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The 52 level II ecological regions that have been delineated are intended to provide a more detailed description of the large ecological areas nested within the level I regions. For example, the Tropical Humid Forests of level I is the region covering coastal portions of the United States and Mexico, and is composed of six level II regions. Level II ecological regions are useful for national and subcontinental overviews of physiography, wildlife, and land use.
Three level I regions (Hudson Plains, Marine West Coast Forests and Mediterranean California) have no level II delineations. The Great Plains, Tropical Dry Forests and Tropical Humid Forests level I regions, on the other hand, each have six level II subdivisions. The table below provides a synopsis of the major physical and biological attributes along with human activities associated with each of the level II ecological regions.
Level II ecoregions are characterized as follows:
- number of ecological regions: 52
- scale of presentation: 1:30 million
- nested within level I regions
- national/regional perspectives
- determination of the areas composing the regions through satellite imagery and appropriate natural resource source maps at broad scales (approximately 1:20 million – 1:30 million)
ECOLOGICAL REGIONS OF NORTH AMERICA | ||||||
| Level I | Landforms; Water Bodies | Surface materials; Soils | Climate (mean annual temperature; mean annual precipitation) | Vegetation | Wildlife
| Human activities |
| Level II Surface (km2) | ||||||
| 1 ARCTIC CORDILLERA 218,225 | ||||||
| 1.1 Arctic Cordillera 218,225 | mountains, glaciers and icefields | largely ice and bedrock; some frozen soils | -20°C to –6°C 200-600 mm | soma Arctic tundra in valleys and at sea level | wide occurrence of ice fields restricts wildlife habitat and species diversity | sparsely settled area; some recreational use and subsistence hunting |
| 2 TUNDRA 2,856,850 | ||||||
| 2.1 Northern Arctic 1,495,255 | hills and plains; some lakes | moraines and some bedrock; frozen soils, continuous permafrost | -17°C to –11°C 100-200 mm | discontinuous Arctic tundra, e.g., ground-hugging shrubs, herbs and lichens | Peary caribou, polar bear, musk ox, snow geese | very low intensity hunting and trapping; oil and gas activities and isolated mining |
| 2.2 Alaska Tundra 390,490 | coastal plain and some hills; some lakes and small ponds | moraines, bogs and fens, marine deposits; frozen soils and permafrost | -13°C to –7°C 100-300 mm | continuous Arctic tundra, low shrubs | Grant's caribou, Richardson's ground squirrel | oil and gas; low intensity subsistence hunting and trapping |
| 2.3 Brooks Range Tundra 162,835 | mountains and some valleys | colluvium, bedrock and moraines; frozen soils and permafrost | -13°C to –7°C 150-300 mm | discontinuous alpine tundra | barren ground caribou | low intensity hunting and trapping |
| 2.4 Southern Arctic 808,270 | rolling hills and plains; numerous lakes | moraines and some exposed bedrock: frozen soils and permafrost
| -11°C to –7°C 200-500 mm | Arctic low to medium shrubs | barren ground caribou, Arctic fox, Arctic ground squirrel, ptarmigan | hunting and trapping; mineral exploration |
| 3 TAIGA 2,799,230 | ||||||
| 3.1 Alaska Boreal Interior 459,780 | plains and some hills | moraines, bogs and fens; frozen soils and permafrost, some forest soils | -9°C to –1°C 200-500 mm | medium to high Arctic shrubs, open coniferous forest | caribou, moose, black bear, wolf | low intensity hunting and trapping: some tourism; locally commercial forestry |
