76-8 Carbon Allocation and Cation Uptake Affected by Ectomycorrhizal Fungus in Nutrient Poor Settings, Using 13CO2 Pulse Labeling

Poster Number 8

See more from this Division: Joint Sessions
See more from this Session: Soils through Time: Critical Zone Studies of Processes and Their Effects (Posters)

Wednesday, 8 October 2008
George R. Brown Convention Center, Exhibit Hall E

Zsuzsanna Balogh-Brunstad1, Richard Gill2 and C. Kent Keller2, (1)Department of Geological and Environmental Sciences, Hartwick College, Oneonta, NY
(2)School of Earth and Environmental Sciences, Washington State University, Pullman, WA
Abstract:
Ectomycorrhizal fungi play a major role in cation uptake of pine trees from base poor soils and it is known that large amounts of photosynthate carbon are allocated belowground to maintain the ectomycorrhizal association. Such allocation may affect soil nutrient status and carbon accumulation on seasonal to ecosystem-development timescales. However, it is largely unknown what is the carbon cost of cation uptake by ectomycorrhizal weathering of forest tree species. We have compared chemical weathering fluxes and pine cation uptake with carbon allocation to pine and microbial biomass of ectomycorrhizal and non-ectomycorrhizal pine seedlings in a laboratory growth study. Red pine seedlings with or without ectomycorrhiza were grown in a base poor medium in a year-long growth chamber experiment. Chemical weathering and denudation fluxes were estimated by mass-balance of Ca2+, K+ and Mg2+ in input and output solutions, in plant biomass and on exchangeable cation sites of the growth medium at the end of the experiment. Before harvest the seedlings were exposed to two pulses of 13CO2, the carbon allocation was estimated by measuring the 13C uptake of pine biomass and phospholipid fatty acids (PLFAs) in the growth medium using a quadruple gas chromatograph mass spectrometer. Ectomycorrhizal treatments accumulated the most biomass and the highest amounts of cations in biomass, which resulted in the highest weathering fluxes and the largest weathering-to-denudation ratios among treatments. These treatments also allocated the largest amounts of labeled carbon into their biomass and to their microbial associates. The PLFAs were only measurable in the ectomycorrhizal treatments. These results suggest that the larger cation uptake of ectomycorrhizal seedlings contributes to larger carbon capture, growth rate and carbon usage efficiency under nutrient poor conditions.

See more from this Division: Joint Sessions
See more from this Session: Soils through Time: Critical Zone Studies of Processes and Their Effects (Posters)