Introduction Identification Distfibution in the Cascade Range

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Introduction Identification Distfibution in rc.- Subalpine is a wide-ranging Subalpine fir is readily distinguish- the Cascade Range conifer in boreal and mountain ed from associated species in the regions of western North America. Cascade Range by its distinctive Subalpine fir occurs the length of Although most abundant in the spirelike form. The 34- to 1-inch- the Cascade Range in Washington Rocky Mountain region, it is also long dark, blue-green needles and and Oregon but is uncommon south a major component of high-eleva- the 21/2- to 4-inch-long purplish-gray of Crater Lake National Park (fig. tion forests in the Cascade Range to black cones also provide positive 2). Near its southern limits it is of Oregon and Washington and in identification (Alexander 1958). increasingly restricted to wet, cool the Olympic Mountains of Wash- Its inner bark contains numerous sites along streams or around ington. tiny resin pockets, lacking in any marshy areas. An earlier report of other indigenous true fir (fig. 1). subalpine fir in California was Recent investigations show that proved erroneous by Haddock subalpine fir often behaves as a (1961), and the southernmost oc- relatively intolerant species and is, currence now known is at Mount therefore, seral on most forested Ashland on the eastern edge of the sites in the Cascade Range. It is Siskiyou Mountains. also an important pioneer species on many severe sites found at Subalpine fir is most common at higher elevations — on talus, lava elevations above 4,000 feet, but is flows, and avalanche tracks and at often found much lower. On west- timberline. These features contrast ern slopes of the Cascade Range, with the shade tolerance and cli- subalpine fir is common to eleva- max status described for subalpine tions below 2,000 feet on the West fir in the Rocky Mountains. Crater lava beds (fig. 2) and often follows talus and avalanche tracks This paper describes the succes- to elevations of less than 3,000 feet. sional status of subalpine fir on On eastern slopes of Washingtons various sites in the Cascade Range Cascade Range, subalpine fir drops and changes being effected by cur- to lower elevations on cool, moist rent epidemic infestations of bal- habitats such as floors of deep val- t‘am woolly aphid (Adelges piceae leys and in frost pockets; e.g., at (Ratzeburg)). Where appropriate, 2,700 feet along Big Meadows contrasts are drawn with the be- Creek in the Chiwawa River drain- havior of subalpine fir in the Rocky age; 2,500 feet in Agnes Creek Mountains. drainage; and 2,000 feet along the Stehekin River, near the upper end Common and scientific names of tree species are listed on page 16. of Lake Chelan. In fact, most forests at elevations above 2,500 to 3,000 feet in glaciated valley floors

Dennis, LaRea June. A taxonomic study of the vascular flora on Ashland Peak, Jack- son County, Oregon. 144 pp., illus. 1959. (Unpublished masters thesis on file at Ore- gon State Univ., Corvallis.)

Figure 1.—Tangential cut through bark; A, subalpine fir, showing numerous resin pockets throughout; B, Pacific silver fir, showing lack of resin pockets. (Magnification 1.6X)

1 on the east side of the Washington Associated Tree of interior subalpine fir forests. Cascade Range contain subalpine Throughout the Rocky Mountains fir and Engelmann spruce as major Species Engelmann spruce is subalpinp firs components. most common companion (Alex- Species associated with subalpine ander 1958). Several other Rocky Sudworth (1908) provides the best fir in the Cascade Range are sum- summary statement on occurrence Mountain associates — e.g., white marized in table 1. Pacific silver spruce, blue spruce, and limber of subalpine fir in the Cascade fir, mountain hemlock, and lodge- Range: "In cool, moist, and, in pine — are absent from the Cas- pole pine are the major associates cades; conversely, Pacific silver fir part, subalpine situations; com- in closed forest stands throughout monly on slopes at timberline, and (always) and mountain hemlock the Cascades except in the Wenat- (usually) are not found in the at its lower limits in protected val- chee Province (Franklin 1965). leys, at heads of streams, and Rocky Mountains. These differ- Major timberline associates are ences in associated tree species about mountain lakes and mea- mountain hemlock and whitebark dows." have important implications in pine. Engelmann spruce is not a successional patterns and compo- constant associate of subalpine fir sition of climax forest. except in the Wenatchee Province and on exceptionally moist, cool habitats scattered throughout the western and southern Cascade Range. This group of associates is somewhat different from those typical

