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Ecological site F236XY165AK
Boreal Woodland Loamy Stream Terraces
Last updated: 2/13/2024
Accessed: 09/17/2026
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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 236X–Bristol Bay-Northern Alaska Peninsula Lowlands
The Bristol Bay-Northern Alaska Peninsula Lowland Major Land Resource Area (MLRA 236) is located in Western Alaska. This MLRA covers approximately 19,500 square miles and is defined by an expanse of nearly level to rolling lowlands, uplands and low to moderate hills bordered by long, mountain footslopes. Major rivers include the Egegik, Mulchatna, Naknek, Nushagak, and Wood River. MLRA 236 is in the zone of discontinuous permafrost. It is primarily in areas with finer textured soils on terraces, rolling uplands and footslopes. This MLRA was glaciated during the early to middle Pleistocene. Moraine and glaciofluvial deposits cover around sixty percent of the MLRA. Alluvium and coastal deposits make up a large portion of the remaining area (Kautz et al., 2012; USDA, 2006).
Climate patterns across this MLRA shift as one moves away from the coast. A maritime climate is prominent along the coast, while continental weather, commonly associated with Interior Alaska, is more influential inland. Across the MLRA, summers are general short and warm while winters are long and cold. Mean annual precipitation is 13 to 50 inches, with increased precipitation at higher elevations and areas away from the coast. Mean annual temperatures is between 30 and 36 degrees F (USDA, 2006).
The Bristol Bay-Northern Alaska Peninsula MLRA is principally undeveloped wilderness. Federally managed land includes parts of the Katmai and Aniakchak National Parks, and the Alaska Peninsula, Becharof, Togiak and Alaska Maritime National Wildlife Refuges. The MLRA is sparsely populated. Principal communities include Dillingham, Naknek, and King Salmon. Commercial fishing in Bristol Bay and the Bering Sea comprises a major part of economic activity in the MLRA. Other land uses include subsistence activities (fishing, hunting, and gathering) and sport hunting and fishing (USDA, 2006).Ecological site concept
This boreal ecological site is on flood plain terraces. Site elevation is between 30 and 850 feet above sea level. Slopes are nearly level to gentle (0 – 4 percent). Soil hydrology, low soil acidity, and a fire regime shape the vegetation on this landform. Low soil acidity, often associated with ericaceous communities, limits soil fertility and restricts vegetation. Rare, brief ponding, particularly in concave areas, supports a deep water table that is reflected in greater amounts of hydrophytic plant species. This site is susceptible to fire, which removes the overstory and increases post-fire diversity of fast growing, herbaceous species.
The reference state supports three communities. The reference plant community is characterized as a coniferous woodland (Viereck et al., 1992). It is composed of a white spruce canopy with an open understory of facultative to upland ericaceous shrubs, graminoid, mosses, and lichens. Post-fire communities are comprised of fast growing herbaceous species and extant shrubs. There is an alternate state on this site that is created by clearing and maintaining land.Associated sites
F236XY111AK Boreal Forest Loamy Flood Plains
F236XY111AK describes high level flood plains. These areas actively flood, unlike the nearby terraces described by F236XY165AK.
R236XY144AK Subarctic Scrub Peat Terraces
R236XY144AK describes wet depressions on terraces. These are features located on the terraces described by F236XY165AK.
Similar sites
F236XY111AK Boreal Forest Loamy Flood Plains
F236XY111AK describes medium and high flood plains. They support a forest community on gravelly alluvial soils. Flood plains are susceptible to flooding and the vegetation reflects this disturbance. The forest is comprised of balsam poplar with resilient shrubs such as willow and alder in the understory. F236XY165AK is differentiated by a lack of flooding disturbance and an coniferous overstory.
Table 1. Dominant plant species
Tree (1) Picea glauca
Shrub (1) Ledum palustre subsp. decumbens
(2) Vaccinium vitis-idaeaHerbaceous Not specified
Physiographic features
This site is on linear and concave slopes on gravelly terraces. Elevation ranges from 30 to 850 feet above sea level. Slopes are nearly level to gentle (0 – 4 percent). This site is found at all aspects. Flooding does not occur, and ponding is usually rare, though may be more frequent in low-lying concave areas.
