Introduction and Backgrounddepts.washington.edu/pnwcesu/reports/J9W88030009_SWAN_Pa...Profile). Further south, and around Lake Clark itself, topographic relief is high (250-3500 ft)

DRAFT

Paleoenvironmental Reconstruction and Landscape Interactions in Lake Clark and other Southwest Alaska Lake Systems,

Southwest Alaska Inventory and Monitoring Network

Module I

Paleoecology and Vegetation History Lake Clark and Katmai Regions

Patricia A. Heiser

UA Geography Program University of Alaska Fairbanks

Fairbanks, AK 99775

September 2007

National Park Service Southwest Alaska Network

Inventory and Monitoring Program

Project / Task Agreement No.: J9W88030009 CESU Cooperative Agreement No.CA9088A0008

DRAFT Paleoecology and Vegetation History Lake Clark and Katmai Regions

Patricia Heiser, UAF Geography Program and Nancy Bigelow, Alaska Quaternary Center

Introduction The Southwest Area Network (SWAN) park units of Southwest Alaska encompass an

extensive range of geographic physiographic, climatic, and ecologic provinces and gradients. Ecosystem types show strong variation across the landscape including relatively dry interior boreal forest, alpine herb tundra, shrub tundra lowlands, and cool coastal forests. Some park units such as Lake Clark are located in transition zones between these major ecosystem types (Spencer 2001). As glaciers retreated and climate ameliorated during the Holocene, significant changes have occurred in the dominant vegetation assemblages in the area. Likewise, Little Ice Age moraines are prominent in many valleys and suggest there might also be detectable records of shorter-term Holocene climatic events. The study of pollen assemblages recorded in lake sediments is one of the most widely used indicators of past environmental changes. Recent studies have shown that late Quaternary vegetation of Alaska and the Bering Strait region has been “marked by great spatial and temporal variability” (Brubaker 2001), and defining patterns of vegetation change through time and at different spatial scales has become critical in determining causal factors and driving forces for landscape change (Bartlein et al 1998). Few studies of vegetation change have been conducted in southwest Alaska. Two pollen records obtained from Idavain and Snipe Lakes in Katmai and Lake Clark National Parks respectively, record distinctive changes in dominant vegetation type over the last ~12,000 years. These cores were compared with records obtained on a transect running from Interior Alaska to Bristol Bay (Brubaker et al 2001). While the information in these cores is valuable to understanding regional landscape dynamics surrounding SWAN systems, it is important to compliment these results with more local, and perhaps higher resolution, and better dated records from transition areas like Lake Clark, and from areas with unusual vegetation patterns such as near Nonvianuk Lake in Katmai National Park (Fig X). Additionally, vegetation studies around lakes from which historic records of salmon abundance are being obtained may be valuable to the interpretation of those records. Salmon history is reconstructed using nitrogen isotopes, and appearance of nitrogen fixing plant species (e.g. alders) may potentially influence the N record used as a proxy for salmon abundance. Vegetation change is also an important component in efforts to understand timing of colonization, succession, and nutrient cycling in riparian habitats and lake systems. This study will complete the picture of landscape change and freshwater ecosystem development in the Southwest Network parks.

http://www.nature.nps.gov/im/units/swan Figure 1. Location of SWAN parks and study areas.

DRAFT Study Areas Two lakes were selected for this paleoecological study across SWAN units. Informally named “Tommy Lake” in Lake Clark National Park and Preserve and “Pikelet” Lake near Nonvianuk Lake in Katmai NP&P were cored in the summer of 2005. The study lakes were chosen for their geomorphic position and surrounding plant communities . TOMMY LAKE

Tommy Lake is located along the southwest shore of Lake Clark approximately 500 meters inland and 40 meters above the current shoreline elevation of Lake Clark. “Tommy Lake” is actually a small pond ~ 2500 m2 with a maximum depth of 2.5 meters. It is one of a series of ponds formed in a covering of thin glacial till over bedrock. Outcrops of bedrock and large erratics influence the elevation and position of Tommy and surrounding lake and ponds.

