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Inner Nashville Basin

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About the Inner Nashville Basin

The Inner Nashville Basin is a region located in central Tennessee, and the only ecoregion entirely contained within the state of Tennessee. It is centered a significant distance east of the city of Nashville, and contains very little of the city's metropolitan area.

This region mostly ranges from flat to rolling plains, with some small knobs and hills. It is significantly flatter and lower-elevation than its surroundings, with elevation ranging from 500-900ft (152-274m) and local relief of 60-400ft (18-122m). This region is almost entirely underlain by low-phosphate limestone; soils are formed on clayey solution residuum derived from the limestone. Soils here tend to be highly fertile, but ecosystems tend to be limited in their extent by phosphorus. The climate is humid and subtropical, with four well-defined seasons and precipitation relatively equally spread throughout the year, although there is a slight wet season peaking in May and a slight dry season in late summer to early fall.

Originally, this region supported a unique forest association of maple, oak, hickory, and ash, somewhat similar to the oak-hickory forests of the surroundings but with more calcium-loving species. In addition, there were limestone cedar glades, which supported a mix of grasslands, savanna, and sparser forest, with eastern redcedar (Juniperus virginiana) dominant, along with poverty oatgrass (Danthonia spicata), winged elm (Ulmus alata), common hackberry (Celtis occidentalis), and some oaks. The cedar glades here have a high proportion of endemic species.

This region has seen considerable urban and residential development in recent years as the Nashville metro area has expanded. There is also significant pastureland, as well as cropland producing mostly hay, and some corn and small grains. The region largely produces beef cattle and dairy. There are some patches of mixed woodland. Eastern redcedar is common, both due to its original occurrence here and its prevalence as an early-successional species on abandoned fields.

This region is entirely surrounded by the Outer Nashville Basin, a region that tends to be slightly hillier and higher-elevation, and has slightly more diverse soils, in places much higher in phosphorus.

References

1. Griffith, G.E.; Omernik, J.M.; and Azevedo, S.H. "Ecoregions of Tennessee (Poster)", U.S. Geological Survey, Reston, VA (1998) Web.