Salmon in Trees? Large Woody Debris in Green Mountain National Forest Streams

Large woody debris (LWD) is an important component of stream ecosystems, especially in regards to fish habitat. It provides shelter for juvenile fish, provides spawning gravel for adult salmon and trout, and is a contributor to organic matter in the stream. Atlantic salmon (Salmo salar) are of particular concern in Green Mountain National Forest (GMNF) in Vermont because they are an endangered species. The fisheries crew at GMNF is working to restore salmon and trout populations in the Forest.

This study focused on collecting data on LWD and summarizing the characteristics and organization of LWD in streams in GMNF. I collected data on instream LWD and riparian zone forest characteristics. I aimed to determine whether basal area in the riparian zone could predict LWD volume instream, whether coniferous or deciduous riparian basal area contributed more to instream LWD, and whether the species composition of riparian zones and that of instream LWD was similar. I used linear models and generalized linear models (GLMs) to answer these questions quantitatively.

In GMNF, riparian basal area is a significant predictor of LWD volume at the 0.01 significance level. Deciduous basal area is also a significant predictor at the 0.01 level and is more strongly correlated to LWD volume than coniferous basal area. In addition, the species composition of riparian zones and instream LWD is similar. Deciduous basal area and coniferous basal area are highly correlated with their respective LWD volumes. These results provide prediction and prioritization capabilities for the fisheries crew in GMNF.

In addition to the results found here, the Northeastern Course Woody Debris model (NE-CWD) created by researchers at the U.S. Forest Service Northern Research Station is being run with the data collected. When the results are available, I will compare them to the field data I collected to determine whether the fisheries crew needs to adjust management activities for LWD. This project provided new products to the U.S. Forest Service in Vermont that were not previously available and will help to adjust the management plan to better manage fish habitat in GMNF, Vermont.