INTRODUCTION
IDENTIFICATION
DISTRIBUTION IN T'E CASCADE RANGE .
ASSOC IATED TREE SPECIES .
SUCCESSION ON T'PICAL FOREST SITES .
Cas‘
cadeRange, Except in g Wenatchee Provin ce .
Wen at chee Provin ce .
SUCCESSION ON SEVERE SITES .
Lav a Flovvs .
Talus and Avalan che Areas .
Tim berlin e“ Krum m holz Areas 12
PESTSAFFE CTING SUBALPINE'
FIR .
SIGNIFICANCE IN LAND MANAGEMENTSUMMAR'.
REFERENCES .
COMMON AND SCIENTIFIC NAMES OFTREE SPECIES MENTIONED IN T'E TEXT
In troduction
Subalpin e fir 1 is a wide - ran gin gcon ifer in boreal an d m oun tainregion s ofwestern North Am erica .
Although m ost abun dan t in the
Rocky Moun t a in region , it is alsoa m ajor com pon en t of high - elevation forests in - the Cascade Ran geofOregon an d Washin gton an d in
the Olym pic Moun ta in s ofWashingt on .
Recen t in vesti ga tion s Show thatsubalpin e fir o ft en beha ves as a
relatively in toleran t species and is,therefore, seral on m ost forestedsites in t he Cascade Ran ge . I t isalso an im portan t pion eer Specieson m an y severe sites foun d at
higher elevation s on talus, lavaflows, an d avalan che tracks and attim berlin e. These features con trastwith the shade t o leran ce an d clim ax status described for subalpin efir in the Rocky Moun tain s.
This pa per describes the succession al sta tus of subal pin e fir on
various sites in the Cascade Ran gean d chan ges bein g effected by cu rren t epidem ic in festation s of balsam woo lly aphid (Adelges piceae
Where appropriat e,con trasts are drawn with t he behavior ofsubalpin e fir in the RockyMoun tain s .
‘Common a nd scien tific n ames oftree speciesare listed on page 16.
Figure I .
— T'
angen tia l cu t through bark;A, su ba lpin efir, showing n umerous resinpocketsI throughou t; B , Pacific silverfir,showinglack ofresin pockets
“
. (Magn ifica t ion1.6X)
2Den n is, LaRea J u n e. A taxon om ic s tudy ofthe v a scu la r flora on Ashla n d Peak , J ackso n Co u n ty, Orego n . 144 pp . , illu s . 1959.
(Unpu blished m a ster’
s thesis on file a t O re
gon Sta te Un iv . , Corva llis .)
Iden tifica tion
Subalpin e fir is readily distin gu ished from associated species in theCascade Ran ge by it s dist in ct ivespirelike form . The t o 1 - in chlon g dark , blue- green n eedles an dthe t o 4- in ch - lon g purplish - grayt o bla ck con es also provide positiveiden tification (Alexan derIt s in n er bark con ta in s n um eroustin y resin pockets, la ckin g in an y
o ther in digen ous true fir (fig.
Dis tribu tion inthe CascadeRange
Subalpin e fir occurs the len gth of
the Cascade Ran ge in Wash in gt onand Oregon but is un com m
'
on southof Cra t er Lake Nation al Park (fig.
Near it s southern l imi ts it isin creasin gly restricted t o wet , coolsites alon g stream s o r aroundm arshy areas. An earlier report Ofsubal pin e fir in Californ ia was
pro ved erron eous by Ha ddockan d the southern m ost oc
curren ce n ow kn own is at Moun tAshlan d on the eastern edge of the
Siskiyou Moun tain s.
Suba lpin e fir is m ost com m on at
eleva t ion s above feet , bu t isoft en foun d m uch lower . O n western slopes of t he Cascade Ran ge
,
suba lpin e fir is com m on t o elevation s below feet on the West
Crater lava beds (fig. 2 ) and Oftenfollows talus an d ava lan che t rackst o elevation s ofless than feet.O n eastern slopes ofWashin gt on ’
s
Cascade Ran ge, subalpin e fir dropst o lower elevation s on cool
,m oist
ha bit at s such as floors of deep v alleys an d in frost pockets; e .g.
,at
feet alon g Big Mea dowsCreek in the Chiwawa River dra inage; feet in Agn es Creekdra in age; an d feet alon g theSt e-hekin River , n ear the upper endof Lake Chelan . In fact , most forest s a t elev ation s above to
‘
feet in glaciated valley floors
on the east s ide of the Washin gton ASSO Cia t TI 'CCCascade Ran ge con ta in subalpinefir and En gelm an n Spruce as m ajor SPCCICScom pon en t s.
Su dworth ( 1908 ) provides the bestsum m ary statem en t on occurren ceO f“ subal pi n e fir in t he C asc adeRan ge : I n co o l , m o ist , an d ,
in
part , subalpin e si tua tion s ; comm ou ly on slopes at tim berlin e, andat it s lower lim its in protected valleys , at heads of stream s, and
about m oun tain lakes an d m ea
dows .