Table 1.—Associates of subalpine fir in different provinces of the Cascade Range

Province Type of forest and species Mount Mount Mount Mount Three Crater Baker Rainier Willamette Adams Hood Sisters Lake Wenatchee Closed forest stands: Mountain hemlock M M M M M M M m Pacific silver fir M M M M M M m m Lodgepole pine m m m M M M M M Western white pine m m m m m m m M m2 m2 m2 Engelmann spruce m In2 m2 M Whitebark pine m m m m m m m m Western hemlock m m m m m m m m Douglas-fir m m m m m m m m Alaska-cedar m m m m m m Noble fir m m m m m m Grand fir m m m m m Shasta red fir m Western larch m m m Ponderosa pine m m Timberline stands: Mountain hemlock M M M M M M M m Whitebark pine m m m M M M M M Pacific silver fir m m m m m m Alaska-cedar m m m Subalpine larch M Engelmann spruce m 1Provinces are as del ned by Franklin (1965). Symbols indicate: M, major associate; m, minor associate. Except a major associate on localized cool, moist, bottom-land sites. 3 Succession on Cascade Range, Excepting general exception to this pattern Wenatchee Province is in the Wenatchee Province of Typical the northeastern Washington Cas- Throughout almost the entire Cas- Forest Sites cade Range, subalpine fir is a seral cades. species on typical forest sites. It The seral status and apparent in- This section considers the succes- invades recently disturbed areas, tolerance of subalpine fir in the sional status of subalpine fir on forming mixed stands with species Cascade Range has not been pre- typical forest sites; i.e., sites hav- such as lodgepole pine. But it fails viously noted. It is consistently re- ing or capable of developing a to perpetuate itself in the shade of ported as more shade-tolerant than closed forest canopy. Two distinc- maturing stands and is gradually any associates, including Engel- tive situations are encountered: replaced by more shade-tolerant mann spruce. Studies have shown subalpine fir as a seral species associates such as Pacific silver fir subalpine fir forms a stable climax in most of the Cascade Range, and and mountain hemlock. The only with white or Engelmann spruce; subalpine fir as a climax species reproduction of subalpine fir is in the Wenatchee Province (fig. 2).

Table 2.—Number of trees by size classes (diameter) and species on a 15- by 25-meter plot in each of six stands containing subalpine fir; the Cascade Range of northern Oregon and southern Washington, 1961-63 Size class (diameter in inches) 2 < 2- 4- 12- 20- 28- Plot and species < 3 feet > 3 feet tall tall 4 12 20 28 36 Big Lake (Willamette National Forest): _ Subalpine fir 661 152 19 3 ( 1) 1 Lodgepole pine: Live 60 12 1 2 1 1 — Dead — — — 24 3 1 — Mountain hemlock 8 1 1 — — — — Hood River Meadows (Mount Hood National Forest): Subalpine fir: Live 8 ( ) — 5 4 3 — _ Dead — — — 3 1 — Lodgepole pine: Live — — — — — 2 — Dead — — — — 1 1 — Pacific silver fir 75 1 — — 1 — — Western white pine — — — — — — ( 1 ) Grand fir — — — — — — ( 1 ) Steamboat Mountain (Gifford Pinchot National Forest): Subalpine fir: Live — — — — 6 4 — Dead — — — — 5 1 — Pacific silver fir 22 4 ( 1 ) ( 1) — — ( 1 ) Mountain hemlock — — — — — 1 — Sunrise Ridge (Mount Rainier National Park): Subalpine fir 8 2 1 5 13 — — Pacific silver fir 248 14 3 1 — ( 1) ( 1 ) Mountain hemlock — ( 1 ) — — — — Timberline Lodge road (Mount Hood National Forest): Subalpine fir: Live — — — 1 5 2 — Dead — — — 2 1 — — Pacific silver fir 765 21 1 1 — ( 1 ) — Mountain hemlock 15 5 3 3 4 — — Santiam Pass (Willamette National Forest): Subalpine fir (dead) — — — 4 2 — — Lodgepole pine (dead) — — — 2 1 — — Pacific silver fir 3,720 15 4 9 1 — — Mountain hemlock 8 2 3 19 6 1 — Western white pine — — — — 1 — — Size class was represented in an adjacent part of the stand (outside the plot). 4 often dominant (Alexander 1958, survive and grow into larger size tain hemlock has just begun to Daubenmire 1952, LeBarron and classes. Consequently, it would not invade the site. Jemison 1953). However, these be represented in the climax for- The Hood River Meadows, Steam- statements regarding tolerance and est. Kittredge (1934) used size- boat Mountain, and Sunrise Ridge successional status of subalpine fir class distribution data in a similar stands (table 2) provide examples are all based on studies conducted fashion to determine successional of more advanced successional in the Rocky Mountains or boreal status of tree species on Star situations. All three stands have Canada. These areas differ from Island, Minnesota. nearly pure subalpine fir over- the Cascade Range in (1) major Size-class distributions in the six stories. At Hood River Meadows environmental features and (2) stands sampled clearly illustrate and Steamboat Mountain, older total absence of Pacific silver fir the seral status of subalpine fir subalpine firs are dying with little and general absence of mountain (table 2). The Big Lake stand or no reproduction. In all three hemlock. In northern Idaho where (table 2, figs. 3 and 4) represents stands, seedlings of Pacific silver mountain hemlock does occur with an early stage of succession. The fir, the most probable climax subalpine fir and Engelmann spruce, overstory consists of subalpine fir species, are abundant. The greater both have proved seral to moun- and lodgepole pine. Many lodge- number of Pacific silver fir seed- tain hemlock. pole pines have died from attacks lings in the Sunrise Ridge plot The conclusion that subalpine fir of mountain pine beetle (Dendroc- reflects presence of a good seed is seral on most forest sites in the tonus monticolae Hopkins) and a source adjacent to the subalpine Cascade Range is based on exam- lodgepole pine sawfly (Neodiprion fir stand. A dense herbaceous inations of many stands. Six stands nanulus Shedl contortae Ross). understory has prevented estab- in various stages of succession were Judged by the large number of lishment of abundant reproduction studied in detail between 1961 and seedlings and saplings present, the at Steamboat Mountain. 1963 to illustrate the role of sub- second generation stand will be The stand on the Timberline Lodge alpine fir. They are located in the predominantly subalpine fir; moun- road (table 2, fig. 5) represents an northern Oregon and southern even more advanced state in suc- Washington Cascade Range (fig. Figure 3.—Lodgepole pine-subalpine fir stand 2). A 15- by 25-meter plot was lo- at Big Lake, Willamette National Forest. cated in each stand studied. On Figure 4.—Interior of lodgepole pine-sub- each plot, all trees in each size alpine fir stand at Big Lake, Willamette class were recorded, by species, National Forest. Note abundance of sub- except for seedlings up to 3 feet alpine fir seedlings and saplings. tall which were tallied on two 1- by 25-meter strips within each larger plot and then projected to a 15- by 25-meter-plot basis. Resulting size-class distributions were used to determine the successional status of subalpine fir based on the following principles. In mature stands, a climax species will usually exhibit the inverse J- shaped distribution curve, typical of tolerant species, when number of individuals are plotted against size class. Largest numbers of individuals are found in the smallest (seedling) size class; representation decreases rapidly with increasing size class. Seral species, however, lack representation in smaller size classes and exhibit gaps in the distribution curve; e.g., in sapling or pole sizes. Such a void in a stand approaching climax indicates seedlings of this species are unable to

