PARENT SESSION
Poster Session #26: Soil Ecology I.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
110
Homogeneity of microbial communities in adjacent forests differing in nitrogen cycling.
LECKIE, SARA*,1, PRESCOTT, CINDY1, NEUFELD, JOSH1, MOHN, WILLIAM1, 1 University of British Columbia, Vancouver, BC, Canada
ABSTRACT- Two distinct forest types dominate the wet zones of northern Vancouver Island, Canada and exhibit marked differences in nutrient cycling. Old-growth cedar-hemlock (CH) forests have thick humus layers and very low nitrogen availability. Younger hemlock-amabilis fir (HA) forests have higher nitrogen availability and exhibit much greater productivity after harvesting. We investigated the forest floor microbial communities to address whether they reflect differences in nutrient availability between the two forests. We expected that the variability of the microbial communities is greater between the two forest types than within. Three layers of the forest floor were sampled at four sites within adjacent CH and HA forests. Bacterial and fungal community fingerprints were generated using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified ribosomal genes as well as phospholipid fatty acid (PLFA) analysis. The results are surprising in that the microbial communities appear to be homogeneous within each forest floor layer, showing no detectable differences between the two forests with different nitrogen availability. Deeper forest floor layers showed less overall variability than surface layers and the microbial community fingerprints were distinct for each layer. This suggests that the degree of decomposition of plant litter and/or microenvironment at different depths is more important in determining the microbial community composition than forest type. Differences in microbial activity, rather than community composition, may be responsible for differences in nutrient cycling and decomposition processes.
KEY WORDS: soil microbial community, DGGE, PLFA, nitrogen availability