Colonization of fire-damaged trees by Ips sexdentatus (Boerner) as related to the percentage of burnt crown

2006·0.14 MB·

by  M. Mercedes Fernández Fernández

©EntomologicaFennica.8December2006
Colonization of fire-damaged trees by Ips sexdentatus
(Boerner) as related to the percentage of burnt crown
M.MercedesFernándezFernández
FernándezFernández,M.M.2006:Colonizationoffire-damagedtreesby Ips
sexdentatus(Boerner)asrelatedtothepercentageofburntcrown.—Entomol.
Fennica17:381–386.
Theaimofthisstudyistodeterminehowbarkbeetlescoloniseafterawildfire.
Five categories of trees were established according to the percentage of burnt
crown(0%,25%,50%,75%and100%)inaPinuspinasterforestinLeónprov-
incethathadbeenburntbyawildfirein1998.During2000and2001astudywas
carriedoutonthepercentageoftreesattackedineachcategory,thedistributionof
attacksonthetreetrunk,crowndecoloration,numberofmaternalgalleriesbored
andthenumberoftreesresistingattack.Only20%ofthetrees(allofthemwith
0% unburnt crown) survived the attack. This study shows the capacity of Ips
sexdentatusasaprimarypestandrecommendstheremovalofdeadanddying
treesafterawildfirebeforeitspopulationgrowslargeenoughtokilltheremain-
inghealthyones.
M.M.FernándezFernández,ÁreadeZoología,Dpto.CienciasAgroforestales,
ETSIIAAdePalencia,UniversidaddeValladolid,Avda,Madrid,44,edificioE,
34071Palencia,Spain;E-mail:[email protected]
Received23February2005,accepted8December2005
1.Introduction speciesthatattackedtreesinthestudiedwildfire
areawasIpssexdentatus(Fernández&Salgado
Every yearalargenumberofdevastatingforest 1999).Thisspeciestransportspathogenicfungal
firesoccur intheIberianPeninsula. Leónisthe spores (Lieutier & Yart 1989, Lieutier et al.
secondmostaffectedprovinceintheCastillaand 1989a),mainlyOphiostomaipsandOphiostoma
Leónregion.Afterawildfire,thereisaconsider- brunneo-ciliatum(Lieutieretal.1989b,Fernán-
ableincreaseinthenumberoftreessusceptibleto dezetal.2004),inthepuncturepitsofthemandi-
colonisationbyxylophagousinsects.Theriskof bles and sides of the pronotum and elytra
barkbeetleattacksincreasesduetothedecreased (Lévieux et al. 1991). After being attacked, the
hostresistance(Geiszleretal.1984)andmortal- treereleasesconstitutiveresin through theresin
ity of fire-injured trees (Thomas & Age 1986, ductsofthephloemandxylem.Thisresinrepels
McCullough et al. 1998). Fire-damaged trees or pitches out the beetles (Christiansen et al.
emithighconcentrationsofvolatileterpenesthat 1987, Långström et al. 1992, Lieutier 2002). A
indicate reduced vigour of the host. These hyper-sensitive reaction develops where a ne-
terpenes may attract beetles – first bark beetles croticareaimpregnatedwithresinousandpheno-
andlateronothersecondaryxylophagousinsects liccompoundspreventsbeetlegalleryconstruc-
–fromoutsidetheburnedarea(Muona&Ruta- tion and fungal proliferation (Berryman 1969,
nen1994). Wong & Berryman 1977, Mattson et al. 1988,
Themostfrequentandeconomicallyharmful Raffaetal.1985,Lieutier1990).
382 FernándezFernández (cid:127) ENTOMOL.FENNICAVol.17
Table1.ValuesforDBH,heightandresinosisinthedifferenttreecategoriesinautumn1999.
