119-Ouachita Mountains

Arkansas and Oklahoma
24,640 sq. km (9,510 sq. mi)

Land use: About 76 percent of this MLRA is forested, about one-fourth of which, mainly in Arkansas, is federally owned. Some is in large holdings, but much of it is in farm woodlots. Lumbering, wood-using industries, and recreation are important throughout the area. Seventeen percent of the MLRA is grazing land, about 5 percent is cropland, and 2 percent is used for miscellaneous purposes. Forage and small grains are the major crops. Pastures are largely a mixture of tame grasses and legumes, but on some small prairie outliers in the west pastures are of native grasses.

Elevation and topography: Elevation ranges from 100 m on the lowest valley floors to 800 m on the highest mountain peaks. These steep mountains are underlain by folded and faulted shale, slate, quartzite, sandstone, and chert. Most of the stream valleys are narrow and have steep gradients, but wide terraces and flood plains border the Ouachita River in western Arkansas. Local relief is in tens of meters to more than 300 meters.

Climate: Average annual precipitation - 1,225 to 1,425 mm, decreasing to 900 mm along the western edge. Precipitation is fairly evenly distributed throughout the year, but the maximum is in spring and early in autumn. Average annual temperature - 16 to 17 C. Average freeze-free period - 200 to 240 days.

Water: The high precipitation, perennial streams, and reservoirs provide abundant water. Several large reservoirs for water storage and flood control are also used for recreation. In the valleys, small ponds, springs, and shallow wells are the main sources of water for domestic use and for livestock.

Soils: The major soils are Udults. They are stony and nonstony and medium textured. These soils have a thermic temperature regime, an udic moisture regime, and siliceous or mixed mineralogy. Well drained, shallow and moderately deep Hapludults (Townley, Pirum, and Sherwood series) are at the higher elevations and on steeper slopes. Well drained, deep and moderately deep Hapludults (Carnasaw, Pirum, and Sherwood series) are on the gentle slopes of ridgetops, benches, and foot slopes. Dystrochrepts (Ouachita series) and Ochraquults (Amy series) on flood plains and Hapludults on terraces in the valleys are minor soils.

Potential natural vegetation: This area supports hardwood-pine forests. The primary overstory species are southern red oak, black oak, white oak, and hickories. Pine constitutes as much as 40 percent of the cover-shortleaf pine on the uplands and loblolly pine on the lower lying alluvial soils. Switchgrass, little bluestem, and indiangrass are the primary grass species in the understory. Prairie cordgrass, plumegrass, low panicums, sedges, and rushes are present in smaller amounts.

(From "Land Resource Regions and Major Land Resource Areas of the United States". United States Department of Agriculture Soil Conservation Service Handbook 296. Dec. 1981. pages 86-87.)