Pacific Northwest Alpine Bedrock and Scree

EVT 7734North Pacific Alpine and Subalpine Bedrock and Scree
CES204.853GNRSparseSparsely vegetated
Summary
This ecological system includes all the exposed rock and rubble above the forest line (subalpine parkland and above) in the North Pacific mountain ranges and is restricted to the highest elevations in the Cascade Range, from southwestern British Columbia south into northern California, and also north into southeastern Alaska. It is composed of barren and sparsely vegetated alpine substrates, typically including both bedrock outcrops and scree slopes, upper mountain slopes, summits and nunataks. Nonvascular- (lichen-) dominated communities are common. Exposure to desiccating winds, rocky and sometimes unstable substrates, and a short growing season limit plant growth. In Alaska, this system usually occurs above alpine dwarf-shrub, herbaceous meadow, and dwarf-shrub-herbaceous systems typically at elevations higher than 915 m (3000 feet) (possibly higher in southeastern Alaska). There can be sparse cover of forbs, grasses, lichens, shrubs and small trees, but the total vascular plant cover is typically less than 25% due to the high cover of exposed rock. Species composition is variable and may include Artemisia arctica, Astragalus alpinus, Carex microchaeta, Minuartia arctica, Salix rotundifolia, Saxifraga sibirica (= Saxifraga bracteata), Saxifraga bronchialis, Sibbaldia procumbens, and Silene acaulis. Common nonvascular genera include Racomitrium and Stereocaulon.
Source: NatureServe Explorer
Distribution
This ecological system is restricted to the highest elevations in the North Pacific ranges, from southeastern Alaska south into northern California.
Source: NatureServe Explorer
Ecologically Associated Plant Species

Plant species that characterize this ecosystem type, organized by vegetation stratum. These are species ecologically associated with the ecosystem, not confirmed present in any specific area.

Short shrub/sapling

Artemisia arctica, Salix rotundifolia

Herb (field)

Antennaria alpina, Astragalus alpinus, Astragalus australis var. olympicus, Boechera horizontalis, Carex microchaeta, Geum rossii var. depressum, Micranthes tischii, Minuartia arctica, Poa alpina, Saxifraga bronchialis, Saxifraga radiata, Sibbaldia procumbens, Silene acaulis

Nonvascular

Brachydontium olympicum
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (7)

Animal species ecologically associated with this ecosystem type based on NatureServe assessment. These are species whose habitat requirements overlap with this ecosystem, not confirmed present in any specific roadless area.

Mammals (3)

Common NameScientific NameG-Rank
Hoary MarmotMarmota caligataG5
Bushy-tailed WoodratNeotoma cinereaG5
American PikaOchotona princepsG5

Birds (2)

Common NameScientific NameG-Rank
Common RavenCorvus coraxG5
Gray-crowned Rosy-FinchLeucosticte tephrocotisG5

Amphibians (1)

Common NameScientific NameG-Rank
Crater Lake NewtTaricha granulosa mazamaeG5T1Q

Insects (1)

Common NameScientific NameG-Rank
Olympic GrasshopperNisquallia olympicaG1G2
Source: NatureServe Ecological System assessment
At-Risk Species Associated with this Ecosystem (6)

Species with conservation concern that are ecologically associated with this ecosystem type. G-Rank indicates global conservation status: G1 (critically imperiled) through G5 (secure). ESA status indicates U.S. Endangered Species Act listing.

Common NameScientific NameG-RankESA Status
Cotton's MilkvetchAstragalus australis var. olympicusG5T1--
Crater Lake RockcressBoechera horizontalisG1--
Ross' AvensGeum rossii var. depressumG5T1--
Olympic SaxifrageMicranthes tischiiG2G3--
Olympic GrasshopperNisquallia olympicaG1G2--
Crater Lake NewtTaricha granulosa mazamaeG5T1QUnder Review
Source: NatureServe Ecological System assessment
State Conservation Ranks (4)

Subnational conservation status ranks (S-ranks) assigned by Natural Heritage Programs in each state where this ecosystem occurs. S1 indicates critically imperiled at the state level, S2 imperiled, S3 vulnerable, S4 apparently secure, and S5 secure. An ecosystem may be globally secure but imperiled in specific states at the edge of its range.