Dr. R. Daubenmire, personal communica- tion. 5 cession. Subalpine firs in the over- Distribution of areas where sub- Sisters Province (Franklin 1965). story canopy are dying and smaller alpine fir is abundant in the Cas- This pattern of occurrence largely size classes are not present. Moun- cade Range reinforces the belief coincides with extensive fires dur- tain hemlock constitutes the bulk that disturbance is necessary for ing historic times (fig. 6). Some of of basal area in this stand. How- establishment of subalpine fir the famous spired subalpine fir ever, it, too, is poorly represented stands. Except in the northeastern stands in the vicinity of Paradise in younger age classes. The major Washington Cascades (Wenatchee Park at Mount Rainier may have climax species appears to be Pacific Province), subalpine fir is rarely a also developed following burning silver fir, which is well represented major component of old-growth (Haines 1962). in younger age classes. Intercession stands. Dense stands containing a of a stand of mountain hemlock large component of subalpine fir Wenatchee Province between stands of subalpine fir (or are generally in areas disturbed The highest elevation forest zone subalpine fir and lodgepole pine) within the last 150 years. in this province is usually the Sub- and a climax forest of Pacific silver alpine Fir-Engelmann Spruce Zone fir is common, especially where a Fire appears to have been the most (Franklin and Trappe 1963). This Pacific silver fir seed source is ab- important disturbing agent; all area is largely free of competitors sent at the beginning of the sere. stands listed in table 1 occurred on more tolerant than subalpine fir — soils with abundant charcoal in mountain hemlock and Pacific sil- The Santiam Pass stand (table 2) surface horizons. The areas of the ver fir occur only locally. Sub- represents a near-climax forest of Cascade Range where subalpine fir alpine fir-Engelmann spruce forests Pacific silver fir and mountain is most abundant, excluding tim- here are much like those of north- hemlock. Subalpine fir is repre- berline and the Wenatchee Prov- ern Idaho in distribution and com- sented only by dead trees. Moun- ince, are the High Cascades prov- position. Not only do they consti- tain hemlock dominates the stand, inces, from the Mount Adams tute the zonal climax forests but, but relative numbers of seedlings Province south through the Three and saplings indicate it, too, will as in northern Idaho, "As a topo- be largely (if not completely) re- edaphic climax, peninsular strips placed by Pacific silver fir. of it [spruce-fir forests] extend to

Figure 5.—Interior of subalpine fir-mountain hemlock-Pacific silver fir stand along Timberline Lodge road, Mount Hood National Forest. Reproduction is almost entirely Pacific silver fir. (The stake (arrow) in this and figures 10 and 11 is 1 meter high and is marked off in decimeter segments.)