Table l .— Associa tes ofsuba lpine fir in d ifferen t prov inces of the Ca scade Ra nge
1
1Prov in ces are as defin ed by Fran klin Sym bols in dica te: M, m a j or assoc ia te; m , m in or assoc ia te .
—’ E xcept a m a j or assocw te on loca liz ed coo l, m ors t, bo t tom - la n d s ites .
Spe'cies associated with'
su ba'
lpin e
fir in the Cascade Ran ge are sum
m arized in table 1 . Pacific sil verfir, m oun tain hem lock , an d lodgepole pin e are the m ajor associat esin closed forest stan ds throughoutthe Cascades except in theWen at
chee Provin ce ( Fra n klinMaj or tim berl in e asso c ia tes are
m oun ta in hem lock an d whitebarkpin e . En gelm a n n spruce is n o t acon stan t associate Of subalpin e firexcept in the Wen atchee Provincea n d on exception ally m o ist , coolhabitats scattered throughout thewestern an d southern CascadeRan ge.
This group of asso ciates is som e
what differen t from t hose typical
of in terior su ba lpin e fir forest'
s.
Throughout the Rocky Moun tainsEn gelm an n spruce is subalpinefir
’
s
m ost com m on com pa n ion - (Alexan der Several other ~ RockyMoun ta in associates e .g. ,
Whitespruce , blue Spruce, a n d l im berpin e are absen t from t he Cas
cades; con versely , Pacific silver fir
( always) an d m oun tain hem lock
(usually ) are n o t foun d in the
Ro cky Moun ta in s . These differen ces in associ ated tree spec iesh ave im porta n t im pli c atio n s insuccession al pa t t ern s an d com posit ion of clim ax forest .
Thisj sect ion con siders the succession
|a l st atus of subalpin e fir on
t ypical forest sites ; i .e . , sites havi n g or capable of developin g acloseid forest can opy . Two dist in c
t iv elsit u a t io n s are en coun tered :
i( 1)S
uba lpin e fir as a seral speciesn rriost of the Cascade Ran ge, and
(2 ) suba lpin e fir as a clim ax speciesin tiie Wen atchee Provin ce (fig.
Table2 .— Number of trees by size classes (d iameter) a nd species on a 15 by 25- meter plo t in ea ch of six stc n :
con ta in ing suba lpi ne fir; the Cascade Ra nge of northern O regon a nd sou thern Wa shington , 196 1- 63
Ca scade Ra nge, Except ingWena tchee Prov ince
Throughout alm ost the en tire Cascade Ran ge , suba lpin e fir is a seralspecies on typical forest sites . Itin vades recen t ly disturbed areas,form ingm ixed stan ds with speciessuch as lodgepol'e pin e. But it failst o perpetuate itself in the shade of
m aturin g stan ds an d is graduallyreplaced by m ore shade- toleran tassociates such as Pacific silver firan d moun tain hem lock . The on ly
gen eral exception t o this patteris in t he Wen atchee Provin cethe n ortheastern Washin gton Ca“
.
cades.
The seral status an d apparen tto leran ce of subalpin e fir in thCascade Ran ge has n ot been preViou sly n oted . It is con sisten tlyported as m ore shade- toleran t t ia n y asso ciates , in cludin g E n g;m an n spruce. Studies have ShO ‘
subalpin e fir form s a stable clin i a
with white or En gelm an n Sprl l afzr
repro ductio n of subal pin e fi
often dom in an t (Alexan der 1958 ,Dauben m ire 1952 , LeBarron and
Jem iso n However, thesestatem en ts regardin g toleran ce andsuccession al status of subalpin e firare a ll based on studies con ductedin the Rocky Moun tain s or borealCan a da . These areas di ffer fromthe Cascade Ran ge in ( 1) m ajoren viro n m en tal features an d (2)otal absen ce of Pacific silver firTn d gen eral absen ce ofm oun tainhem lock . In n orthern Idaho wherem oun tain hem lock does occur withsubalpin efir and E ngelm an n spruce,bo th have proved seral t o m ount ain hem lock .
3
r
i‘
he con clusion that suba lpin e firis seral on m ost forest sites in theCascade Ran ge is based on examin at ion s ofm an y stan ds. Six stan dsin various stages ofsuccession werestudied in deta il between 1961 and1963 t o illust rate the role of sub
alpin e fir . They are located in then ort hern Oregon an d southernWashin gton Cascade Ran ge (fig.
A 15 by 25- m eter plot was loca t ed in each stan d studied . On
each plo t,all trees in each s ize
class were recorded , by spec ies,
except for seedlin gs up t o 3 feett all which were tallied on t wo 1
by 25- m eter stri ps w i thin each
larger plot an d then projected t o a15 by 25- m eter- plot basis.
