Recruitment of Large Wood

Step Wise Guide

Riparian Management

· If there is timber harvest near streams, how can that influence the recruitment of large woody debris to streams?

One concern about timber harvest near streams, including thinning, is whether alteration of forest vegetation will lead to significant changes in the recruitment of large wood to streams. Large woody debris in channels is considered a fundamentally important component of stream ecosystems, including forming pools, storing sediment and creating refuges in conditions of high flows. A history of timber harvest or wildfire that alters vegetation conditions near streams can lead to areas of low wood recruitment. This, in combination with a history of stream cleaning and other in-channel, can result in low wood volumes in streams and thus poorer habitats.

NetMap contains a tool for calculating the recruitment of large woody debris based on the riparian forest conditions.

Step 1: Go to NetMap's Riparian Management Module>In-stream Wood Recruitment>Project (reach) scale. This tool can calculate the wood recruitment for a single year or for decades to centuries, given that the user supply forest growth (and death) forecasts (using forest growth models such as FVS, Oregonan, Zelig etc.). If a buffer width is selected that leads to a reduction of wood loading (compared to the untreated condition) or if thinning in the riparian zone leads to a lower wood recruitment rate, the analyst can calcuate how many trees to directionally fell into the stream (tree tipping) to offset the loss and or to enhance wood loading. This tools is used at the individual stream reach or project scale.

By the end of 2013, NetMap will contain a tool for calculating the wood recruitment across an entire watershed, either for a single year or for deacdes to centuries.

This tool can be used in conjunction with other riparian tools such as thermal loading. It can also be combined with estimates of fish habitat quality and erosion potential etc.