A biome is a large ecological area defined by its specific climate, vegetation, and animal life. These regions are shaped by environmental factors, creating distinct natural communities. Understanding a biome provides insight into the interconnectedness of a region’s environment and its living organisms.
Arkansas’s Dominant Biome
Arkansas predominantly falls within the Temperate Deciduous Forest biome, which covers much of the eastern United States. This biome is defined by its four distinct seasons, including hot, humid summers and mild to cool winters. The state receives moderate to high rainfall, averaging 40 to 60 inches annually. Average annual temperatures hover around 60-61°F (15-17°C), providing a suitable climate for broadleaf trees.
Dominant plant life includes various oak species (white, red, post), several hickory species, maples, sweetgum, American elm, and tuliptree. These trees shed their leaves seasonally, a defining feature of deciduous forests, contributing to vibrant fall foliage. This vegetation supports diverse animal life, including white-tailed deer, black bears, various bird species, small mammals, reptiles, and amphibians.
Regional Ecological Distinctions
While the temperate deciduous forest covers most of Arkansas, the state’s diverse physiography creates notable ecological distinctions. Arkansas is broadly divided into several natural divisions, each with specific geological and ecological characteristics.
The Ozark Mountains in northern Arkansas feature rugged terrain dominated by oak-hickory forests, though shortleaf pine can be found on drier, south-facing slopes. These mountainous areas, with rocky and acidic soils, support over 200 endemic species. To the south, the Ouachita Mountains are notable for their east-west trending ridges and valleys, supporting mixed pine-hardwood forests, often featuring loblolly and shortleaf pine alongside oak and hickory. This region has approximately 48 species found nowhere else.
In eastern Arkansas, the flat Mississippi Alluvial Plain (the Delta) contrasts with mountainous regions. This area, with fertile alluvial soils, was historically covered by extensive bottomland hardwood forests, including cypress, tupelo, and various water oaks. Much of this plain has been converted to agriculture, but remaining wetlands serve as habitats for migratory waterfowl along the Mississippi Flyway. Southern Arkansas is home to the Gulf Coastal Plain, characterized by rolling hills and sandy soils that primarily support pine forests (loblolly and shortleaf pines), mixed with some hardwoods and wetlands. The Arkansas River Valley, situated between the Ozarks and Ouachitas, represents a transitional zone with a mix of forest, woodland, savanna, and prairie ecosystems.
Influences on Arkansas’s Biomes
Several environmental factors shape Arkansas’s biomes and contribute to its ecological diversity. The prevailing humid subtropical climate (Cfa under the Köppen system) directly supports temperate deciduous forests. This climate provides the warmth and consistent precipitation, averaging 50 to 54 inches annually, to sustain lush forest growth. Distinct seasonal temperature shifts, from summer highs around 90°F (32°C) to winter lows near freezing, drive the deciduous nature of dominant tree species.
Topography also plays a significant role, with elevations ranging from the low-lying Mississippi Alluvial Plain to Mount Magazine, the state’s highest point at 2,753 feet (839 meters). These variations create localized differences in temperature and rainfall, influencing plant communities and soil types. Cooler temperatures and higher precipitation in mountainous regions lead to different forest compositions compared to warmer lowlands.
An extensive network of water bodies further defines Arkansas’s ecological landscape. Major rivers like the Mississippi, Arkansas, White, Ouachita, and Red, along with numerous lakes, create unique riparian zones, floodplains, and wetlands. These aquatic environments support diverse fish species and provide habitats for migratory birds.
Finally, varied soil types across Arkansas, from rich alluvial deposits in the Delta to rocky mountain soils and sandy Coastal Plain soils, directly determine which plant communities can thrive.