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34. Western Gulf Coastal Plain The principal distinguishing characteristics of the Western Gulf Coastal Plain are its relatively flat topography and mainly potential natural . Inland from this region, the plains are older, more irregular, and have mostly vegetation in the Louisiana portion ( 35) or -type vegetation potentials to the west in Texas (Ecoregion 33). Largely because of this flat land and relatively fertile , a higher percentage of the land is in cropland than in bordering ecological regions. Rice and soybeans are the principal crops across the region, while grain sorghum and cotton are also grown mostly in the Texas portion. Urban and industrial land uses have expanded greatly in recent decades in some parts of the region, and oil and gas production is common. of Louisiana Quaternary-age deltaic sands, silts, clays, and gravel underlie much of the Northern The Texas-Louisiana Coastal Marshes region is characterized by extensive freshwater and Ecoregions denote areas of general similarity in and in the type, quality, and quantity Environmental Protection Agency, 2006; Omernik, 1987). It is part of a collaborative project Commission for Environmental Cooperation Working Group, 1997, Ecological regions of – 34a Humid Gulf Coastal Prairies on this gently sloping coastal plain. The original vegetation 34g saltwater coastal marshes, few bays, and lack of barrier islands. There are many , of environmental resources. They are designed to serve as a spatial framework for the research, primarily between USEPA–National Health and Environmental Effects Research Laboratory toward a common perspective: Montreal, Commission for Environmental Cooperation, 71 p. was mostly tallgrass with gallery along . Little bluestem, big bluestem, , bayous, tidal channels, and canals. The streams and rivers that supply nutrients and sediments yellow Indiangrass, brownseed paspalum, and switchgrass were dominant grasses, in a mixture with to this region are primarily from the humid pine belt of Ecoregion 35. Soils are very poorly drained assessment, management, and monitoring of ecosystems and components. By (Corvallis, ), U.S. Geological Survey (USGS), U.S. Department of –Natural Gallant, A.L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as a hundreds of other herbaceous species across these prairies. Almost all of the coastal prairies have Histosols and Entisols with muck or surface textures. The region, called the Chenier Plain in Fresh marsh near Sweet . Louisiana coastal Live oaks and hackberry are canopy dominants recognizing the spatial differences in the capacities and potentials of ecosystems, ecoregions Resources Conservation Service (NRCS), Louisiana Natural Heritage Program (LNHP) within the tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency, been converted to cropland, pasture, crawfish aquaculture, or urban land uses. Some loblolly pines, Louisiana, is almost treeless. The cheniers, or narrow ridges paralleling the shoreline, rise to about support a sport hunting industry, a on many chenier ridges that parallel the Gulf stratify the environment by its probable response to disturbance (Bryce and others, 1999). Louisiana Department of Wildlife and Fisheries (LDWF), Louisiana Geological Survey (LGS), EPA/600/3-89/060, 152 p. and historically “islands” of longleaf pine, occur in the northern part of the region in the transition to five feet in elevation but occupy only about three percent of the region. Live oaks and hackberries growing alligator industry, and the trapping of shoreline. Palmetto and prickly pear cactus are Ecoregion 35. Soils in the Louisiana portion are mostly poorly or somewhat poorly drained Alfisols are dominant canopy species on many of the ridges, with an understory of palmetto and prickly pear fur-bearing animals. Photo: Cindy Steyer, NRCS two elements of the understory. Photo: LNHP Ecoregions are general purpose regions that are critical for structuring and implementing and Louisiana Department of Environmental Quality (LDEQ). Collaboration and consultation also Griffith, G.E., Bryce, S.A., Omernik, J.M., Comstock, J.A., Rogers, A.C., Harrison, B., Greenwade, J., occurred with the Louisiana Department of Agriculture and Forestry (LDAF), Louisiana Casby-Horton, S., Hatch, S.L., and Bezanson, D., 2004, Ecoregions of Texas (color poster with map, with silt loam or silty clay loam texture, while some Vertisols and Mollisols also occur. Pimple cactus. Extensive cordgrass marshes occur in the more saline areas with maidencane and sawgrass ecosystem management strategies across federal agencies, state agencies, and nongovernment mounds of loamy sand were prevalent across the prairie terrace, providing micro- variation. on fresh marshes. The and marshes support abundant , supply wintering grounds Department of Natural Resources, U.S. Department of Agriculture–Forest Service (USFS), U.S. descriptive text, and photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:2,500,000. organizations responsible for different types of resources in the same geographical areas (Omernik Covering the Holocene alluvial floodplain deposits of the larger and wider streams or for globally significant populations of ducks and geese, and provide habitat for small mammals and Army Corps of Engineers (USACE), U.S. Fish and Wildlife Service (USFWS), and USGS–Center McMahon, G., Gregonis, S.M., Waltman, S.W., Omernik, J.M., Thorson, T.D., Freeouf, J.A., Rorick, A.H., 34c bayous, the Floodplains and Low Terraces ecoregion is distinct from the surrounding alligators. Brown shrimp and white shrimp are commercially important. Sport fishery species such and others, 2000). A Roman numeral hierarchical scheme has been adopted for different levels of as red drum, black drum, southern flounder, and spotted seatrout occur in the coastal bays. ecological regions. Level I is the coarsest level, dividing North America into 15 ecological for Resources Observation and Science. This project is associated with an interagency effort and Keys, J.E., 2001, Developing a spatial framework of common ecological regions for the prairie uplands of Ecoregion 34a. The region in Louisiana has some similarities to the floodplain conterminous : Environmental Management, v. 28, no. 3, p. 293-316. forests of Ecoregion 35b to the north. In most of Ecoregion 34c, however, the floodplains and low The Lafayette Loess Plains had coastal prairie natural vegetation similar to Ecoregion 34a, regions. Level II divides the into 52 regions (Commission for Environmental to develop a common framework of ecological regions (McMahon and others, 2001). Reaching 34j that objective requires recognition of the differences in the conceptual approaches and mapping terraces have a different bottomland forest than the floodplains of Ecoregion 35. Bottomland forests but are capped with a loess veneer associated with the Valley. Well to poorly Cooperation Working Group, 1997). At level III, the continental United States contains 104 Omernik, J.M., 1987, Ecoregions of the conterminous United States (map supplement): Annals of the of pecan, water oak, live oak, and elm are typical, with some bald cypress on larger streams. In drained Alfisols and Mollisols with silt loam surface textures developed on the late Pleistocene-age methodologies applied to develop the most common ecoregion-type frameworks, including those Association of American Geographers, v. 77, p. 118-125, map scale 1:7,500,000. The prairies and marshes of the Western Gulf Coastal Plain (34) once supported an abundance of ecoregions and the conterminous United States has 84 ecoregions (U.S. Environmental Protection wildlife, including bison and red wolves, and a , reptile, and bird species. Almost Louisiana, the region includes the Mermentau and its larger tributaries, as well as parts of terraces. The historical vegetation dominated by big bluestem, little bluestem, yellow Indiangrass, developed by the USFS (Bailey and others, 1994), the USEPA (Omernik 1987, 1995), and the Agency [USEPA], 2006). Level IV is a further subdivision of level III ecoregions. Explanations of Omernik, J.M., 1995, Ecoregions – a framework for environmental management, in Davis, W.S., and all of the prairie has been converted to cropland, especially rice. Coastal marshes are important Lacassine Bayou and tributary streams. Large portions of forest have been removed. Current land switchgrass, and other herbaceous species has been replaced by crops of rice, soybeans, cotton, Snow geese feed in rice fields in Ecoregion 34a. Eunice Cajun Prairie in Ecoregion 34a. The prairies U.S. Department of Agriculture– Conservation Service (1981). As each of these frameworks is Simon, T.P., editors, Biological assessment and criteria – tools for water resource planning and decision habitat for marine fishes and crustaceans as well as for waterfowl and migratory birds. Photo: Greg cover is a mix of deciduous forest, upland mixed and deciduous forest, along with some sugarcane, sweet potatoes, and wheat, along with crawfish aquaculture. Urban expansion in the area Louisiana’s coastal wetlands provide winter once supported an abundance of native species. the methods used to define the USEPA’s ecoregions are given in Omernik (1995, 2004), Omernik Linscombe, LSU Agricultural Center cropland and pasture. Soils in the Louisiana portion are mostly very poorly and poorly drained Alfisols has been substantial. There is more pasture compared to the large extent of small grains production habitat for 50% of the Mississippi flyway Essentially all of the prairies have been converted to further refined, their differences are becoming less discernible. Each collaborative ecoregion making: Boca Raton, Florida, Lewis Publishers, p. 49-62. waterfowl population. Photo: John Pitre, NRCS cropland, but small areas are being restored. Photo: and others (2000), and Gallant and others (1989). and Entisols with silt loam or very fine sandy loam surface textures. in Ecoregion 