Percentageof DBH Height(m) Resinosis(%)
burntcrown mean±S.D. 0 1 2
0(greentrees) 28.26±3.95 9.31±0.85 70 20 10
25(bluetrees) 25.79±2.63 9.54±0.31 50 10 40
50(yellowtrees) 25.26±3.79 8.83±1.13 80 10 10
75(redtrees) 24.44±2.77 8.34±0.60 80 20 0
100(blacktrees) 23.71±2.22 8.38±0.13 80 20 0
Theaimofthepresentstudywastodetermine 2.2.Fieldprocedure
(1)howtheaffectedtreesarecolonised(distribu-
tionoftheattacksinthetreetrunk)and(2)there- In autumn 1999, 50 remaining resin pines were
lationshipwiththepercentageofburntcrownto selected and classified into five categories (10
propose sanitary measures applicable to burnt treespercategory)tostudythecolonizationbyI.
forests and therefore slow down large-scale at- sexdentatusfromspringtoautumnduring2000–
tacksbyI.sexdentatus. 2001. Thecategorieswereestablishedbasedon
the percentage of burnt crown as follows: (1)
treeswithunburntcrowns(foliage100%intact,
2.Materialandmethods i.e.greentrees);(2)treeswith25%burntcrown
(bluetrees);(3)treeswith50%burntcrown(yel-
2.1.Studyarea lowtrees);(4)treeswith75%burntcrown(red
trees);(5)treeswith100%burntcrown,butwith
ThestudyareaislocatedintheSierradelTeleno freshphloemonthetrunk(blacktrees).Noneof
(León,NWSpain)at1,100ma.s.l.;itisanatural thetreeshadpreviouslybeenattackedbyI.sex-
P. pinaster Aiton forest of ca. 11,500 ha dentatusorotherscolytidsduring1999.
(29TQG2984U.T.M).Althoughfiresoccurfre- The DBH and height of the selected trees
quentlyinthisarea,therecoverypotentialishigh were measured at the beginning of the study.
duetothealmosttwomillionseedlings/hafound Trunkresinosis(aparameterusedforestimating
afterfires(Tapiaetal.1998). fireintensity)wasalsocalculatedandclassified
TheclimateisMediterraneanwithlongharsh intothreecategories:0(noresinonthetrunk),1
wintersandadryperiodlastingfromJulytothe (mediumresinosis)and2(highresinosis)(Table
end of September (Ministerio de Agricultura 1).
1980).Meanannualprecipitationis712mmand In 2000, the percentage of attacked trees in
meanannualtemperature+10ºC.Aninteresting
featureofthelocalclimateisthefrequencyofdry
stormsandlowprecipitationinspringandsum-
mer,whichoftencausecrownfires.Forexample,
in1979and1991,2,000haburned;in1993,400
ha, and in 1997, 700 ha (Sánchez 1990). How-
ever,the1998wildfirethatburnedover3,000ha
wasthelargestrecordedinthestudyarea.Itwas
favoured by high summer temperatures, strong
windsandlowprecipitationespeciallyduringthe
three months prior to the fire (September)
(Santallaetal.2002).Thefirewasofmediumin-
tensity and affected the tree crowns. The study
areawasclosetothefireperimeter;consequently,
Fig.1.Crowndecolorationforeachtreecategoryin
someofthetreeshadburntcompletelyandothers autumn2000.White:damagedneedles;grey:dry
remainedpartiallyintact. needles,andblack:noneedlesatall.
ENTOMOL.FENNICAVol.17 (cid:127) Colonizationoffire-damagedtreesbyIpssexdentatus 383
Table2.Percentageofattackedtreesandentranceholesdetectedinspringandautumn2000,percentageoflivetreesin2001
andpercentageofmaternalgalleriesboredineachtreecategory.S=Spring,A=Autumn.
%trees %trees Entranceholes %oftrees Maternal
burntcrown attacked alive galleries/m2
in2000 S2000 A2000 in2001 (mean±S.D.)
S A meann0/m2%<1m %>1m meann0/m2%<1m %>1m S A 2000–2001
0(greentrees) 0 10 0 0 0 11.27 100 0 70 20 5.28±7.13
25(bluetrees) 20 80 24.69 100 0 98.78 90 10 0 0 20.55±7.48
50(yellowtrees) 30 50 37.82 100 0 63.04 60 40 0 0 9.33±5.45
75(redtrees) 70 90 91.21 85 15 117.2 78 22 10 0 8.78±11.44
100(blacktrees) 20 50 26.86 100 0 67.16 100 0 0 0 9.44±5.54
each category was recorded and the number of equal variances were checked prior to analyses
entranceholes/m2detectedinthefirstandsecond (Sokal&Rohlf1996).