LACLTommy Lake

Pikelet Lake

KATM

Figure 2. Satellite image showing location of Tommy Lake in Lake Clark National Park (LACL) and Pikelet Lake in Katmai National Park (KATM).

The vegetation in the Lake Clark region is highly varied due to topographic variation and strong climatic gradients (wetter to east, drier to the west). The western side of the park is dominated by a series of linear lakes dammed by terminal moraines that mark the extent of glacial ice from Alaska Range valleys to the east. Low ridges and subdued mountains between these lakes are host shrub/alpine tundra and occasional scattered spruce in the valley floors. The northern part of the park, by the Stony River, is boreal in character, with black spruce, muskeg, aspen and birch, and subject to wildfire (NPS Ecological Profile). Further south, and around Lake Clark itself, topographic relief is high (250-3500 ft) with steep valley walls and deep glacially carved valleys. Lake Clark occupies a very deep fault controlled glacial valley. Vegetation is a mosaic of spruce and mixed spruce/birch or cottonwood forests, paper birch, low shrubs dominated by dwarf birch, dwarf shrub tundra with ericaceous

Figure 3. Vegetation classification around Lake Clark.

DRAFT shrubs, scattered wetlands, and alpine tundra. Dense alder zones cover alluvial and scree slopes between the mixed hardwood spruce forests around the lake, and the higher alpine zones (NPS Ecological Profile). In general Lake Clark valley is located at an ecological intersection between interior boreal forest, upland shrub tundra, mixed spruce/birch forest of glaciated valleys, and humid coastal forests along Cook Inlet on the east side of the Alaska Range. Of interest. is the timing of the arrival of spruce trees, and the likely ‘source’ for spruce expansion into the Lake Clark valley after deglaciation. Also of interest is the timing and nature of the arrival of alder, which shows dramatic increases in abundance ~7,000 cal yr BP in Snipe Lake and in other pollen records in SW Alaska.

Tommy Lake

Figure 4. Vegetation classification and satellite image of landscape around Lake Clark and Tommy Lake.

The vegetation at the shoreline and adjacent to the pond is a mixture of sedges (Carex sp. and Eriophorum sp.), horsetail (Equisetum sp.) and shrubs such as Myrica gale [sweetgale], shrub birch (both Betula glandulosa and B. nana), willows (Salix sp.) and ericads (Vaccinium vitis-idaea [lowbush cranberry], Vaccinium sp. [blueberry], Empetrum hermaphroditum. [crowberry], Ledum decumbens [narrow leaf Labrador tea], and Andromeda polifolia [bog rosemary]). Interestingly, no Alnus (alder) was encountered near Tommy Lake, although the mountainside above the lake and the slopes descending to Lake Clark have abundant alder. Spruce are present a short distance (<20 m) from the shoreline, mainly Picea mariana (black spruce). White spruce (P. glauca) was not seen at the lake, but probably grows on well-drained sites above the lake. The emergent vegetation within the pond includes buckbean (Menyanthes trifoliata), pondweed (Potamogeton sp.), and possibly water milfoil (Myrophyllum sp.). Hippuris (mare’s tail) was probably also present, but not emergent. Methods:

Approximately 5.5 meters of sediment were retrieved from Tommy Lake in overlapping cores. The lake was cored in the deepest basin in approximately 2.5 meters of water. Overlapping drives were aligned using numerous and distinct volcanic ashes and ash sequences present through the cores. Cores were split, described, and sampled for tephra analysis, radiocarbon dating, and pollen analysis. For the pollen study, volumetric samples were collected from the core and processed using slightly modified techniques outlined in Faegri and Iversen, 1989. This includes additional washes in hot KOH to remove lignins and in some cases, a

