Year of Award

2011

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Forestry

Department or School/College

College of Forestry and Conservation

Committee Chair

John Goodburn

Commitee Members

Carl Fiedler, James Habeck

Keywords

bearing trees, change in fire intensity, fire exclusion, General land office survey notes, point to tree sampling, section corner

Abstract

ABSTRACT A Century of Change in Forest Structure and Fire Regime Condition Class in a Western Montana Ponderosa Pine/Douglas-fir Forest - Restoring historical forest conditions is often a driving force behind forest management activities today. However, determining historical, pre-settlement conditions can be challenging. Utilizing General Land Office (GLO) survey notes to reconstruct historical stand structure is one method to achieve this goal. Original GLO survey notes from 1902 were used to reconstruct historical stand condition in a 2,694 acre ponderosa pine/ Douglas–fir forest. Surveyed corners or their approximate locations were relocated. The procedure for establishing bearing trees by the original surveyor was duplicated in the field at these corner locations in 2007, including tree data to the nearest 1 inch diameter class to produce a modern day version of the original 1902 notes. A point-to-tree sampling system was then applied to both the 1902 and 2007 bearing tree data to determine tree density (trees/acre) and basal area stocking by species and diameter class for each data set. My hypothesis was that between 1902 and 2007, tree density increased, quadratic mean diameter decreased, and species composition shifted from nearly pure ponderosa pine to ponderosa pine/Douglas-fir as a result of timber harvesting and fire exclusion, I also hypothesized that the fire regime for the stand has changed from one of low intensity fire in 1902 to one with high potential for stand-replacing fire in 2007. These hypotheses were supported in the process of data analysis, modeling, and interpretation. The number of trees/acre increased from 37 in 1902 to 202 in 2007. There was also a big increase in basal area from 82 ft2/ac in 1902 to 204 ft2/ac in 2007. Quadratic mean diameter at one foot above ground line decreased during the period from 20.1” to 13.6”. In 1902, species composition based on proportional basal area was 97% ponderosa pine and 3% Douglas-fir, but by 2007 this had changed to 60% ponderosa pine and 40% Douglas-fir. Furthermore, the fire regime has changed from low severity with low potential for crown fire in 1902, to high severity with a high risk of stand-replacing wildfire in 2007.

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© Copyright 2011 Robert Michael Rich