| 3.2 Taiga Cordillera 223,870 | mountains and narrow valleys | colluvium, moraines, and rock; primarily frozen soils and some weakly-developed acidic forest soils | -10°C to –5°C 300-700 mm | medium to high alpine shrubs, open coniferous forests | Dall sheep, caribou, black and grizzly bear, wolf, gyrfalcon | low intensity hunting and trapping; tourism; some mineral exploration |
| 3.3 Taiga Plains 701,625 | plains; some lakes | moraines, bogs, lacustrine and some alluvium; primarily frozen soils with some wet soils and organics | -10°C to –1°C 200-500 mm | Arctic tundra meadow and wetland associations, open conifer stands | moose, caribou, black bear, wolf | low intensity hunting, trapping and fishing; oil and gas extraction; some tourism |
| 3.4 Taiga Shield 1,413,955 | hills and some plains; numerous small lakes | bedrock and moraines; primarily some nutrient-poor acidic forest soils | -8°C to –1°C 200-800 mm | open shrubs and sedge meadows, open conifer forest | moose, caribou, black bear, wolf, snowshoe hare, waterfowl (black ducks) | low intensity hunting, trapping and fishing; mineral exploration; some tourism |
| 4 HUDSON PLAINS 334,530 | ||||||
| 4.1 Hudson Plains 334,530 | coastal plains and wetlands | marine deposits, bogs and fens; frozen organic soils and nutrient-poor acidic forest soils | -4°C to –2°C 400-800 mm | Arctic tundra and boreal forest transition | some moose, caribou, black bear and polar bear, well known for waterfowl habitat | low intensity subsistence hunting, trapping and fishing; limited sport tourism |
| 5 NORTHERN FORESTS 2,363l,825 | ||||||
| 5.1 Softwood Shield 1,427,115 | hills with some plains; numerous lakes | bedrock interspersed with moraines and some fluvium; nutrient-poor forest soils | -2°C to –6°C 550-1,500 mm | primarily conifers (white and black spruce, balsam fir, jack pine), lichens and shrubs | woodland caribou, white-failed deer, moose, beaver, black bear, lynx, great horned owl | forestry, hydropower, mining; tourism subsistence and commercial hunting, trapping and fishing |
| 5.2 Mixedwood Shield 569,245 | Plains with some hills; numerous lakes and wetlands | bedrock interspersed with moraines and some fluvium and lacustrine; nutrient-poor, leached forest soils with pockets of fine textured soils | 1°C to 9°C 500-1,200 mm | mixedwoods: conifers (white and black spruce, balsam fir, jack pine), balsarn poplar, oak, sugar maple and beech | white-tailed deer, racoon, skunk, wolf | forestry; local mining; tourism |
| 5.3 Atlantic Highlands 367,465 | hills and some plains | soma bedrock interspersed with moraines and marine deposits; nutrient-poor, leached forest soils with pockets of fine- textured soils | 4°C to 9°C 900-1,500 mm | wide range of mixedwoods, including hemlock, balsam air, red and white pine, sugar maple, red spruce | white-tailed deer, moose, black bear, skunk, eastern gray squirrel, eastern bluebird | forestry; local agriculture; local mining; Borne fishing; major tourism |
| 6 NORTHWESTERN FORESTED MOUNTAINS 1,788,950 | ||||||
| 6.1 Boreal Cordillera 647,830 | high mountains and some wide valleys | mountains and some colluviurn; nutrient-pour forest soils | -10°C to -5°C 300-700 mm | boreal forest (black and white spruce, lodgepole pine) and some alpine vegetation | woodland caribou, Dall sheep and small furbearers | mining, forestry; commercial trapping; local tourism |
| 6.2 Western Cordillera 1,141,120 | high mountains and some wide valleys | bedrock, colluvium and moraines; nutrient-poor forest soils | 1°C to 10°C 700-3,000 mm | alpine to conifer forest (subalpine fir, Douglas fir, ponderosa pine) to semi-arid shrubs and grassland | mule deer, elk, black bear, bighorn sheep, cougar, Steller's jay | forestry; grazing; tourism |