Table 2. Representative physiographic features
Slope shape across (1) Linear
(2) Concave
Slope shape up-down (1) Linear
Geomorphic position, terraces (1) Tread
Landforms (1) Plains > Terrace
(2) Valley > Terrace
Runoff class Negligible to low Flooding frequency None Ponding duration Brief (2 to 7 days) Ponding frequency Rare Elevation 30 – 850 ft Slope 0 – 4 % Water table depth 0 in Aspect W, NW, N, NE, E, SE, S, SW Table 3. Representative physiographic features (actual ranges)
Runoff class Negligible to low Flooding frequency None Ponding duration Brief (2 to 7 days) Ponding frequency None to occasional Elevation 0 – 980 ft Slope 0 – 4 % Water table depth 31 – 60 in Climatic features
The climate of this site reflects that of the MLRA, which is described as maritime polar (EPA, 2013). Temperatures are moderated by the nearby Bristol Bay and norther Pacific bodies of water. Annual precipitation ranges from 21 – 34 inches with approximately 40 percent occurring during the June-September growing season (PRISM, 2018).
Table 4 Representative climatic features
Frost-free period (characteristic range) 80-100 days Freeze-free period (characteristic range) 70-90 days Precipitation total (characteristic range) 20-30 in Frost-free period (actual range) 80-100 days Freeze-free period (actual range) 70-90 days Precipitation total (actual range) 20-40 in Frost-free period (average) 90 days Freeze-free period (average) 80 days Precipitation total (average) 30 in Characteristic rangeActual rangeBarLineFigure 1. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 2. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 3. Monthly maximum temperature range
BarLineFigure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6 Annual average temperature pattern
">Influencing water features
Due to its landscape position, this site is generally not influenced by wetland or riparian water features. Concave areas are typically small and may support a higher degree of facultative wet wetland species. Precipitation is the main source of water.
Soil features
Soils are young and weakly developed Inceptisols (Soil Survey Staff, 2013). Soils are very deep and well drained. They support a cryic temperature regime and an udic moisture regime. Parent material is primarily organic material over gravelly alluvium.
Soils are weakly developed, as indicated by a cambic horizon and an ochric epipedon. This affects the plant community that develops on this site. Soil is extremely to moderately acidic, which is common with ericaceous communities. Soil hydrology does not generally affect vegetation on these soils. Soils are well drained. However, concave areas have a deep water table that is reflected in greater amounts of hydrophytic plant species.
Correlated soil components in MLRA 236: Tunravik, Oxyaquic Humicryepts; D36-Boreal woodland gravelly terraces; D36-Boreal woodland loamy terraces, moist; E36-Boreal forest-gravelly terracesTable 5. Representative soil features
Parent material (1) Alluvium
Surface texture (1) Silt loam
Drainage class Well drained Permeability class Moderate Soil depth 60 – 0 in Surface fragment cover <=3" 0 – 2 % Surface fragment cover >3" Not specified Available water capacity
(0-10in)1.8 – 2.3 in Soil reaction (1:1 water)
(0-10in)3.7 – 5.8 Subsurface fragment volume <=3"
(Depth not specified)47 % Subsurface fragment volume >3"
(Depth not specified)Not specified Table 6. Representative soil features (actual values)
Drainage class Moderately well drained to well drained Permeability class Moderate Soil depth 60 – 0 in Surface fragment cover <=3" 0 – 2 % Surface fragment cover >3" 0 % Available water capacity
(0-10in)1.8 – 2.8 in Soil reaction (1:1 water)
(0-10in)3.7 – 6 Subsurface fragment volume <=3"
(Depth not specified)0 – 49 % Subsurface fragment volume >3"
(Depth not specified)0 % Ecological dynamics
This site is on terraces with well drained alluvial soils. Local site factors including soil characteristics and a fire regime support three communities in the reference state. The reference plant community is a white spruce woodland with ericaceous shrubs, bluejoint, mosses, and lichens in the open understory.
Vegetation on this site reflects the underlying soil. These well drained soils support plants that are primarily identified as facultative to upland species. Soil drainage and the moderately to extremely acidic soil is often associated with the ericaceous community in the understory.
