Phil Monsanto, U.S. Forest Service
Date of Award
Master of Environmental Management (MEM)
Environmental Science and Management
1 online resource (46 pages)
Forest management -- Mt. Hood National Forest (Agency : U.S.), Douglas fir -- Thinning, Forest biodiversity, Understory plants, Plant communities
Variable density thinning (VDT) is a method of restoration thinning that attempts to increase ecosystem resilience and spatial heterogeneity in forest stands to more closely resemble mosaic-like patterns characteristic of late-successional forests, which consist of clusters of multiple trees, individual trees, and gaps. This study examines the spatial patterning of overstory trees resulting from VDT of conifer forests in Mt. Hood National Forest in the western Cascade Mountains and compares these patterns with reference conditions. Stem maps were created from field surveys of study plots within one mature stand and six thinned stands designated as Late-Successional Reserve (LSR) with varying minimum inter-tree spacing distances and implementation methods (designation by description and designation by prescription). A cluster analysis and global point pattern analysis were conducted for each of the seven stands. Spacing-based prescriptions below 15 feet resulted in approximately twice as many trees belonging to large clusters compared to reference conditions. Additionally, the results suggest that the designation by prescription method produces forest spatial patterns that are more similar to reference conditions than the designation by description method. This suggests that more flexible prescriptions that incorporate site-specific information should be utilized for restoration thinning in LSR stands.
Huston, Emma, "Effects of Variable Density Thinning on Spatial Patterns of Overstory Trees in Mt. Hood National Forest" (2018). Master of Environmental Management Project Reports. 34.