DRAFT slightly longer soak in a boiling water bath during acetolysis. Prior to analysis, a known quantity of exotic spores (Lycopodium) were added to the samples. Lycopodium exotics were counted in tandem with the pollen, so that the pollen concentration can be assessed. Pollen grains were identified based on comparison with the reference collection at UAF’s paleocology laboratory or with various published atlases and keys, such as Faegri and Iversen, 1989; McAndrews et al., 1973; Moore et al., 1991. Pollen frequencies were calculated on a variety of pollen sums. Trees, herbs and forb frequencies are based on a sum of those taxa (= Pollen sum); spore frequencies (Pteridophytes) are based on the pollen sum plus the spore sum; aquatic frequencies are based on the pollen sum plus the aquatic sum, and the Pediastrum frequency is based on the pollen sum plus the Pediastrum sum. This method of calculation prevents the non-terrestrial and non-seed producing plants from overwhelming the terrestrial pollen signal.

Tommy Lake / Lake Clark Pollen History Four major pollen zones are preserved in the Tommy 05 core (Figure 5). Herb zone (547-530 cm). The basal two samples represent the final stages of the herb zone, when graminoids (grasses and sedges) and forbs dominate the landscape. The transition to the birch zone occurred about 14,500 cal yr Bp (12,000 14C BP), when Betula (birch) pollen frequencies abruptly increase from about 20% to nearly 70%. Birch zone (530- 410 cm). The birch zone encompasses more than 1 m of sediment, spanning from about 14,500to 10,000 cal yr BP (12,000 to 7000 14C BP). While birch pollen dominates, willow, ericads, graminoids and some forbs are also present. The concentration (# pollen grains/cc of sediment) of herbaceous pollen does not markedly decrease with the birch rise, indicating that these taxa (grasses, sedges, Artemisia, and other forbs) continued to be a significant part of the vegetation. The vegetation was probably a birch shrub tundra, with occasional herbs, willows, and ericads, especially at the end of the zone. When it was possible to identify the ericads to the species level, Empetrum (crowberry) and Ledum (Labrador tea) were also probably present. Monolete spore (ferns) frequencies present an interesting picture. Ferns are sensitive to warmth and moisture; an increase in spore frequencies may indicate climatic amelioration. Two fern peaks are present in the birch zone, separated by a period of low spore frequencies. This may correlate with the “fern gap as noted by Peteet and Mann, 1997 in their work from Kodiak Island. However, the current chronology for Tommy places the onset of fern dip at about 13,500 cal yr BP, about 700 years before the Kodiak record. Fern spores and Pediastrum nets (an alga) are abundant towards the end of this zone, Pediastrum may be an indicator of overall lake productivity. Both taxa may be responding to increasing early Holocene warmth, but the Pediastrum peak is slightly earlier than the fern peak, indicating other factors may also be important. Alder zone (410-170 cm). The alder zone includes more than 2 m of sediment, from about 10,000 to 3800 cal yr BP (7000 to 3400 14C BP). Alder frequencies increase rapidly from less than 5% to over 70% over the space of 10 cm. The frequencies are highest at the onset of the period (ca. 80%), decreasing to about 50% by the period’s end. Alder is a prolific pollen producer and the pollen frequency over-represents the actual plant abundance on the landscape. 20% frequency probably indicates local presence of the plant (Anderson et al., 1991). Low

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DRAFT frequencies of Populus pollen (probably cottonwood) are present at the onset of the zone, indicating scattered trees may have grown as gallery stands along stream margins. Ericaceous, graminoid, and forb pollen, while present, are less abundant than the preceding zone. Sweet gale (Myrica gale) appears in the pollen record at about 240 cm (ca 5200 cal yr BP). Myrica is not common in boreal pollen records from Alaska; its presence here suggests the plant has grown around the lake (as it does today) since the mid-Holocene. The vegetation during the alder zone was a mixed alder and birch shrub tundra (including Myrica at the lake) with minor amounts of cottonwood, willow and other shrubs. Spruce zone (170-0 cm). This zone encompasses 3800 cal yr BP. to the present. Spruce (Picea) pollen is present at low frequencies prior to this zone; the taxon may have been present in the region at this time, but probably was not growing near Tommy Lake until roughly 3000 cal yr BP. Like alder, spruce is an abundant pollen producer. As a rule of thumb, 5% to 10% spruce frequency indicates it was growing locally.( Anderson et al., 1991; Hu et al., 1993). After about 3000 cal yr BP the vegetation was probably not markedly different from today’s vegetation. Towards the end of the zone, ericads, Sphagnum, and monolete spores increase, probably indicating increasing soil moisture.