34a to the west. Narrow hardwood forests occur along some streams and lowlands. Deanna Parker, Cajun Prairie Preservation Society project, such as this one in Louisiana, is a step toward attaining consensus and consistency in Omernik, J.M., 2004, Perspectives on the and definition of ecological regions: Environmental The approach used to compile the ecoregion map of Louisiana is based on the premise that ecoregion frameworks for the entire nation. Management, v. 34, Supplement 1, p. s27-s38. ecological regions can be identified through the analysis of the spatial patterns and the composition of biotic and abiotic characteristics that affect or reflect differences in ecosystem Literature Cited: Omernik, J.M., Chapman, S.S., Lillie, R.A., and Dumke, R.T., 2000, Ecoregions of Wisconsin: 35. South Central Plains Bailey, R.G., Avers, P.E., King, T., and McNab, W.H., editors, 1994, Ecoregions and subregions of the Transactions of the Wisconsin Academy of Sciences, Arts, and Letters, v. 88, p. 77-103. Ecoregion 35 is composed of rolling plains that are broken by nearly flat fluvial terraces, bottomlands, sandy low hills, and low cuestas. Its terrain is unlike the flatter, less dissected Mississippi Alluvial quality and integrity (Wiken, 1986; Omernik, 1987, 1995). These characteristics include , Plain (73) or the Western Gulf Coastal Plain (34). Uplands are underlain mainly by poorly-consolidated Tertiary coastal plain deposits, and soils are mostly acidic sandy loams, silt loams, sands, and sandy physiography, vegetation, climate, soils, land use, wildlife, and . The relative United States (map): , D.C., U.S. Department of Agriculture–Forest Service, map scale U.S. Department of Agriculture–Soil Conservation Service, 1981, Land resource regions and major land 1:7,500,000. clay loams. Bottomlands and terraces are veneered with Quaternary alluvium, terrace deposits, or loess. The lithologic mosaic is complex and distinct from the strictly Quaternary deposits of Ecoregions 34 importance of each characteristic varies from one ecological region to another regardless of resource areas of the United States: Agriculture Handbook 296, 156 p. + map. and 73. Natural vegetation of uplands was historically dominated by longleaf pine and in the south (35e and 35f), and shortleaf pine/hardwood forests in the north (35a). Southern ecoregion hierarchical level. Bryce, S.A., Omernik, J.M., and Larsen, D.P., 1999, Ecoregions – a geographic framework to guide risk U.S. Environmental Protection Agency, 2006, Level III ecoregions of the continental United States floodplain forest of hardwoods and bald cypress typified bottomlands. Covering parts of Louisiana, , east Texas, and , Ecoregion 35 is mostly in forests or , with less than 20% characterization and ecosystem management: Environmental Practice, v. 1, no. 3, p. 141-155. (revision of Omernik, 1987): Corvallis, Oregon, USEPA–National Health and Environmental Effects in cropland. Commercial pine plantations are extensive. Timber production, livestock grazing, and oil and gas production are major land uses. Cropland dominates the leveed bottomlands of the Red River. Louisiana contains barrier islands and coastal lowlands, large river floodplains, rolling and hilly Research Laboratory, Map M-1, various scales. The rolling Tertiary Uplands have a great diversity of and species. In Louisiana, loblolly pine forests, and hardwood-dominated forests along streams. Some small, scattered prairies coastal plains with evergreen and deciduous forests, and a variety of aquatic habitats. There are 6 Chapman, S.S., Griffith, G.E., Omernik, J.M., Comstock, J.A., Beiser, M.C., and Johnson, D., 2004, 35a Ecoregions of Mississippi (2 sided color poster with map, descriptive text, summary tables, and Tertiary deposits are mostly Eocene clays, silts, and sands, with some Paleocene sediments with many rare are associated with areas of calcareous clay soils. On more mesic sites, some Wiken, E., 1986, Terrestrial ecozones of Canada: , Environment Canada, Ecological Land to the west. Soils are mostly well or moderately well drained Ultisols and Alfisols, typically with American beech or magnolia-beech-loblolly pine forests occur. Some sandstone outcrops of the level III ecoregions and 28 level IV ecoregions, and most of these continue into ecologically photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:1,000,000. Classification Series no. 19, 26 p. similar parts of adjacent states (Chapman and others, 2004; Griffith and others, 2004; Woods and sandy and loamy surface textures. In many areas of Ecoregion 35a, commercial pine plantations Catahoula Formation have distinctive barrens or glades that contain several rare species. Seeps in Fire historically was, and still is, an important Yellow pitcher plants (Sarracenia alata) are a Chapman, S.S., Kleiss, B.A., Omernik, J.M., Foti, T.L., and Murray, E.O., 2004, Ecoregions of the Woods, A.J., Foti, T.L., Chapman, S.S., Omernik, J.M., Wise, J.A., Murray, E.O., Prior, W.L., Pagan, J.B., have replaced the native shortleaf pine-hardwood forest. Prominent native trees include shortleaf sand hills support acid bog species including southern sweetbay, gallberry, wax-myrtles, fetterbush, component of longleaf pine forests of Ecoregion characteristic species of hillside bogs of others, 2004). 35. In the absence of fire, longleaf pine and Ecoregion 35. Photo: LNHP Mississippi Alluvial Plain (color poster with map, descriptive text, summary tables, and photographs): Jr., Comstock, J.A., and Radford, M., 2004, Ecoregions of Arkansas (color poster with map, descriptive pine, loblolly pine, southern red oak, post oak, black oak, white oak, hickories, and sweetgum. insectivorous plants, orchids, and wild azalea. Currently, the ecoregion in Texas and Louisiana has many of its associated plants and animals are The ecoregion map on this poster was compiled at a scale of 1:250,000, and depicts revisions and Reston, Virginia, U.S. Geological Survey, map scale 1:1,150,000. text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey, map scale American beautyberry, sumac, greenbriar, and hawthorn are common understory species. The more pine forest than the oak-pine and pasture land cover more typical to the north in 35a. Large replaced by other species. Photo: Bill Platt, LSU sandier areas often have more bluejack oak, post oak, and stunted pines. The is dissected parts of the region are public National Forest land. subdivisions of earlier level III ecoregions that were originally compiled at a smaller scale (U.S. 1:1,000,000. by numerous small streams. Flow is often intermittent in summer or early fall. It is one of The Flatwoods ecoregion occurs on mostly flat to gently sloping Pleistocene sediments. Louisiana’s drier regions, with 51 to 55 inches annual precipitation in the northwest portion. Many 35f Soils are poorly to moderately well drained Alfisols and Ultisols with mostly silt loam state and globally rare plant and animal species are found in this region. Timber production is the textures. They are generally more poorly drained than many areas of Ecoregion 35e to the north, 94˚ 93˚ 92˚ 91˚ 90˚ 89˚ dominant land use, along with livestock grazing, poultry production, and oil and gas activities. and tend to be less clayey than in 34a to the south. This ecoregion once was dominated by longleaf The Floodplains and Low Terraces ecoregion is nearly level, veneered by Holocene pine flatwoods and savannas, but also supported other mixed pine-hardwood forest types. The Crossett Longleaf pine forests occur on parts of the rolling Southern Tertiary Uplands (35e) in the Kisatchie 35b 65 National Forest. About 13.8 million acres of softwood and hardwood forests cover Louisiana, alluvium, and contains natural levees, swales, oxbow lakes, and meander scars. Many parts longleaf pine was characterized by longleaf pine over a great diversity of herbaceous 35 Lake nearly half of the state. 62% of these forests are owned by private, non-industrial landowners, 29% of Ecoregion 35b are frequently flooded, and forested wetlands are characteristic. There is a distinct species, with the structure and composition varying from the more open forests of the wet savannas Jack Lee by forest products industries, and 9% are owned by the public. Louisiana’s mild climate and vegetation change from adjacent upland ecoregions into bottomland hardwood forest, with to the more closed forests of the dry flatwoods. Flatwood are characterized by pimple ARKANSAS 73 33˚ abundant rainfall give it one of the fastest tree-growing cycles in North America. Photo: LDEQ 33˚ O 34 Western Gulf Coastal Plain similarities to the Mississippi Alluvial Plain (73). Water oak, willow oak, sweetgum, blackgum, mounds, small hillocks that are abundant across the flats. On steep slopes, along streams and other u 73i w American elm, red maple, and swamp chestnut oak are typical. Bald cypress and water tupelo occur areas where fire was less frequent, forests contained loblolly pine, sweetgum, white oak, southern n a 35b e o B c 35c m h 73i c 34a Northern Humid Gulf Coastal Prairies in semi-permanently flooded areas. These bottomlands provide important habitat for a variety of red oak, willow oak, blackgum, and hollies. Although greatly reduced from its original extent, o lo 35a i o a d t h The Louisiana pine snake is considered one of the The red-cockaded woodpecker, an endangered a t c ar 73j fish and wildlife. Soils include Alfisols, Inceptisols, and Entisols and are generally somewhat poorly longleaf pine continues to characterize a significant portion of the area. Beech-magnolia was not a B M r 34c Floodplains and Low Terraces rarest snakes in North America. Its historical species, lives in old-growth pine forests, mainly u e drained to very poorly drained, clayey and loamy. extensive, occurring in narrow areas along some streams and mesic slopes. This region is warmer, 35a u v Yazoo City range included longleaf pine woodlands on deep of longleaf pine, in the southeastern United o i

