Implications of Riparian Management Strategies on Wood in Streams of the Pacific Northwest

Abstract

Riparian forest management plans for numerous regions throughout the world must consider long-term supply of wood to streams. The simulation model OSU STREAM-WOOD was used to evaluate the potential effects of riparian management scenarios on the standing stock of wood in a hypothetical stream in the Pacific Northwest, USA. OSU STREAMWOOD simulates riparian forest growth, tree entry (including breakage), and inchannel processes (log breakage, movement, and decomposition). Results of three simulation scenarios are reported. The first scenario assessed total wood volume in the channel from Douglas-fir plantations clearcut to the stream bank using three rotation periods (60, 90, and 120 yr). Without a forested riparian management zone, accumulation of wood in the channel was minimal and did not increase through time. In the second scenario, response of total wood volume to forested riparian management zones of widths between 6 m and 75 m was evaluated. Total wood volume associated with the 6 m wide nonharvested forest for forest ages Ն240 yr was 32% of the standing stock associated with a nonharvested forest buffer one potential tree height in width. Maximum standing stock associated with the channel for nonharvested riparian forests Ն30 m required 500-yr-old forests. In the third scenario, contribution of wood from forest plantations beyond nonharvested forests of various widths was explored. Forest plantations associated with nonharvested riparian buffers with widths Ͼ10 m contributed minimal amounts of wood volume to the stream. These results suggest that forest age and width of the nonharvested buffers are more important than the rotation age of plantation forests in providing long-term supplies of wood to streams.

Using reference conditions in ecosystem restoration: an example for riparian conifer forests in the Pacific Northwest

“…4 and 5), which are structural attributes important to a number of species. Dead trees !50 cm are large enough to be stable in most streams, are a size preferred by many cavity nesting birds, and generally are large enough to form snags and large wood that are long-lived structural elements in forest and stream ecosystems (Mannan et al 1980, USDA and USDI 1994, Beechie and Sibley 1997, Meleason et al 2003, Fox and Bolton 2007. While snag sizes are important, the density of snags may also be important for some species (e.g., birds that forage on snags prefer nesting sites in areas of high snag density (Raphael and White 1984)).…”

Substrate Form Determines the Fate of Bryophytes in Riparian Buffer Strips

“…A narrow buffer strip is also probably more similar to a wildfire disturbance along a stream than a clearcut, since natural processes such as production of dead trees and uprootings can continue, shaping microtopographic variation and substrate heterogeneity (cf. Meleason et al 2003). The focus on riparian forests and buffer strips has mostly considered larger watercourses (Moore and Richardson 2003).…”

Dynamics of wood in stream networks of the western Cascades Range, Oregon

“…Most wood is contributed by streamside forests from within 40 m of the stream (Harmon et al 1986;McDade et al 1990;Swanson et al 1990;Meleason et al 2003), but taller than the 60 m height commonly achieved by mature and old-growth Douglas-fir can contribute wood from greater distances. The percent length of each 50 m stream segment adjacent to a harvest unit or road was calculated using GIS software for each of four harvest distances on either side of the stream line: 0 m, 1-10 m, 10-20 m, and 20-40 m. These values were grouped into 0 m, 1-40 m, and >40 m for analysis.…”

“…Many natural processes and forest management practices -clear-cutting and plantation forestry, roads, floods, geomorphic processes, and other mechanisms -also influence wood dynamics in streams (Keller and Swanson 1979;Reeves et al 1995;Johnson et al 2000;Benda et al 2002). Wood dynamics in streams have been described using wood budgets and routing analyses (Lancaster and Hayes 2001;Benda et al 2002;Meleason et al 2003).…”

“…The framework includes wood contributions from streamside forests to streams (Fig. 1b) by tree fragmentation, windthrow, bank erosion, and other processes (Keller and Swanson 1979;Lienkaemper and Swanson 1987;McDade et al 1990;Johnson et al 2000;Meleason et al 2003). It also includes effects of forest harvest, roads, and natural processes, such as wildfire and windthrow, on delivery of wood to streams (Benda and Sias 1998;Zelt and Wohl 2004).…”