RESTORATION OF THE CALAVERAS NORTH GROVE · 2020. 3. 29. · averaged about 60 to 80 large, mature...
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RESTORATION OF THE CALAVERAS NORTH GROVE CALAVERAS NORTH GROVE RESTORATION The California Department of Parks and Recreation has begun a major project to restore the health of the North Grove forest ecosystem – a project that will take several years to complete. Funding for this project has been provided by the Sierra Nevada Conservancy, an agency of the State of California. Crews will be thinning the forest of small and medium sized trees, creating a forest that we believe will reflect the species composition and stand density of a natural ecosystem. These actions in turn will reduce two major threats common to many forests in the Sierra Nevada: fire and insect attack. WHY IS THE FOREST IN NEED OF RESTORATION? Prior to the 1860s, the forests of the Sierra Nevada existed in a natural state, with the various species of trees controlled by the processes of nature. Some species, such as ponderosa pine, were found in open, sunny stands on ridge tops and south facing slopes. Shade tolerant species, such as white fir, were concentrated in somewhat denser stands on the cooler north facing slopes and within the well‐shaded grove of mature giant sequoias. These relationships were maintained by exposure to frequent, low intensity, unregulated fires. Scientists have determined that fires occurred in the landscape about every ten years ‐ so frequently, in fact, that fuels did not have much of a chance to build up, and each subsequent fire would usually be patchy and of low intensity. Such fires did little damage to the large, old growth trees that dominated the forest, but did make life difficult for young trees, few of which could survive to maturity. This may sound like a bad thing, but limiting the reproduction of the forest was essential to keeping it healthy and intact. When humans began actively managing the forest one of the first things done was to prevent these periodic fires, which was thought at the time to be a good thing. Tree reproduction flourished and the forest became more and more dense, while at the same time the fuels that could feed a fire became heavier and more continuous over the landscape. Three things happened, as a result: 1) The species that did well in a shaded forest were very successful at creating new trees, while those whose seedlings needed lots of sunlight produced fewer and fewer offspring as the forest became darker, and – in the case of ponderosa pine – essentially stopped reproducing. 2) The increased density of trees was trying to compete in an ecosystem that did not also have corresponding increase in the vital
Transcript of RESTORATION OF THE CALAVERAS NORTH GROVE · 2020. 3. 29. · averaged about 60 to 80 large, mature...
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.