Result in g si ze - class distributionswere used t o det erm in e t he su c
c essio n a l st a tus of suba l pin e firbased on the fo llowin g prin ciples.
- n m ature stan ds, a clim ax specieswill usually exhibit the in verse Jshaped distribution curve, typicalf t o leran t species, when n um berf in dividuals are plotted aga in stize class . Largest n um bers of in i
div idu als are foun d in the sm allest( seedlin g) size class; represen tationd ecreases rapidly with in creasin gize class . Seral species, however,
.l -l represen tation in sm a ller sizeclasses an d exhibit gaps in the dist ribu t ion curve; e .g. , in saplin g orIole sizes . Such a vo id in a stand
pproaching clim ax in dica t es seedlin gs of this species are un able to
'Dr. R . Da u benm ire, person a l comm u n ica
tion .
survive an d grow in to larger sizeclasses . Con sequen tly
,it would n ot
be represen ted in t he clim ax forest . Ki t tredge ( 1934 ) used S i zeclass distribution data in a sim ilarfashion t o determ in e succession alst a tus of tree species o n StarIslan d
,Minnesot
Size- class distribution s in the six
stan ds sam pled clearly illustratethe seral status of subalpin e fir
( table The Big Lake stan d
( table 2 , figs . 3 and 4) represen tsan early stage of succession . The
overstory con sists o-f subalpin e fir
and lodgepole pin e . Man y lodgepole pin es have died from attacksofm oun tain pin e beetle (Den droc;
ton u s mon t icolae Hopkin s) an d alodgepole pin e sawfly (N eodiprion
n an u lu s Shedl con tortae Ross) .
Judged by the large num ber of
seedlin gs and saplin gs presen t, thesecon d gen eration stan d will bepredom in an tly subalpine fir;m oun
Figitre 3 .
—Lodgepolepin e- su ba lpin efir standa t BigLake, Willamet te N a t ion a l Forest .
cession . Subalpin e firs in the overst ory can opy are dyin g and sm allersize classes are n o t presen t . Mount ain hem lock con stit utes t he bu lkOf basal area in t his stan d . 'owever, it , _
t oo , is poorly. represen t edin youn ger age classes. The m ajorclimax species appears t o be Pacificsilver fir, which is well represen tedin younger age classes. In tercessionof a stan d Of
'
m o u n t ain hem lockbetween st an ds of subalpin e fir (orsubalpin e fir an d lodgepole pin e)and a clim ax forest of Pacific silverfir is com m on
,especially where a
Pacific silver fir Seed source is absen t a t the begin n in g of the sere.
The San tiam Pass stan d ( t able 2)represen t s a n ear- clim ax forest ofPacific s ilver fir an d m oun tainhem lo ck . Subalpin e fir is repre
sen t ed on ly by dead trees. Mou n
tain hem lock dom in ates the stan d,but relat ive n um bers of seedlin gsan d saplin gs in dicat e it , t oo ,
w illbe largely ( if n ot com plet ely ) replaced by Pacific silver fir.
Figu re 5.
— In terior ofsu ba lpin e fir - m ou n ta in hem lock -Pa cific s ilver fir sta nd a long Tim berlin e Lodge road, Mou n t'ood N a tion a l Forest .
Reprodu ct ion is alm os t en tirely Pa cific silver fir. (The s take (arrow) in this and figu res 10 and 11 is 1 meter high and is m a rked in
decimeter segmen ts.)
Distribu t ion of areas where ‘
sub
a lpin e fir is abun dan t in the Cascade Ra n ge rein forces t he bel ieft hat disturban ce is n ecessary forest ablishm en t of suba l pin e fir
st an ds. Except in the n ortheast ernWashin gt on Cascades (Wen at cheeProvin ce), subalpin e fir is rarely am aj or com ponen t of old - growthstan ds. Den se stan ds con t ain in g alarge com pon en t of suba lpin e fira re gen erally in areas disturbedwithin t he last 150 years.
Fire appears to have been the m ostim porta n t disturbin g agen t ; allst an ds listed in table 1 occurred onso ils w i t h abun dan t charcoa l insurface horizon s . The areas of theCascade Ran ge where subalpin e firis m ost abu n dan t , . exclu din g t im
berlin e an d the Wen atchee Provin ce
,are the High Cascades prov
in ces, from t he Moun t Adam s
Provin ce south through the Three
Sisters Provin ce (Fran klinThis pa t t ern of occurren ce largelycoin cides w ith ext en sive fires du rin ghist oric tim es (fig. Som e of
t he fam o u s Spired suba l pi n e firstan ds in t he vicin ity of ParadisePark at Moun t Rain ier m ay havea lso developed fo llow in g burn in g(Hain es
Wena tchee Prov ince
The highest elevation forest zon ein this provin ce is usually the Subalpin e Fir- En gelm an n Spruce'one(Fran klin an d Trappe Thisarea is largely free of com petitorsm ore t oleran t than subalpin e firm oun tain hem lock an d Pacific silv er fir o ccur on l y lo cally . Subalpin e fir- En gelm an n spruce forestsh ere are m uch like those of n orthern Idaho in distribution and com
position . N ot on ly do t hey con stit ute t he zon al - clim ax forests but
,
as in n orthern Idaho ,
“ As a topoedaphic clim ax
,penin sular strips
of it'spruce- fir forests'exten d to
rather low elevation s where theyoften expan d t o cover the floors ofii ost pockets in valleys surroun dedby som e represen tative of the
Thuja - Tsuga. zon e'
(Dauben m ire
Size - class dist ribu t ion s of speciesin typica l stan ds from the n orthea stern
,Washington Cascades provide con clusive eviden ce ( t able 3)that subalpin e fir is the m aj or cli
Species in m an y spruce- fir
st an ds. In fact , at eastern edges Ofhigh east - west - t ren din g ridges (e.g.
