Ecoregions are geographic areas where climate, soils, landforms, and plant and animal communities are similar enough to function as a cohesive ecological unit. Unlike state or county boundaries, which are based on human decisions, ecoregions reflect natural patterns in rainfall, temperature, vegetation, and soil that directly influence how plants grow.
For home gardeners, understanding ecoregions provides a more accurate guide for plant selection than hardiness zones alone because it considers the full range of environmental conditions, not just winter temperatures. Choosing plants suited to your ecoregion helps improve establishment, reduce inputs like water and fertilizer, and increase resistance to pests and environmental stress, ultimately leading to a more resilient and sustainable garden.
More information on EcoRegions is available from the U.S. Environmental Protection Agency (EPA):
EcoRegion Descriptions
Driftless Area
8.1.5 Eastern Temperate Forest; Mixed Wood Plains; Driftless Area
Location: This region spans both sides of the upper Mississippi River valley—southeast Minnesota, southwest Wisconsin, northeast Iowa, and northwest Illinois.
Climate: The ecoregion has a severe, mid-latitude, humid continental climate, marked by warm summers and severe winters, with no pronounced dry season. The mean annual temperature is approximately 7°C to 9°C. The frost-free period ranges from 140 to 170 days. The mean annual precipitation is 825 mm, and ranges from 760 to 965 mm. Snowfall is common in winter.
Vegetation: The region is a mosaic of prairie with little bluestem, Indiangrass, and sideoats grama, and forests of bur oak and white oak. In more mesic areas, forests of sugar maple, basswood, and red oak, and riparian forests with elm, river birch, silver maple, and ash.
Hydrology: The region has many perennial streams. Springs and spring-fed streams are also common. There are few natural lakes, but some small reservoirs and farm ponds.
Terrain: The hilly uplands of the Driftless Area easily distinguish it from surrounding ecoregions. Much of the area consists of a deeply dissected, loess-capped, bedrock dominated plateau featuring gently sloping to rolling summits with steeper valley walls and bluffs. Rock outcrops are common, with shale, sandstone, dolomite, and limestone. The region is also called the Paleozoic Plateau because the landscape’s appearance is a result of erosion through rock strata laid down in the Paleozoic Era. Although there is evidence of glacial drift in the region, the influence of the glacial deposits has done little to affect the landscape compared to the subduing influences in adjacent ecoregions. Alfisols, Entisols, and Mollisols are dominant, with mesic soil temperature regimes and udic soil moisture regimes.
Wildlife: White-tailed deer, coyote, gray fox, red fox, beaver, raccoon, fisher, otter, mink, gray squirrel, red-shouldered hawk, turkey vulture, ruffed grouse, wild turkey, northern pike, walleye, largemouth bass are found in the region.
Land Use/Human Activities: Some pasture and cropland are featured on flatter uplands, woodlands and forest on steeper slopes and ravines. Livestock and dairy farming are major land uses and have had a major impact on stream quality. Corn, soybeans, feed grains, and hay are principal crops. Larger towns include Rochester, Winona, Decorah, Dubuque, Prairie du Chien, and La Crosse.
Interior River Valleys and Hills
8.3.2 Eastern Temperate Forest; Southeastern USA Plains; Interior River Valleys and Hills
Location: Ecoregion 8.3.2 is located in the central part of the Mississippi basin where large rivers such as the Ohio and Missouri meet the Mississippi River. It spans southeast Iowa, southwestern and southern Illinois, eastern Missouri, southeastern Indiana, and western Kentucky.
Climate: Mostly, the ecoregion has a severe, mid-latitude, humid continental climate, marked by hot summers and cold winters. The mean annual temperature is approximately 10°C to 14°C. The frost-free period ranges from 170 to 220 days. The mean annual precipitation is 1,057 mm, ranging from 860 to 1,320 mm.
Vegetation: Bottomland deciduous forests and swamp forests were once extensive on poorly-drained, nearly level, lowland sites but most have been replaced by cropland and pastureland. Along the Mississippi were silver maple, American elm, and green ash, with pin oak, pecan, bur oak, sycamore, honey locust, hickories, and black walnut. Bottomland forests had pin oak, bur oak, Shumard oak, cherrybark oak, overcup oak, swamp white oak, and swamp chestnut oak, and sweetgum. Some upland forests contain mixed oak forests of post oak, southern red oak, white oak, black oak, and shagbark hickory, while mesic sites include beech, yellow-poplar, sugar maple, and northern red oak.
Hydrology: There are numerous perennial streams and rivers, low to moderate gradient. Silt and sand dominate lowland channels while upland streams are rockier. Streams typically have lower nutrient, alkalinity, and hardness levels than in ecoregion 8.3.3. Wetlands are common on lowlands and bottomlands. Some oxbow lakes and reservoirs are sited in the valleys.
Terrain: Many wide, flat-bottomed terraced valleys, valley slopes and river bluffs occur in this region. Illinois and Indiana contain dissected glacial till plains. The region is mostly underlain by Carboniferous period sedimentary rock and is lithologically distinct from the limestones, calcareous shales, and dolomites of the Interior Plateau (8.3.3) and the unconsolidated coastal plain sediments of the Mississippi Alluvial Plain (8.5.2). Broad, low gradient valleys occur and are filled with alluvium, loess, and lacustrine deposits. Alfisols and Mollisols are dominant, with mostly mesic soil temperatures and udic and aquic soil moisture regimes.
Wildlife: White-tailed deer, badger, weasel, raccoon, bobwhite quail, Carolina chickadee, redback salamander, copperbelly water snake, timber rattlesnake, eastern box turtle, snapping turtle, paddlefish, various darters are among the abundant wildlife that were native in this region.