asses

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KELET LAKE e (58o58’36.43”N, 155o39’33.19”W) is a small pond located at the south

i

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Spruce expansion. The late arrival of spruce to the Lake Clark area (at ca. 3500 cal yr BP) is consistent with its ultimate migration from the north, where spruce was present by at Snipe Lake (about 40 km to the north) by about 5800 cal yr BP (Brubaker et al., 2001). Trees may have crossed the low pseparating the two lakes. Some of the passes are about 300 m in elevation and today spruce are present in scattered localitiewhich increase in density towards the approaches to the Lake Clark basin. In any case, the current chronology suggests tmigration from Snipe Lake took more than 2000 cal yr.

Tommy Lake

Snipe Lake

. PI Pikelet Lakend of Pike Lake, approximately 6 km southwest from the outlet of Nonvianuk Lake, in KatmaNational Park and Preserve. The basin is separated from the larger lake by a 2-4 meter gravel ridge. The surface of Pikelet is slightly higher than Pike (<20cm) and a 2m wide wet spot, witvery little water exchange evident, may join the lakes at higher water levels. Pike Lake, Pikelet and surrounding small lakes are kettles formed in glacial tilmoraine deposited by a glacier flowing NW out of the Coville valley. The lakes are located just behind the crest of the terminal moraine that appears contemporaneous with the moraine bounding Nonvianuk Lake. These moraines are assigned to the Iliamna Stade of the Late Wisconsin glaciation (~18 k yr ago) (Reihle and Detteman 1993).

DRAFT

Nonvianuk Lake

Pikelet

moraine crests

Kukaklek

Nonvianuk

Idavain

Coville

a. b.

Figure 7. Pikelet Lake study area including nearby lakes and vegetation cover.

with the moraine crest at about 600 feet. The low moraines and outwash plains slope to near sealevel along the Alagnak and Kvichak Rivers, which empty into Bristol Bay about 75 kilometers to the west. Vegetation around Nonvianuk and Kukaklek lakes is dominantly shrub tundra on the low-relief hills. Thin bands of alder are present on steeper slopes at the head of Nonvianuk an

forest corresponds very closely to the moraine crest, with the mixed forest zone occupying the moraine crest. The location for this study was chosen because of the unusual pattern of spruce inthe area. To the south and around Naknek Lake, treeline reaches to elevations of 900-1000 feet.

The topography surrounding Pikelet Lake is more subdued than the relief around LakeClark and Tommy LGlacial valleys carved by ice flowing from the eastand southeast are occupied by Kulik amoraine dammed Nonvianuk Lake just to the northeast of the study site. The morianal topography in which Pikelet Lake has formed was deposited by ice flowing from the sthorough valleys now occupied by Grosvenor and Colville lakes. Whilpeaks between the glavalleys reach to 3500 feet, the lowlands in frontof the lakes, a

ake.

nd

outh

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re of lower elevation and subdued relief. Pike Lake is at an elevation at 584 feet,

d Kulik lakes and the Coleville valley to the south, alder is otherwise scattered on the landscape. An interesting and somewhat anomalous ‘tongue’ of spruce and mixed forest extends from the south, up the Coleville into the Nonvianuk / Alagnak drainage. The pattern of boreal / mixed

Figure 6. Pikelet Lake location and terminal moraines from Coville and Nonvianuk.

