Karst Alpine Herbaceous Meadow and Heath Biophysical Setting Southern Alaska

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1 Karst Alpine Herbaceous Meadow and Heath Biophysical Setting Southern Alaska Conservation Status Rank: S4 (apparently secure) Introduction The Karst Alpine Herbaceous Meadow and Heath Biophysical Setting is represented by herbaceous or heath vegetation growing near or above treeline on calcareous soils (Figure 1). This setting is uncommon in Alaska s coastal rainforest zone. The calcareous substrate, high elevation and geographic proximity to glacial refugia (e.g. Queen Charlotte Islands) provides unique habitat for rare taxa, regional endemics and disjunct species (Jaques 1973). Owing largely to their remote alpine location, impacts are thought to be low. Figure 1. Karst herbaceous meadow on Chichagof Island, Alaska. Distribution The karst alpine herbaceous meadow and heath biophysical setting is uncommon in Southeast Alaska. Occurrences are characteristically on the upper sections of moderate to steep slopes over karst in the Boundary Ranges and the Alexander Archipelago, including Admiralty, Chichagof, Kosciusko, Kuiu, Hecata, and Prince of Wales Islands (Figure 2). The karst alpine herbaceous meadow and heath distribution map was developed from the intersection of the mesic herbaceous and dwarf shrub landcover classes of the Alaska Landcover Map (Boggs et al. 2015) and the of karst topography mapped by Albert and Schoen (2006). 1

2 Figure 2. Distribution of the Karst Alpine Herbaceous Meadow and Heath Biophysical Setting in Southeast Alaska. Note that the areas of occupancy in this map are buffered for greater visibility. Climate Southeast Alaska has a cool, wet maritime climate (Gallant et al. 1995, Nowacki et al. 2001). The mean annual precipitation in coastal rainforests ranges from 135 to 390 cm (including snowmelt) with 80 to 600 cm falling as snow. Average summer temperatures range from 7 to 18 C; average winter temperatures range from -3 to 3 C. Environmental Characteristics Karst topography is formed by the differential dissolution of sedimentary rock such as limestone by the infiltration of weakly-acidic surface water. The resulting landscape may be characterized by sinkholes, springs, and depressions. Southern Alaska is underlain by extensive carbonate bedrock (ca. 2,100 km 2 ) in the areas of Chichagof, Kuiu, Hecata and Prince of Wales Islands in the Alexander Archipelago, which supports the karst communities described herein. The carbonate rocks of the Alexander Archipelago originated on tropical Pacific Islands and were transported northeastward by plate tectonics; their current location represents the greatest displacement of tropical limestone to high latitudes in an archipelago setting in the world (Aley et al. 1993). Due to subsurface dissolution chambers, snowmelt drains rapidly from karst topography and produces few meltwater channels at the ground surface. Channels that do develop extend only a few meters along the 2

3 surface before traveling underground (Jaques 1973). This rapid drainage makes alpine calcareous soils in Southeast Alaska seasonally xeric habitats with soil moisture characteristics resembling the drier tundra habitats of more continental areas (Jaques 1973, Duffy 1993). Rock outcrops, cliffs and ledges are common features of karst in alpine and subalpine areas. Frost commonly splits large boulders from bedrock, forming cliffs, talus slopes and blockfields. Soil disturbances, including avalanches, soil sloughing and rock movement occur frequently and inhibit the development of meadow and heath vegetation. Vegetation and Succession Karst Herbaceous Meadows: Karst alpine meadows occupy small patches on the landscape and support calciphytic plant species. Vegetative cover, usually ranging from 50 to 75%, is not as continuous as it is in noncalcareous meadows (Figure 3; Jaques 1973). Most karst in Southeast Alaska have moderate to steep surface slopes and subsurface hydraulic gradients, as well as very high rainfall. These characteristics enable more rapid karst development and vegetation change. Figure 3. Karst alpine herbaceous meadow in Glacier Bay National Park and Preserve, Alaska. Heath is the primary vegetation in the alpine zone of Southeast Alaska where species composition varies with snow cover and summer moisture conditions (Figure 4; Jacques 1973). Despite its abundance on other substrates in the alpine, true alpine heath vegetation is extremely limited on calcareous parent materials, especially on dry limestone ridgetops. Heath vegetation found on limestone ridgetops may include the following species: the dwarf shrubs Empetrum nigrum and Harrimanella stelleriana, the low shrubs Vaccinium caespitosum and V. uliginosum, and the herbs Achillea millefolium, Cornus canadensis, Geum calthifolium, Huperzia selago and Lupinus nootkatensis. In areas of limestone, heath vegetation is more commonly found on protected gentle slopes or cirque basins, where sufficient soil development occurs. The ericaceous heath species that dominate on acidic substrates are not present on calcareous substrates in any abundance (Jacques 1973). Succession on calcareous sites can proceed from herbaceous meadow to dwarf shrub to forest. In a British Columbia study, bare limestone was colonized by the dwarf shrub Dryas drummondii, the grasses Festuca brachyphylla and Trisetum spicatum, and the forbs Arenaria rubella, Cerastium beeringianum, Polygonum 3

