Document: JER-3-76-12

Snag and large woody debris dynamics in riparian forests.

BARKER, J.R.* ¹, P.L.RINGOLD ¹ and M.BOLLMAN ²

Dynamac Corporation, Corvallis OR 97333 USA ¹
U.S. Environmental Protection Agency, Corvallis OR 97333 USA ²

Abstract:
Important components of riparian forests are snags and streamside large woody debris (LWD) because they are functional in maintaining water quality and providing habitat for numerous plants and animals. To effectively manage riparian forests, it is important to understand the dynamics of snags and LWD in riparian forests. A probability sample stratified by stream size and forest type selected 110 sites for study in western Oregon. Snag and LWD size, density, and frequency by species were measured with distance upslope from the stream channel within a 40 by 40-m plot. This information was used to develop an importance value index (IVI) to readily allow comparison among ecological meaning groups. Ecological groupings were ecoregion, stream order, streamside geomorphic surface, elevation, and management practice and they were used to statistically evaluate patterns of snag and woody debris dynamics in western Oregon. Data analyses show that snag and LWD dynamics differ with stream size, elevation, geomorphic surface, and management practice. Some examples are: (1) Snag IVIs were higher on the transition slope than on the floodplain or terrace; (2) The IVI for LWD was higher on the floodplain and terrace than the transition slope; (3) Snag IVI in the no-harvest and altered forest stands was greater than in the plantation or natural-regeneration forest stands; (4) LWD was more prevalent in the natural-regeneration stands than in the other management groups; and (5) Snag IVI increased with increasing elevation.

Keywords: Riparian forests, Snags, Large Woody Debris

This abstract is being presented at: 10:30 AM in session:
RIPARIAN ECOLOGY