Previous research on coarse woody debris (CWD) indicated that moisture
content and initial heterotrophic colonization of decaying wood can affect
the decomposition process. Six heterotrophic treatments were created to
simulate the effects of physical penetration of the bark and wood and the
transmission of ascomycetes versus basidiomycetes into CWD. In 1995,
360 Douglas-fir (Pseudotsuga menziesii) were randomly placed at five
replicate sites in old-growth stands. Each site had 6 heterotrophic (HET) x
2 moisture combinations (TENT). One set of logs representing the
treatment combinations was used for sampling respiration and another set
was used to measure volume affected by insect gallery excavations and
fungal rot and to determine decay rates. Respiration was sampled three
times during the summer of 2001. The results indicated that the HET
treatments were no longer affecting respiration rates. Analysis of the
average of the three sampling periods revealed no TENT effect but
examinations of the individual sampling dates suggests that tented logs
might have higher respiration rates than non-tented logs as summer
progresses. In the aggregate, the TENT treatment reduced moisture
content from 45% to 36%, a 20 percent reduction in moisture levels. The
HET and the TENT treatments did not affect decay rates. The mean
density change for the logs was -0.072 g/cm�� �� 0.03 and the mean decay
constant was 0.026 �� 0.011. The TENT treatment did affect heterotrophic
activity. The mean volume of wood borer excavation and extent of brown
rot was higher in the tented logs (256 cm��) than in the non-tented logs
(59.9 cm��). There was also a statistically significant interaction between
the HET and TENT treatments. The largest differences in volume affected
by wood borers and fungal rot were found in treatments that injected
ascomycetes into the experimental logs. In sum, there was limited
evidence that the differences in moisture content caused by the TENT
treatment affected the decomposition process but the HET treatments
appear to not be directly influencing decomposition after six years. The
findings suggest differences in the initial community composition of
heterotrophs have a decreasing impact on the decomposition process as it
progresses. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32268 |
| Date | 10 June 2003 |
| Creators | Barker, Jason Scot |
| Contributors | Schowalter, Timothy D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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