4 viviparum and Saxifraga oppositifolia. With increasing organic accumulation and acidification, the dwarf shrubs Cassiope mertensiana, C. stelleriana, and Phyllodoce glanduliflora, and the forbs Luetkea pectinata and Saxifraga nelsoniana ssp. pacifica colonized. After further soil development, several tree species, including Abies lasiocarpa (subalpine fir), Picea sitchensis (Sitka spruce), and Callitropsis nootkatensis (yellow cedar) established (Archer 1964). The movement of trees into treeless areas above timberline appears to be taking place in many areas of the Pacific Northwest (Brink 1959, Franklin 1971). In the alpine, consistent reduction of snowpack encourages colonization of Phyllodoce-Cassiope heath vegetation by Abies lasiocarpa and Tsuga mertensiana (Archer 1964). Additional evidence of treeline expansion is evident on Prince of Wales Island where isolated copses of Tsuga mertensiana are found on south-facing slopes above the elevation of the continuous subalpine forest. On calcareous sites these trees are associated with Abies lasiocarpa (Jacques 1973). Figure 4. Karst alpine heath in Glacier Bay National Park and Preserve, Alaska. Conservation Status Rarity: The occurrence of high-latitude, alpine-subalpine karst meadows (total area 70 km 2 ) in an archipelago may be limited to the Alexander Archipelago (Aley et al. 1993). Threats: Threats to the karst alpine herbaceous meadow and heath biophysical setting include recreation, and any activities that influence the balance between surface and ground water inflow and discharge. Trend: Owing largely to their remote alpine location, the extent and condition of these meadows is not expected to change in the short or long term. Species of Conservation Concern The mammal and plant species listed below are designated critically imperiled or vulnerable either globally (G1-G3) or within Alaska (S1-S3) and are known or suspected to occur in this biophysical setting (Table 1, 4

5 Table 2). Please visit the Alaska Center for Conservation Science website for species descriptions (ACCS 2016). Table 1. Mammal species of conservation concern within the Karst Alpine Herbaceous Meadow and Heath Biophysical Setting. Common Name Scientific Name Global Rank State Rank Habitat Description Alexander Archipelago wolf Canis lupus ligoni G4T2T3 S3 California myotis Myotis californicus G3G4 S2 Primarily found in rugged coastal spruce-hemlock forests supporting prey such as deer, small mammals, and spawning salmon. Suspected to occur in karst caves associated with this biophysical setting. Table 2. Plant species of conservation concern within the Karst Alpine Herbaceous Meadow and Heath Biophysical Setting. Scientific Name Global Rank State Rank Habitat Description Botrychium spathulatum G3 S1 Botrychium tunux G3? S2 Cypripedium montanum G4 S2 Draba incerta G4 S3 Found in alpine and subalpine meadows. Some sources describe soil preferences as calcareous or alkaline. Found in alpine and subalpine meadows. Some sources describe soil preferences as calcareous or alkaline. Found at the northern edge of its range in St. Elias Mountain and the northern Alexander Archipelago, where it is disjunct from southern British Columbia populations. Often found on calcareous scree slopes of Prince of Wales Island. More common in the Rocky Mountains. Ligusticum calderi G3G4 S2 Known principally from the Queen Charlotte Islands and northern Vancouver Island in British Columbia. In Alaska occurs on moist, rocky, limestone at high elevations on Kodiak Island, Dall Island and southern Prince of Wales Island. Lonicera involucrata G4G5 S3 Occurs on karst alpine landscape on Dall Island. Packera subnuda var. moresbiensis GNRT3T4 S3 Polystichum setigerum G3 S3 Romanzoffia unalaschcensis G3 S3S4 Known only from the extreme southeastern coast of Alaska, the Queen Charlotte Islands, and northern Vancouver Island, it frequently occurs on limestone talus in the alpine. Endemic to the Pacific Northwest. Grows on karst and other substrates in lowland coastal forests in British Columbia and Alaska. Occurs from Kodiak Island west through the Aleutians. A disjunct population also found on Heceta Island in Southeast Alaska on a blocky talus slope under a limestone cliff. Acroscyphus sphaeophoroides GNR S1 This lichen occurs on base-enriched rock and conifer wood in exposed coastal hypermaritime and subalpine localities (Goward 1999). It is rare in North America, where the only known populations occur on rock outcrops along alpine ridges in southern Alaska and British Columbia. 5