,
Wen atchee Moun tain s , . ChelanMoun ta in s, En tiatE n gelm an n spruce is a m in or com
pon en t or even absen t from m anysu balpin e fir stan ds (Franklin and
Trappe Eastern ext rem itieso f t hese ridges are relatively dry,
despite their elevation , an d En gelm an n spruce is ei t her absen t orconfin ed t o m o ister habitat s.
Figu re 6 .—Su ba lpin efirgrow ingon a tract bu rn ed
ington , Willam et te N a t ion a l Forest .a bou t 1900, n earMou n t Wash
I r ble 3 .— Number of trees by size classes (d iam eter) a nd species o n a 15 by . 25- meter plo t in each of
three sta nds con ta in ing suba lpine fir; Wena tchee Prov in ce of the Cascade Ra nge, 196 1- 63 1
Pinegra ss R idge
Suba lpine fir
Western hemlock
1Wena tchee Provin ce is as defined by Fran klinQSize class was represen ted in an a dj acen t part of the stan d ( ou tside the plo t) .
flow surfaces in this an
McKen zie Pass lava fircen tral Oregon Cascadesfir Shares pion eer status Vtain hem lock an d white
young“
surfaces, such as lava floOr
“
tallus slopes ,“
O r clim a t ica'
seVerelregion s n ear tim berlin e . The
rem arit able Success Of suba lpin e firas a pion eer species is a ccoun ted
low s
a flows in southern Washan d n orthern Oregon , sub
fir is often t he m ajor treeFor example, it is them ost
t ion s
ize classes ( d iam eter) (a nd species o n :a 15 by 25- meter plo t
suba lpine fir; Ca sca de Ra nge la va flow commun it ies, 196 1- 63
Size class (d iameter in in ches )
on Big Lava Beds (fig. an ex
ten sive flow lo cat ed between theWin d River valley an d Moun tAdam s in southern Washin gt on .
O n the West Crater lava flows inthe sam e area , subalpin e fir is codom in an t with Douglas - fir overalm ost t he en t ire surfa ce
,even
exten din g t o elevation s lower thanfeet . The forest - on theWest
Cra t er fiows is very sim il ar t o aDouglas - fir - subalpin e fir association described by Roach ( 1952) ona part of the cen tral Oregon NashCrater l ava flow . Bo t h are openforest s growin g in a broken crustof blo ck basalt . Greater n um bersofseedlin gs an d saplin gs - (table 4andRoach suggest suba lpin efir is m ore aggressive a t pion eerin gt he site t han is Douglas—fir. Subalpin e fir is also a m ajor tree specieson som e raw lava surfaces southwest OfMoun t St . Helen s, althoughlodgepole pin e is m ore com m on on
The forests grow inglava flows are compara tLim itin g factors in regenrelated t o subst rate — 1
and , with lim it ed tree c(
subalpin e fir is able t can d m ain t ain it self. Sizt ribu t ion s of tree specilava flow st an ds Show leviden ce of succession( t able Suba l pin e fidu cin g in sufficien t abLa t least m ain t ain it s pmthe st an d . Accordin gly
,t i
exem plify sit ua tio n s v
alpin e fir is an edapl
species.
I t m ust ben o t ed , howsubalpin e fir is n o t pre
recen t lava flows in t h
Ran ge . Com position of lava flowcom m un ities depen ds upon m anyfact ors, som e ofthe m ost im port an tbein g characteristics of t he flowsurface, elevation , a n d ava ilableseed sources. Roach ( 1952 ) n o t edsu balpin e fir m ay be absen t from
portion s of a lava flow well w ithinit s geographic ran ge.
Ta lu s a nd Av a la nche Area sSubalpin e fir is a clim ax species on
high - elevation talus (fig. 8 ) and on
a valan che tracks in t he CascadeRan ge. In theWashin gton Cascades
( in cludin g Wen atchee Provin ce), itis often the m ajor tree species andis som etim es the on ly on e presen t
(especially on talus). Frequen tlyt he authors have traveled throughforest s con tain in g little or n o su b
alpin e fir, on ly to com e upon in terv en in g talus or slide areas where itis abun dan t . This phen om en on is
subalpin e fir occu
pen in sular exten sion seleva t ion s.