| 7 MARINE WEST COAST FORESTS 2,548,435 | ||||||
| 7.1 Marine West Coast Forests 692,970 | high and low mountains with some hills and valleys | bedrock, colluvium and moraines; nutrient-poor forest soils | 5°C to 12°C 600- 6,000 mm | alpine to temperate rainforests (western red cedar, western hemlock, Sitka spruce, Douglas fir, redwood) | grizzly bear, black bear, elk, black-tailed deer, shrew mole, golden eagle, blue heron. blue jay, salmon | intensive forestry; tourism; fishing; local urbanization and agriculture |
| 8 EASTERN TEMPERATE FORESTS 2,578,435 | ||||||
| 8.1 Mixedwood Plains 490,590 | mainly plains, some hills, many small lakes | moraines and lacustrine; forest soils, fine textured soils | 4°C to 10°C 720-1,200 mm | oak, hickory, maple, beech. and some pine and basswood | white-tailed deer, moose, gray squirrel | major urban areas; agriculture (dairy, fruit); some forestry and tourism |
| 8.2 Central USA Plains 253,665 | smooth plains | moraines with some lacustrine; calcium-enriched prairie soils, forest soils on moraine | 7°C to 13°C 760-1,100 mm | formerly oak, hickory, elm, ash, beech, maple with more prairie to the west | white-tailed deer cottontail rabbit, gray squirrel | agriculture (major corn and soybean area), locally important dairy area; major urban areas |
| 8.3 Southeastern USA Plains 946,770 | irregular plains, low hills | residuum and some loess; weakly developed soils | 13°C to 19°C 1,000-1,600 mm | oak, hickory, loblolly and shortleaf pine | white-tailed deer, gray squirrel, armadillo, wild turkey, northern cardinal, mockingbird
| forestry; agriculture (tobacco, hogs, cotton); urban areas |
| 8.4 Ozark and Ouachita- Appalachian Forests 518,690 | hills and low mountains, some wild valleys | residuum and colluvium; weakly developed soils | 17°C to 18°C 1,000-2,000 mm | mixed oaks with hickory, also white pine, birch, beech, maple, hemlock | black bear, white-tailed deer, chipmunk, wild turkey | forestry; coal mining; some local agriculture; tourism |
| 8.5 Mississippi Alluvial and soutbeastern Coastal Plains 368,720 | flat plains; many wetlands | alluvium and coastal marine deposits; fine-to medium-textured forest soils, organics | 13°C to 27°C 1,100-1,800 mm | bottomland forests (ash, oak, tupelo, baldcypress); southern mixed forests (beech, sweet gum, magnolias, oaks, pine, saw palmetto) | white-tailed deer, opossum, armadillo, American alligator, mockingbird, egret | forestry and agriculture (citrus, soybeans, cotton); tourism; fishing |
| 9 GREAT PLAINS 3,543,875 | ||||||
| 9.1 Boreal Plains 644,560 | plains | moraines and lacustrine; nutrient-poor acidic soils | -2°C to 2°C 300-625 mm | trembling aspen with black arid white spruce, balsam fir | woodland caribou, beaver, wolf, coyote, red fox | forestry and agriculture with some oil and gas industry; hunting and recreation |
| 9.2 Temperate Prairies 785,400 | mainly irregular plains, flatter to the northwest; numerous small lakes and wetlands | moraines with some loess in the south, some lacustrine; mainly calcareous soils | 2°C to 13°C 400-1,000 mm | formerly tall grass/aspen parkland, currently cropland | white-tailed deer, waterfowl, pheasant, meadowlark | agriculture (cereal grain, livestock, feedlots) |
