Natural Resources
Conservation Service
Major Land Resource Area 227X
Major Land Resource Area
Accessed: 04/29/2026
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Next, learn more about the selected ecological site and its characteristic dynamics by browsing the ecological site description and exploring alternative state and transition model formats.
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Ecological sites
Major Land Resource Areas
Ecological site photos
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precipitation
frost free days
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Precipitation
Frost free days
Elevation
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Soil texture
Site occurs along a river or stream AND is frequently to occasionally flooded
Site does not occur along a river or stream, OR, site occurs near a river or stream but never or very rarely floods
Site floods frequently, resulting in plant communities dominated by willows, graminoids, alders, and poplars (ESG 1 - Low Floodplains)
Site floods rarely or occasionally, resulting in spruce establishment and mixed forests of conifers, willow, alders, and poplar (ESG 2 - High Flood Plains)
Soils are very poorly-drained
Soils are drier than very poorly
Site occurs on a riverbank dominated by sedges and grasses. Willows and other shrubs are sparse or absent
R227XY500AK – Loamy Riverbanks
R227XY500AK – Loamy Riverbanks
Site does not occur on a riverbank…OR, if site is adjacent to the stream channel it supports willows as well as sedges, grasses, and herbs
Site occurs on floodplains and supports herbaceous and woody scrub vegetation
R227XY205AK – Loamy Flood Plain, Wet
R227XY205AK – Loamy Flood Plain, Wet
Site occurs on Wet depressions and supports a wet sedge-low scrub community
R227XY501AK – Wet Depressions
R227XY501AK – Wet Depressions
Soil textures are sandy and gravelly
R227XY200AK – Gravelly Flood Plains, Moderately Wet
R227XY200AK – Gravelly Flood Plains, Moderately Wet
Soil textures are coarse-loamy or finer
R227XY201AK – Loamy Flood Plains, Moderately Wet
R227XY201AK – Loamy Flood Plains, Moderately Wet
Soils are somewhat poorly-drained to moderately well-drained
F227XY100AK – Loamy Flood Plains
F227XY100AK – Loamy Flood Plains
Soils are well-drained to excessively well-drained
F227XY101AK – Loamy High Flood Plains
F227XY101AK – Loamy High Flood Plains
Shallow soils, with bedrock less than 20 inches (50 cm) below the mineral soil surface (ESG 7 - Shallow Bedrock)
Soils not shallow, bedrock greater than 20 inches (50cm) below the mineral soil surface
Elevations below 2900 feet
F227XY110AK – Mountain Slopes, Shallow
F227XY110AK – Mountain Slopes, Shallow
Elevations above 2900 feet
R227XY203AK – Upper Mountains Slopes, Shallow
R227XY203AK – Upper Mountains Slopes, Shallow
Permafrost soils, frozen less than 60 inches (150 cm) below the soil surface throughout the year (ESG 4 - Frozen Terraces and Uplands)
Soils not frozen within 60 inches (150 cm) of the soil surface for at least part of the year
Soils ruptic, with high amounts of freeze-thaw action resulting in a broken pit and mound surface topography on silty lacustrine sediments
F227XY109AK – Glaciolacustrine Uplands, Ruptic
F227XY109AK – Glaciolacustrine Uplands, Ruptic
Soils not ruptic (as described above)
Soils are very poorly-drained
R227XY105AK – Terraces, Wet
R227XY105AK – Terraces, Wet
Soils drier than very poorly-drained
Soil poorly-drained or somewhat poorly-drained
Soils moderately well-drained or well-drained
Site occurs on stream terrace
F227XY103AK – Stream Terraces Frozen
F227XY103AK – Stream Terraces Frozen
Site occurs on lacustrine terrace, outwash terrace, or till plain
F227XY107AK – Glaciolacustrine Uplands, Frozen
F227XY107AK – Glaciolacustrine Uplands, Frozen
Site occurs as a frozen peat mound (pingo or palsa) 2-30 feet in height, consisting of frozen organic soil material underlain by a large mass of ice
F227XY111AK – Peat Mounds
F227XY111AK – Peat Mounds
Site occurs on high floodplain or stream terrace
F227XY102AK – Laomy High Flood Plains, Frozen
F227XY102AK – Laomy High Flood Plains, Frozen
Site occurs in an exposed upland position, prone to wind scour AND does not support forest plant communities (ESG 6 - Exposed Uplands)
Site is not prone to wind scour AND supports forest vegetation (ESG 5 - Non-frozen Terraces and Uplands)
Site occurs on very steep lacustrine escarpments, 20-80% slopes
F227XY800AK – Escarpments
F227XY800AK – Escarpments
Site occurs on pitted outwash plains and hills, 0-30% slopes
R227XY204AK – Gravelly and Sandy Hills
R227XY204AK – Gravelly and Sandy Hills
Soils sandy to sandy-skeletal in texture AND excessively-drained to somewhat excessively-drained
