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 community composition and function in boreal forest soils: landscape controls and feedback to ecosystem processes.
Waldrop, Mark*,1, Harden, Jennifer1, Manies, Kristen1, 1 United States Geological Survey, Menlo Park, CA
ABSTRACT- Boreal forest ecosystems are being impacted by a variety of factors that affect ecosystem structure and function. Climate change is a major driving force behind changes in fire regimes, plant community distributions, potential terrestrialization, and permafrost melt, yet the mechanisms that drive ecosystem response to them are not well understood. Understanding ecosystem biogeochemical response to global climate change requires an explicit consideration of the linkages between the aboveground and belowground biotic communities. However, we have very little baseline data concerning the primary factors that structure soil microbial communities. We focused on the soil fungal community because of their limited diversity yet importance to soil C cycling (e.g. decomposition). We hypothesized that the biomass and diversity of soil fungi would increase with successional stage (time since fire), and with increase soil drainage. We further hypothesized that greater fungal biomass and diversity would increase the capacity of the soil microbial community to decompose recalcitrant carbon, thus affecting biogeochemical cycling. Fungal community composition was analyzed by amplifying the internal transcribed spacer (ITS) region of fungal DNA, followed by DGGE. DGGE results were also compared to a new Denaturing High Performance Liquid Chromatography (DHPLC) method. The rapid DHPLC method uses retention time, temperature, and chemical denaturation to separate DNA fragments based on size and GC content. Microbial functional capabilities were analyzed utilizing functional enzyme assays. Preliminary results indicate that landscape type (soil drainage) and successional stage have a strong influence on fungal community composition. Shifts in fungal community composition, in turn, affect the capacity of the soil community to decompose recalcitrant C. We create a model of fungal community development in boreal forests and use this to explain non-linearities in C cycle processes.
Key words: boreal forest, soil fungi, carbon cycle, climate change