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

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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