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Scientific Name: Boreal Ice-Scour Rivershore
Unique Identifier: CES103.589

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Summary: This riparian system occurs in the extreme northeastern and north-central U.S. and adjacent Canada. It develops along the shores of northern rivers, where early spring snowmelt and ice-scour exert a strong influence on the vegetation. The ice prevents floodplain forests from developing; the vegetation consists of shrublands, tall grasslands, graminoid-forb-dwarf shrub shoreline seeps, and rivershore outcrops. Characteristic shrubs include Alnus incana and Alnus viridis ssp. crispa (= Alnus crispa), Myrica gale, Spiraea alba, Cornus sericea, Salix eriocephala and many other Salix spp., and Dasiphora fruticosa ssp. floribunda. Characteristic herbaceous species vary with the setting; Calamagrostis canadensis is ubiquitous, and other herbs include Symphyotrichum novi-belgii, Carex spp. (including Carex flava, Carex garberi, Carex viridula), Deschampsia cespitosa, Andropogon gerardii, Schizachyrium scoparium, Allium schoenoprasum, Triantha glutinosa, Spartina pectinata, Solidago uliginosa, Doellingeria umbellata (= Aster umbellatus), Agrostis scabra, and many others. Soils in some areas remain saturated; other patches are well-drained for most of the growing season. The location and extent of shrub versus herb cover will vary in time and space according to how recent and severe the scour events have been. The continual weathering of glacial deposits in the river channel can produce relatively high pH conditions; this and periodic natural disturbance create conditions for many regionally rare plant species.

Classification Approach: International Terrestrial Ecological Systems Classification (ITESC)

Classification Comments: Need to clarify the conceptual boundaries between this and the boreal rivershores in central and eastern Canada. This ecological system undoubtedly occurs further west into central Canada, as far west as northern Alberta. It was not mapped in the SunCor Alberta boreal forest mapping project.

Component Associations
Association Unique ID Association Name
CEGL002186 Cornus sericea - Salix spp. - (Rosa palustris) Shrub Swamp
CEGL002314 River Mudflats Sparse Vegetation
CEGL006062 Alnus incana - Cornus (amomum, sericea) / Clematis virginiana Shrub Swamp
CEGL006142 Triantha glutinosa - Carex garberi Riverscour Wet Meadow
CEGL006427 Calamagrostis canadensis - Doellingeria umbellata - Spartina pectinata Riverscour Wet Meadow
CEGL006437 Prunus pumila var. depressa / Deschampsia cespitosa Riverscour Wet Meadow
CEGL006532 Campanula rotundifolia - Packera paupercula - (Aquilegia canadensis) Riverscour Sparse Vegetation


Land Cover Class: Mixed Upland and Wetland
Spatial Pattern: Linear
Natural/Seminatural: No
Vegetated ( > 10% vascular cover):
Upland: Yes
Wetland: Yes
Isolated Wetland: No

Diagnostic Classifiers
Primary Classifier Secondary Classifier
Shrubland (Shrub-dominated)  
Riverine / Alluvial  
Very Short Disturbance Interval  
Flood Scouring  
Intermittent Flooding Intermittent interval, Spring Flooding
Intermittent Flooding Intermittent interval, Summer Flooding
Moderate (100-500 yrs) Persistence  

Non-diagnostic Classifiers
Primary Classifier Secondary Classifier
Toeslope/Valley Bottom  
Mesotrophic Soil  
Circumneutral Soil  
Acidic Soil  
Mineral: W/ A-Horizon <10 cm  
Mesotrophic Water  
Saturated Soil  

Vegetation Composition (incomplete)
Species Name Rounded Global Status Growth Form Stratum Char-
Domi-nant Con-stant
Cover Class %
Alnus incana G5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Alnus viridis ssp. crispa T5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Myrica gale G5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Dasiphora fruticosa ssp. floribunda T5 Broad-leaved evergreen shrub Shrub/sapling (tall & short)    
Parnassia glauca G5 Flowering forb Herb (field)    
Symphyotrichum novi-belgii G5 Flowering forb Herb (field)    
Triantha glutinosa G5 Flowering forb Herb (field)    
Calamagrostis canadensis G5 Graminoid Herb (field)    

Color legend for Distribution Map
Nation: United States
United States Distribution: ME, NHpotentially occurs
Nation: Canada
Canadian Province Distribution: NB, QC
Global Range: Far northern New England, extending into adjacent Canada and with scattered locations southward to central New England. Distribution west of New England is not well documented.

Biogeographic Divisions
Division Code and Name Primary Occurrence Status
103-Boreal C: Confident or certain
201-Laurentian-Acadian C: Confident or certain
202-Central Interior and Appalachian P: Predicted or probable

The Nature Conservancy's Conservation Ecoregions
Code Name Occurrence Status
48 Great Lakes Confident or certain
63 Northern Appalachian-Boreal Forest Confident or certain

MRLC 2000 Mapzones
Code Name Occurrence Status
50 Central Great Lakes Uplands Never was there
51 Great Lakes Plains Never was there
63 Finger Lakes Never was there
64 Northeastern Highlands Predicted or probable
66 The North Woods Confident or certain

National Mapping
ESLF Code (Ecological System Lifeform): 9332

West Landfire Legend: No
East Landfire Legend: No

Element Description Edition Date: 11Apr2007
Element Description Author(s): S.C. Gawler

Ecological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, K. Snow, J. Teague, and R. White. 2003-present. Ecological systems of the United States: A working classification of U.S. terrestrial systems. NatureServe, Arlington, VA.

  • Gawler, S. C., and A. Cutko. 2010. Natural landscapes of Maine: A classification of vegetated natural communities and ecosystems. Maine Natural Areas Program, Department of Conservation, Augusta.

  • Sperduto, D. D., and W. F. Nichols. 2004. Natural communities of New Hampshire: A guide and classification. New Hampshire Natural Heritage Bureau, DRED Division of Forests and Lands, Concord. 242 pp.

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Citation for Bird Range Maps of North America:
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Version 7.1 (2 February 2009)
Data last updated: March 2019