© 1996 Heron Publishing—Victoria, Canada
Long- and short-term flooding effects on survival and sink–source relationships of swamp-adapted tree species
Mitko N. Angelov (1), Shi-Jean S. Sung (2), Ron Lou Doong (1), William R. Harms (3), Paul P. Kormanik (2) and Clanton C. Black, Jr. (1, 4)
1. Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA / 2. Institute of Tree Root Biology, Forestry Sciences Laboratory, Southern Research Station, USDA Forest Service, 320 Green Street,
Athens, GA 30602, USA / 3. Center for Forested Wetlands Research, Forestry Sciences Laboratory, Southern Research Station, USDA Forest Service, 2730
Savannah Highway, Charleston, SC 29414, USA / 4. Author to whom correspondence should be addressed / Received April 3, 1995
Summary
About 95% of swamp tupelo (Nyssa sylvatica var. biflora (Walt.) Sarg.) and sweetgum (Liquidambar styraciflua L.) seedlings survived continuous root flooding for more than two years, whereas none of the swamp chestnut oak (Quercus michauxii Nutt.) and cherrybark oak (Q. falcata var. pagodifolia Ell.) seedlings survived one year of flooding. Death of oak seedlings occurred in phases associated with periods of major
vegetative growth, e.g., after bud burst in spring, after summer stem elongation, and during the winter deciduous stage, suggesting
that stored reserves and sources were inadequate to maintain the seedlings when vegetative sinks were forming. Additional
evidence that flooding induced a source deficiency in oak was that leaves of flooded oak were 65 to 75% smaller than leaves
of nonflooded oak. Flooded swamp tupelo seedlings had a normal leaf size and patchy stomatal opening compared with nonflooded
seedlings.
Flooding caused increases in alcohol dehydrogenase (ADH) specific activity in taproot cambial tissues and increases in starch
concentrations of swamp tupelo seedlings that were reversed when seedlings were removed from flooding. Flooding had little
effect on soluble sugar concentrations in swamp tupelo or sweetgum. In the long-term flood–dry–flood treatment, in which all
species had survivors, upper canopy leaf photosynthetic rates were higher in all species during the dry period than in nonflooded
controls, whereas their starch and soluble sugars concentrations were similar to those of nonflooded controls. Based on seedling
survival and the sink–source relationships, the order of flood tolerance was: swamp tupelo > sweetgum > swamp chestnut oak
> cherrybark oak.
Keywords:
alcohol dehydrogenase, cherrybark oak, flood tolerance, Liquidambar styraciflua, Nyssa sylvatica var. biflora, patchy stomata, photosynthesis, Quercus falcata var. pagodifolia, Quercus michauxii, sinks, sources, starch, sucrose, swamp chestnut oak, swamp tupelo, sweetgum.