Fire is the major documented disturbance regime. High-intensity and low-intensity fires differentially affect post-disturbance vegetation. The severity of a burn generally refers to the proportion of the surface organic mat and tree canopy consumed during a fire (Chapin et al., 2006). It is difficult to gauge or estimate the typical fire on this site. The site location near flood plains lends protection during wildfires. Fuel load is relatively low in this woodland. However, the organic layer on this site is thin in these weakly developed soils, so even a low-intensity fire could damage root stock and the seedbank. The fire cycle is hypothesized to be between 75 and 100 years on this site, based on tree ages and depth to charcoal in the soil.
Willows are slightly to moderately browsed by moose. This does not appear to affect the ecological processes of the site.
This site supports one alternate state. Areas cleared for agronomic or cultural purposes support a unique vegetative community. These areas are common in and around villages. The disturbed soil supports a unique community of primarily herbaceous plants, which are commonly mowed or otherwise maintained during the growing season.
The information in this Ecological Dynamics section, including the state-and-transition model (STM), was developed based on current field data, professional experience, and a review of the scientific literature. As a result, all possible scenarios or plant species may not be included. Key indicator plant species, disturbances, and ecological processes are described to inform land management decisions.State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
T1A - Cultural/agronomic land use. R2A - Cultural/agronomic land use recovery. State 1 submodel, plant communities
1.1A - Fire. 1.2A - Time and growth without disruptive fire. 1.2B - Fire. 1.3A - Time and growth without disruptive fire. State 2 submodel, plant communities
State 1
Reference StateThe reference state supports three community phases, which are distinguished by the developed structure and dominance of the vegetation and by their ecological function and stability. The reference community phase is a needleleaf woodland. The presence of each community is dictated temporally by fire.
This report provides baseline inventory data on the vegetation. Future data collection is needed to provide further information about existing plant communities and the disturbance regimes that result in transitions from one community to another. Common and scientific names are from the USDA PLANTS database. Community phases are characterized by the Alaska Vegetation Classification System (Viereck et al., 1992).Community 1.1
White spruce/lingonberry-black crowberry
Figure 7. Typical area of community 1.1.
Figure 8. Frequency and canopy cover of plants in community 1.1.
The reference plant community is a white spruce needleleaf woodland (Viereck et al., 1992) that has low and dwarf shrubs, mosses, and lichens in the understory and open areas. Shrubs throughout the understory include lingonberry (Vaccinium vitis-idaea), black crowberry (Empetrum nigrum), marsh Labrador tea (Ledum palustre ssp. decumbens), dwarf birch (Betula nana), and bog blueberry (Vaccinium uliginosum). Other species may include spirea (Spiraea stevenii), resin birch (Betula glandulosa), willows (Salix spp.), bluejoint (Calamagrostis canadensis), Altai fescue (Festuca altaica), fireweed (Chamerion angustifolium), horsetails (Equisetum spp.), and fewflower meadow-rue (Thalictrum sparsiflorum). Sporadic individual trees, including paper birch (Betula papyrifera), Kenai birch (Betula papyrifera var. kenaica), balsam poplar (Populus balsamifera), and quaking aspen (Populus tremuloides), may be present. These trees commonly are remnants from earlier community phases. Mosses, dominantly feathermosses, and lichens, dominantly snow lichens (Stereocaulon spp.), make up a large portion of the ground cover. The ground cover may also include herbaceous litter and woody litter. Some areas are bare soil.
Dominant plant species
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white spruce (Picea glauca), tree
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lingonberry (Vaccinium vitis-idaea), shrub
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black crowberry (Empetrum nigrum), shrub
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bog blueberry (Vaccinium uliginosum), shrub
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marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
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dwarf birch (Betula nana), shrub
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bluejoint (Calamagrostis canadensis), grass
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splendid feather moss (Hylocomium splendens), other herbaceous
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Schreber's big red stem moss (Pleurozium schreberi), other herbaceous
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knights plume moss (Ptilium crista-castrensis), other herbaceous
Community 1.2
Kenai birch-quaking aspen/lingonberry-dwarf birch
Figure 9. Typical area of community 1.2.
Figure 10. Frequency and canopy cover of plants in community 1.2.
The late fire community phase is a mixed woodland that has a dense understory of low and dwarf shrubs. This community consists of mixed deciduous Kenai birch and quaking aspen and coniferous white spruce. Understory shrubs include lingonberry, black crowberry, dwarf birch, bog blueberry, and marsh Labrador tea. Other species may include paper birch, willow (Salix spp.), bluejoint, Altai fescue, fireweed, and horsetails. Various mosses are common. Lichen may be present, but the total cover depends on the period since the last fire. Other ground cover typically includes herbaceous litter and woody litter. Some areas are bare soil.
