restoration of the calaveras north grove · 2020. 3. 29. · averaged about 60 to 80 large, mature...
TRANSCRIPT
RESTORATIONOFTHE CALAVERASNORTHGROVE
CALAVERAS NORTH GROVE RESTORATION
TheCaliforniaDepartmentofParksandRecreationhasbegunamajorproject torestorethehealthoftheNorthGroveforest ecosystem – aprojectthat willtakeseveralyearstocomplete.FundingforthisprojecthasbeenprovidedbytheSierra NevadaConservancy,an agencyoftheStateofCalifornia.
Crews willbethinning theforest ofsmalland mediumsizedtrees,creatinga forestthat webelievewillreflect thespeciescompositionandstanddensityofanaturalecosystem.TheseactionsinturnwillreducetwomajorthreatscommontomanyforestsintheSierraNevada: fireandinsect attack.
WHYISTHEFORESTINNEEDOFRESTORATION? Prior tothe 1860s,the forestsof theSierraNevadaexisted ina naturalstate, withthevariousspeciesoftreescontrolledbytheprocessesofnature.Somespecies,suchasponderosapine,werefoundinopen,sunnystandsonridgetopsandsouthfacingslopes.Shadetolerantspecies,suchaswhitefir,wereconcentrated insomewhatdenserstandsonthecoolernorthfacingslopesandwithinthewell‐shadedgroveofmature giantsequoias.Theserelationshipsweremaintainedbyexposuretofrequent,lowintensity, unregulatedfires.
Scientistshavedeterminedthatfiresoccurred in thelandscapeabouteverytenyears‐sofrequently,infact,thatfuelsdidnot havemuchofachancetobuildup,andeachsubsequentfirewouldusuallybepatchyandoflowintensity.Suchfiresdidlittledamagetothelarge,old growthtreesthatdominatedtheforest,butdidmakelifedifficultfor youngtrees, fewofwhichcouldsurviveto maturity.Thismaysoundlikeabadthing,butlimitingthereproductionoftheforestwasessentialtokeepingit healthyand intact.
Whenhumansbeganactivelymanagingtheforestoneofthefirstthingsdonewastopreventtheseperiodic fires,whichwas thoughtatthetimetobeagoodthing.Treereproductionflourishedandtheforestbecamemoreand moredense,whileat the sametime thefuelsthat couldfeed afirebecame heavierand morecontinuousoverthelandscape.Threethingshappened,asaresult:
1) Thespecies thatdidwellinashadedforestwereverysuccessfulatcreatingnewtrees,whilethosewhoseseedlingsneededlotsofsunlightproducedfewerand feweroffspringas theforest becamedarker,and–inthecaseofponderosa pine– essentially stoppedreproducing.
2) Theincreaseddensity oftreeswas tryingtocompetein anecosystemthatdid notalsohavecorrespondingincreasein thevital
resourcesneeded forgrowth,especiallysoilmoisture.Thetreeswithdrewwaterfrom theground atagrowingratewhiletheaverage amountofwater(fromannualrainandsnowfall)remainedthesame. Asthis problemgrew,treesessentiallyexperiencedmanyartificiallyinduceddroughtyears.
3) Thelongperiodbetweenfires,coupledwiththeimmenselyincreasedamountoffuel,guaranteed thatfuture fireswouldbevery,very,destructive tothe trees,wildlife,andwatersheds.
WHAT ARE WE TRYING TO DO? Ecologistsfeelthatthe primevalforestsof the parkaveraged about60to80large,maturetrees peracre,withreproductionlimited tosmallpatchesscatteredthroughoutthestand.Today,wehavemanyparts oftheforest thathave 300to400 trees peracre,andsometimesmanymore!Reproductionisnowevenlydistributedthroughouttheforest,butmostlyconsistsofshadelovingspecies,especiallywhitefirand incensecedar evenunderneath themajesticponderosapines. Our goalsareto restore normaldensitiesand distributionsofallspecies, andtoallowfiretoplayitshistoricalroleintheforestecology.
WHAT ABOUT THE GIANT SEQUOIAS?
Fireplayedanimportantroleinthe ancientforest, anditwasacriticalfactor intheecologyofgiant sequoias;in theabsence offrequent fire,there hasbeena failureofthespeciesto reproduceand theold‐growthtreesthathavenaturally toppledanddiedhavenotbeenreplaced.The groveis nowdisappearing–very,veryslowly,ofcourse,butifleftunchecked,disappearancewillbetheultimateandtragicresult.
Thefrequentfires that naturallyoccurredinsequoiagrovesbefore man‐madesuppressioncausedthe massivereleaseofseedsfromthe canopyofthebigtrees –perhapsasmanyas200,000seedsPERTREE!Ifthisrainofseedsoccurredundersuitableconditionsitcouldresult inacarpetofseedlingsacrosstheforestfloorprovidinga suitablebank ofyoungtrees,someofwhichwouldsurvive tobecomesaplings,someofwhichwouldsurvive tobecomepolesizedtrees,untilfinallyoneeventually survivestoreplace the parenttree.
Wewillbeusingfireto burnmuchofthebiomass generatedbythisthinning project;whenwestartworkingwithinthegroveitself,we will strategicallyplacethefiresinsuchawaysoastostimulateseedrelease and(hopefully)successfulreproduction.
WHAT HAPPENS NEXT? Oncethestructureofthe foresthas beenrestored, weintendto maintain the workbyputtingfirebackintoitsnaturalrole.Deliberatelyignitedandcloselycontrolledsmallfireswillbesetwhenitcanbedonesafely.Hopefully,inyourfuturevisitstotheforest youwillseeahealthy,vibrant,andproductiveNorthGrove.