metre of tree trunk from the ground for both
springandautumn(Table2).Samplingwascar-
riedoutevery15daysfromApriltoOctober.At 3.Results
the end of the field season, changes in the tree
crowns were recorded for each category of tree 3.1.Percentageofattackedtrees
(Fig.1).Someofthemhadnoneedles(i.e.allhad
fallenoff),othersweredry(dry,reddishneedles Inspringandautumn2000,thenumberoftrees
onthecrown)ordamaged(treeswithmoregreen attackedbyI.sexdentatusineachselectedcate-
foliageandsomeyellowishneedles). gory was counted. In spring, the highest value
Inspringandautumn2001thepercentageof foundfortheattackedtreeswas70%forredtrees,
livetreeswasrecorded.InOctober2001,thebark whilethegreentreesshowednosignsofattack.
wasstrippedandthenumberofmaternalgaller- Samplinginautumnshowedthat90%ofthered
ies/m2boredin2000and2001wasrecordedfor treesand80%ofthebluetreeshadbeenattacked.
eachtreecategory(Table2). Asbeinglesssusceptible,only50%oftheyellow
andblacktrees,andonegreentree,hadbeenat-
tacked(Table2).
2.3.Statisticalanalyses Thegreentreeswereattackedin2001.Atthe
beginningofthesamplingperiod(spring),three
Because of missing cells, it was not possible to ofthemweredeadbuttheothersevenwerestill
perform a two-way Analysis of Variance alive.Inautumn,onlytwogreentreeswerestill
(ANOVA)withinteractiontotestdifferencesin alivewhiletheothershaddiedbecauseofI.sex-
thenumberofmaternalgalleriesamongtreecate- dentatusattacksduringthatyear.
gories(thefiveclassesaccordingtothepercent-
ageburntcrown;seeabove)andresinosisgroups
(thethreeclassesaccordingtodegreeofresinosis 3.2.Percentageofentranceholes
on tree trunks;,see above). Therefore, separate andtheirdistributiononthetreetrunk
ANOVAswereusedtotestthedifferencesamong
the tree categories and among the resinosis Thenumberofentranceholescountedinspring
groups.One-wayANOVAwasalsousedtotest 2000showedthattheattacksoccurredinthefirst
differencesinthedegreeofresinosisamongthe metre from the ground, except for the red trees
treecategories.Thesignificantresultsweresub- that had 15% of the holes bored in the second
jectedtoTukey’sposthoctestforpairwisecom- metre. Thehighestnumber ofholes/m2wasob-
parisonsofmeans.Assumptionsofnormalityand servedinredtrees,followedrespectivelybyyel-
384 FernándezFernández (cid:127) ENTOMOL.FENNICAVol.17
low, black and blue trees. In autumn, entrance trees had the lowest number of galleries bored
holesweredetectedinthefirstmetreofthetrunk (Table2).
of one green tree. In the blue and yellow trees, Thenumberofmaternalgalleriesintheblue
holeswereobservedinthesecondmetrefromthe trees(treeswith25%ofburntcrown)washigher
ground,thepercentagebeinghigherintheyellow thaninanyothercategory(Table2).Thediffer-
trees.Theredtreeshadmoreholesinthesecond ences between the tree categories were signifi-
metreinautumnthaninspring.Asfortheblack cant(F =10.12,p<0.001).However,onlythe
4,35
trees,thesituationwasthesameasinspring,that bluetreesdifferedfromtheothertreecategories
is,noentranceholesweredetectedinthesecond (p <0.02 in all Tukey tests for the comparisons
metrefromtheground(Table2).Thesetreeswere with blue trees; p >0.32 for the comparisons
the most affected by fire and were subjected to amongtheothertreecategories).
heavy attacks by secondary xylophagous Cole- Intermsofthenumberofmaternalgalleries,
optera,suchasCerambycidaeandBuprestidae. nosignificantdifferenceswerefoundamongthe
In2001,theentranceholesinthegreentrees resinosisgroups(F =0.28,p=0.75).However,
2,37
couldnotbecountedbecauseofthelownumber within the resinosis group 2 (the strongest resi-
ofattacksintheverythickbark.Maternalgaller- nosis), blue trees (25% burnt crown) with the
ieswereobservedinfourgreentreeswhenwede- highestnumberofmaternalgalleries/m2hadthe
barkedthetreesattheendofthesamplingperiod highestdegreeoftrunkresinosis(40%;Table1).
inOctober2001.However,inanotheronenogal- Correspondingly,thegreentreeshadfewersuc-
lerieswereobserved. cessfulmaternalgalleriesandlowresinosis.