F227XY108AK – Gravelly and Sandy Terraces
F227XY108AK – Gravelly and Sandy Terraces
Soils finer than sandy in texture AND well-drained
Site occurs on stream terraces
F227XY104AK – Stream Terraces
F227XY104AK – Stream Terraces
Site does not occur on a stream terrace
F227XY106AK – Glaciolacustrine Uplands
F227XY106AK – Glaciolacustrine Uplands
Long term average mean annual precipitation
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- 0 – 10cm (0 – 4in)
- 10 – 15cm (4 – 6in)
- 15 – 20cm (6 – 8in)
- 20 – 25cm (8 – 10in)
- 25 – 30cm (10 – 12in)
- 30 – 35cm (12 – 14in)
- 35 – 40cm (14 – 16in)
- 40 – 50cm (16 – 20in)
- 50 – 60cm (20 – 24in)
- 60 – 80cm (24 – 31in)
- 80 – 100cm (31 – 39in)
- 100 – 120cm (39 – 47in)
- 120 – 140cm (47 – 55in)
- 140 – 500cm (55 – 197in)
—
cm
Long term average frost free days
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- 0 – 30days
- 30 – 50days
- 50 – 70days
- 70 – 90days
—
days
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- 400 – 600m (1300 – 2000ft)
- 600 – 800m (2000 – 2600ft)
- 800 – 1000m (2600 – 3300ft)
- 1000 – 1200m (3300 – 3900ft)
—
m
- No filter
- 0 – 3%
- 3 – 5%
- 5 – 10%
- 10 – 15%
- 15 – 20%
- 20 – 25%
- 25 – 30%
- 30 – 35%
- 35 – 40%
- 40 – 45%
- 45 – 50%
- 50 – 60%
- 60 – 70%
- 70 – 80%
- 80 – 90%
- 90 – 100%
—
%
- No filter
- Alluvial fan
- Escarpment
- Flood plain
- Hill
- Lake terrace
- Mountain
- Mountain slope
- Outwash plain
- Terminal moraine
- Terrace
- Till plain
Soil surface texture
- No filter
- Clay loam
- Fine sand
- Fine sandy loam
- Loam
- Sand
- Silt
- Silty clay
- Silty clay loam
- Silt loam
- Sandy loam
- Very fine sandy loam
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Ecological site keys
MLRA 227X - Provisional Ecological Site/Group Key
I.
Site occurs along a river or stream AND is frequently to occasionally flooded
A.
Site floods frequently, resulting in plant communities dominated by willows, graminoids, alders, and poplars (ESG 1 - Low Floodplains)
1
Soils are very poorly-drained
i.
Site occurs on a riverbank dominated by sedges and grasses. Willows and other shrubs are sparse or absent
... R227XY500AK – Loamy Riverbanks
ii.
Site does not occur on a riverbank…OR, if site is adjacent to the stream channel it supports willows as well as sedges, grasses, and herbs
a.
Site occurs on floodplains and supports herbaceous and woody scrub vegetation
... R227XY205AK – Loamy Flood Plain, Wet
b.
Site occurs on Wet depressions and supports a wet sedge-low scrub community
... R227XY501AK – Wet Depressions
2
Soils are drier than very poorly
B.
Site floods rarely or occasionally, resulting in spruce establishment and mixed forests of conifers, willow, alders, and poplar (ESG 2 - High Flood Plains)
II.
Site does not occur along a river or stream, OR, site occurs near a river or stream but never or very rarely floods
A.
Shallow soils, with bedrock less than 20 inches (50 cm) below the mineral soil surface (ESG 7 - Shallow Bedrock)
B.
Soils not shallow, bedrock greater than 20 inches (50cm) below the mineral soil surface
1
Permafrost soils, frozen less than 60 inches (150 cm) below the soil surface throughout the year (ESG 4 - Frozen Terraces and Uplands)
i.
Soils ruptic, with high amounts of freeze-thaw action resulting in a broken pit and mound surface topography on silty lacustrine sediments
... F227XY109AK – Glaciolacustrine Uplands, Ruptic
ii.
Soils not ruptic (as described above)
b.
Soils drier than very poorly-drained
1)
Soil poorly-drained or somewhat poorly-drained
b)
Site occurs on lacustrine terrace, outwash terrace, or till plain
... F227XY107AK – Glaciolacustrine Uplands, Frozen
2)
Soils moderately well-drained or well-drained
a)
Site occurs as a frozen peat mound (pingo or palsa) 2-30 feet in height, consisting of frozen organic soil material underlain by a large mass of ice
... F227XY111AK – Peat Mounds
b)
Site occurs on high floodplain or stream terrace
... F227XY102AK – Laomy High Flood Plains, Frozen
2
Soils not frozen within 60 inches (150 cm) of the soil surface for at least part of the year
i.
Site occurs in an exposed upland position, prone to wind scour AND does not support forest plant communities (ESG 6 - Exposed Uplands)
b.
Site occurs on pitted outwash plains and hills, 0-30% slopes
... R227XY204AK – Gravelly and Sandy Hills
ii.
Site is not prone to wind scour AND supports forest vegetation (ESG 5 - Non-frozen Terraces and Uplands)
a.
Soils sandy to sandy-skeletal in texture AND excessively-drained to somewhat excessively-drained
... F227XY108AK – Gravelly and Sandy Terraces
b.
Soils finer than sandy in texture AND well-drained
The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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