6 rather low elevations where they often expand to cover the floors of frost pockets in valleys surrounded by some representative of the Thuja-Tsuga zone" (Daubenmire 1952). Size-class distributions of species in typical stands from the northeastern Washington Cascades provide conclusive evidence (table 3) that subalpine fir is the major climax species in many spruce-fir stands. In fact, at eastern edges of high east-west-trending ridges (e.g., Wenatchee Mountains, Chelan Mountains, Entiat Mountains), Engelmann spruce is a minor component or even absent from many subalpine fir stands (Franklin and Trappe 1963). Eastern extremities Figure 6.—Subalpine fir growing on a tract burned over about 1900, near Mount Wash- of these ridges are relatively dry, ington, Willamette National Forest. despite their elevation, and Engel- mann spruce is either absent or confined to moister habitats.

Table 3.—Number of trees by size classes (diameter) and species on a 15- by 25-meter plot in each of three stands containing subalpine fir; Wenatchee Province of the Cascade Range, 1961-631

Size class (diameter in inches)

<2 Plot and species 2- 4- 12- 20- 28- < 3 feet > 3 feet 4 12 20 28 36 tall tall Pasayten River: Subalpine fir 636 48 5 2 1 3 2 Engelmann spruce 16 5 2 — 1 2 4 Lodgepole pine ( 2 ) - 1 - - — Chiwawa River: Subalpine fir 116 56 2 2 4 2 ( 2) ( 2) Engelmann spruce 8 2 6 - ( 2 ) 2 Western white pine — — — — — — 1 ( 2) Grand fir 8 — — 1 1 1 Pinegrass Ridge:

Subalpine fir 880 141 23 2 6 1 ( 2) Engelmann spruce 48 6 1 4 — 2 1 Western hemlock 8 — — — — 1 — Western redcedar — — — 1 1 — — Western white pine — — — — — 1 (2 ) Lodgepole pine — — — I — ( 2 ) - ..- Douglas-fir — — — — — — (2 ) 1Wenatchee Province is as defined by Franklin (1965). 2Size class was represented in an adjacent part of the stand (outside the plot). 7 Succession on on Big Lava Beds (fig. 7), an ex- flow surfaces in this area. On the tensive flow located between the McKenzie Pass lava flows in the Severe Sites Wind River valley and Mount central Oregon Cascades, subalpine Adams in southern Washington. fir shares pioneer status with moun- Subalpine fir is often a pioneer in On the West Crater lava flows in tain hemlock and whitebark pine. the development of a forest on the same area, subalpine fir is co- severe, generally inhospitable sites. dominant with Douglas-fir over The "forests" growing on these These may be raw, geologically almost the entire surface, even lava flows are comparatively open. young surfaces, such as lava flows extending to elevations lower than Limiting factors in regeneration are or talus slopes, or climatically 2,000 feet. The forest on the West related to substrate — not light — severe regions near timberline. The Crater flows is very similar to a and, with limited tree competition, remarkable success of subalpine fir Douglas-fir-subalpine fir associa- subalpine fir is able to establish as a pioneer species is accounted tion described by Roach (1952) on and maintain itself. Size-class dis- for by its ability to become estab- a part of the central Oregon Nash tributions of tree species in most lished on sites too severe for less Crater lava flow. Both are open lava flow stands show little or no hardy competitors together with forests growing in a broken crust evidence of successional change its ability to enlarge colonies of block basalt. Greater numbers (table 4). Subalpine fir is repro- through layering. On most of these of seedlings and saplings (table 4 ducing in sufficient abundance to severe sites, the forest will not and Roach (1952)) suggest subalpine at least maintain its proportion of close over for centuries, and sub- fir is more aggressive at pioneering the stand. Accordingly, these stands alpine fir is essentially a climax the site than is Douglas-fir. Sub- exemplify situations where sub- species. alpine fir is an edaphic climax alpine fir is also a major tree species species. Lava Flows on some raw lava surfaces south- On lava flows in southern Wash- west of Mount St. Helens, although It must be noted, however, that ington and northern Oregon, sub- lodgepole pine is more common on subalpine fir is not present on all alpine fir is often the major tree recent lava flows in the Cascade species. For example, it is the most important tree at upper elevations

Table 4.—Number of trees by size classes (diameter) and species on a 15- by 25-meter plot in each of three stands dominated by subalpine fir; Cascade Range lava flow communities, 1961-63 Size class (diameter in inches) <2 Plot and species 2- 4- 12- 20- 28- < 3 feet > 3 feet 4 12 20 28 36 tall tall

Big Lava Beds:

Subalpine fir 32 22 16 24 2 — — ____, Western white pine (1) — — — — —

West Crater lava flow:

Subalpine fir 16 10 4 8 14 — —

Douglas-fir — (1) — 1 — 2 ( 1 )

McKenzie Pass lava flow:

