PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Fungal and Bacterial Derived Organic Matter in Forest Stands Exposed to Elevated Carbon Dioxide and Ozone.

Knorr, Melissa^*,1, Frey, Serita¹, Zak, Don², ¹ University of New Hampshire, Durham, NH, USA² University of Michigan, Ann Arbor, Michigan, USA

ABSTRACT- Soil amino sugar concentrations have been used to assess the relative contribution of bacteria and fungi to the accumulation of microbial-derived organic matter in soils. We quantified amino sugar concentrations in soils collected from beneath trembling aspen (Populus tremuloides Michx.), paper birch (Betula papyrifera Marsh.), and sugar maple (Acer saccharum Marsh.) growing under ambient or elevated levels of atmospheric CO₂ (ambient and 560 L L^-1) and O₃ (ambient and 55 L L^-1). The amino sugars glucosamine, galactosamine, and muramic acid were extracted, purified, and analyzed by gas chromatography. Total amino sugar concentrations ranged from 640-1810 mg/g soil and were not significantly different between the control and elevated CO₂ plots. Amino sugar concentrations were 18% higher in plots exposed to elevated O₃ (with or without elevated CO₂), due primarily to an increase in fungal-derived glucosamine concentrations. These results are consistent with a previous study demonstrating that the degradation of fungal or bacterial cell wall materials was higher beneath plants grown under elevated CO₂, and that elevated atmospheric O₃ eliminated this effect.

Key words: amino sugars, carbon dioxide, ozone