Inthedegreeofresinosis,nosignificantdif-
ferences were found among the tree categories
3.3.Percentageoflivetrees, (F =1.86,p=0.13).
4,45
andcrowndecoloration
Inspring2001,samplingwascarriedoutongreen 4.Discussion
andredtrees,theonlyonesstillalive:onlyseven
greentreesandoneredtreewerestillalive.Inau- Crown scorch, foliage and bud mortality and
tumn,onlytwogreentreeswerestillalive(Table stemdamageinthebarkandcambiumlayerall
2);therestofthetreeshaddied. occurafterawildfireanddeterminewhetherthe
Inautumn2000,wenoticedthatthecolourof impacted trees survive. While complete scorch
thetreecrownsinallfourcategorieshadchanged causesrapidtreedeath,manytreeswithpartially
(exceptfortheblacktreeswithcompletelyburnt scorchedcrownssurvive.Thisstudyshowedthat
needles).Thesechangesintheinitialcolourofthe barkbeetlesinducemortalityinfire-injuredtrees
crowns were observed four months after the I. primarilyinthesecondyearfollowingfire.This
sexdentatus attack, when 55% of the selected patternhasalsobeenobservedbySantoroetal.
treeshaddied(Fig.1). (2001)inPinusponderosafordifferentspeciesof
IpsinNorthAmerica,wherehalfofthetreesat-
tacked in 1998 died in 1999, and the remainder
3.4.Abundanceofmaternalgalleries were partly girdled by the attacks, which in-
creases vulnerability to fires, insects and patho-
Thenumberofmaternalgalleriescountedinfour gens.
ofthefivecategoriescorrespondstotheattacksin Inourstudy wenoticedthatinspring2001,
2000.Thefinalmeannumberofmaternalgaller- 100% of the trees with 25% (blue trees), 50%
iesinthegreentreescorrespondstotheattacksin (yellow trees) and 100% (black trees) burnt
both2000and2001. crownhaddiedandonly10%ofthosewith75%
After debarking the trees, the blue trees had burnt crown (red trees) survived. The last red
the highest mean number of maternal galler- treesdiedsixmonthslater.Theblacktreesdied
ies/m2, followed by the black and yellow (with from the fire-caused damage, whereas all the
similar values) and red trees; finally, the green trees in the other categories, regardless of the
ENTOMOL.FENNICAVol.17 (cid:127) Colonizationoffire-damagedtreesbyIpssexdentatus 385
damage level, were attacked by bark beetles in secondaryxylophagousbeetles,suchasBupres-
2000andconsequentlydiedasaresultofthebee- tidae and Cerambycidae. The green trees (0%
tleattack.Asforthegreentrees,althoughmore burnt crown) will be attacked later on, at the
informationisneededfor2001onthenumberof phasewhenthepopulationofemergingbeetlesis
attacksandtheirdistribution,webelievethatthey high.InScotspine,Ehnströmetal.(1995)found
haddiedasaresultofI.sexdentatusattacks.At that most of the trees attacked by Tomicus
the end of the sampling season (October 2001) piniperdahadlessthan30%greencrown,while
onlytwogreentrees(0%burntcrown)werestill theWashingtonStateDepartmentofNaturalRe-
alive. sources(2001)affirmedthatapproximately40%
Thebluetrees,with25%burntcrown,hadthe of Pinus ponderosa pines with 50% or more
highestnumberofmaternalgalleriesandalsothe crownscorcharekilledbybarkbeetles.
highestvaluefortrunkresinosis.Ourstudyalso Weconcludethatthemosteffectivewaytore-
showed that when colonization started, I. sex- ducetheriskofmortalityinhealthystandingtrees
dentatusboredmoreholesintheredtreesthathad istoremovenearbydeadanddyingtreesbefore
low trunk resinosis levels. This coincides with theI.sexdentatuspopulationgrowslargeenough
observationsbyLieutieretal.(1988),Mattsonet tomoveinandattackhealthy,lessinjuredorre-
al.(1988)andFeeneyetal.(1998)whohavesug- coveringtrees.
gestedthattheresinflowisadefencereactionofa
tree to fire. In our study, the highest resin flow
wasobservedintheblue,yellowandgreentrees References
thathadgreatertreevitality;however,thesesub-
tledifferenceswerenotstatisticallysignificant. Berryman,A.1969:ResponseofAbiesgrandistoattack
Attheendofthecolonizationperiodin2000, by Scolytus ventralis (Coleoptera, Scolytidae). —
Can.Entomol.101:1033–1041.
theredtreeshadsufferedthehighestnumberofI.