t 35b Bayou D’Arbonne y 34g Texas-Louisiana Coastal Marshes sandy uplands of Ecoregion 35 in west-central States. In 2000, there were about 12,500 birds

u 73h R r Pleistocene Fluvial Terraces wetter, flatter, less dissected, and lower in elevation than ecoregions 35a and 35e. Streams are low a The are nearly level, poorly-drained, underlain by Pleistocene a e

B o v

R Philadelphia Louisiana and eastern Texas. They depend on throughout their range. Photo: E.B. Smith, USFS e i

35c Lake 35c y B a 35c gradient and sluggish. In the eastern part of the region near the boundary with 35g, more loess

i R 35c v 34j Lafayette Loess Plains unconsolidated terrace deposits, and often covered by pine-hardwood flatwoods. The broad

h a Bastrop Lake Providence pocket gophers for food and their burrows for y

e o i

o c B occurs, the landscape becomes more dissected, and it supports a mixed hardwood-pine forest.

r zo Photo: Memphis Zoo r p shelter. u flats and gently sloping terraces are lower and less dissected than 35a, but higher than the a

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Lake p Y The Red River Bottomlands contain the floodplain and low terraces of the Red River D floodplains of 35b and 35g. Soils are typically well to poorly drained Alfisols and Ultisols with 35b i 73 35 South Central Plains Claiborne 73i 35c r 35g 35g s e loamy and sandy surfaces. Loblolly pine and a variety of lowland oaks are common and are adapted within Ecoregion 35. The region of broad bottomlands includes the meandering Red River Caddo 73i i s v 35a Tertiary Uplands ss i to the prevailing hydro-xeric regime. A vertical sequence of terraces occurs. The lowest terrace is channel, oxbow lakes, meander scars, ridges, and backswamps. The Holocene alluvium associated i

Lake u Minden R Canton

o M k nearly flat, clayey, and has extensive hardwood wetlands. Higher terraces become progressively with Red River deposition developed well to somewhat poorly drained Vertisols and Entisols with

y 35a a c 35b Floodplains and Low Terraces a l 35b 73h B older and more dissected with less extensive wetlands. They are dominated by pine flatwoods, or a clayey and loamy, reddish-brown, neutral to calcareous surfaces. The lithology contrasts with the TEXAS B 73i 73d g 35c Pleistocene Fluvial Terraces 35c Shreveport Ruston r i mixed forest of pine and oak. In some parts of Ecoregion 35c to the east, the mid-level terrace is Pleistocene terrace deposits of Ecoregion 35c and the Tertiary sediments of Ecoregion 35a. Some 35a ive B 35e Southern Tertiary Uplands veneered with windblown silt deposits (loess). The southernmost piece of 35c, around Marksville, is major native trees of the bottomland hardwood forests on the Red River include water oak, R R Cross 35c Monroe e 73j 35f Flatwoods a Pleistocene terrace of the Prairie Allogroup, with some similarities in soils and historical natural sweetgum, willow oak, overcup oak, Nuttall oak, honey locust, water locust, river birch, red maple, Lake d vegetation to that of the Lafayette Loess Plains (34j). The prairie has been converted to agriculture. green ash, and American elm. There are some plant distribution differences between the floodplains f u Tallulah 35g Red River Bottomlands of Ecoregion 35g and 35b. Currently in Ecoregion 35g, most natural woodland has been cleared for e 73j The Southern Tertiary Uplands ecoregion covers the majority of Louisiana’s longleaf 35c Lake 35c o 35e cropland and improved pasture, although some woodland still occurs in very poorly drained and B 73d pine range west of the Mississippi River. The region of Tertiary geology is more hilly and 35 Bistineau 65 Southeastern Plains frequently flooded areas. Cotton, soybeans, corn, wheat, and rice are principal crops in 35g of R 73i 73i 73d Jackson dissected than the Flatwoods (35f), and soils are generally better drained over the more permeable Longleaf pine in grass stage in Ecoregion 35e. The Red River Bottomlands ecoregion (35g) has i Vicksburg Louisiana, with some sugarcane in the southern portion. The Red River historically carried high silt Longleaf pine is unique among pines in its ability been greatly modified with flood control and

