Riparian forest replacement of mesic vegetation on Watts Bar Reservoir shores, East Tennessee

Author

Carin Couch Loy

Date of Award

5-1994

Degree Type

Thesis

Degree Name

Master of Science

Major

Human Ecology

Major Professor

Clifford C. Amundsen

Committee Members

B.E. Wofford, B. Otsby

Abstract

Watts Bar Reservoir was created in 1942 by closure of a dam which inundated 180 kilometers of the Tennessee Valley. Water pooled above the historic river floodplain up into the mesic pre-reservoir habitat, eliminating the historic riverine riparian habitat. Reservoir water levels are now managed such that flood periodicity of the 4400 hectare (ha) of potentially riparian habitat is counter-seasonal to local streams and rivers. Winter pool lows are alternated with summer highs such that the greatest extent of inundation takes place during the growing season. Two seasonal aquatic pool edges have been imposed and, where geomorphology and topographic allow, woody riparian communities are developing above the summer shores (higher pool) on once mesic sites.

Transects taken within the 1900 ha summer shore riparian zone show that the reservoir's effect on the shoreline forest vegetation has not been uniform. Vegetation was observed to be different both in kind and size, between transect locations. For example, canopy heights ranged between 12 meters (m) and 24 m; yield ranged between 8 m²/ha and 35 m²/ha; canopy closure ranged between 75 and 95 percent; and pole counts (indicating reproduction) ranged between 4 per transect and 30 per transect. Slope ranged between 1.5 and 40 percent.

The depth of unsaturated soil also differed between sites, with roughly half of the sites having an unsaturated soil thickness of greater than 0.3 m at the shore. However, when transect sites were divided by this criterion and statistics performed on quantitative results, the only significant measured difference between the two groups was in canпору cover, which was greater for the sites with more species responsive to soil inundation.

In spite of the variation in hydric expression, a strong influence from the historic mesic forest was observed at most sites. Litter weights were observed to range widely from 1 to 9 metric tons per hectare (mt/ha), but the average and median weights were the same (5 mt/ha). Soils also appeared to be fairly uniform, which was attributed to their historic alluvial parent material.

Recommended Citation

Loy, Carin Couch, "Riparian forest replacement of mesic vegetation on Watts Bar Reservoir shores, East Tennessee. " Master's Thesis, University of Tennessee, 1994.
https://trace.tennessee.edu/utk_gradthes/11598