Relationships of channel characteristics, land ownership, and land use patterns to large woody debris in western Oregon streams

Regression tree analysis was used to test the relationship of channel and aquatic habitat characteristics from 3793 stream reaches in western Oregon State to the abundance of large woody debris (LWD). Stream reaches were drawn from diverse ownerships and land uses - land cover types over a broad geographic extent. When all land uses land covers were considered, ownership and land use patterns were related to LWD abundance. When nonforested land uses were excluded, however, these factors became less important. In forested streams, LWD abundance was predicted primarily by stream gradient and bankfull channel width, with the volume, frequency, and size of LWD pieces decreasing as channel size increased. Within forested lands, stand age and forest distribution were related to LWD size but had small correlations with LWD volume and abundance. The strong relationship of stream gradient and bankfull channel width with LWD suggests that in forested areas, the most significant factor related to LWD counts is the geomorphology of stream reaches and their surrounding areas. Land managers in western Oregon who want to improve aquatic habitat quality may want to direct their efforts to increasing LWD in larger streams, which typically include smaller quantities of LWD.