Figu re 7,
— (Left lower left) Su ba lpinefirgrow ing on Big La va Beds in the sou thernWashington Cascade Range.
Figu re 8 .
— Su ba lpin efir on an ex
n ea r BumpingLake, Snoqualm ie N a tion a
N o te layeringpresen t n ear bases ofm any
AS on l ava flows , subalpin e fir ~is
presen t as a pion eer Species. 'et,it
form s a t opo edaphic clim ax on
t hese sites because the open stan dsand exclu siOn o f poten tia l com petitors have m in im ized com petitionfrom o t her tre
‘
es . O n ta lus the
lim it in g en v iron m en t al factor isa gain t he substrate , whereas on
avalan che tracks it is,
usually re
peat ed sn ow slides. Abun dan t layerin g of subal pin e fir grow in g onthese habit ats is a very useful adapt at ion for their colon ization .
Tim berline
Subalpin e fir is a con spicuous feature of tim berlin e forests in the
Cascade Ran ge. This area of subalpin e m eadows an d groups of subalpin e fir, m oun tain hem lock
, and
whitebark pin e (fig. 9) is som etim es
called the Hudson ian 'on e. I t is aten sion zon e, a dyn am ic eco ton ebet ween tree an d treeless v eget at ion , in which chan ges are con
st an t ly takingplace du e t o allogen i c lon g an d short - termclim atic variation s) as well as autogen i c ( chan ges in en viron m en tbrought about by plan ts) factors.
Succession al sequen ces am on g treespecies are som etim es obscured bya llogen ic chan ges in en viron m en tand, therefore, discernm en t ofnat
ecology'
of the t imberlin e an d a lpin e vege
ta t ion of the Three Sisters, Oregon . 111 ppillus. 1960. (Unpu blished Ph.D. thesis on filea t Oregon Sta te Un iv . , Corvallis.)
Figu re 9. Su balpin e tree groups n ear t im berlin e on Sun rise Ridge, Moun t Ra in ier N a t iona l Park . Groups arepredom in an tly su balpinefir and whitebark pine.
ecotoneoftheeasl5:
beeninitiate
ural patterns in forest successionrequire exten sive, deta iled obser
v at ion s. Detailed studies ofn aturalsu ccession j am on g tim berlin e treespecies in gt h
'
ewetter portion s oft he Washin gton Cascade Ran geare discussed here. Although t imberlin e forests in the Wen atcheeProvin ce are rel atively poorlykn own , open n ess of the stan ds andla ck ofm ore toleran t arborescen tcom peti t ors in sure subalpin e fir aperm an en t place there.
Subalpin e fir occupies a som ewhatdichotom ous succession a l positionat tim berlin e in the wetter region sof the Washin gton Cascade Ran ge.
I t perpetuates itself in Open sub
alpin e forest region s an d in a certain lim ited sen se can be con sidereda clim ax Species
“
. But,it does n ot
n ecessarily ret ain possession ofih
dividual areas which it colon izes.
Chan ges are con stan tly takin gplace. There
.
is good eviden ce thatfam ily grou pS
'
of subalpine firan d m oun tain hem lock have beenin vadin g heather or m eadow com
m u n it ies for the last 50 years (Brink’
1959 ,Fran klin Brockman
(1949)m en tion s growth an d coalescen ce of subalpin e tree groups
an d resultin g replacem en t ofm ea
dow vegeta tion by forest . Subalpin e fir is
'
often t he leader inthese in vasion s (Brin k 1959, Franklin although it is som etim es
accom pan ied by m oun tain hem lock
(Van Vecht enfi'
Cooper Butwhat of succession durin g developm en t an d expan sion of. these treegroups?
Adefin ite sequen ce in tree Speciesis associa t ed
l
with growth an d ex
pan sion of subalpin e tree groups.
It was repeatedly observed durin gexam in ation s of n early 100 “
fam
ily' groups of various S i zes (andpresum ably ages) in t he GoatRocks Wildern ess an d at Sun riseRidge an d Paradise Park on Moun tRa in ier, all in western Washin gt on .
In itiation Of a n ew'
group. apparen tly begin s w ith an in dividual orsm all group of seedlin gs. The in it iL
at or'
m ay be subalpin e fir or whitebark pin e, the latter often becomin gestablished in sm all groups (fig.
10) from buried con es or'roden t or
bird '
. seed caches. Moun t ain hemlock was n ot a common pion eer in
1. GeorgeWendell lll. ilw
the_
'
Mou n t Rain ier area,althoughit does in itiate m eadow in vasionelsewhere.
'
As the sm all patches of seedlin gsdevelop , they exert an ever- in creas
in g in fluen ce on the m icroclim at et he blackbody effect causin g
ear lier sn owmelt an d therebylen gthen ing the growin g season .
