Effects of Vegetation and Disturbance on Fungal Communities in the Western Cascades of Oregon.

The use of high throughput molecular methods that allow for the
study of bacterial communities in environmental samples is commonplace
in microbial ecology. Until recently, fungal community ecology has
focused on isolation, collection of sporocarps, or collection of
ectomycorrhizal roots. The techniques used to extract and amplify DNA
from environmental samples are relatively new to the world of fungal
community ecology. Many fungi are difficult to isolate. Collection and
identification of sporocarps and root tips is time-consuming. Sporocarp
production may vary from year-to-year. Here, we present three studies
using length heterogeneity PCR (LH-PCR) with the general fungal primers
ITS1-F and ITS4 for the internal transcribed spacer region of rRNA to examine changes in fungal community composition in response to changes
in vegetation, and disturbance events. In the first study, we used LH-PCR
to examine differences in fungal community composition along transects
from the forest to the meadow sites at two sites in the western Cascades of
Oregon. We found dramatic differences in fungal community composition
due to vegetation type and found an intermediate community in the
transition zone between meadow and forest. In the second and third
studies, we used LH-PCR to identify treatment effects in two manipulative
experiments. In both studies, LH-PCR allowed us to observe the changes in
community dynamics and identify some of the factors involved in
community changes following disturbance. In the second study, we found
that fungal succession occurred rapidly when cores were transferred to
new environments. We also found evidence that succession occurred more
slowly when roots were excluded. In the third study, we used bacterial
primers in addition to the fungal ITS primers. We found that presence of
live roots rather than either aboveground litter inputs or seasonal
differences in sampling times were the greatest determinant of both fungal
and bacterial communities at the Detritus Input and Removal Treatment
plots 6 years after initiation.