StateS-Rank
AKSNR
CASNR
ORSNR
WASNR
Roadless Areas (29)

Inventoried Roadless Areas where this ecosystem is present, identified from LANDFIRE 2024 Existing Vegetation Type spatial analysis. Coverage indicates the proportion of each area occupied by this ecosystem type.

Oregon (6)

AreaForestCoverageHectares
Mt. Hood AdditionsMt. Hood National Forest13.7%722.25
Brown Mt.Winema National Forest2.4%29.7
Mt. BaileyUmpqua National Forest2.2%162.99
Sky Lakes BWinema National Forest1.0%40.77
Brown MountainRogue River National Forests1.0%26.91
Bend WatershedDeschutes National Forest0.8%49.77

Washington (23)

AreaForestCoverageHectares
Pasayten RimOkanogan National Forest15.2%1,052.64
Myrtle LakeWenatchee National Forest14.9%670.86
SawtoothOkanogan National Forest10.7%5,304.96
Liberty BellOkanogan National Forest9.4%4,144.86
Hidden LakeMt Baker-Snoqualmie National Forest7.8%205.29
TeanawayWenatchee National Forest5.7%1,668.6
ChelanWenatchee National Forest5.5%1,653.39
Mt. Baker WestMt Baker-Snoqualmie National Forest5.2%536.85
TiffanyOkanogan National Forest3.7%326.79
Gotchen CreekGifford Pinchot National Forest2.1%63.45
Mt. Baker NorthMt Baker-Snoqualmie National Forest2.1%142.29
Eagle RockMt Baker-Snoqualmie National Forest1.9%267.39
Alpine Lakes Adj.Wenatchee National Forest1.9%437.94
Jefferson RidgeOlympic National Forest1.8%48.24
Mt. Baker MaMt Baker-Snoqualmie National Forest1.7%171.54
Glacier Peak GMt Baker-Snoqualmie National Forest1.6%54.27
ManastashWenatchee National Forest1.6%71.1
Glacier Peak KMt Baker-Snoqualmie National Forest1.5%289.53
White Chuck MountainMt Baker-Snoqualmie National Forest1.4%32.94
Glacier Peak HMt Baker-Snoqualmie National Forest1.2%48.24
Twin LakesWenatchee National Forest1.1%96.39
Rock CreekWenatchee National Forest0.6%77.58
EntiatWenatchee National Forest0.5%141.21
Methodology and Data Sources

Ecosystem classification: Ecosystems are classified using the LANDFIRE 2024 Existing Vegetation Type (EVT) layer, mapped to NatureServe Terrestrial Ecological Systems via a curated crosswalk. Each EVT is linked to the USNVC (U.S. National Vegetation Classification) hierarchy through pixel-level co-occurrence analysis of LANDFIRE EVT and NatureServe IVC Group rasters across all roadless areas.

Vegetation coverage: Coverage percentages and hectares are derived from zonal statistics of the LANDFIRE 2024 EVT raster intersected with roadless area boundaries.

Ecosystem narratives and community species: Sourced from the NatureServe Explorer API, representing professional ecological assessments of vegetation composition, environmental setting, dynamics, threats, and characteristic species assemblages.

IVC hierarchy: The International Vegetation Classification hierarchy is sourced from the USNVC v3.0 Catalog, providing the full classification from Biome through Association levels.

Component associations: Plant community associations listed as components of each NatureServe Ecological System. Association data from the NatureServe Explorer API.

State ranks: Conservation status ranks assigned by NatureServe member programs in each state where the ecosystem occurs.