Chararas, C. 1967: Recherches sur l’attractivité exercée
sexdentatus attacks. They were the only ones
par divers conifères a l’égard d’Ips sexdentatus. —
withentranceholesabovethefirstmetrefromthe
Ann.Soc.Entomol.Fr.3:777–785.
ground. This indicates that the trees with over Christiansen,E.,Waring,R.,&Berryman,A.1987:Resis-
75%affectedcrownswerethemostattractivefor tanceofconiferstobarkbeetleattack:searchingfor
thisspecies. generalrelationships.—ForestEcol.Manag.22:89–
106.
Thenumberofmaternalgalleriescountedat
Ehnström,B.,Långström,B.&Hellqvist,C.1995:Insects
theendof2001showedthatthebluetrees(with
inburnedforests-forestprotectionandfaunalconser-
50% green crowns) provided the best substrate
vation(preliminaryresults).—Entomol.Fennica6:
forlarvaldevelopment;thesetreeswerefollowed 109–117.
by the black, yellow and red ones with statisti- Feeney,S.,Kolb,T.,Covington,W.&Wagner,M.1998:
callysignificantdifferences. Influence on thinning and burning restoration treat-
ments on presettlement ponderosa pines at the Gus
Thegreentrees,thoughnotdirectlyaffected
Pearson Natural Area. — Can. J. Forest Res. 28:
bythefire,sufferedpost-firedroughtconditions
1295–1306.
andwerethelasttobeattacked(fourofthemwere Fernández,M.&Salgado,J.1999:Susceptibilityoffire-
attackedin2001)becauseofthehighbeetlepo- damagedpinetrees(PinuspinasterandPinusnigra)
pulation that developed in the other fire-injured toattacksbyIpssexdentatusandTomicuspiniperda
(Coleoptera;Scolytidae).—Entomol.Gen.24:105–
trees. Two years after the fire, only 20% of the
114.
green trees had survived. This finding indicates
Fernández,M.,García,A.&Lieutier,F.2004:Effectsof
thatI.sexdentatusisaprimaryparasitecapableof
variousdensitiesofOphiostomaipsinoculationson
attackinghealthytrees,assuggestedbyotherau- Pinus sylvestris in north-western Spain. — Forest
thors(Chararas1967,Gil&Pajares1986). Pathol.34:213–223.
Basedonourresults,itcanbededucedthatall Geiszler,D.,Gara,R.&Littke,W.1984:Barkbeetleinfes-
tationsoflogdepolepinePinuscontortavarmurray-
P.pinastertreeswith25–50%burntcrownsare
anafollowingafireinsouthcentralOregonUSA.—
thefirsttobeattackedbyI.sexdentatusandcon-
Z.Ang.Entomol.98:389–394.
sequently die. The black trees (100% burnt
Gil,L.&Pajares,J.1986:Losescolítidosdelasconíferas
crown)aremainlyusedfortheestablishmentof enlaPenínsulaIbérica.—MinisteriodeAgricultura,
386 FernándezFernández (cid:127) ENTOMOL.FENNICAVol.17
PescayAlimentación,I.N.I.A,Madrid.194pp.[In NorthAmerica.—Annu.Rev.Entomol.43:107–127.
Spanish.] Ministerio de Agricultura 1980: Caracterización agro-
Långström, B., Hellqvist, C., Ericsson, A. & Greef, D. climáticadelaprovinciadeLeón.—DirecciónGen-
1992:InduceddefensereactioninScotspinefollow- eraldeProducciónAgraria.SubdirecciónGeneralde
ing stem attacks by Tomicus piniperda L. — laProducciónVegetal.Madrid,España.162pp.[In
Ecography15:318–327. Spanish.]
Lévieux, J., Cassier, P., Guillaumni, D. & Roques, A. Muona,J.&Rutanen,I.1994:Theshort-termimpactof
1991: Structures implicated in the transportation of fireonthebeetlefaunainborealconiferousforest.—
pathogenic fungi by the european bark beetle, Ips Ann.Zool.Fenn.31:109–121.
sexdentatusBoerner:ultrastructureofamycangium. Raffa,K.,Berryman,A.,Simasko,J.,Teal,W.&Wong,B.