Land Use/Human Activities: Less than half of this area is in cropland, about 30 percent is in pasture, and the remainder is in forest. Corn, soybeans, wheat, and hay are typical crops. There is some oil and gas production. In a few areas, extensive surface and underground coal mines occur and have significantly degraded downstream habitat and water quality, although underground coal mining probably peaked in this region about a century ago. Larger towns and cities include Moline, Rock Island, Galesburg, Quincy, Columbia, Jefferson City, St. Louis, Effingham, Cape Girardeau, Mt. Vernon, Carbondale, Marion, Terre Haute, Evansville, Owensboro, and Paducah.
Western Corn Belt Plains
9.2.3 Great Plains; Temperate Prairies; Western Corn Belt Plains
Location: The Western Corn Belt Plains stretches across southern Minnesota, most of central and western Iowa, eastern South Dakota, eastern Nebraska, northwest Missouri, and northeast Kansas.
Climate: The ecoregion has a severe, mid-latitude, humid continental climate, marked by hot summers and cold winters. The mean annual temperature is approximately 6°C in the north to 12°C in the south. The frost-free period ranges from 140 to 200 days. The mean annual precipitation is 800 mm, ranging between 610 and 1,000 mm and occurring mainly in the growing season.
Vegetation: Once a tallgrass prairie covered with little bluestem, big bluestem, Indiangrass, switchgrass, numerous forbs, and with small areas of bur oak and oak-hickory woodlands, the region has nearly all been converted to agricultural land.
Hydrology: There are intermittent and perennial streams, many of which have been channelized. A few areas have natural lakes. Surface and groundwater contamination from fertilizer and pesticide applications as well as from concentrated livestock production is a regional issue.
Terrain: The topography consists of nearly level to gently rolling glaciated till plains and hilly loess plains. Thick loess and glacial till cover the Mesozoic and Paleozoic shale, sandstone, and limestone. Mollisols and Alfisols are dominant with mesic soil temperatures and udic soil moisture.
Wildlife: Regional wildlife includes white-tailed deer, beaver, raccoon, red-tailed hawk, barn owl, bobwhite quail, western meadowlark, Canada goose, pheasant, gray partridge, mallard, teal, Great Plains toad, walleye, northern pike, bluegill, sunfish.
Land Use/Human Activities: Over 75 percent of the Western Corn Belt Plains is now used for cropland agriculture and much of the remainder is in forage for livestock. It is one of the most productive areas in the world for growing corn and soybeans. Hog and cattle production and some dairies also occur. Larger towns and cities include Mankato, Worthington, Albert Lea, Austin, Sioux Falls, Sioux City, Fort Dodge, Mason City, Ames, Des Moines, Marshalltown, Waterloo, Cedar Falls, Cedar Rapids, Iowa City, Omaha, Council Bluffs, Lincoln, Atchison, Maryville, and St. Joseph.
Central Irregular Plains
9.2.4 Great Plains; Temperate Prairies; Central Irregular Plains
Location: This ecoregion spans southern Iowa, northern and western Missouri, eastern Kansas, and northeastern Oklahoma.
Climate: The ecoregion has a severe, mid-latitude, humid continental climate in the north and a milder humid subtropical climate to the south. It is marked by hot summers and mild to cold winters. The mean annual temperature is approximately 10°C to 16°C, with a frost-free period of between 165 and 235 days. The mean annual precipitation is 983 mm, ranging from 865 to 1,145 mm. Most of the rain falls during the growing season though there is snow in winter.
Vegetation: The historical vegetation is a grassland/forest mosaic with wider forested strips along the streams, compared to ecoregion 9.2.3 to the north. The grassland was an allgrass prairie with little bluestem, big bluestem, switchgrass, and Indiangrass, and the forests are oak-hickory woodlands with red oak, white oak, bur oak, chinkapin oak, post oak, shagbark hickory, and bitternut hickory.
Hydrology: Perennial streams are common; in some areas many are channelized. Some large rivers cross the region. A few large reservoirs occur. Groundwater is highly mineralized in some areas.
Terrain: Rolling and irregular plains are common in this area, with some cuestas and low hills: topographically it is more irregular than the Western Corn Belt Plains (9.2.3) to the north, The region, however, is less irregular than the ecoregions to the south and east. Geology is mostly Pennsylvanian period sandstone, shale, limestone, and coal. Loess overlies clayey glacial drift in the north; Mollisols and Alfisols are typical, with mesic and thermic soil temperatures and udic and aquic soil moisture regimes.
Wildlife: White-tailed deer, badger, raccoon, skunk, muskrat, cottontail rabbit, mink, Canada geese, bobwhite quail, western meadowlark, ring-neck pheasant.
Land Use/Human Activities: The region presents a mosaic of land uses, with cropland, woodland, and grassland. Agriculture here includes the production of corn, soybeans, wheat, alfalfa, hay, grain sorghum, cattle, and broiler chickens. There is some oil and gas production and mining of high-sulfur bituminous coal occurs, although less now than formerly. The disturbance of coal strata in southern Iowa and northern Missouri has degraded water quality and affected aquatic biota. Larger towns and cities include Ottumwa, Kirksville, Mexico, Warrensburg, Topeka, Lawrence, Fort Scott, Independence, Miami, Claremore, Tulsa, Broken Arrow, and Muskogee.
Other Regions
Information on other regions is available in North American Terrestrial Ecoregions—Level III (PDF).
More Information
- Sustainable Gardening Library's EPA EcoRegions Interactive Map
- Gardening in Iowa Zones
- Heat Zone Map of Iowa
- Climate Zones from NOAA
- 2023 USDA Plant Hardiness Zone Map
- EcoRegions from EPA
Source: Sustainable Gardening Library