DRAFT To the north and west, spruce is much more scattered, and does not reach above 600 feet arounIlliamna and Kukaklek Lakes. Field studies of tree rings at Nonvianuk Lake revealed that mof the trees were approximately 90 years old , and may have germinated shortly after tKatmai eruption. This site was specifically chosen for its potential in evaluatin

d ost

he 1912 g some of the

ite

osa) Picea

lauca) are widely scattered, separated by birch, alder, and willow shrubs on the western shore Petasites sp.) on the eastern shore. No black spruce (Picea

ariana)

on core was retrieved from Pikelet lake in the summer of 2005. Core

r the

t as those present in Tommy Lake

len zone

factors influencing spruce treeline, distribution on the landscape, and colonization events. Previous studies (Tae, 1997) have suggested that volcanic eruptions or other geologic disturbance events may induce changes in plant communities or colonization. The emergent vegetation at Pikelet includes water lily (Nuphar polysepalum) and mare’s tails (Equisetum sp.). Sedges (Carex sp.) and mare’s tails (Equisetum sp.) dominate the shoreline vegetation, though marsh cinquefoil (Potentilla palustris) and Rubus sp. are also qucommon. Ridges and slopes descending to the lake have vegetation typical of somewhat better-drained settings, including abundant willow shrubs (Salix sp.), shrub birch (Betula glanduland heath vegetation. Alder (Alnus incana) is present in patches. White spruce trees (gand mare’s tails and coltsfoot (m or birch trees (Betula neoalaskana) were noted in the vicinity of Pikelet. Pikelet Lake Pollen History A 2.8 m long pistdrives were offset in to ensure overlapping drives. Both core holes ended in sandy pebble gravel at approximately 560 cm. Pollen analyses for Pikelet follow the same methods as outlined foTommy Lake core above. Pikelet Lake does not exhibit pollen zones as distincto the north. The alder rise, so abrupt at Tommy Lake, is more gradual in Pikelet and is not accompanied by a significant drop in birch. We define zones for Pikelet Lake nonetheless, to help aid discussion and interpretation of the core (Figure 8).

Birch Zone (276-235 cm). The basal date for Pikelet Lake, and the beginning of this polis 11006+40 cal yr BP (~10,000 14C yr BP) and it runs to 9400 cal yrBP (8400 14C BP)from the bottom of the core shows relatively abundant amounts (70%) of Betula (birch) pollen, with ~20% graminoids. Ericads, willows, and Artemisa are also present. These relative percentages are similar to the Birch Zone identified in the Tommy core and is is likely correlative. The lack of an earlier Herb zone, as seen in Tommy, may be a result of a later d

. Pollen

ate of

lix

this brief shift probably flects expansion of cottonwood and willow along streams and perhaps lake shores. As in other

l ts

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lake formation (11,000 at Pikelet vs 15,000 cal yr BP at Tommy). Whether this indicates a laterglacial advance/retreat in the Katmai area vs. Lake Clark, or simply a late forming lake in a terminal moraine will be discussed in a following paper on glacial histories of the region.

Populus-Willow Peak (240 cm). At 240 cm (ca. 9800 cal yr BP), there is a small peak in Sa(willow) and Populus (cottonwood or aspen). This is the local expression of the widespread Populus zone that is well-developed to the east (c.f. Wein and Farewell lakes), but is less important in southwest Alaska (Brubaker et al., 2001). At Pikelet, reregions, this expansion may reflect the Holocene Thermal Maximum, which in Alaska is dated between about 12,000 and 9000 cal yr BP (Kaufman et al., 2004). Alder-Birch Zone (235-10 cm). Alder and birch pollen dominate the record after about 9400 cayr BP. At this time, the relative amounts of Betula (birch) and Alnus (alder) increase as amounof Salix (willow), Poaceae (grasses), Cyperaceae (sedges), Artemesia, and Apiaceae (umbe