7
The group en larges by layerin g ofsubalpin e fir as well as establishm en t of n ew t rees from seed (fig.
Moun tain hem lock seedlin gs
'Swedberg, Ken n eth Charles. The con iferouseco ton e of the ea s t slopes of the n orthernOregon Cascades . 118 pp., illu s . 1961 . (Unpu blishedPh.D. thes is on file a t Oregon Sta teUn iv . , Corva llis .)'See foo tn o te 4.
See foo tn ote 5
becom e est ablished within pro
t ect ion'
of subalpin e fir an d Whitebark pin e . Subalpin e fir and whitebark pin e fail t o reproduce insh aded areas a n d are gra dua llyelim in ated from the cen ter part ofthe group by m oun tain hem lock .
The largest,an d presum ably old
est , st an d which could be positivelyiden tified as a suba l pin e forestgroup was abou t 100 by 400 feetin
_size an d com pletely surroun ded
by m eadow veget ation .
~Here, suba lpin e fir (m a t ure an d reprodu c
tion ) and occasion al whit ebark pin ewere co n fin ed t o t he m argin s ofthe grO I
'
Ip. The cen ter was dom ina t ed by large overm a ture m ounta in hem locks, am on g which werescat t ered abun dan t seedlin gs, sap
Figure — Su ba lpine forest groups in early stagesofdevelopm en t . Group in upperpictu re appea rs to ha vebeen in it ia ted by whitebark pine ; group in lowerpictu reby su ba lpin efir. Som e m oun ta in hem lock seedlings ha vebecom e
’
esta blished w ithin theprotect ion ofla rger su ba lpin efir and whitebark pin e. E xpans ion ofgroups is takingpla ce largely by layering ofsu ba lpin efir. In the lower
pictu re, no te tha t whitebark pin e saplings are confin ed tothe m argin ofthegroup . Sun rise Ridge, Moun t Ra in ier
N a t ion a lPark.
Figu re 10 . left) Whitebl
ark pin e seedlings insu ba lpin e m eadow which proba bly developed froma bird or roden t seed ca che. Seedlinggroups of thistype often in it ia te developm en t ofa su ba lpine forestgroup . Sun rise R idge, Mou n t Ra in ier N a t ion a lPark .
llin gs , an d poles of Pacific silver fir.
gion s such
Wyom in g (Gri ggs 1938 ) a n d on
cin der flats in the cen tral OregonCascade Ran ge .
8 In these areas,“
tim ber atolls'are foun d in which
groups of subalpin e fir an d otherSpecies expan d outward by layering an d seedin g but leave the cen
t er of the group hollow or vacan t .
Krumm ho lz AreasKrum m holz refers to in dividual
an d sm all groups of trees growin gabove tim berlin e . These trees arecharacteristica lly con torted and
dwarfed du e t o severe alpin e clim ate (hen ce
“ krum m ho l z, a Germ an term m ean in g crooked or ben twood). Here, en vironm en tal in fluen ces are m uch m ore im portan t inseedlin g establishm en t than com
petition for m oisture an d light
8See footnote 5.
r acm c su v'
en rm
sUBAipim : FIR
River.
Subalpin e fir gr
stream bot toms an d aroun d 1
m oun tain m eadows (fig. 13 )t rem ely sen sitive t o t he aph
S t an ds grow in g on an d arou r
Figu re 12 . Schem a t ic diagram show ingthe developm en t ofsu ba lpin e forest groupson western slopes ofthe WashingtonCascade Range.
am on g tree species . Subalpin e firis especi ally a da pted t o t his en
. v ironm en t because of it s ability tolayer. Other species, n otably subalpin e larch or whitebark pin e, m ay
exten d t o h igher elevation s, but asin gle established suba lpin e fir iscapable ofcolon iz in g a greater areathan a n in dividua l of an y O therspecies in t he krum m ho l z region .
Seral or clim ax desi gn ation s are
usually n ot applied t o tree speciesin krumm holz stan ds, but subalpin efir is defin itely a pion eer in thisen viron m en t . Archer ( 1964) hasdescribed a succession al sequen cein krum m holz stan ds in coastalBritish Co lum bia in which sub
alpin e fir succeeds Al aska - cedaran d is in t urn replaced by m ountain hem lock .
The in sect an d disease sit u a t iO'
i
with suba l pin e fir is gen erallypoorly kn own , though the speciesapparen t ly has few en em ies. Som
prim ary roo t diseases , suchArm illa ria m ellea Vahl ex Fr. and
F om es a n n osu s (Fries) Karst , areapparen t an d bark beetles such asPseu dohylesin u s gra n dis Swai n .
an d Dryocoetes co nfu sas Swaiilahave been kn own t o attack a few,trees, but the total im pact of thesepests has n ot appeared sign ifican t .
