HR: 0830h
AN: B21B-0708    [PDF]
TI: Effects Of Fungal-Mineral Interactions On Chemical Weathering And Denudation Processes - Observations From Experimental Ecosystems
AU: * Balogh, Z
EM: zsuzsa@wsu.edu
AF: Department of Geology, Washington State University, PO. Box 642812, Pullman, WA 99164-2812 United States
AU: Keller, C
EM: ckkeller@wsu.edu
AF: Department of Geology, Washington State University, PO. Box 642812, Pullman, WA 99164-2812 United States
AU: Dickinson, J
EM: jtd@wsu.edu
AF: Department of Physics, Washington State University, PO. Box 642814, Pullman, WA 99164-2814 United States
AB: A mesoscale (`sandbox') lysimeter experiment was performed at Hubbard Brook Experimental Forest, New Hampshire, to study plant-growth influences on chemical weathering and chemical denudation. Weathering was estimated by mass balance for 5 and 15-year intervals, and denudation was monitored as the product of drainage flow and concentration for 20 years in large (7.5x7.5x1.5m) fully lined sandboxes a.) planted with red pine (Pinus resinosa Ait.), and b.) kept free of vascular vegetation. Mass-balance equations included base cations (Ca, Mg, and K) in precipitation inputs and drainage outputs, and changes of base cation contents in biomass and soil. Scanning Electron Microscopy (SEM) and Environmental-SEM studies of the coarse sandbox soils were used for detection of mycorrhizal fungal association with roots, fungal development and attachment features on mineral grain surfaces. In the non-vascular system chemical weathering and denudation fluxes did not change significantly during the monitored period, but denudation fluxes were 1.3-1.4 times higher than weathering fluxes. In the vascular ecosystem the chemical weathering flux was 3 and 1.8 times greater than the denudation flux over 5 and 15 years, respectively, but both rates decreased over time. In our experiment the pines retarded denudation and accelerated weathering relative to the nonvascular system, thereby increasing available nutrient pools. The SEM and ESEM studies indicated more weathering features (etch pits, cracks, wholes, channels, and secondary minerals) in the mineral surfaces of the vascular system associated with the mycorrhizal fungal hyphae. Profiles of base-cation concentrations in soil water suggest that hyphal-mineral surface attachment might also insulate cation uptake from bulk soil water and hydrologic loss. The sandbox study offers insight into short-term effects of ecosystems on global biogeochemical processes.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting