Physiological, Morphological and Growth Responses to Rhizosphere Hypoxia by Seedlings of North American Bottomland Oaks

摘要

Bottomland oak species of the southern United States are distributed along topographical gradients in floodplains. Because differences in soil aeration are associated with these gradients, we tested the hypothesis that oak species will exhibit diverging resistance to rhizosphere hypoxia. Four species which occupy different sites in floodplains, Quercus lyrata, Q laurifolia, Qphellos, and Q nigra, were used in two experiments designed to examine seedings responses during establishment and late in the first growing season. In both experiments, hypoxia tolerance was evaluated through measurements of gas exchange, biomass accumulation, and shoot and root growth. Evidence of oaks differing in resistance to rhizosphere hypoxia is presented, and results are discussed in relation to species distribution in floodplains.