ve 35c B 65f Southern Pine Plains and Hills sediments. Soils are Ultisols and Alfisols with silt loam to loamy sand textures. The Pliocene-age to r O 73d Photo: Dot

l loads and was almost continuously turbid compared to other rivers of Ecoregion 35. With the to survive fire at such a young age. drainage projects and removal of bottomland S

a The low gradient, turbid Red River winds through Ecoregion 35g. Cropland is much more Eocene-age geology contains a variety of siltstones, sandstones, and calcareous and acidic clays. u Paul, NRCS hardwood forest. The region now contains a C c Caney Creek a a 65p Southeastern Floodplains and Low Terraces extensive than elsewhere in the South Central Plains (35). Continual efforts are made to control construction of the lock and dam system throughout its extent in Louisiana, silt load has lessened. k l s c Historical vegetation was dominated by longleaf pine-bluestem woodlands, but a variety of forest cropland and pasture with only minor areas of i to h surface water and drain wet soils. L n Reservoir r i Natural vegetation and other biota, hydrology, and land uses are similar to parts of Ecoregion 73. Photo: USACE 35a e t types were present, including shortleaf pine-hardwood forests, calcareous forests, mixed hardwood- forested wetland. a C a Winnsboro k r R 35c e e 73 Mississippi Alluvial Plain B e iv B D k a e a r y 73a Northern Holocene Meander Belts u y 35a o o g 35b 73d u 73i u d Mansfield e 35e 73d Northern Backswamps 65. Southeastern Plains m 73h 32˚ Although mostly tree-covered, these irregular plains have a mosaic of cropland, pasture, woodland, and forest land cover. Natural vegetation in the Louisiana portion was predominantly upland longleaf on 73h Arkansas/Ouachita River Holocene Meander Belts 32˚ a pine woodlands, with smaller areas of oak-pine and mixed hardwood forest. Uplands are underlain by poorly consolidated Pleistocene and Pliocene deposits, and soils are mostly acidic sandy loams, silt 73i Arkansas/Ouachita River Backswamps loams, and sandy clay loams. Although Pleistocene-age loess deposits do influence soil characteristics in the Louisiana part of the ecoregion, mainly in the western half, the region received substantially R 73a i ve 73d 73j Macon Ridge less loess deposition than Ecoregion 74 to the west. Elevations and relief are greater than in the Southern Coastal Plain (75) and Mississippi Alluvial Plain (73). Streams are low- to moderate-gradient with Winnfield r mostly sandy substrates. Commercial pine plantations are extensive. Timber production and dairy and beef cattle farming are major land uses, with urban and residential development increasing.

r

e 73d 73k Southern Holocene Meander Belts

35c v

i The Southern Pine Plains and Hills ecoregion extends across southern Mississippi and region are composed mostly of Pliocene or early Pleistocene-age deposits that are generally sandy, 35c 35e 74 R 73l Southern Pleistocene Valley Trains 65f Alabama and a portion of eastern Louisiana, covering what was once part of the longleaf gravelly, and porous. Soils are mostly well to moderately well drained Ultisols and Alfisols with 73d 73 Natchitoches as 73m Southern Backswamps pine belt. This area in Louisiana was historically rolling longleaf pine woodlands, broken by creek fine sandy loam or silt loam surface texture. Some cattle, horse, and hay ranches occur, as well as 35c 73m T e n s 35c 73n Inland Swamps Laurel and river bottoms with mixed loblolly pine-hardwood forests. Today, almost all of the longleaf pine some poultry and dairy production.

forests are gone, replaced mostly by mixed forests of recent incidental origin and slash and loblolly Southeastern Floodplains and Low Terraces comprise a riverine ecoregion of large rivers L

i 35c 73k 73o Deltaic Coastal Marshes and Barrier Islands pine plantations. The longleaf pine forest provided habitat for now rare or endangered species such 65p

t and backwaters with , swamps, and oxbow lakes. Substrates of the low-relief region Dairy is a major industry in Ecoregion 65f, The threatened gopher tortoise finds habitat in t 73l B l as the red-cockaded woodpecker and gopher tortoise. In Louisiana, subsurface materials of the

e l are a mix of sands, silts, and clays, resulting in well to poorly drained Entisols and Inceptisols with although it has declined in recent years. The the longleaf pine forests of ecoregions 65f and Lake R Catahoula a 73m 74 Mississippi Valley Loess Plains silt loam or fine sandy loam surfaces. River swamp forests of bald cypress and water tupelo and state’s dairy industry is concentrated in 75a. Many different animal species use the iv c Washington, Tangipahoa, St. Helena, Livingston, gopher tortoise burrows during various stages of e Lake k The Bogue Chitto begins near Brookhaven, Mississippi, meanders southward and flows into the West Pearl River Canal Iatt r R oak-dominated bottomland hardwood forests provide important wildlife corridors and habitat. The Photo: LNHP i 73m and East Feliciana parishes, with about 400 dairy their life cycle.

R v Natchez 74a Bluff Hills south of Bogalusa. It is the largest western tributary to the Pearl River system. The Bogue Chitto is valuable for its

e e low terraces are mostly forested, although some small patches of pasture or cropland are found on farms. Photo: Paul Wallace, NRCS 35b r , sports fishing, and aesthetic beauty. Increased from gravel and sand mining, dairy farming, d 74c Southern Rolling Plains silviculture, and road construction, and high levels of fecal coliform and mercury impair its water quality. Fish species terrace areas that are better drained. In Louisiana, the region includes only the larger, wider R Photo: USFWS i diversity and the abundance of benthic minnows and darters has declined over the past 30 years. floodplains of Ecoregion 65, the Pearl and Bogue Chitto rivers. v 73m 74d Baton Rouge Terrace er 73l Toledo Bend 75 Southern Coastal Plain Hattiesburg Reservoir 35g Alexandria 73m 75a Gulf Coast Flatwoods 73. Mississippi Alluvial Plain 73k McComb R This riverine ecoregion extends from southern , at the confluence of the Ohio River with the Mississippi River, south to the Gulf of Mexico. The Mississippi River watershed drains all or parts of 35c e 75i Floodplains and Low Terraces Vernon d thirty-one states, two Canadian provinces, and approximately 1,243,000 square miles before the river finally reaches the Gulf. The Mississippi Alluvial Plain is mostly a broad, flat alluvial plain with river R iv Lake er 75k Gulf Barrier Islands and Coastal Marshes terraces, swales, and levees providing the main elements of relief. Soils are typically finer-textured and more poorly drained than the upland soils of adjacent Ecoregions 35 and 74, although there are some 35e Leesville areas of coarser, better-drained soils. Winters are mild and summers are hot, with temperatures and precipitation increasing from north to south. Bottomland deciduous forest covered the region before much 73m of it was cleared for cultivation. The ecoregion contained one of the largest continuous wetland systems in North America. The widespread loss of forest and wetland habitat, however, has impacted wildlife 73m Marksville and reduced bird populations, although it is still a major bird migration corridor. Today, constructed levees restrict the river from overflowing, opening large areas for extensive agricultural use. Almost all 35c of the region is in cropland, and it receives large inputs of pesticides. In Louisiana, cotton, corn, soybeans, pasture, and rice are major crops in the northern and central parts and sugarcane, soybeans, and pasture are dominant in the southern part. Between the levees that parallel the Mississippi River is a corridor known as the “batture lands.” The batture lands are hydrologically connected to the Mississippi Cocodrie MISSISSIPPI 31˚ 31˚ o Lake 65p River, are flood-prone, and contain remnant habitat for “big river” species (e.g., pallid sturgeon) as well as river-front plant communities. They are too narrow to map as a separate level IV ecoregion. c

