The effects of clearcut silviculture (road building, clearfelling, cable logging, and site preparation) were evaluated using long-term peakfow records for three small watersheds (60-101 ha) and six large basins (62-640 km 2) in the western Cascades of Oregon, USA. After a calibration period, two of the small watersheds were treated while the third remained untreated (control). Analysis indicated that peakfow increases following treatments were dependent upon peakfow magnitude. Peakfow increases averaged approximately 13-16% after treatment for 1-yr recurrence interval events, and 6-9% for 5-yr recurrence interval events. For the six large basins, multiple linear regression analyses of peakfows relative to: (1) peakfow magnitude; and (2) difference in percent area harvested provided mixed results. While signifcant (p < 0.05) relationships were found in half of the analyses, the explained variance (�r 2) due to harvesting was generally small (1-7%).

The modulus of elasticity and the tensile strength were determined for a sample of live Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) roots collected in the Oregon Coast Range. Most of the roots displayed both a "form" modulus of elasticity and a "material" modulus of elasticity. The form modulus occurred as a tortuous root straightened out, whereas the material modulus developed following this initial straightening as the wood fibers within the root directly resisted elongation. The average form and material moduli of elasticity were, respectively, 185 and 503 MPa, whereas the average tensile strength was 17 MPa.

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A series of dynamic loading tests were conducted on a small skyline logging system (15.8 mm [5/8 inch] skyline) operating in a second-growth Douglas fir stand. The tests included free vibration tests and logging tests with turns weighing from 1.5 to 9 kN [340 to 2050 lbs]. Natural frequency and damping were evaluated from free vibration tests, and the free vibration portion of logging tests. Dynamic load magnitude was evaluated for logging tests with natural and artificial breakouts of turns with a range in turn weights, and for a series of logging tests with the same turn. The natural frequencies of the guylines were in good agreement with simple cable theory. However, the presence of the carriage on the skyline resulted in measured natural frequencies significantly lower than simple cable theory would predict. Damping of the tailspar system and the skyline averaged about 10% of critical damping, but was highly variable from test to test. Dynamic load magnitude, whether expressed as the load peak produced by turn break-out, or the maximum cyclic load, was highly variable, with coefficients of variation ranging from 31 to 79%.Even a series of logging tests with the same twolog turn produced maximum cyclic loads with a coefficient of variation of nearly 40%.

Stream crossings designed to simulate a natural streambed inside a culvert are commonly used to meet criteria where fish passage is required. Currently, there has been little research that quantitatively examines the flow patterns within these streambed simulation culverts. A model is presented that estimates the percent of a cross section that is within the swimming ability of juvenile fish developed from velocity measurements on first‐generation stream simulation culverts — those culverts with a continuous gravel bed. The model, developed with regression techniques, uses physical and hydraulic parameters including discharge, total cross sectional area, Froude number, and relative roughness, and was tested directly against velocity distributions computed from field measurements and in a culvert design mode. Results were favorable, although larger percentage errors exist, particularly at small flow depths. The model appears to underestimate the percent of channel cross section at or below a limiting velocity, hence it is generally conservative in design mode.