| 9.3 West-Central Semi-Arid Prairies 911,425 | irregular plains, table- lands and low hills | moraines and lacustrine in the north; residuum, alluvium, and eolian; sand deposits in the south, prairie soils | 2°C to 8°C 250-650 mm | formerly native short grass prairie (wheat grass, porcupine grass), currently cropland | pronghorn antelope, jackrabbit, black-tailed prairie dog, mule deer, sage grouse, magpie | agriculture (cattle and sheep grazing, wheat, barley, hay) |
| 9.4 South-Central Semi-Add Prairies 1,003,375 | smooth and irregular plains, and tablelands | alluvium, loess and residuum; calcareous soils | 7°C to 21°C 250-750 mm | short grass prairie in the north and grasslands with mesquite, juniper, and oak in the south | jackrabbit, white-tailed deer, armadillo, mourning dove, magpie, vulture | agriculture (sorghum. wheat, cattle feedlots, goats, sheep |
| 9.5 Texas-Louisiana Coastal Plain 64,615 | flat plains arid some barrier islands | alluvium and wetlands; calcareous soils, some rich in organics | 18°C to 25°C 750-1,300 mm | southern cord grass/bluestern grass area; much of this is currently in agriculture | alligator, armadillo, rattlesnakes, ducks, pelican, plover, sandpiper | petrochemical industry; agriculture (rice, sorghum, cattle pasture); fishing; tourism |
| 9.6 Tamaulipas-Texas Semi-Arid Plain 134,500 | plains end low hills | alluvium; saline, fine-textured soils | 22°C to 26°C 300-400 mm | thorn shrubs as lotebrush, granjeno, mesquite, gavia, cenizo, halophilous vegetation near the coast | black bear, cougar, Texas white-tailed deer, collared peccary, beaver, eastern mole, Berlandier's tortoise, rock rattlesnake, Mexican duck, blue-winged teal, white-winged dove | agriculture (corn, cartamus, sunflower, beans, sorghum), grazing; manufacturing; tourism |
| 10 NORTH AMERICAN DESERTS 2,027,460 | ||||||
| 10.1 Western Interior Basins and Ranges 1,014,840 | plains with low and high mountains and some tablelands | colluvium, alluvium, bedrock, some loess; dry calcareous soils | 2°C to 16°C 150-1,200 mm | sagebrush, shadscale, greasewood, juniper, Mexican piñon, invasive cheatgrass and several other tufted grasses | mule deer in mountains, pronghorn antelope, sage grouse, magpie | some agriculture in the north, grazing; local mining; tourism |
| 10.2 Sonoran and Mohave Deserts 398,120 | plains with low mountains | alluvium and bedrock; shallow, saline soils | 13°C to 24°C 50-250 mm | creosote bush, burro sage, paloverde, ocotillo, saguaro, joshua tree | Sonora, pronghorn antelope, mule deer, bighorn sheep, antelope jackrabbit, desert tortoise, horned rattlesnake, Gila monster, bald eagle, Mexican falcon, greater roadrunner, Gambel's quail, scaled quail | local agriculture (vegetables, dates, citrus fruits) under irrigation; urban areas; industry, mining |
| 10.3 Baja Californian Desert 103,935 | plains with low hills and mountains | bedrock and colluvium; shallow, saline soils | 10°C to 20°C <300 mm | many endemic species: cirio, copalquín, elephant tree, cardón, Adam tree, agaves, cholla, and abundant tufted lichens | Peninsular pronghorn antelope, bighorn sheep, ring-tailed cat, Baja California rock squirrel, red diamondback rattlesnake, Baja California rattlesnake, golden eagle, osprey, California quail | agriculture under irrigation. grazing; salt mining; tourism national parks, protected areas |
| 10.4 Chihuahuan Desert 5l0,565 | plains with low mountains, some high mountains | colluvium and some bedrock- saline desert soils | 10°C to 18°C 100-600 mm | tarbush, creosote, yucca, lechuguilla, prickly pear, tobosa end grama grasses | mule deer, bighorn sheep, coyote, black-tailed jackrabbit, Mexican prairie dog, bolson tortoise, desert tortoise, Mexican alligator lizard, rattlesnakes, scaled quail, burrowing owl | low intensely land use overall, local vegetable and cotton, grazing; mining, industry; urban areas |