Subalpine fir 8 2 3 1 — — —

Whitebark pine — ( 1 ) — 1 1 — —

Mountain hemlock — 2 — 1 1 — — 1Size class was represented in an adjacent part of the stand (outside the plot). 8 Range. Composition of lava flow high-elevation talus (fig. 8) and on especially striking in the Mount communities depends upon many avalanche tracks in the Cascade Baker and Mount Rainier Prov- factors, some of the most important Range. In the Washington Cascades inces (Franklin 1965) where dense being characteristics of the flow (including Wenatchee Province), it old-growth forests of Pacific silver surface, elevation, and available is often the major tree species and fir, hemlocks, and cedars occupy seed sources. Roach (1952) noted is sometimes the only one present many acres totally lacking in sub- subalpine fir may be absent from (especially on talus). Frequently alpine fir. Yet, where talus or an portions of a lava flow well within the authors have traveled through avalanche train causes a break in its geographic range. forests containing little or no sub- the dense forest, open stands of alpine fir, only to come upon inter- subalpine fir occur as islands or as Talus and Avalanche Areas vening talus or slide areas where it peninsular extensions from higher Subalpine fir is a climax species on is abundant. This phenomenon is elevations.

Figure 7.—(Left- lower left) Subalpine fir growing on Big Lava Beds in the southern Washington Cascade Range.

Figure 8.—Subalpine fir on an extensive talus near Bumping Lake, Snoqualmie National Forest. Note layering present near bases of many trees. As on lava flows, subalpine fir is ural patterns in forest succession and resulting replacement of mea- present as a pioneer species. Yet, it require extensive, detailed obser- dow vegetation by forest. Sub- forms a topoedaphic climax on vations. Detailed studies of natural alpine fir is often the leader in these sites because the open stands succession among timberline tree these invasions (Brink 1959, Frank- and exclusion of potential competi- species in the wetter portions of lin 1966), although it is sometimes tors have minimized competition the Washington Cascade Range accompanied by mountain hemlock from other trees. On talus the are discussed here. Although tim- (Van Vechten, Cooper 1942). But limiting environmental factor is berline forests in the Wenatchee what of succession during develop- again the substrate, whereas on Province are relatively poorly ment and expansion of these tree avalanche tracks it is usually re- known, openness of the stands and groups? peated snow slides. Abundant lay- lack of more tolerant arborescent ering of subalpine fir growing on competitors insure subalpine fir a A definite sequence in tree species these habitats is a very useful adap- permanent place there. is associated with growth and ex- tation for their colonization. pansion of subalpine tree groups. Subalpine fir occupies a somewhat It was repeatedly observed during Timberline dichotomous successional position examinations of nearly 100 "fam- Subalpine fir is a conspicuous fea- at timberline in the wetter regions ily" groups of various sizes (and ture of timberline forests in the of the Washington Cascade Range. presumably ages) in the Goat Cascade Range. This area of sub- It perpetuates itself in open sub- Rocks Wilderness and at Sunrise alpine meadows and groups of subalpine forest regions and in a cer- Ridge and Paradise Park on Mount alpine fir, mountain hemlock, and tain limited sense can be considered Rainier, all in western Washington. whitebark pine (fig. 9) is sometimes a climax species. But, it does not Initiation of a new group appar- called the Hudsonian Zone. It is a necessarily retain possession of in- ently begins with an individual or tension zone, a dynamic ecotone dividual areas which it colonizes. small group of seedlings. The initi- between tree and treeless veg- Changes are constantly taking ator may be subalpine fir or white- etation, in which changes are con- place. There is good evidence that bark pine, the latter often becom- stantly taking place due to allo- "family" groups of subalpine fir ing established in small groups (fig. genic (e.g., long- and short-term and mountain hemlock have been 10) from buried cones or rodent or climatic variations) as well as auto- invading heather or meadow com- bird seed caches. Mountain hem- genic (changes in environment munities for the last 50 years (Brink lock was not a common pioneer in brought about by plants) factors. 1959, Franklin 1966). Brockman Van Vechten, George Wendell III. The Successional sequences among tree (1949) mentions growth and coales- ecology of the timberline and alpine vege- species are sometimes obscured by cence of subalpine tree groups tation of the Three Sisters, Oregon. 111 pp., allogenic changes in environment illus. 1960. (Unpublished Ph.D. thesis on file and, therefore, discernment of nat- at Oregon State Univ., Corvallis.)

Figure 9.— Subalpine tree groups near timberline on Sunrise Ridge, Mount Rainier National Park. Groups are predominantly subalpine fir and whitebark pine.