6 Scientific Name Global Rank State Rank Habitat Description Seligeria acutifolia G3G5 S1 This moss of calcareous substrates is rare but widespread. In North America, it is known from only a few localities in British Columbia and Alaska. Plant Associations of Conservation Concern No plant associations of conservation concern are known or suspected to occur within this biophysical setting. Additional study is required to evaluate whether this biophysical setting supports plant associations of conservation concern. Classification Concept Source The classification concept for this biophysical setting is based on Jacques (1973). Literature Cited ACCS (Alaska Center for Conservation Science) Rare Plant Data Portal. April 28, ACCS (Alaska Center for Conservation Science) BIOTICS Animal Data Portal. April 28, Albert, D., and J. Schoen GIS mapping and conservation assessment of terrestrial ecosystems in Southeast Alaska. The Nature Conservancy and Audubon Alaska. Aley, T., C. Aley, W. R. Elliot, and P. W. Huntoon Karst and cave resource significance assessment Ketchikan area, Tongass National Forest, Alaska. Ozark. Underground Laboratory, Protem, Missouri. Archer, A. C Some synecological problems in the alpine zone of Garibaldi Park. Pages 5-18 in V. J. Krajina, ed. Ecology of the forests of the Pacific Northwest Vol. 2. University of British Columbia, Vancouver, Canada. Brink, V. C A directional change in the subalpine forest-heath ecotone in Garibaldi Park, British Columbia. Ecology 40: Duffy, M Results of the 1993 rare plant survey, U.S. Forest Service, Alaska Region. Prepared for the U.S. Forest Service, Alaska Region, Juneau, Alaska. Alaska Natural Heritage Program, University of Alaska Anchorage, Anchorage, Alaska. Franklin, J. F Invasion of subalpine meadows by trees in the Cascade Range, Washington and Oregon. Arctic and Alpine Research 3: Gallant, A. L., E. F. Binnian, J. M. Omernik, and M. B. Shasby Ecoregions of Alaska. U.S. Geological Survey Professional Paper Goward, T The lichens of British Columbia: Illustrated keys. Part 1 Foliose and squamulose species. B.C. Ministry of Forests Special Report Series 8. Victoria, British Columbia. Jaques, D. R Reconnaissance botany of alpine ecosystems on Prince of Wales Island, Southeast Alaska. Thesis, Oregon State University, Corvallis, Oregon. Nawrocki, T., J. Fulkerson, and M. Carlson Alaska Rare Plant Field Guide. Alaska Natural Heritage Program, University of Alaska Anchorage. 352 pp. Nowacki, G., M. Shephard, P. Krosse, W. Pawuk, G. Fisher, J. Baichtal, D. Brew, E. Kissinger, and T. Brock Ecological subsections of Southeast Alaska and neighboring areas of Canada. Draft Rep. U.S. Forest Service, Tongass National Forest, Juneau, Alaska. 6