| 11 MEDITERRANEAN CALIFORNIA 198,975 | ||||||
| 11.1 Mediterranean California 198,975 | flat plains, plains with low mountains, some high mountains | colluviurn and alluvium; bedrock; calcareous soils to weakly developed, neutral forest soils | 7°C to 25°C 250-1,000 mm | central valley was formerly grasslands; oak woodlands, chaparral, chamiso, coastal sagebrush, pine forest | mule deer, black-tailed deer, coyote kit fox, jackrabbit, southern sea otter, Lewis woodpecker | Mediterranean-type agriculture (fruits/ vegetables/dairy); urban areas: oil and gas, industry; recreation and tourism |
| 12 SOUTHERN SEMI-ARID HIGHLANDS 270,340 | ||||||
| 12.1 Western Sierra Madre Piedmont 194,945 | piedmont, hills and plains | colluvium and bedrock; calcareous, weakly developed neutral soils | 10°C to 18°C 600-1,000 mm | shrub and grasses to Mexican piñon and ponderosa pine, oak, juniper | coyote, badger, (striped) skunk, white- sided jackrabbit, spotted ground squirrel, bullsnake, northern harrier, white-winged dove, band-tailed pigeon | range grazing and agriculture |
| 12.2 Mexican High Plateau 75,395 | high elevation plains and hills | colluvium and alluvium; coarse and clayey soils | 10°C to 18°C 300-600 mm | mesquite, dryland shrubs and grasses | kit fox, white-sided jackrabbit, spotted ground squirrel, red-tailed hawk | agriculture and range grazing; industry; tourism |
| 13 TEMPERATE SIERRAS 630,045 | ||||||
| 13.1 Upper Gila Mountains 105,255 | low and high mountains | colluvium end bedrock; calcareous, weakly developed soils | 0°C to 13°C 400-850 mm | ponderosa pine/white fir forest at higher elevations; lower elevations have Oak, juniper, Mexican piñon and chaparral | mule deer, porcupine, red squirrel, red-faced warbler, yellow-eyed junco, Steller's jay, red-tailed hawk | some forestry at upper elevations; recreation; grazing |
| 13.2 Western Sierra Madre 203,625 | volcanic mountains | colluvium and alluvium; coarse and clayey soils | 10°C to 18°C 600-1,500 mm | conifer and oak forests (pine, piñon, fir, spruce, oaks, madrone) | cougar, timber wolf, white-tailed deer, gray fox, coati, Arizona ridge-nosed rattlesnake, golden eagle, wild turkey, thick-billed parrot. eared trogon | forestry; extensive grazing (cattle and sheep) |
| 13.3 Eastern Sierra Madre 58,105 | sedimentary mountains | colluvium; shallow soils | 10°C to 18°C 600-3.000 mm | conifer and oak forests, cloud forests, red pine, sweet gum, oak, alder, walnut | black bear, bobcat, white-tailed deer, cottontail rabbit, arboreal alligator lizard, peregrine falcon, maroon-fronted parrot, wild turkey | forestry; agriculture, coffee plantations |
| 13.4 Transversal Neovolcanic System 118,795 | volcanic mountains arid plains | alluvium and colluvium: volcanic and clayey soils | 10°C to 18°C 1,000-2,000 mm | conifer and oak forests (pine, fit, white cedar, oak, madrone black cherry, Mexican hawthorn) | badger, long-tailed weasel, volcano rabbit, Mexican alligator lizard, axolotl, black-tailed rattlesnake, Mexican pygmy rattlesnake. black-crowned night-heron, long-tailed wood partridge | forestry; agriculture, extensive grazing (cattle and sheep); main industrial area; nearly 40% of Mexican population lives here |
| 13.5 Southern Sierra Madre 118,025 | geologically complex mountains | colluvium and alluvium; shallow soils and clayey soils | 10°C to 26°C 1,000-3,000 mm | conifer end oak forests; cloud forests, pin, oak, fir, árbol de las manitas | West Mexican chachalaca, neotropical otter, Mexican woodnymph | forestry; agriculture (plantations and traditional); tourism |
