Rice, Stanley A. , Schrader, James , Graves, William , Gibson, J. Phil , Morningstar, Dawn .
Shade tolerance in the seaside alder (Alnus maritima) and the hazel alder (Alnus serrulata).
The seaside alder (Alnus maritima) is a rare tree species found in only three small populations, two of which are in Oklahoma (ssp. oklahomensis) and in Georgia (ssp. georgiensis). The hazel alder (Alnus serrulata) is, in contrast, widespread throughout the eastern United States. We hypothesized that this difference may be due to a greater shade tolerance in the hazel alder than in the seaside alder, which allows clumps to persist. Field densiometry measurements in both Georgia and Oklahoma indicate that clumps of hazel alder are found in the shade more often than are clumps of seaside alder. Chlorophyll measurements on leaves from field individuals show greater chlorophyll production in shade than in sun conditions, and in hazel alders than in seaside alders. Densiometry and chlorophyll measurements are consistent with the hypothesis of greater shade tolerance in hazel than in seaside alders. Lack of sunny, wet conditions may therefore severely limit the regeneration of seaside alders by seed.
1 - Southeastern Oklahoma State University, Biological Sciences, Box 4027, Durant, Oklahoma, 74701-0609, USA
2 - Iowa State University, Horticulture, Horticulture Building, Ames, Iowa, 50011-1100, USA
3 - Agnes Scott College, Biological Sciences, 141 E. College Ave., Decatur, Georgia, 30030
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 10:30 AM