ConiferTransplantSurvivalinUrbanForestsBenPeterson
ObjectiveWhatistheeffectofmulchand/orsupplementalirrigationonthesurvivalandgrowthrateoftwotransplantedshadetolerantconiferseedlings:1.westernredcedar(Thujaplicata)2.westernhemlock(Tsugaheterophylla)
Methods• StudyconductedatthreeurbanforestparksonMercerIsland,WA• Clearedeachplantingplotsofallweeds(5’diameter)• 2species:Bare‐rootwesternredcedarandwesternhemlockseedlings(500+total)• Fourtreatmentsplantedinarandomizedblockdesign:
• Bareground(control)• 3’ringofmulch(arboristswoodchips)(4”deep)• Irrigationsupplement(acellulosebasedgelthatslowlyreleases1qt
ofwaterovera3‐monthperiod)• Mulch+irrigationsupplement
• SurvivalandGrowth(height&diameter)monitoredfortwoyears
ResultsSurvival:• Mulchedtreeshadasignificantlyhighersurvivalratethannon‐mulchedtrees(forbothcedarandhemlock).• Therewasnosignificantdifferenceinsurvivalbetweenplantswithandwithouttheirrigationsupplement(IS)
Growth:• TherewasnosignificantdifferenceingrowthoverthetwoyearperiodforeitherthemulchorIStreatment.
Recommendations• Usemulchtoincreasethechancesofsurvival.• (Evenmoremulchmaybebetter.)• Don’twastemoneyonirrigationgels,theydidn’tmakeadifferenceinthisstudy.• NeithermulchorISincreasedtreegrowth,soifincreasedgrowthisyourgoal,trysomethingelse.
Thanksto:AmandaStuckey,KernEwing,Soo‐HyungKim,PaulWestBeniscurrentlypursuingamastersdegreeinRestorationEcologywithDr.KernEwing.Additionalresearchwaspartofthisstudy.Tofindoutmoreyoumaycontacthimatbmp4@u.washington.edu
Bareground(control)
Mulch
Irrigationsupplement(IS)
Mulch+IS
Treatments
average%survival
cedar hemlock
allmulchedtrees
51% 45%
allnon‐mulchedtrees
34% 22%
BackgroundNativeconifertreesinPugetSoundareaurbanforestsareindecline.Logginginthelate1800’sleadtoapaucityofconifersandconiferseedsource.Thenativedeciduoustrees(bigleafmaple&alder)thatreplacedtheconifersarenearingtheendoftheirlifespan.Atthesametime,invasiveplantsinurbanforestspreventnewtreeestablishment.Becauseoftheseissues,littlenewnaturalconiferregenerationhasoccurred.Thisstudyexamineswaystoimproveestablishmentsuccessoftwoconiferousspecies(westernredcedarandwesternhemlock)thatareparticularlydifficulttogetestablishedinurbanforestrestoration.
