Masters Theses

Date of Award

12-2006

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Matthew J. Gray

Committee Members

Jennifer A. Franklin, Ray C. Albright

Abstract

The afforestation of hardwood bottomlands is an expanding conservation practice in the southeastern United States. Understanding relative flood tolerance of hardwood bottomland seedlings is fundamental to ensuring restoration success. Thus, I examined the combined effects of 3 early growing season flood duration treatments (0, 15, and 30 days) and the natural flood regime on willow (Quercus phellos, WIO), Nuttall (Q nuttallii, NTO) and overcup (Q lyrata, OCO) oak seedlings in a 6-ha replanted west Tennessee bottomland. Seedlings (n = 5,003) were planted from January-March 2004 in a randomized design. All seedlings were uniquely tagged, survival assessed, and height and diameter measured for each individual in fall 2004 for pre-treatment baseline data. In 2005 and 2006,I applied flood treatments after seedling bud break initiated, which was mid-April each year. Survival was measured in July and fall 2005 and July 2006. Overall survival was 96%, 89%, and 84% for OCO, NTO, and WIO, respectively. Survival of NTO and WIO was greatest in control impoundments that did not experience prescribed early growing season flooding. I measured height and diameter in fall 2004 and 2005, and calculated second growing season growth as the difference between 2004 and 2005 measurements. All species exhibited the least growth when subjected to the 30-day treatment. Interestingly, growth of NTO and WIO were greater in the 15-day treatment than in the control treatment, which suggests a possible benefit of short duration early growing season flooding. Seedlings of each species were collected in May 2005 and 2006 (n = 36/species/year), and shoot and root biomass, root length, and root sugar and starch concentrations measured. Seedling transpiration was measured for 36 seedlings/species in July 2005 and 72 seedlings/species in July 2006; soil respiration was measured for the same seedlings in July 2005. In general, all physiological variables decreased as flood duration increased. My results suggest that early growing season flooding may negatively impact survival, growth and physiology of bottomland oak seedlings. Furthermore, I ranked relative flood tolerance given the magnitude of seedling response variables, and suggest that flood tolerance decreases from OCO to NTO to WIO. Managers should consider planting seedlings in a candidate bottomland based on species specific flood tolerances. Inasmuch as elevation and flooding depth and duration are correlated, I recommend that natural resource practitioners manage low elevations in bottomlands that flood frequently as moist soil wetlands, plant NTO at medium elevations, plant WIO with NTO at medium-high elevations, and plant WIO exclusively at higher elevations that flood infrequently to increase the likelihood of restoration success. Although OCO seedlings are very flood tolerant and likely could withstand frequent and deep flooding, I do not recommend planting OCO at lower bottomland elevations, because their acorns are not preferred by waterfowl and the value of OCO timber is low.

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