o T Sugarcane is the major crop in the southern Cotton is one of the major crops in the northern c 73m Northern Holocene Meander Belts Jasper a a The ecoregion is a flat to nearly flat floodplain 20 to 30 feet above the adjacent ecoregions 73a and 73d on the east side. On the western side, reaches of Ecoregion 73k. Photo: David Nance, part of Ecoregion 73. Although eradication

r n 74a n 73a

e A g containing the meander belts of the present and past courses of the Mississippi River. Point elevations of Macon Ridge are nearly the same as in the lithologically and physiographically USDA programs have reduced their numbers, pesticide v i

i

Bayou p bars, natural levees, swales, and abandoned channels marked by meander scars and oxbow lakes are distinct Arkansas/Ouachita River Holocene Meander Belts (73h). Native forest types range from applications are still needed to protect the crop a R Historically, A 74c Photo: NRCS

35 DeRidder h from the boll weevil. t the Louisiana

c common. Its abandoned channel network is more extensive than in the Southern Holocene Meander those of better drained bottomlands dominated by willow oak, water oak, and swamp chestnut oak o h Oakdale 35f a 65f Bogalusa black bear was a 65p B Belts (73k). The natural levees were the most conspicuous of the meander belt, and their to upland hardwood forests dominated by white oak, southern red oak, and on drier sites, post oak. f common a Saint Francisville o 65 73k l 73m g distribution influenced human settlements, transportation routes, and agricultural and industrial Prairies and loblolly pine-dominated areas may also have occurred. Today, Ecoregion 73j is a throughout the a u 73m y Amite e activities in northeast Louisiana. Ecoregion 73a is underlain by Holocene alluvium; it lacks the mosaic of cropland and pasture, with some woodland and forest. Cotton, corn, soybeans, and wheat Mississippi a Ch Alluvial Plain

35b Ville R it Pleistocene glacial outwash deposits of Ecoregion 73j. Soils are mostly Vertisols, Inceptisols, and are the major crops, and aquaculture is important in some areas.

i t C o (73). Now, the

v New Roads

Platte R e Alfisols with silt loam, silty clay loam, and clay textures. On natural levees, soils are more coarse-

o The Southern Holocene Meander Belts ecoregion stretches from just north of Natchez, endangered

35b r i 73k m v textured, better drained, and higher than those on levee back slopes and point bars. They grade to 73k Mississippi south to , Louisiana. Similar to the Northern Holocene Meander bear’s TEXAS 73m i e The native vegetation of the Mississippi Alluvial Plain ecoregion has been mostly converted to t r preferred s e cropland. Only scattered small remnants remain of the original bottomland hardwood forest. Photo: poorly-drained clays in abandoned channels and swales. Natural vegetation varies with site e Belts (73a), point bars, oxbows, natural levees, and abandoned channels occur. This region, woodland n Jim Wark 35f A characteristics, mainly soil texture and hydroperiod. Coarser soils have fewer oaks and more an R however, has a longer growing season, warmer annual temperatures, some hyperthermic soils, and habitat is C Opelousas m es i P sugarberry, elm, ash, pecan, cottonwood, and sycamore than Ecoregion 73d. Widespread draining limited to small v i Hammond e more precipitation than its northern counterparts of 73a and 73h. Soils are somewhat poorly and d e t 74d a

r e e Eunice r r u l of wetlands and removal of bottomland forests occurred with cropland expansion. Bottomland areas in the

n e o 73m Baton Covington poorly drained Inceptisols, Entisols, and Vertisols. The ecoregion contains minor species such as i v e y

i R backswamps u a The Mississippi River system in the Southern

b Port Allen 75a hardwood forest restoration programs have reversed this trend since 1985. Cotton, corn, soybeans,

R i

q B Rouge Biloxi live oak, laurel oak, and Spanish moss that are generally not found in the more northerly regions. a i and 75i v Holocene Meander Belts (73k) has been S p B R e and pasture are the main crops, and some catfish production and other aquaculture occur. The bottomland forests have been cleared and the region has been extensively modified for bottomlands. z modified and engineered for flood control and a r e i Gulfport Photo: LDWF u y v The Northern Backswamps ecoregion is made up of low-lying overflow areas on agriculture, flood control, and navigation. The levee system is extensive throughout the region. navigation. Photo: USACE N e

e o r ie l u IPPI SO 73d s u ISS UN a 34c MISS D floodplains, and includes poorly-drained flats and swales. Water often collects in its Soybeans, sugarcane, cotton, corn, and pasture are the major crops, with crawfish aquaculture common. Houston Rive c u r 75 r al o B Bay Saint Louis swamps, lakes, and low gradient streams. These were areas generally not affected by lateral river- C y e T Slidell The Southern Pleistocene Valley Trains ecoregion is a continuation of the northern valley a n Plaquemine i e Lake 34a B m c channel migrations. Soils are mostly gray to black Vertisols, developed from clayey alluvium of 73l 35b e h train regions in Mississippi, Arkansas, and . It is composed of scattered small u e Maurepas overbank or slack-water deposits. These soils commonly have a high shrink-swell potential and are Jennings aq Lafayette remnants of early-Wisconsin glacial outwash deposits, similar to those of Macon Ridge (73j). This Lake Charles Bayou Pl 75k locally rich in organic material. Water levels are seasonally variable. Native vegetation in wettest 34c . 73k Lake ecoregion, however, has warmer annual temperatures, a longer growing season, and higher annual 34a R areas is generally dominated by bald cypress–water tupelo forest; slightly higher and better drained u Crowley 34j Pontchartrain rainfall. Soils are somewhat poorly and poorly drained Alfisols, Inceptisols, and Vertisols with a t sites have overcup oak–water hickory forest; and highest, best-drained areas support willow oak or n 73m loamy and clayey surfaces. Some species occur here that are not present in the Macon Ridge (73j) e 73n Nuttall oak forest. Today, bottomland forest, cropland, farmed wetlands, and pasture occur. rm or Western Lowlands Pleistocene Valley Trains (73g) ecoregions to the north in Arkansas. Overcup 34 Me 73o Backswamps are important areas for capturing excess nutrients from local waters and for storing oak, Nuttall oak, honey locust, elm, water oak, sweetgum, blackgum, and hickory are the most Beaumont e Lake 30˚ water during heavy rain events. common tree species. This region is generally higher than the adjacent Southern Backswamps 30˚ 73n Borgne New New Orleans S The Arkansas/Ouachita River Holocene Meander Belts ecoregion is a flat to nearly flat (73m) ecoregion and soils are more sandy and better drained than the heavy clay soils of the Yellow-throated vireo and other migratory Oaks, hickory, and ash, with palmetto