| 13.6 Central American Sierra Madre and Chiapas Highlands 26,240 | granitic and sedimentary mountains | residuum and colluvium; deep clayey soils | 18°C to 22°C 2,000-4,000 mm | conifer and oak forests; cloud forests (pine, oak, sweet gum) | red-lipped alligator lizard, horned guan, quetzal, white-breasted haw) | forestry; tourism; coffee plantations |
| 14 TROPICAL DRY FORESTS 246,260 | ||||||
| 14.1 Gulf of Mexico Dry Coastal Plains end Hills 33,885 | plains and hills | colluviumn and alluvium; clayey and calcareous soils | 24°C to 26°C 600-800 mm | deciduous and thorn forests (Texas ebony, cerón, copal rnesquite) | jaguar, chachalaca, wild turkey, green parakeet, red-crowned parrot | extensive grazing, agriculture |
| 14.2 Northwestern Plain of the Yucatán Peninsula 14,165 | Karst plain, wetlands | colluvium and alluvium; calcareous soils | 24°C to 28°C 600-800 mm | deciduous forests (gummo-limbo, cordia/canalete, tepeguaje, angelica tree) | paca, hog-nosed Skunk, black-throated bobwhite, lesser roadrunner | henequén plantations; tourism |
| 14.3 Western Coastal Plain, Hills and Canyons 84,225 | plains, canyons and hills | alluvium and colluvium; clayey and calcareous soils | 24°C to 26°C 500-600 mm | deciduous forest (gum bumelia, camachile, tepeguaje, copale, ceiba) | neotropical otter, green iguana, bald eagle, northern goshawk, San Blas jay, military macaw | traditional and commercial agriculture, grazing |
| 14.4 lnterior Depressions 64,900 | depression | alluvium and bedrock; shallow soils | 24°C to 28°C 400-800 mm | deciduous and thorn forests (copale, cuajiote, leadtree, tepeguaje. lemonwood); xeric shrubland | tropical ground squirrel, ring-tailed cat, black iguana, beaded lizard, balsas screech owl | commercial agriculture (irrigation) ,traditional agriculture, grazing |
| 14.5 Southern Pacific Coastal Plain and Hills 39,915 | plains and hills | alluvium and bedrock; shallow soils | 22°C to 26°C 600-1,000 mm | deciduous forest (copale, ceiba, bonete, amole, cordia, camachile) | ring-tailed ground squirrel, green iguana, American crocodile, boa, ornate cantil, West Mexican chachalaca | commercial agriculture plantations; tourism |
| 14.6 Sierra and Plains of El Cabo 9,170 | hills and plains | alluvium; shallow, weakly developed soils | 22°C to 24°C 600-1,000 mm | deciduous forest (mesquite, huisache, elephant tree, hog plum, palo de arco) oak/pine forest on summits | mule deer, cape shrew, San Lucan gecko, Pacific water snake. Baja California whiptail, cape pygmy owl | tourism |
| 15 TROPICAL HUMID FORESTS 311,120 | ||||||
| 15.1 Gulf of Mexico Humid Coastal Plains and Hills 141,390 | coastal plains and hills, wetlands | alluvium and colluvium; poorly-drained and clayey soils | 22°C to 24°C 2,000-4,000 mm | tall and medium-height evergreen forests (paque, allspice tree, palms, sombrerete, breadnut, copai-yé wood, mahogany, mangrove, forbes) | tapir, white-lipped peccary, spider monkey, vampire bat, Morelet's crocodile, green iguana, fer de lance, Muscovy duck, scarlet macaw, happy eagle, keel-billed toucan | extensive grazing, agricultural plantations; petroleum industry; tourism |
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Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Commission for Environmental Cooperation. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Commission for Environmental Cooperation should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content. |
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