10 the Mount Rainier area, although become established within pro- lings, and poles of Pacific silver fir. it does initiate meadow invasion tection of subalpine fir and white- Mountain hemlock reproduction elsewhere. bark pine. Subalpine fir and white- was sparse and confined to rotten bark pine fail to reproduce wood. It appears, therefore, that As the small patches of seedlings shaded areas and are gradually Pacific silver fir will be the major develop, they exert an ever-increas- eliminated from the center part of climax species in a family group ing influence on the microclimate the group by mountain hemlock. originally started by seedlings of — the blackbody effect causing subalpine fir and whitebark pine. earlier snowmelt and thereby The largest, and presumably old- lengthening the growing season. est, stand which could be positively The development of subalpine tree The group enlarges by layering of identified as a subalpine forest groups is illustrated schematically subalpine fir as well as establish- group was about 100 by 400 feet in figure 12. Significantly, the suc- ment of new trees from seed (fig. in size and completely surrounded cessional sequence is the same as 11). Mountain hemlock seedlings by meadow vegetation. Here, sub- that encountered well below tim- alpine fir (mature and reproduc- berline following destruction of Swedberg, Kenneth Charles. The coniferous tion) and occasional whitebark pine dense Pacific silver fir-mountain ecotone of the east slopes of the northern Oregon Cascades. 118 pp., illus. 1961. (Un- were confined to the margins of hemlock forests. This develop- published Ph.D. thesis on file at Oregon State the group. The center was domin- mental pattern also contrasts with Univ., Corvallis.) ated by large overmature moun- the development of subalpine tree See footnote 4. tain hemlocks, among which were groups in comparatively drier re- See footnote 5. scattered abundant seedlings, sap- gions such as the Teton Range of

Figure 11.—Subalpine forest groups in early stages of development. Group in upper picture appears to have been initiated by whitebark pine; group in lower picture by subalpine fir. Some mountain hemlock seedlings have become established within the protection of larger subalpine fir and whitebark pine. Expansion of groups is taking place largely by layering of subalpine fir. In the lower picture, note that whitebark pine saplings are confined to the margin of the group. Sunrise Ridge, Mount Rainier National Park.

Figure 10.— (Below left) Whitebark pine seedlings in subalpine meadow which probably developed from a bird or rodent seed cache. Seedling groups of this type often initiate development of a subalpine forest group. Sunrise Ridge, Mount Rainier National Park.

11 Wyoming (Griggs 1938) and on among tree species. Subalpine fir Pests Affecting cinder flats in the central Oregon is especially adapted to this en- Cascade Range." In these areas, vironment because of its ability to Subalpine Fir "timber atolls" are found in which layer. Other species, notably sub- groups of subalpine fir and other alpine larch or whitebark pine, may The insect and disease situation species expand outward by layer- extend to higher elevations, but a with subalpine fir is generally ing and seeding but leave the cen- single established subalpine fir is poorly known, though the species ter of the group hollow or vacant. capable of colonizing a greater area apparently has few enemies. Some than an individual of any other primary root diseases, such as "Krummholz" Areas species in the krummholz region. Armillaria mellea Vahl ex Fr. and "Krummholz" refers to individual Fomes annosus (Fries) Karst, are and small groups of trees growing Seral or climax designations are apparent and bark beetles such as above timberline. These trees are usually not applied to tree species Pseudohylesinus grandis Swaine characteristically contorted and in krummholz stands, but subalpine and Dryocoetes confusus Swaine dwarfed due to severe alpine cli- fir is definitely a pioneer in this have been known to attack a few mate (hence "krummholz," a Ger- environment. Archer (1964) has trees, but the total impact of these man term meaning crooked or bent described a successional sequence pests has not appeared significant. wood). Here, environmental influ- in krummholz stands in coastal The important enemy of subalpine ences are much more important in British Columbia in which sub- fir in the Pacific Northwest is an seedling establishment than com- alpine fir succeeds Alaska-cedar introduced pest from Europe — the petition for moisture and light and is in turn replaced by moun- balsam woolly aphid (Adelges tain hemlock. Chermes) piceae (Ratzeburg)). See footnote 5. Of native true firs, subalpine fir is the most sensitive to balsam woolly aphid (Mitchell 1966), and epidemic infestations of the woolly aphid have been responsible for dramatic changes in the ecology of subalpine fir over a wide area. Since discovery of the aphid in 1954 (Johnson and Wright 1957), the pest has killed subalpine fir along the Cascade Range from Mount Rainier in central Washington to Crater Lake in southern Oregon. The southward spread of the aphid in the Crater Lake area is con- tinuing, although it is nearing the southern limit of subalpine fir. In the north, around Mount Rainier, the status of the aphid is unknown. One spot infestation of undeter- mined size has been found north of Mount Rainier, in the Middle Fork drainage of the Snoqualmie River. Mortality due to the balsam woolly aphid is sometimes quite severe. Subalpine fir growing in moist stream bottoms and around lower mountain meadows (fig. 13) is ex- tremely sensitive to the aphid. Stands growing on and around

Figure 12.— Schematic diagram showing the development of subalpine forest groups on western slopes of the Washington Cascade Range.