The im portan t en em y of subalpin efir in t he Pacific Northwest is anin troduced pest from Europe the
balsam woolly aphid (AdelgesCherm es) piceae
Of n ative true firs, subalpin e fir isthe m ost sen sitive t o balsam woollyaphi d (M i t chel l an d epi
dem i c in festation s of t he w ool“
aphi d have been respon sible fo rdram atic chan ges in the ecology or
subalpin e fir over a wide area . Sin cediscovery of t he aphid in 1954
( John son an d Wri ght - the
pest has killed suba lpin e fir alongt he Cascade Ran ge from Mou It
Ra in ier in cen tra l Washin gton rO
Crater Lake in southern Oregon .
lava beds have a lso suffered severe
dam age. Over 80-percen t m ortalitywas observed in a m a ture st andgrowin g on t he West Crater lavaflow in the Win d River drain age
of southwest Washin -gt on . Signi
fican t m ortality has also been Ob
served in other lava beds , par t icu larly at low er elevation s.
Con ceivably, aphid outbreaks couldel im in ate subalpin e fir from localized areas. In closed , m ixed st an ds,the aphid
“
w ill hasten replacem en tofsuba lpin e fir by m ore toleran tspecies . Greatest im pact of the
aphi d appears t o be on t he pio
n eerin g ability Of suba lpin e firt hose in stan ces where t he fir invades lava beds; ta lus Slopes, oldbeaver m arshes, et c . Adversit ies Ofthe physical en vironm en t a lreadycon siderable in these situation sare greatly m agn ified by the aphid .
Also , the aphid’
s habit of settlin gon term in al buds in hibits n ew
growth an d reduces thepossibilityof seed production , further redu c
ingeffect iven ess of subalpin e fir incolon i zin g n on forested lan d and
m ain ta in in g it s ten uous ho ld insom e areas.
Fortun ately , m ortality is seldomcom plete in an in fested area . Sup
pressed trees an d poor- site treesare far less sen sit ive t o aphid infest at ion s than was on ce believed .
E v en in areas where m ortality ishea vy , a few l arge trees n earlyalways escape atta ck , because of
chan ce, local en vironm en t, or possibly gen etic characterist ics . Butthe m ost. sign ifican t charact eristicof in festation pattern s is that attacks are m ost abun dan t. an d m ostserious a t low er elevations . Sub
alpin e fir above t o feetis rarely attacked , and a wide zoneleft betw een t im berlin e and the
n fest at ion area . 'ere, it appears,su ccession w ill proceed n orm ally
,
without in terferen ce from the bal
sam woolly aphid .
Figure 13 .— Des.truction ofsu ba lpin efir by ba lsam woolly
in m any stands su rround ing m ou n ta in m eadows in the weste
Lookou tMou n ta in , WillametteN a t iona l Forest.
is completeCascades ofOregon .
E cologi cally , subalpin e fir is a veryim portan t species in high- elevationforests. AS a forest pion eer on lavaflows, avalan ches, and other severesi tes in t he hi gh Cascades, it isprobably un equaled . By providin gcover on these an d fire- dev astatedtracts , subalpin e
“
fir can be a dis
t in ct asset in wa t ershed_pro t ec
t iori. .an d“
landscape rehabilitation .
In commercial m an agem en t of suba l pin e fir f-orest s, foresters m ustcon si der the tree
’
s successionalstatus as well as the probable1mpa ct of t he balsam woolly aphid .
I n t he Wen atchee Provin ce, subal pin e fir is bo th abun dan t andfree of aphid in fest ation . In
_this
area ,subal pin e fir w ill be favored
by shelt erwood orselection cuttin gSin ce it is the m ost toleran t speciesn ormally presen t , an d clearcuttin g
'
will ten d t o favor associated , less
toleran t species . Silvicultural kn owledge developed in Rocky Moun tainsubalpin e fir stan ds (Alexan der1958 .Daubenm ire 1952 , LeBarrona n d Jem ison 1953 ) can be drawnupon with reason able safety un tildet ailed stu dies have been con
ducted in theWen atchee Provin ce.
Elsewhere in the Cascade Range,subalpin e fir has little com m ercialvalue, isgenerally in fest ed by _
bels
'
am woo lly aphid , a n d behaves asa n in to leran t species . It is som e
tim es logged alon g with Other highelevation species,
“ but low stum page va lues ren der tim ber salesaim ed specifically a t subalpin e firim practical . In “
m an y cases, suchstan ds arebest left
'
alon e salvabletim ber values are n ot com m en su r
a t e with losses of other m ultipleu se values . However, in sta ndswhere tim ber harvestin g 1s plann ed , i t m ust be reco gn i zed thatshelterwo od or selective cuttin gwill favor regen erat ion
'
of speciesother than subalpin e fir, especiallyif subalpin e fir seed source is elimin a t ed . The closed stan ds wouldhave little or n o advan ce regen eration presen t .
forest sites, is producin g a drdownward trend in im portansubalpine fir in areas of aphidfest at ion .
