First Advisor

Jeffrey Gerwing

Community Partner

Phil Monsanto, U.S. Forest Service

Date of Award

2018

Document Type

Project

Degree Name

Master of Environmental Management (MEM)

Department

Environmental Science and Management

Physical Description

1 online resource (46 pages)

Subjects

Forest management -- Mt. Hood National Forest (Agency : U.S.), Douglas fir -- Thinning, Forest biodiversity, Understory plants, Plant communities

DOI

10.15760/mem.5

Abstract

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.

Description

A report submitted in partial fulfillment of the requirements for the degree of Master of Environmental Management.

Persistent Identifier

https://archives.pdx.edu/ds/psu/26258

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