From alligator- and bear-prowled swamps to shark-cruised bays and seabird rookeries, Louisiana showcases impressive ecological diversity -- an environmental richness mirroring its beautifully jumbled-together human culture. Encompassing the vast, convoluted mouth of North America’s greatest drainage, the Mississippi River, the state is notable for its expanses of wild wetlands, but timbered hollows and upland savannas are also part of its natural character.

Louisiana’s physical terrain, in conjunction with its humid-subtropical climate, provides a foundation for its sundry panoply of ecosystems. At the broadest scale, all of the state belongs to the Atlantic-Gulf Coastal Plain, which eases gently seaward. More specifically, the hilly-to-level uplands of the South Central Plains cover northwestern and west-central Louisiana; the bottomlands, terraces and bluffs of the Mississippi River system dominate eastern and southeastern Louisiana, extending into a great bird’s-foot delta in the Gulf of Mexico.

Louisiana’s subdued uplands include a range of forest, savanna, grassland and wetland ecosystems. Among the more distinctive are the eastern red-cedar woodlands of the calcareous, or lime-rich, Jackson Formation in north-central Louisiana. Far more widespread, especially historically, are savannas of longleaf pine, one of the defining ecological landscapes of the southern Atlantic-Gulf Coastal Plain. Alkaline soils support airy oak groves and grassy salt barrens, while rough ravine slopes are cloaked in rich hardwood forests of beech, oak, sweetgum, magnolia and hickories.

Much of Louisiana is sodden bottomland, from floodplain swamp to flatwoods ponds and glimmering marshlands. Among the most extensive such communities is the baldcypress-tupelo swamp, common along river channels but also poorly drained depressions and swales. Some of the greatest remaining tracts in the country reside in the Atchafalaya Basin, which also boasts huge expanses of freshwater marsh. American alligators, anhingas, water moccasins, egrets, gars, turtles, muskrats -- life in Louisiana bottomlands throbs with diversity.

Louisiana’s coastal habitats include salt marshes, coastal prairies and maritime forests -- including the live-oak hammocks thriving atop “cheniers,” former beach ridges fronting the coastline in southwestern Louisiana. Mangrove shrub-swamps grow on the estuarine fringes of the Deltaic Plain of southeastern Louisiana, composed of stunted black mangroves -- larger and more widespread in Florida -- on the northern fringe of their natural range. Nearshore communities include lush seagrass beds, important foraging ground for such rare marine creatures as sea turtles and manatees.