PARENT SESSION
Oral Session #17: Wetland Ecology. Presiding: E. Weiher.
Monday, August 6, 2001. 1:00 PM to 4:15 PM. Hall of Ideas H.
Physiological response of three riparian sedges to different ground water depths.
Steed, James1,2, DeWald, Laura1, Kolb, Thomas1, 1 2
ABSTRACT- Revegetation efforts in degraded riparian meadows would be enhanced by a better understanding of the influence of ground water on the growth and physiology of transplanted sedges. In a greenhouse experiment, we subjected recently extracted plugs of Carex lanuginosa, C. nebrascensis, and C. rostrata, to three simulated ground water table depths (4,19, and 35cm). Ground water depth treatments were maintained at a constant depth for 16 weeks, then water levels were dropped over a period of 6 weeks. Gas exchange, water relations, and above- and belowground biomass were measured on multiple occasions during each phase. Adjustment of rooting depth, without adjustment of root/shoot ratios, allowed each species to maintain favorable Pn under different ground water levels. When ground water levels dropped, initial increases in Pn and Gw followed by rapid declines after week 4 suggested that anaerobic conditions hindered growth under shallow but constant ground water depths. Additionally, C. rostrata maintained less negative mid-day water potentials than the other species, despite lower root/shoot ratios, greater aboveground production, and similar Pn. These results suggest transplanted sedge plugs may be less tolerant of shallow ground water tables than naturally established sedges.
KEY WORDS: sedges, ground water table, water relations, gas exchange