Dominant plant species
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white spruce (Picea glauca), tree
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Kenai birch (Betula papyrifera var. kenaica), tree
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quaking aspen (Populus tremuloides), tree
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lingonberry (Vaccinium vitis-idaea), shrub
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black crowberry (Empetrum nigrum), shrub
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dwarf birch (Betula nana), shrub
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marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
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bluejoint (Calamagrostis canadensis), grass
Community 1.3
Black crowberry-dwarf birch/bluejoint
Figure 11. Typical area of community 1.3.
Figure 12. Frequency and canopy cover of plants in community 1.3.
The early fire community phase is closed low scrubland (Viereck et al., 1992) that includes low and dwarf shrubs. This community consists dominantly of black crowberry, dwarf birch, and marsh Labrador tea. Other common plants include spirea, bog blueberry, lingonberry, and bluejoint. Live trees that survived a fire and stunted and regenerative trees may be present. The ground cover is dominantly moss; lichens are rare. Other ground cover includes herbaceous and woody litter.
Dominant plant species
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black crowberry (Empetrum nigrum), shrub
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dwarf birch (Betula nana), shrub
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marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
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bog blueberry (Vaccinium uliginosum), shrub
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lingonberry (Vaccinium vitis-idaea), shrub
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beauverd spirea (Spiraea stevenii), shrub
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bluejoint (Calamagrostis canadensis), grass
Pathway 1.1A
Community 1.1 to 1.3
White spruce/lingonberry-black crowberry
Black crowberry-dwarf birch/bluejointFire. A low-intensity fire removes trees and taller shrubs, but pockets of low vegetation remain. The reduced competition for light and space may allow pioneer graminoids and forbs to colonize and pockets of low and dwarf shrubs to propagate. Based on the age of the trees, fires occur once every 60 to 100 years.
Pathway 1.2A
Community 1.2 to 1.1
Kenai birch-quaking aspen/lingonberry-dwarf birch
White spruce/lingonberry-black crowberryNatural succession: Time and growth without disruptive fire. As burned areas recover, white spruce reproduces and regenerates. Competition for light and space may lead to a decrease in the population of deciduous trees, such as shade-intolerant quaking aspen (Lavertu et al., 1994; Howard, 1996). The large shrub community continues to diversify. The period needed for this transition currently is unknown. It likely depends on factors such as the rate of seed production of white spruce and the annual growth rate of trees and shrubs.
Pathway 1.2B
Community 1.2 to 1.3
Kenai birch-quaking aspen/lingonberry-dwarf birch
Black crowberry-dwarf birch/bluejointFire. A low-intensity, fast-burning fire may remove trees and taller shrubs but allow pockets of low vegetation to remain. The reduced competition for light and space may allow pioneer graminoids and forbs to colonize and pockets of low and dwarf shrubs to propagate. The frequency of fire in the late fire community phase currently is unknown.
Pathway 1.3A
Community 1.3 to 1.2
Black crowberry-dwarf birch/bluejoint
Kenai birch-quaking aspen/lingonberry-dwarf birchNatural succession: Normal time and growth without disruptive fire. As burned areas recover, tree species colonize. Shrubs and graminoids continue to diversify as new niches are created, but the total cover may decrease. The period needed for this transition currently is unknown. It likely depends on factors such as the growth rate of trees, distance to a seed source, and reproduction and growth rates of colonizing and extant shrubs.
State 2
Cultural/Agronomic StateThis alternate state is a result of land clearing near and in villages and towns. Trees and shrub are cleared by machinery. Areas surrounding buildings and those that have been cleared for lawns or agricultural uses, such as apiaries, are included.
This disturbance generally transitions the vegetation to community phase 2.1. Commonly, these areas are mowed to keep graminoids and forbs at a maximum height. Replanting may revert this state to the reference state, but field data of this hypothesized transition are not available.Community 2.1
Bluejoint/common chickweed-fireweed meadow
Figure 13. Typical area of community 2.1.
Figure 14. Frequency and canopy cover of plants in community 2.1.