12 lava beds have also suffered severe damage. Over 80-percent mortality was observed in a mature stand growing on the West Crater lava flow in the Wind River drainage of southwest Washington. Signi- ficant mortality has also been observed in other lava beds, partic- ularly at lower elevations. Conceivably, aphid outbreaks could eliminate subalpine fir from localized areas. In closed, mixed stands, the aphid will hasten replacement of subalpine fir by more tolerant species. Greatest impact of the aphid appears to be on the pioneering ability of subalpine fir — those instances where the fir in- vadeg lava beds, talus slopes, old beaver marshes, etc. Adversities of the physical environment — already considerable in these situations — are greatly magnified by the aphid. Also, the aphids habit of settling on terminal buds inhibits new growth and reduces the possibility of seed production, further reduc- ing effectiveness of subalpine fir in colonizing nonforested land and maintaining its tenuous hold in some areas. Fortunately, mortality is seldom complete in an infested area. Sup- pressed trees and poor-site trees are far less sensitive to aphid infestations than was once believed. Even in areas where mortality is heavy, a few large trees nearly always escape attack, because of chance, local environment, or pos- sibly genetic characteristics. But the most significant characteristic of infestation patterns is that attacks are most abundant and most serious at lower elevations. Sub- alpine fir above 5,500 to 6,000 feet is rarely attacked, and a wide zone is left between timberline and the infestation area. Here, it appears, succession will proceed normally, Figure 13.— Destruction of subalpine fir by balsam woolly aphid is complete without interference from the bal- in many stands surrounding mountain meadows in the western Cascades of Oregon. sam woolly aphid. Lookout Mountain, Willamette National Forest.

13 Significance in Esthetically, subalpine fir is un- ;Summary equaled as a dramatic backdrop. Land Management More than any other species, sub- Subalpine fir has a far different alpine fir symbolizes high-elevation ecological role in most parts of the Ecologically, subalpine fir is a very beauty, a sense of eternity, and Cascade Range than it does in important species in high-elevation wilderness. Most outdoor enthus- ocky Mountain spruce-fir forests. forests. Asa f st_pioneer on lava iasts in the West could scarcely is seral on sites which flows, ava anches, and others-e-v-ere imagine a mountain meadow with- will support closed forest standst- sites in the high Cascades, it is out subalpine fir. In high-use rec- jt regenerates following disturbance probably unequaled. By providing reation areas, such as National end is gradually eliminated by cover on these and fire-devastated Parks, this factor deserves much more tolerant associates such as tracts, subalpine fir can be a dis- consideration. Alpine meadows may mountain hemlock and Pacific tinct asset in watershed protec- need some management to keep silver fir. On some other sites, such tion and landscape rehabilitation. the wilderness image that the pub- as recent lava flows and talus, sub- In commercial management of sub- lic has been conditioned to expect. alpine fir pioneers and is main- alpine fir forests, foresters must It is not yet clear what the full tained as a topoedaphic or edaphic consider the trees successional effects of balsam woolly aphid will climax species. In open subalpine status as well as the probable im- be on subalpine fir and, as a con- forests near timberline -(forest pact of the balsam woolly aphid. sequence, the natural ecology and groups,scattexed-through subalpine In the Wenatchee Province, sub- management of the Cascade Range. ..meadow.4,-it often pioneers but is alpine is both abundant an The outbreak has not yet run its sometimes replaced by mountain free of infestation. In this course; it still appears to be spread- hemlock and Pacific silver fir if area, subalpine fir will be favored ing in many areas. Nevertheless, forest succession is allowed to con- by shelterwoOd or seleClion—Ctiffing present indications are that stands tinue. The ability of subalpine fir since it is the most forerarit species on the east side of the Cascades to enlarge original colonies by lay- normally present, and clearcutting will not be damaged by the aphid. ering partially accounts for its suc- will tendto favor associated, less Elsewhere, high-elevation stands, cess as a pioneer species on some tolerant spe-CieY. Siliictiltural knowl- from 5,500 or 6,000 feet to timber- of these difficult sites. In the north- edge developed jn •Rocky Mountain line, will probably also escape sig- eastern part of the Cascade Range subalpine fir stands jAlexander nificant infestation. Many low-ele- -(-Wenatehee-Provinee),, more toler- 1958, Daubenmire 1952, LeBarron vation stands are apparently doom- ant associates of subalpine fir are and Jemison 1953) can be drawn ed, destruction by the aphid hav- generally lacking. There it is a upon with reasonable Afely,untif ing been almost complete. Ecolog- climax species, occupying the same detailed studies have been con- ically, the widespread death of ecological niche as in interior ducted in Ihe:Wenatchee Proving?. subalpine firs in pioneer situations ountain ranges. Elsewhere in the Cascade Range, — around meadows, avalanche sam woolly aphid is causing subalpine fir Fins Tittre-eommeiCial areas, and lava beds — is partic- significant mortality in many sub- value, is generally infested by bal- ularly serious because there often alpine fir stands in Oregon and sam woolly aphid, and behaves as appears to be no other tree species southern Washington, virtually an intolerant species. It is some- capable of taking its place. Loss of eliminating it from some areas. times logged along with other high- subalpine fir from commercial for- This destruction, coupled with the elevation species, but low stump- est stands is at least economically seral role of subalpine fir on most age values render timber sales less serious since many other species forest sites, is producing a drastic aimed specifically at subalpine fir of higher or equivalent value are downward trend in importance of impractical. In many cases, such adapted to these sites. subalpine fir in areas of aphid in- stands are best left alone — salvable festation. timber values are not commensur- ate with losses of other multiple- use values. However, in stands where timber harvesting is plan- ned, it must be recognized that shelterwood or selective cutting will favor regeneration of species differ thaan subalpine fir, especially if subalpine fir seed source is eliminated. The closed stands would have little or no advance regeneration present.

