The abundance and spatial heterogeneity of coarse woody debris (CWD)
on the forest floor is a prominent feature of Pacific Northwest (PNW) forest
ecosystems. The effect of CWD on soil solution chemistry, nutrient cycling and
availability, soil physical structure and formation of soil organic matter,
however, remains unknown. Therefore, studies on the spatial and temporal
imprint of CWD on forest soils are timely and can fill critical gaps in our
understanding of the role of CWD in PNW forest ecosystems. I investigated the
effect of CWD on soils and soil solution at the H.J. Andrews Experimental Forest
in a two-part study. Mineral soils were sampled beneath CWD to a depth of 60
cm. The top 15 cm of soil was also repeatedly sampled for seasonal differences.
Control leachate, CWD leachate and soil solution from control soils and from
under CWD were collected from the fall of 1999 until the spring of 2001. Results
indicated that CWD leachates were much more acidic than water leaching from
the forest floor without CWD. Intermediate stages of CWD decomposition had
the highest concentrations of hydrophobic compounds and polyphenols of all
stages of decay. Correspondingly, surface soils sampled from under well-decayed
CWD were more acidic and had more exchangeable acidity and
aluminum, and a lower percent base saturation than soils under the forest floor.
Nutrient pools were not different under CWD, although nitrogen fluxes were
slower under CWD. Although we had hypothesized that the spatial variability
of CWD inputs may affect forest soils under CWD, we found that the spatial
variability is much more temporal than I had hypothesized and is limited to the
top five centimeters of the underlying soil. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32386 |
| Date | 03 April 2002 |
| Creators | Spears, Julie D. H. |
| Contributors | Lajtha, Kate |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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