) 0.8 (0–1)

Table 3. Shrub inventory for three species seeded in Site 1, Barnett Ranch Reserve. Values are mean counts of five plots (5.7 m2) followed by range of low to high counts per plot. Barnett Ranch Reserve, Ramona, California, June 2011.

26 Natural Areas Journal Volume 36 (1), 2016

fective. Manual removal of exotic forbinflorescencestoeliminateseedrainwaseffectiveforH. incana andotherboltingexoticforbs(i.e.,Sonchus asper (L.)Hillssp.asper and Centaurea melitensis L.),butdidnotreduceshorter-staturedexoticforbspecies(i.e.,Erodium spp., S. gallica, L. arvensis)(DiTomaso2002;Radosevichetal.2007). Thispracticewasrelativelylaborintensive, but could be useful in limitedsituations (Table4).AnaddedbenefitofexoticgrasscontrolisreducingtheeasilyignitablewildfirefuelprovidedbysenescedgrassesinlandscapesthroughoutSouthern

California(Cioneetal.2002;Allenetal.2005;Belletal.2009).

One concern of using a broad-spectrumherbicide, such as glyphosate, is thatthenative specieswill alsobe impacted.Nevertheless, native species cover wassignificantlygreaterthanuntreatedplotsinallyearsexceptthefirst.Thisindicatesthatthetimingofourtreatmentswasappropri-atetocontrolexoticplantswhileallowingnatives togrow.Thephenologyofmanynativespeciesislaterthanexoticgrassesandforbs(SteersandAllen2010).Evenif

nativesweredamagedbyherbicide,asuf-ficientnumbersurvivedorgerminatedafterherbicideapplication that theycontinuedto show a positive response to herbicidetreatments.Controlofexoticforbs(mainlyErodiumspp.)wassuccessfulfrom2006to2008,butnot in the long term in thisstudy. We switched to the grass-specificherbicidefluazifopin2009toreducedam-agetonativeforbs,but thisalsoallowedexoticforbstoflourish(Figure1b).PriorstudiesindicatedthatErodiumcicutarium (L.)Aiton,andotherspeciesofErodium,are controlled by fluazifop (Christopher

Materials Labor Total

Herbicide 1X Annual broadcast herbicide application1 $354 $250 $604

Herbicide 1X plus Annual broadcast herbicide application1

$354 $250

seeding Seeding2

$2,000 $50

Annual broadcast herbicide application1

$354 $250

Seeding2

$2,000 $50

Inflorescence trimming3 0 $3,500

Annual broadcast herbicide application1

$354 $250

Spot spray herbicide4

$52 $720

Annual broadcast herbicide application1

$354 $250

Spot spray herbicide4

$52 $720

Seeding2

$2,000 $50

Annual broadcast herbicide application1

$354 $250

Seeding2

$2,000 $50

Spot spray herbicide4

$52 $720

Inflorescence trimming3

0 $3,500

De-thatch before seeding5

$10,000

Seeding2

$2,000 $50

Activity------------------------ $/ha -----------------------

Treatment

$2,654

Herbicide 1X plus

seeding plus

inflorescence

trimming

$6,154

Herbicide 2X $1,376

1 Broadcast herbicide application for 2006–2009; materials were glyphosate at 5 L/ha/year x $13/L x 4 years = $260, fluazifop at

1.3L/one year x $72/ L = $94; labor cost at $20/hour x 2.5 hour/ha/year x 5 years = $250.2 Seed cost from suppliers invoice and recommended seeding rates; labor at $20/hour x 2.5 hour/ha for hand seeding.

3 Inflorescence trimming = utilizing a string trimmer or swing blade, 148 hours/ha x $20/hour in 2010, 49 hours/ha x $20/hour in

2011, applied across all herbicide treated plots. 4 Spot spray application for 2006–2009; material was glyphosate at 1 L/ha/year x $13/L x 4 years = $52; labor cost $20/hour x 9

hour/year x 4 years = $720.5 De-thatch labor cost at $20/hour x 500 hours/ha = $10,000 in first year only.

Herbicide 2X plus

seeding$3,426

Herbicide 2X plus

seeding plus

inflorescence

trimming

$6,926

Control $12,050

Table 4. Field management activity costs, on a per hectare basis in US dollars, March 2006 through April 2011, Barnett Ranch Reserve, Ramona, Cali-fornia.