14 References Alexander, R. R. Franklin, Jerry F. Johnson, NormanE., and Wright, 1958. Silvical characteristics of 1965. Tentative ecological prov- Kenneth H. subalpine fir. U.S. Forest Serv. inces within the true fir-hem- 1957. The balsam woolly aphid Rocky Mountain Forest lock forest areas of the Pacific problem in Oregon and Wash- Range Exp. Sta. Pap. 32, 15 Northwest. U.S. Forest Serv. ington. U.S. Forest Serv. Paci- pp., illus. Res. Pap. PNW-22, 31 pp., fic Northwest Forest Range Archer, Clifford Anthony. illus. Exp. Sta. Res. Pap. 18, 34 pp., 1964. Some synecological prob- illus. lems in the Alpine Zone of 1966. Invasion of subalpine mea- Kittredge, Joseph, Jr. Garibaldi Park. In Ecology of dows by A bies lasiocarpa in 1934. Evidence of the rate of the Forests of the Pacific the Mount Rainier Area. forest succession on Star Is- Northwest, 1962-1963, by V. (Abstr.) Northwest Sci. 40:38. land, Minnesota. Ecology 15: J. Krajina, 2 v., pp. 5-18, illus. and Trappe, James M. 24-35. Univ. Brit. Columbia Dept. 1963. Plant communities of the Langille, H. D., Plummer, Fred G., Biol. Bot. northern Cascade Range: a Dodwell, Arthur, and others. Brink, V. C. reconnaissance. (Abstr.) North- 1903. Forest conditions in the 1959. A directional change in the west Sci. 37:163-164. Cascade Range Forest Re- subalpine forest-heath ecotone Griggs, Robert F. serve, Oregon. U.S. Geol. Surv. in Garibaldi Park, British 1938. Timberlines in the north- Prof. Pap. 9, 298 pp., illus. Columbia. Ecology 40:10-16, ern Rocky Mountains. Ecol- LeBarron, Russell K., and Jemison, illus. ogy 19:548-564, illus. George M. Brockman, C. Frank. Haddock, Philip G. 1953. Ecology and silviculture of 1949. Trees of Mount Rainier 1961. New data on distribution the Engelmann spruce-alpine National Park. 49 pp., illus. of some true firs of the Pacific fir type. J. Forest. 51:349-355, Seattle: Univ. Wash. Press. Coast. Forest Sci. 7:349-351. illus. Cooper, William S. Haines, Aubrey L. Mitchell, Russel G. 1942. Vegetation of the Prince 1962. Mountain fever. Historic 1966. Infestation characteristics William Sound region, Alaska; conquests of Rainier. 255 pp., of the balsam woolly aphid in with a brief excursion into illus. Portland, Oreg.: Oreg. the Pacific Northwest. Pacific post-Pleistocene climatic his- Hist. Soc. Northwest Forest Range tory. Ecol. Monogr. 12:1-22, Hofmann, J. V. Exp. Sta. U.S. Forest Serv. illus. 1917. Natural reproduction from Res. Pap. PNW-35, 18 pp., Daubenmire, R. seed stored in the forest floor. illus. 1952. Forest vegetation of north- J. Agr. Res. 11:1-26, illus. Roach, Archibald W. ern Idaho and adjacent Wash- 1952. Phytosociology of the Nash ington, and its bearing on con- Crater lava flows, Linn Coun- cepts of vegetation classifica- ty, Oregon. Ecol. Monogr. 22: tion. Ecol. Monogr. 22:301- 169-193, illus. 330, illus. Sudworth, George B. 1908. Forest trees of the Pacific slope. U.S. Dep. Agr. 441 pp., illus.

15 Common and Scientific Names of Tree Species Mentioned in the Text Abies amabilis (Dougl.) Forbes Pacific silver fir Abies grandis (Dougl.) Lindl. grand fir Abies lasiocarpa (Hook.) Nutt. subalpine fir Abies magnifica var. shastensis Lemm. Shasta red fir Abies procera Rehd. noble fir Chamaecyparis nootkatensis (D. Don) Spach Alaska-cedar Larix lyallii Parl. subalpine larch Larix occidentalis Nutt. western larch Picea engelmannii Parry Engelmann spruce Picea glauca (Moench) Voss white spruce Picea pungens Engelm. blue spruce Pinus albicaulis Engelm. whitebark pine Pinus contorta Dougl. lodgepole pine Pinus flexilis James limber pine Pinus monticola Dougl. western white pine Pinus ponderosa Laws. ponderosa pine Pseudotsuga menziesii (Mirb.) Franco Douglas-fir Tsuga heterophylla (Raf.) Sarg. western hemlock Tsuga mertensiana (Bong.) Carr. mountain hemlock