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Lower Boston Mountains

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About the Lower Boston Mountains

The Lower Boston Mountains are the more southerly and lower-elevation band of the Boston Mountains. This region is mostly located in northern Arkansas, but extends slightly into northeastern Oklahoma. Together with its upper counterpart, this is one of the best-preserved and least-disturbed ecoregions in the eastern United States.

This region consists of low mountains, high, rounded hills, and elevated, dissected plateaus. Elevations mostly range from 200-1,900 feet, but reach up to 2,300. Local relief ranges from 150-800 feet. The bedrock is a mix of sandstone, shale, lime-rich sandstone, sandy limestone, and siltstone. Taller mountains are usually capped with erosion-resistant sandstone, whereas side-slopes are underlain by a mix of sandstone, siltstone, and shale.

The climate is humid and subtropical, slightly cooler than lower-elevation areas to the south. Total precipitation decreases to the west and increases with elevation, but the seasonality also changes. This region has a bimodal precipitation pattern, with rainfall peaking in May and again in autumn, and drier summers and winters. Moving west, the May rainy season becomes more pronounced but autumn become drier.

This region was mostly forested, with small areas of open forest and savanna on uplands, especially in the west. Natural forest cover was probably a mix of oak-hickory-pine and oak-hickory on most sites, but with considerable diversity. Dominant trees probably included northern red oak, white oak, post oak, scarlet oak, black oak, blackjack oak, pignut hickory, shagbark hickory, mockernut hickory, and shortleaf pine. Shortleaf pine was particularly abundant on drier, south-facing slopes. Narrow floodplains and low terraces supported bottomland forests of sweetgum, various willows, birch, American sycamore, hickories, southern red oak, and white oak.

This area is mostly forested nowadays, and sparsely populated, and forest cover is presumably similar to its original state. There is some pastureland and hay production on flatter sites, but there is little agriculture overall, much less than areas farther north. The primary land uses are logging and recreation. This region has some of the highest-quality, least disturbed streams anywhere in North America, owing both to the geology and absence of activities disrupting stream quality. A majority of this region is protected public land, mostly as part of the Ozark National Forest. Although most of the forests here have been logged and represent second-growth, there are large tracts of old-growth forest, including shortleaf pine, post oak, blackjack oak, black oak, white oak, and northern red oak.

This region partly surrounds the higher-elevation Upper Boston Mountains to the north. On either side of this region, it bordered to the north by the Springfield Plateau, alternating several times with the Dissected Springfield Plateau-Elk River Hills. To the south, it is bordered by the lower-elevation, less rugged Arkansas Valley Hills, which can be seen as the foothills to these mountains and a transitional region to the lower regions of the Arkansas Valley. In the far west, the region opens up directly to the Arkansas Valley Plains to the south, and in a tiny region it directly borders the Arkansas River Floodplain. This region is bordered to the west by the Osage Cuestas.

References

1. Woods A.J., Foti, T.L., Chapman, S.S., Omernik, J.M., Wise, J.A., Murray, E.O., Prior, W.L., Pagan, J.B., Jr., Comstock, J.A., and Radford, M. "Ecoregions of Arkansas (Poster)", U.S. Geological Survey, Reston, VA (2004) Web.