Estheti ca ll y , subalpin e fir is u n
equaled as a dram atic ba ckdrop .
More than an y other Species, subalpin e fir sym bolizes high - elevationbeauty , a sen se of etern i ty , andwildern ess:Most outdoor en thu s
iast s in t he West could scarcelyim agin e a m oun tain m eadow withou t subalpin e fir. In high - u se rec
rea t ion a reas, such as Na tio n alParks, this factor deserves m uchcon sideration . Alpin em eadows m ayn eed some m an agem en t t o keepthe wildern ess im age that the public has been con dition ed t o expect .
I t is n o t yet clear wha t t he fulleffects of balsam woolly aphid willbe on suba lpin e fir an d ,
as a consequen ce
,t he n a t ural eco lo gy and
m an agemen t of the Cascade Ran ge.
The outbreak has n o t“
yet ru n its
course; it still appears to be spread ;
in g in _
m an y areas . Nevertheless,presen t in dications are that stan dson t he east
_si de of t he Cascades
w ill n o t be dam aged“
by the aphid .
Elsewhere, high - elevation stan ds,from or feet t o tim berlin e, will probably also escape Sign ifican t in festation . Man y low - ele
vation stan ds are apparen tly doomed
,d estruction by t he aphid hav
in g been alm ost com plete. E cologically ,
t he widespread death Ofsubalpin e firs in pion eer situation s
a roun d m eadows, avala n chearea s , a n d l ava beds is partieu larly serious because there oftenappears t o be n o other tree Speciescapable of takin g it s place.
~LOSS of
subalpin e fir from com m ercial forest stan ds is at least econ om icallyless serious sin cem an y other speciesof higher or equivalen t value are
adapted t o these sites.
Summ ary
Suba l pin e fir ha s a far differei
ecolo gical role in m ost parts of t lCascade Ran ge than it doesRocky Moun tain spruce- fir forestSuba lpin e fir is seral on sitesWhi(will support closed forest stan dit regen erates followin g distu rban ra n d is gradu al l y. el im in ated tm ore tolera n t associ ates suchm ou n t ain hem lo ck an d Pacif
silver fir. O n som e other sites, su (as recen t lava flows and ta lus, su lal pin e fir pio n eers an d is m a il
t ain ed as a t opoedaphic or edaph
clim ax species. In open su balpir
forests n ear tim berl in e ( foregroups scattered through subalpirm eadow s), it often pion eers butsom et im es replaced by m ou n t ai
hem l o ck a n d Pacific si l ver firforest succession is allowed t o CO'
t in u e . The ability of subalpin e ft o en large origin al colon ies by la:erin g partially accoun ts for it s su o
cess as a pion eer species on sorr
ofthese difficult sites. In the n ortl
eastern part of t he Cascade Rang(Wen atchee Provin ce), m ore. tolean t associates of subagen era l l y l ac kin g . Tclim ax species, occu pyieco lo gi ca l n i che as im oun tain ran ges .
B a lsam wool ly a phidsign ifican t m ortality inalpin e fir st an ds
'
in O
southern washin gton
Scien titie Nam es
Abies am abilis (Dougl . ) Forbes Pacific silver fir
Abies gra nd is (Dougl . ) Lin dl . gran d fir
Abies la s ioca rpa (Hook ) Nut t . subalpin e fir
Ab ies m agn ifica v ar. shasten sis Lem m . Shasta red fir
Abies procera Rehd n oble fir
Chama ecypa ris noo tka ten s is (D . Don ) Spach Alaska - cedar
La rht lya llu Parl . subalpin e larch
La n x occ iden ta lis N utt . western larch
P iceaenge lm a n n n Parry En gelm ann Spruce
P icea gla u ca (Moen ch) Voss white spruce
P icea pu ngens En gelm . blue spruce
Pinq a lbica u lis En gelm . whitebark pin e
P inu:s co n torta Dougl . lodgepole pin e
P in u'
s flexilis Jam es lim ber pin e
P in us m on t ico la Dougl . western White pin e
P in us po nderosa Laws . pon derosa pin e
Pseuldo tsuga m en ziesn (Mirb Fran co Douglas- fir
Tsu heterophylla (Raf ) Sarg . west ern hem lock
Tsug'l
a m erten s ia na (Bong ) Carr. m oun tain hem lockl
The FO REST'SERVICE of the
U. 5. DEPARTMENT O F AGRICULTUREis dedicated to the principle of mul
t iple use ma nagement . of the Na t ion ’s
forest reso u rces for. susta ined yieldsof wood, wa ter,
‘
forage, w ildlife; a nd
recrea t ion .ii'
h-roughforestry resea rch,
coopera t io n with the , Sta tes a nd priva te
forest owners, and management of
the Na t ional Forests and Na t iona l
Grasslands; it Strives — l as directed
byCongress to prov ide increasmgly
grea ter serv ice growing Na t ion .
AF PS O G DE N . UTA' 6 8 - 3 3 9
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