—Can.Entomol.123:245–254. 1985:Effectsofgranfirmonoterpenesonthefiren-
Lieutier,F.1990:Lesréactionsdedéfensedupinsylvestre graverbeetle,Scolytusventralis(Coleoptera,Scoly-
(Pinussylvestris)contrelesattaquesd’insectesscoly- tidae),anditssymbionticfungus.—Environ.Ento-
tides.—C.R.Acad.Agric.Fr.76:3–12. mol.14:552–556.
Lieutier,F.2002:Mechanismsofresistanceinconifersand
Sánchez, P. 1990: Selvicultura y ordenación del pino
bark beetle attack strategies. — In: Wagner, M.,
resinero(PinuspinasterAit.)enlasierradelTeleno
Clancy,K.,Lieutier,F.&Paine,T.(eds),Mechanisms
(León).—Montes56:69–76.[InSpanish.]
anddevelopmentofresistanceintreestoinsects:31–
Santalla,S.,Salgado,J.,Calvo,L.&Fernández,M.2002:
75. Academic Publishers, Dordrecht, The Nether-
ChangesintheCarabidaecommunityafteralargefire
lands,Kluwer.332pp.
inaPinuspinasterstand.—In:Trabaud,L.&Prodon,
Lieutier, F.& Yart, A. 1989: Preferenda thermiques des
A. (eds), Fire and Biological Processes: 215–231.
champigons associés à Ips sexdentatus Boern, et
BackhuysPublishers,Leiden,TheNetherlands.345
Tomicus piniperda L. (Coleoptera, Scolytidae). —
pp.
Ann.ForestSci.46:411–415.
Santoro,A.,Lombardero,M.,Ayres,M.&Ruel,J.2001:
Lieutier,F.,Yart,A.,Garcia,J.,Poupinel,B.&Levieux,J.
Interactionsbetweenfireandbarkbeetlesinanold
1988: Do fungi influence the establishment of bark
growthpineforest.—ForestEcol.Manag.144:245–
beetlesinScotspine?.—In:Mattson,W.,Levieux,J.,
254.
Bernard-Dagan,C.(eds),Mechanismsofwoodyplant
Sokal,R.&Rohlf,F.1996:Biometry.—Freeman,San
defensesagainstinsects:searchforpattern.Springer-
Francisco.887pp.
Verlag,NewYork–Berlin–Heidelberg.
Lieutier,F.,Cheniclet,C.&Garcia,J.1989a:Comparison Tapia,R.,Gil,L.&Pardos,J.1998:Lospinares(Pinus
ofthedefensereactionofPinuspinasterandPinus pinaster Ait.) de las estribaciones de la sierra del
sylvestristoattacksbytwobarkbeetles(Coleoptera, Teleno (León): La influencia del incendio en su
Scolytidae) and their associated fungi. — Environ. ordenación.—Montes52:115–120.[InSpanish.]
Entomol.18:228–234. Thomas, T. & Age, J. 1986: Prescribed fire effects on
Lieutier,F.,Yart,A.,Garcia,J.,Ham,M.,Morelet,M.& mixedconiferforeststructureatCraterLakeOregon,
Levieux, J. 1989b: Champignons phytopathogènes USA.—Can.Entomol.16:1082–1087.
associésàdeuxcoléoptèresscolytidaedupinsylvestre WashingtonStateDepartmentofNaturalResources2001:
(Pinus sylvestris L.) et étude préliminaire de leur Foresthealthalert:fireinjurytotrees.—Washington
agressivitéenversl’hôte.—Ann.ForestSci.43:201– StateDepartmentofNaturalResources,No01–122,
216. U.S.A.
Mattson, W., Levieux, J. & Bernard-Dagan, C. 1988: Wong,B.&Berryman,A.1977:Hostresistancetothefir
Mechanismofwoodyplantdefenseagainstinsects.— engraverbeetle.Lesiondevelopmentandcontainment
Springer-Verlag,NewYork. ofinfectionbyresistantAbiesgrandisinoculatedwith
McCullough,D.,Werner,R.&Neumann,D.1998:Fire Trichosporiumsymbioticum.—Can.J.Bot.55:2358–
andinsectsinnorthernandborealforestecosystemsof 2365.