73k D Iberia 73h floodplain containing the meander belts of the present and past courses of the lower backswamps. Cropland and pasture is common with corn, soybeans, and cotton as major crops. songbirds depend on the bottomland hardwood understory, are common plants in Ecoregion 73. CHANDELEUR N Port Arthur Abbeville 73n A Arkansas and Ouachita rivers. Point bars, natural levees, swales, and abandoned channels marked forest for resting and shelter. Photo: LNHP Conversion to cropland has caused widespread 34g SOUND L The Southern Backswamps ecoregion is generally warmer, has a longer frost free period, loss of forest and wetlands. Photo: LNHP B 73n S 73m Crawfish has Sabine Grand I by meander scars and oxbow lakes are common and characteristic. Soils on natural levees are more and has more precipitation than the Northern Backswamps (73d). Similar to 73d, soils are Lake a 73n always been Calcasieu Lak 34g Lake 73o y Lac des coarse-textured, well-drained, and higher than those on levee back slopes and point bars. Soils grade 73n ou Allemands mostly poorly drained, clayey Vertisols, rich in organic matter. Wetlands are common and flooding recognized as a Cameron 73o R Bald cypress and tupelo are native in the wettest areas of the Northern and Southern Backswamps to poorly-drained clays in abandoned channels and swales. Overall, soils have less organic matter occurs frequently. Bottomland hardwood forests are more prevalent in this region than in the delicacy by the Thibodaux U 73o (Ecoregions 73d and 73m). Photo: LNHP Cajun people. E than in the Northern Holocene Meander Belts (73a). Bayou Bartholomew inhabits the longest adjacent Southern Holocene Meander Belts (73k), where cropland is common. Channelization and Lake L The bayous, White Lake Morgan City E section of abandoned channels. It flows against the edge of the South Central Plains (35), receives flood control systems have modified this region and impacted many of the wetland habitats. VERMILION Lafo Salvador D sloughs, and ur N ch drainage from it, and has sufficient habitat diversity to be one of the most species-rich streams in swamps support WEST COTE e A The Inland Swamps ecoregion marks a transition, ranging from the fresh waters of the BAY 73o H North America. Bayou Bartholomew supports over half of all known mussel species found in an abundant 73k C 73n Southern Backswamps (73m) at the northern extent of the intratidal basins to the fresh, BLANCHE BAY 73n Louisiana. Within an abandoned course, bald cypress and/or water tupelo typically grow in the population of 73n brackish, and saline waters of the deltaic marshes of Ecoregion 73o. It includes a large portion of this native modern stream channel adjacent to a strip of wet bottomland hardwood forest dominated by 73o Houma BRETON SOUND the Atchafalaya Basin. Soils are mostly poorly or very poorly drained, clayey Entisols and invertebrate. overcup oak and water hickory. The remainder of the native forest has largely been cleared and Vertisols. Swamp forest communities are dominated by bald cypress and water tupelo, which are Crawfish MARSH ISLAND production is drained for cropland and pastureland. Corn, cotton, and soybeans are the main crops. generally intolerant of brackish water except for short periods. In areas where freshwater flooding is L F O EAST COTE ATCHAFALAYA BAY M also an G U F M iss The flats, swales, and natural levees of the Arkansas/Ouachita River Backswamps important BLANCHE BAY 73o i more prolonged, the vegetative community is dominated by grasses, sedges, and rushes. This region E s Alligators are found in aquatic habitats throughout X 73n s 73i ecoregion include the slackwater areas along the Arkansas and Ouachita rivers, where water aquaculture I C contains one of the largest bottomland hardwood forest swamps in North America. Deposits include most of Louisiana. Harvesting of wild and farm- O i often collects into swamps, oxbow lakes, ponds, and sloughs. In contrast to the Northern venture. Photo: BARATARIA pp organic clays and peats up to 20 feet thick, and inter-bedded fresh- and brackish-water carbonaceous Paul Wallace, NRCS raised alligators is economically important in the i Rive state. Photo: Jeffery Giering, LDAF BAY r Backswamps (73d), this region is widely veneered with natural levee deposits. Soils derived from clays. The levees in place on either side of the Mississippi River have diverted much of the river these deposits are Alfisols, Vertisols, and Inceptisols that are generally more loamy and better flow from its natural tendency to flow into the Atchafalaya Basin. Large concrete structures prevent POINT drained than the clayey soils of the Northern Backswamps (73d). As a result, willow oak and water diversion into the Atchafalaya River, and flow from the Red River is also controlled. While this AU FER oak are native instead of other species adapted to wetter overflow conditions. Drainage canals and helps control flooding, it has also modified the region and contributed to the loss of wetland habitat. SCALE 1:1 000 000 ISLAND 73o 73o Grand Isle ditches are common. This artificial drainage and the sandy veneer of natural levee deposits help Brackish and saline marshes dominate the Deltaic Coastal Marshes and Barrier Islands 15 10 5 0 15 30 mi Level III ecoregion explain why Ecoregion 73i is more easily and widely farmed than the Northern Backswamps (73d). 73o ecoregion. The region supports vegetation tolerant of brackish or saline water including TIMBALIER Soybeans, corn, cotton, and rice are important crops but forests and forested wetlands also occur. Level IV ecoregion CAILLOU BAY TERREBONNE saltmarsh cordgrass, marshhay cordgrass, black needlerush, and coastal saltgrass. Black BAY Parish boundary BAY The prominent Macon Ridge is underlain almost entirely by Pleistocene glacial outwash occurs in a few areas, and some live oak is found on Grand Isle and along old natural levees. 30 20 10 0 30 60 km 73j that was transported to Arkansas and Louisiana by the Mississippi River and deposited by State boundary Extensive organic deposits lie mainly below sea level in permanently flooded settings resulting in braided streams. It was subsequently veneered with loess, thicker on the eastern side. Its loessial the development of mucky surfaced Histosols. Sediments of silts, clays, and peats contain large Albers Equal Area Projection ES Louisiana’s coastal wetlands are an ecological, cultural, and economic treasure. Within Louisiana’s Alfisols, with silt or silt loam textures, contrast with the alluvial soils of the Northern Holocene ISLES DERNIER 29˚ amounts of methane, oil, and hydrogen sulfide gas. Inorganic sediments found within the ecoregion 29˚ Standard Parallels 30˚ N and 32˚ N coastal wetlands, there exists more than half of the tidal marshes found in the lower 48 states, oil Meander Belts (73a) and Arkansas/Ouachita River Holocene Meander Belts (73h). Ecoregion 73j is are soft and have high water contents. They will shrink dramatically upon draining. The wetlands Louisiana contributes about 28% of the total In addition to fish and wildlife value, wetlands and gas pipelines that deliver more than a quarter of the nation’s energy supplies, one of the world’s higher in elevation, better drained, and supports drier plant communities than adjacent ecoregions volume of U.S. fisheries, with a value of about reduce storm and erosion damage, detain flood- largest port systems, and fisheries that supply more than a quarter of the seafood consumed in the and marshes act as a buffer to help moderate flooding and tidal inundation during storm events. $1 billion annually. Photo: NRCS waters, recharge groundwater aquifers, and lower 48 states. Photo: Anne Marino, USACE 73a, 73d, 73h, and 73i. The eastern edge of Macon Ridge is higher than its western side, averaging Lack of sediment input, delta erosion, land subsidence, and rising sea levels threaten the region. maintain water quality. Photo: Larry Handley, USGS

