Major Land Resource Area 220X

Alexander Archipelago-Gulf of Alaska Coast

Accessed: 03/27/2025

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MLRA 220 - Alexander Archipelago-Gulf of Alaska Coast - Master Key

I. Elevation typically between 0 and 3000 feet and vegetation representative of the subalpine and maritime life zones. This vegetation represents the Alexander Archipelago-Gulf of Alaska Coast Area (MLRA 220).

A. Elevation between 1500 and 3000 feet and vegetation representative of the subalpine life zone. ... Key 2 – Subalpine Ecological Sites Key

B. Elevation typically between 0 and 1500 feet and vegetation representative of the maritime life zone. ... Key 3 – Lowland Maritime Ecological Site Key

II. Elevation ≥ 3000 feet and vegetation representative of the alpine life zone. Alpine vegetation belongs to the Southern Alaska Coastal Mountains Area (MLRA 222).

Subalpine Ecological Sites Key

I. Parent material is alluvium. Site associated with flood plains.

A. persistent water table throughout the growing season. ... R220XY362AK – Subalpine Sedge Wet Flood Plain

B. drier soils then above. ... R220XY361AK – Subalpine Shrub Dry Flood Plain

II. Parent material not alluvium and landform not associated with flood plain.

A. Soils are primarily organic material over bedrock.

1 Dry soils, folistic. ... F220XY338AK – Subalpine Forests Dry Organic Slopes

2 Wet soils, histic. ... F220XY204AK – Subalpine Forests Organic Wet Slopes

B. Not as above. Parent material typically colluvium and/or residuum.

1 Soil parent material is calcareous. ... F220XY202AK – Subalpine Woodlands Gravelly Dry Slopes, Limestone

2 Soil parent material is not calcareous.

i. Site associated with avalanche chutes or soil creep. Alder is typically common and dominant.

a. Avalanche chutes. ... R220XY349AK – Subalpine Scrub Gravelly Dry Chutes

b. Site associated with soil creep. Soils commonly have buried, mixed, and/or broken soil horizons. Soils with thick A-horizons are common. ... R220XY358AK – Subalpine Scrub Gravelly Dry Slopes

ii. Not as above.

a. Well- to moderately-well drained soils. Soils do not have a persistent water table at any depth during the growing season.

1) Occurs at the lowest band of subalpine vegetation. Trees more productive compared to es 350. Krummholz and alpine species less common. ... F220XY200AK – Subalpine Forest Gravelly Dry Slopes

2) Occurs at the highest band of subalpine vegetation. Trees less productive compared to es 200. Krummholz and alpine species more common. ... F220XY350AK – Subalpine Woodland Gravelly Dry Slopes

b. Wetter soils then above. ... F220XY205AK – Subalpine Woodlands Gravelly Moist Slopes

Lowland Maritime Ecological Site Key

I. Hydrologic-driven (water influenced) communities

A. Coastal hydrology controlled: ES Group Coastal/Estuaries

1 Alluvium parent material ... R220XY450AK – Estuarine Herbaceous Loamy Floodplain

2 Marine and fluvial marine deposits

i. Silty and clayey marine deposits with flooding and potential ponding ... R220XY329AK – Estuarine Herbaceous Tidal Marsh

ii. Sandy deposits and eolian sands

a. Water table above 30 inches ... R220XY424AK – Estuarine Herbaceous Sandy Beach Plain

b. no water table above 30 inches ... R220XY422AK – Estuarine Herbaceous Dry Sand

B. Inland hydrology controlled

1 Open, non-channel, hydrology: ES Group 2 - Open Wetlands

i. Open woodland, depressions ... R220XY434AK – Maritime Scrubland Peat Plain Depression

ii. Forested plains and slopes

a. High slopes on mountains and hills ... F220XY447AK – Maritime Forest Loamy Organic Slopes

b. Low slopes on coastal plains and outwash ... F220XY455AK – Maritime Forest Sandy Coastal Plain

2 Riparian, or channel driven, hydrology: ES Group 1: Floodplains and drainageways

i. Active floodplains

a. Lower floodplain along channel, shrub dominated ... R220XY426AK – Maritime Shrub Low Flood Plain

b. Higher floodplain or floodplain step, above channel, forest dominated ... F220XY427AK – Maritime Forest Gravelly High Floodplain

ii. Drainageways

a. Steeper sloping drainageways on mountain slopes and hills ... R220XY444AK – Maritime Scrub Gravelly Steep Drainageways

b. Lower sloping drainageways along coastal plains and outwash ... R220XY425AK – Maritime Shrub Drainageway

II. Not hydrologically driven (nor water influenced) communities

A. Shrub and scrub driven upland or neutral sites: ES Group 6 - Upland Scrub

1 Steep active slopes (Avalanche driven communities) ... R220XY443AK – Maritime Scrub Loamy Steep Slopes

2 Steep, stable or less active slopes, shallow soils ... R220XY446AK – Maritime Scrub Loamy Escarpments

B. Tree, or forested, driven sites

1 Higher Elevation and slope driven sites: ES Group 5 - Forested Slopes and Mountains

i. Shallow organic soils ... F220XY439AK – Maritime Stunted Woodland Shallow Organic Slopes

ii. Non-organic soils

a. Coarser textured soils (sands and gravels)

1) Alluvial soils and alluvium driven sites ... F220XY430AK – Maritime Forest Sandy Plain Alluvial Fan

2) Gravelly slopes ... F220XY441AK – Maritime Forest Gravelly Slopes

b. Finer textured, loamy soils

1) Mid to low elevation slopes

a) Warmer, south aspect slopes ... F220XY468AK – Maritime Forest Loamy Slopes Warm

b) Steeper, non-aspect affected slopes ... F220XY442AK – Maritime Forest Loamy Steep Slopes

2) High elevation slopes ... W1220X433 – Maritime Forest Loamy Slopes

2 Lower elevation hills and flat sites: ES Group 4 - Forested flats and hills

i. Shallow soils ... F220XY440AK – Maritime Forest Loamy Plains

ii. Deep to very deep soils

a. Eolian or wind deposited materials ... F220XY466AK – Maritime Forest Sandy Plains Eolian

b. Alluvial or outwash materials

1) Alluvium on stream terraces ... F220XY460AK – Maritime Forest Gravelly Alluvial Plains

2) Glacial outwash and till deposits ... F220XY432AK – Maritime Forest Gravelly Plain

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