conifer transplant survival in urban forests ben peterson · 2013-06-06 · conifer transplant...

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.