94˚ 93˚ 92˚ 91˚ 90˚ INTERIOR–GEOLOGICAL SURVEY, RESTON, VIRGINIA–2006 89˚ 74. Mississippi Valley Loess Plains This ecoregion stretches from the Ohio River in western Kentucky to Louisiana. It consists primarily of irregular plains, some gently rolling hills, and bluffs near the Mississippi River. The presence of thick deposits of loess is one of the distinguishing characteristics. The Bluff Hills in the western portion contain soils that are very deep, steep, silty, and erosive. Flatter topography is found to the east, and streams tend to have less gradient and more silty substrates than in the Southeastern Plains ecoregion (65). To the east, upland forests dominated by oak, hickory, and both loblolly and shortleaf pine, and to the west, southern mesophytic forests characterized by beech, southern magnolia, and American holly, were the dominant natural vegetation. Agriculture is now the typical land cover in the Kentucky and Tennessee portion of the region, while in Mississippi and Louisiana there is a mosaic of forest, pine plantations, pasture, and cropland. Level III Ecoregions of the Conterminous United States The Bluff Hills ecoregion in Louisiana, locally called the Tunica Hills, has a base of sand, warmer average annual air temperatures, greater annual rainfall, and a transition to slightly warmer 1 Coast Range 29 57 Huron/Erie Lake Plains PRINCIPAL AUTHORS: Jerry J. Daigle (NRCS), Glenn E. Griffith (Dynamac Corporation), 74a clay, silt, and gravel capped by thick loess. This region has deeper loess, more relief, is soils. Although less dissected than the Bluff Hills (74a), the region has more irregular and dissected 1 2 77 2 Puget Lowland 30 Edwards Plateau 58 Northeastern Highlands James M. Omernik (USGS), Patricia L. Faulkner (LNHP-LDWF), Richard P. McCulloh (LGS), more dissected, and is generally more forested than neighboring 74c. The dissected loess landscape topography than adjacent 74b to the north in Mississippi. Soils reflect this diversity with Ultisols, 3 Willamette Valley 31 Southern Texas Plains 59 Northeastern Coastal Zone 15 41 42 Lawrence R. Handley (USGS-National Wetlands Research Center [NWRC]), Latimore M. has a mosaic of microenvironments, including dry slopes and ridges, moist slopes, ravines, Alfisols, and Entisols that are thinner than in 74a and 74b, with slightly coarser surface textures. 10 4 32 60 Northern Appalachian Plateau and Uplands bottomland areas and small cypress swamps. Soils are mostly well drained loamy Alfisols. Species The historic forests contained shortleaf pine, loblolly pine, and upland oaks and hickories. Pine is West Fork Thompson Creek in Ecoregion 74c Wooded areas of the Bluff Hills (74a) and the 48 49 Smith (The Nature Conservancy), and Shannen S. Chapman (Dynamac Corporation). 82 5 Sierra 33 East Central Texas Plains 61 Erie Drift Plain northeast of St. Francisville. Low stream numerous small stream valleys provide suitable 1 3 with more northern affinities occur far to the south in this region. This combination of northern and naturally more prevalent here than in 74a and 74b. Land cover now is mostly mixed pine-hardwood gradients and slow flows between heavy rains habitat for wild . Photo: Lynn Betts, NRCS 4 11 42 6 Southern and Central 34 Western Gulf Coastal Plain 62 North Central Appalachians southern and creates a diverse assemblage of species. A forest of southern magnolia and forest, pine plantations, pasture, and cropland. Some oil and gas production and cattle ranching 16 result in high sediment loads being deposited 17 43 50 58 63 Middle Atlantic Coastal Plain COLLABORATORS AND CONTRIBUTORS: Bradley Spicer (LDAF), Sue Smith (LDEQ), Photo: LDEQ 58 and Oak Woodlands 35 South Central Plains beech, with a mix of other mesophytes, oaks, and hickories, is the general natural vegetation type. occur here. The eastern boundary of this region is broad, with a gradual transition to Ecoregion 65. within the stream channel. 51 50 64 Northern Paul Heinrich (LGS), John Novosad (USFS), Bill Vermillion (USFWS), Charles Demas 9 17 46 7 Central California Valley 36 Sweetgum, Carolina basswood, Florida sugar maple, hophornbeam, tulip poplar, and unique The Baton Rouge Terrace ecoregion occurs on the Pleistocene Prairie Terraces and is 78 83 59 65 Southeastern Plains (USGS), Dennis Demcheck (USGS), C. Edward Proffitt (USGS-NWRC), Philip Crocker 80 12 17 57 60 58 8 Southern California Mountains 37 Arkansas Valley mesophytic herbs are also found here. Ecoregion 74a in southern Mississippi and Louisiana has 74d lower in elevation and has flatter topography than Ecoregion 74c to the north. Similar to 52 53 66 Blue Ridge 56 62 9 Eastern Cascades Slopes and Foothills 38 (USEPA), Barbara Kleiss (USACE, ERDC-Waterways Experiment Station), Jan Boydston more southern magnolia, water oak, and Spanish moss than in the north. The cool ravines contain other parts of Ecoregion 74, loess is thicker to the west. The soils are mostly Alfisols with brown or 62 67 Ridge and Valley 18 44 47 10 Columbia Plateau 39 Ozark Highlands some higher gradient streams and areas of gravel substrate, creating distinct aquatic habitats. Severe grayish-brown, silt loam surfaces that developed in the loess parent materials. High sodium soils are Sprawling over more than 120 square 57 61 67 (LDEQ), Alan Woods (Oregon State University), Pat O'Neil (USGS), Brian Moran (Indus miles, growth, traffic congestion, and 5 19 64 84 11 Blue Mountains 40 Central Irregular Plains 68 Southwestern Appalachians erosion has occurred in many parts of 74a, particularly when the soils lack adequate vegetative common. The natural vegetation was influenced by the unusual soil conditions and by different 13 54 69 Central Appalachians Corporation), John Hutchinson (Science Applications International Corporation), Jack urban redevelopment have become 55 70 12 Snake River Plain 41 Canadian Rockies cover. Louisiana black bear, Webster’s salamander, and eastern chipmunk occur in this region. forest types occurring in adjacent regions, with some upland hardwoods to the northwest, hardwood important issues in the greater Baton 1 21 40 63 Wittmann (USGS), and Tom Loveland (USGS). 7 20 25 13 Central Basin and Range 42 Northwestern Glaciated Plains 70 Western Allegheny Plateau The highly dissected area of Ecoregion 74 is known as the Tunica Hills. Erosion has carved loess The Southern Rolling Plains occur on younger, Miocene- and Pliocene-age geologic flatwoods and spruce pine-hardwood mixed forests across extensive broad flats, and many areas of Rouge area. The city’s population 71 Interior Plateau topography into microenvironments including dry slopes and ridges, moist slopes, ravines, and increased substantially after Hurricane 6 27 14 Mojave Basin and Range 43 Northwestern 74c 72 69 REVIEWERS: Martin Floyd (NRCS), Anthony Lewis (Louisiana State University), and Chris bottomlands. Beech-magnolia forest dominates the area. Photo: LNHP formations (almost all Pliocene in Lousiana) compared to the Loess Plains (74b) to the north bottomland hardwoods. Large areas of the mixed pine-hardwood forest have now been cleared for Katrina struck New Orleans in 2005. 