This community is a mesic graminoid herbaceous meadow (Viereck et al., 1992). It consists of graminoids and forbs, including bluejoint, rough bentgrass (Agrostis scabra), common chickweed (Stellaria media), and fireweed. The presence or absence of trees and shrub depends on the preference of the landowner. The ground cover varies, but it typically includes abundant herbaceous litter from mowing.
Dominant plant species
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bluejoint (Calamagrostis canadensis), grass
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rough bentgrass (Agrostis scabra), grass
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common chickweed (Stellaria media), other herbaceous
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fireweed (Chamerion angustifolium), other herbaceous
Transition T1A
State 1 to 2Clearcutting in villages and towns causes this transition. This disturbance is drastic, which suggests no threshold allows the plant community to remain in the reference state. Continued mowing of this grassland community, as described by community phase 2.1, keeps this plant community stable.
Restoration pathway R2A
State 2 to 1It is hypothesized that alternate state 2 will return to the reference state if mowing and other anthropogenic disturbances are ceased. Standing shrubs and trees in nearby areas and an existing seed bank support recolonization. A full transition back to the reference state may require planting of native species. The period needed for this transition depends on factors such as the extent of the original clearing, previous and current land uses, cessation of anthropogenic disturbance, and period without natural fire.
Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 1.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Inventory data references
Modal points for Community 1.1 08SS09703 08SS09704 08LL07201 10TD09604 10SS10403 Modal points for community 1.2 08LL07202 09SS02501 Modal points for community 1.3 09SS10103 08AO06602 Modal points for community 2.1 08LL06302
References
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Viereck, L.A., C. T. Dyrness, A. R. Batten, and K. J. Wenzlick. 1992. The Alaska vegetation classification. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station General Technical Report PNW-GTR-286..
Other references
Chapin, F. S., III; L.A. Viereck; P. Adams; K. Van Cleve; C.L. Fastie; R.A. Ott; D. Mann; and J.F. Johnstone. 2006. Chapter 7: Successional processes in the Alaskan boreal forest. In Alaska’s Changing Boreal Forest. F. Stuart Chapin and Mark W. Oswood, Institute of Arctic Biology; Keith van Cleve, Forest Soils Laboratory, University of Alaska, U.S. Department of Agriculture, Forest Service; Leslie A. Viereck, Forest Soils Laboratory, Institute of Northern Forestry; and David L. Verbyla, Department of Forest Sciences, University of Alaska, editors. Oxford University Press, New York, New York. Pages 100-116.
Howard, J. L. 1996. Populus tremuloides. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Available at https://www.fs.fed.us/database/feis/plants/tree/poptre/all.html. Accessed May 7, 2013.
Kautz, D.R., P. Taber, and S. Nield, editors. 2012. Land Resource Regions and Major Land Resource Areas of Alaska. United States Department of Agriculture, Natural Resources Conservation Service (USDA–NRCS).
Lavertu, D., Y. Mauffette, and Y. Bergeron. 1994. Effects of stand age and litter removal on the regeneration of Populus tremuloides. Journal of Vegetation Science. Volume 5: 561-568.
PRISM Climate Group. (PRISM) Oregon State University. https://prism.oregonstate.edu. Date created October 2018. Accessed 3 Mar 2023.
Scenarios Network for Alaska and Arctic Planning (SNAP). Historical Monthly Temperature – 1km, 1901-2009. http://ckan.snap.uaf.edu/dataset/. Accessed 20 Mar 2023.
Scenarios Network for Alaska and Arctic Planning (SNAP). Historical monthly and derived precipitation products downscaled from CRU TS data via the delta methods – 2km, 1901-2009. http://ckan.snap.uaf.edu/dataset/. Accessed 20 Mar 2023.
Soil Survey Staff. 2013. Simplified Guide to Soil Taxonomy. USDA-Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE.
United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.
US Environmental Protection Agency (EPA). Level III Ecoregions of the Conterminous United States. UP ESP Office of Research and Development. Corvallis, OR. http://edg.epa.gov/. Created 16 Apr 2013. Accessed 20 Mar 2023.Contributors
Phil Barber
Sue Tester
Michael Margo
Kendra Moseley
Steph Schmit
Steff Shoemaker
Jamin JohansonApproval
Kirt Walstad, 2/13/2024
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 09/17/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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