Volume 36 (1), 2016 Natural Areas Journal 2�

andHoltum2000;SteersandAllen2010),but the dominant species at our site, E. botrys, was not controlled. We furtherattributethepersistenceofexoticforbstotheirlongevityintheseedbankcomparedtotheexoticgrassseedbank(Radosevichetal.2007;CoxandAllen2008a).Exoticforbcoverdecreasedannuallyfrom2006through2008whentreatedwithherbicide,but the lack of effective control in 2010apparently allowed the exotic forbs tore-infest the area resulting in very highpercentcoverin2010(Figure1band1e).Experiments that compared competitionofexoticforbs(especiallyErodiumspp.)withexoticgrass(GillespieandAllen2004;CoxandAllen2011)showedthatErodiumdidnotinhibitnativeforbestablishmentasmuchasexoticgrasses,suggestingcontrolofexoticforbsmaynotalwaysbecriticalforrestoration.Inotherwords,continuingtheannualherbicideapplicationuntiltheexotic forb seedbank was depleted maynotbecosteffectiveandmayalsonega-tivelyimpactseedproductionbynatives.Furthermore, these were relatively smallplots and could easily be reinvaded byadjacentweedyvegetation(Baythavongetal.2009).Allrestorationsitesareuniqueand will require adaptive managementtailored to the local conditions (ClewellandRieger1997).

Our results, aswell as published studiesonrestorationseeding,supporttwoconclu-sions.Oneisthatseedingwassuccessfulin introducing (or re-introducing) someofthesespeciestoourstudysites(Table3) (EliasonandAllen1997;Cioneet al.2002; Cox andAllen 2008b). The otheristhateliminatingtheexoticgrasseswasclearly beneficial to germination andestablishmentoftheseseededspecies,asalso supported by other studies (Eliasonand Allen 1997; Cox and Allen 2008b,2011;MarushiaandAllen2011;Kimballet al. 2014). Mowing and de-thatchingexoticplantswasthemostexpensiveandleastsuccessfulpractice,especiallywhencomparedtousinganherbicide(Table4)(Allenetal.2005).Establishmentofpur-chasednativeseedwaslessthan0.1%oftheseedsown.Wedonothaveanexplana-tion for this result, but lackof sufficientprecipitationfollowingsowingisalikelycause (EliasonandAllen1997;Cioneet

al. 2002).The expense of the purchasedseedclearlyoutweighsthebenefitinthiscase,andshouldbeweighedinsituationswhereanativeseedbankispresent.

ACKNOWLEDGMENTS

We thank Christopher True for field as-sistance,theCountyofSanDiegoDepart-mentofParksandRecreationfortheuseoftheBarnettRanchOpenSpaceReservefor this research, and theCountyofSanDiegoLandUseandEnvironmentGroupforfunding.

Carl Bell is Emeritus Extension Advisor, University of California Cooperative Ex-tension, San Diego, CA. He has BA and MA degrees from California State University Long Beach. His research efforts have focused on management of invasive plant species and competition between native and exotic plants in natural habitats. He is a Past President and Honorary Member of the California Weed Science Society.

Edith B. Allen is Professor and Coopera-tive Extension Specialist in the Department of Botany and Plant Sciences, University of California, Riverside. She has a BS degree from Tufts University, and MS and PhD degrees in Botany from Rutgers University and the University of Wyoming. Her research interests include restoration ecology, invasive species ecology, and soil and mycorrhizal ecology. She is a Fellow of the AAAS, a Fulbright Specialist Award recipient, and past president of the Soil Ecology Society.

Kristin Weathers is currently Associate Faculty in Biology at Mount San Jacinto Community College in San Jacinto, Califor-nia. She has a BS from Trinity University, an MS from Colorado State University, and a PhD from University of California, Riverside. Previously she worked as a contractor managing restoration and weed management projects on a Superfund site and as natural resource support for the US Marine Corps. Her research interests include restoration and wildland weed management with particular interest in methods that can be feasibly implemented on larger scales.

Milt McGiffen graduated from the Pennsyl-vania and North Carolina State Universi-ties, then worked at the Illinois Natural History Survey as a Research Biologist for seven years. After earning his PhD from the University of Illinois, he worked for a year as a Research Agronomist at the USDA’s North Central Soil Conservation Laboratory. Since 1992, Milt has been an Extension Specialist at the University of California and is currently the Vice Chair for Extension in the Department of Botany and Plant Sciences.

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