28 40 71 15 Northern Rockies 44 Nebraska Sand Hills 72 Interior River Valleys and Hills in Mississippi and Tennessee, and it has a warmer climate. The climatic shift from 74b includes pasture, cropland, and urban uses. Urban uses cover about fifty percent of the region. 39 16 Batholith 45 Piedmont 73 Mississippi Alluvial Plain Reid (LNHP-LDWF). 8 14 22 68 65 17 Middle Rockies 46 Northern Glaciated Plains 74 Mississippi Valley Loess Plains 66 6 26 38 45 18 Basin 47 75 Southern Coastal Plain CITING THIS POSTER: Daigle, J.J., Griffith, G.E., Omernik, J.M., Faulkner, P.L., McCulloh, 37 67 76 Southern Florida Coastal Plain 81 23 36 73 63 19 Wasatch and Uinta Mountains 48 Lake Agassiz Plain R.P., Handley, L.R., Smith, L.M., and Chapman, S.S., 2006, Ecoregions of Louisiana (color 75. Southern Coastal Plain 20 Plateaus 49 Northern Minnesota Wetlands 77 North Cascades 25 poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. The Southern Coastal Plain extends from South Carolina and Georgia through much of central Florida, and along the Gulf coast lowlands of the Florida Panhandle, Alabama, Mississippi, and eastern 79 23 78 Klamath Mountains 27 29 21 Southern Rockies 50 Northern Lakes and Forests Geological Survey (map scale 1:1,000,000). Louisiana. Consisting mostly of flat plains, it also includes barrier islands, coastal , marshes, and swampy lowlands along the Gulf and Atlantic coasts. In Florida, an area of discontinuous highlands 74 65 22 Arizona/ Plateau 51 North Central Hardwood Forests 79 Madrean Archipelago 32 35 contains numerous lakes. This ecoregion is lower in elevation with less relief and wetter soils than the Southeastern Plains (65). Once covered mainly by longleaf pine flatwoods and savannas, this 24 33 23 Arizona/New Mexico Mountains 52 Driftless Area 80 Northern Basin and Range ecoregion also had a variety of other forest communities that supported slash pine, pine, pond cypress, beech, sweetgum, southern magnolia, white oak, and laurel oak. Land cover in the region is now 30 73 24 Chihuahuan Deserts 53 Southeastern Wisconsin Till Plains 81 Sonoran Basin and Range mostly slash and loblolly pine, often mixed with various hardwoods, bottomland hardwood forest in some low-lying areas, citrus groves in Florida, pasture for beef cattle, and urban land. This project was partially supported by funds from the USEPA Region 6, Biocriteria Program and 75 25 High Plains 54 Central Corn Belt Plains 82 Laurentian Plains and Hills 34 83 Eastern and Hudson Lowlands USEPA–Office of Science and Technology through a contract with Dynamac Corporation. The Gulf Coast Flatwoods is a narrow region of nearly level terraces and alluvial and sluggish rivers and backwaters with ponds, swamps, and oxbow lakes. Soils are mostly loamy 31 26 55 Eastern Corn Belt Plains 75a 27 Central Great Plains 56 Southern Michigan/Northern 84 Atlantic Coastal Pine Barrens deltaic deposits composed of Quaternary-age sands and clays. Soils are a mix of poorly to Entisols. River swamp forests of bald cypress and water tupelo and oak-dominated bottomland Electronic versions of ecoregion maps and posters as well as other ecoregion resources are available at 76 28 Indiana Drift Plains moderately well drained Entisols, Alfisols, and Ultisols with silty and fine sandy loam surfaces. hardwood forests provide important wildlife habitat. http://www.epa.gov/wed/pages/ecoregions.htm. Historically, longleaf pine dominated the broad flats and low ridges, forming more densely-stocked The Gulf Barrier Islands and Coastal Marshes ecoregion extends west from the Florida Urban and suburban development north of Lake Pine plantation in Ecoregion 75a. Scorched tree flatwoods and open savannas. A high natural fire frequency was typical, often sparked by lightning 75k Pontchartrain in 75a is creating a more fragmented trunks occur when understory vegetation is Panhandle across the Alabama and Mississippi coasts to the Pearl River area of Louisiana. landscape. Photo: LA Statewide 2004 DOQQ controlled with fire. Photo: Brent Yantis, NASA/ULL Map Source: USEPA, 2006 and fueled by grasses, and maintained the open pine flatwoods and savannas. While most of the In Louisiana, the sediments of this region are associated more with the Pearl River than Mississippi longleaf pine savannas have been lost, remnant savannas are centers of biodiversity supporting a River deltaic deposits. The region east of Louisiana has salt and brackish marshes, dunes, beaches, variety of grasses, sedges, rushes, and an array of wildflowers: red lilies, orange milkweeds, yellow and barrier islands. In Louisiana, tidal freshwater marshes occur, such as those on the delta plains of pitcher plants, white, orange, and pink orchids, lavender butterworts, and purple sundews. Much of the larger rivers. Soils are very poorly drained Histosols and Entisols with mucky surfaces. The the landscape is now in mixed forest or pine plantations, while some better-drained land has been ecoregion provides habitat for many waterfowl, shorebird, sea turtle, and fish species, as well as for cleared for pasture or crops. Dominant land uses include woodland, wildlife habitat, and urban. muskrat, nutria, raccoon, otter, mink, and alligator. Nearby coastal erosion of islands composed of 75i Floodplains and Low Terraces are a continuation of the riverine 65p ecoregion across the deltaic deposits, land subsidence, and rising sea levels threaten the terrestrial habitats of the region. US Army Corps Southern Coastal Plain. The broad floodplains and terraces of the Pearl River are the only The Pearl River flows south from central Mississippi and empties into the Gulf of Mexico through Lake Borgne and the portion of the region in Louisiana. Composed of stream alluvium and terrace deposits of sand, silt, Mississippi Sound. The Pearl is a winding, slow moving river with a large sand bar in almost every bend. Sycamore and willow of Engineers Pine savannas were once more common in Ecoregion 75a. Longleaf pine was once the predominant trees line the banks along with stands of mixed hardwoods, pine, and gum. Photo: Carrie Robertson, www.gulfmex.org. Right: Indigo tree species, with a very diverse herbaceous layer. Photo: Alice Dossett clay, and gravel, along with some organic muck and swamp deposits, the region includes large Environmental Laboratory bunting and other migratory songbirds depend on the bottomland hardwood forests for resting and shelter. Photo: Charles L. Jordan