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Figure 9. Pikelet core top showing Katmai ash and pollen cha

cores where the identifications have beePikelet is consistent with the local vegetation, which is all white spruce. Alder pollen frequencies also increase after the 1912 Katmai erupsuggesting alders grew more abunthen than for much of the Holocene. post 1912 Katmai alder rise is also seen at Little Takli island, off the south coast of the Al

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rom white spruce (P. glauca). This is unusual, as ent (sometimes abundant) in all Alaska boreal pollen n made. The dominance of white spruce pollen at

tion, dantly

A

aska Peninsula igelow, 2004). The Katmai ash is low in nitrogen (Shipley, 1919), which may have favored

rs such as alder or other legumes. However, like the spruce above, climatic factors

and

f e sample) of spruce pollen just prior to the Katmai ashfall may

reflect spruce retraction due to LIA cooling. The question remains however whether the spruce after the eruption are due to the ashfall itself or to post LIA climate

decrease. The reduction of alder pollen between about 9300 and 8000 cal yr BP is unusual adifficult to explain, unless alder was in fact less common on the landscape. After 8000 cal yr BP, the pollen frequencies of all the taxa fluctuate slightly, but without any clear pattern.

Alder-Spruce zone (10-0cm). The top 10 cm (ca. 100 yrs ago to the present) of the Pikelet pollen diagram records small but significant changes (increases in spruce and alder) in the pollen record. Spruce was probably present in the region much earlier, by about 2500 cal yr BP (as indicated by persistent, but low frequencies [<5%] of spruce pollen). However, spruce was probably not growing locally (and only as widely scattered trees as they are today) until possibly as early as about 500 years ago (when pollen percentages first cross the 5% threshold [Hu et al., 1993]). An increase in spruce pollen to 10% indicates the forest spread, or increased in density after the 1912 Katmai eruption. This expansion may have been due to ash-induced release of the existing spruce, as has been suggested for Kodiak Island at the same time (Tae, 1997). Howevclimatic factors such as post Little Ice age amelioration can not be excluded. The spruce powhere identifications are possible, is nearly all fblack spruce pollen (P. mariana) is pres

(Bnitrogen fixecannot be excluded Discussion Climate vs. ash fall effects on the vegetation The presence of the 7 cm-thick 1912 Katmai ash in the Pikelet pollen core provides an excellent opportunity to asses climate vs. tephra affects on the vegetation. Prior to the 1912 eruption, theLittle Ice Age (LIA) was the dominant factor affecting the climate in the region. The LIA is a widespread period of cooling which in Alaska dates generally from about AD 1700 to about AD1900. Ice advances in coastal areas (Wiles, Kaufman), narrow tree rings (Darrigo Jacoby) possibly intensification of the Aleutian low (Darrigo) all suggest climate deterioration, probably cooler summers. The amount of cooling was probably small (ca. 0.5° C), but would have been significant in areas where cool summers already limited tree growth. At Pikelet, the briereduction (as measured in only on

and alder increasesamelioration and glacial retreat.

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McAndrews, J. H., Berti, A. A., and Norris, G. (1973). "Key to the Quaternary Pollen and sporesof the Great Lakes Region." Royal Ontario Museum, Toronto.

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Shipley, J. W. (1919). The nitrogen content of volcanic ash in the Katmai eruption of 1912. OhioJournal of Science 19, 213-223.

Alaska." Unpublished M. Sc. thesis, University of Alaska Fairbanks. er, L.B., Anderson, P.M, and Hu, F.S. [PDF] 2001. Vegetation ecotone dynamics in Southwestern Alaska during the Late Quaternary. Quaternary Science Reviews 20: 175-

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[PDF] 2001. Effects of Holocene Alnus expansion on aquatic productivity, nitrogen cycling, and soil development in southwestern Alaska. Ecosystems 4: 358-368.

Ecological Profile: Lake Clark National Park and Preserve

Introduction and Backgrounddepts.washington.edu/pnwcesu/reports/J9W88030009_SWAN_Pa...Profile). Further south, and around Lake Clark itself, topographic relief is high (250-3500 ft)

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