Historical and contemporary disturbance regimes in central interior dry forests of British Columbia
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Brookes, Wesley
issued: 2019-04-17T16:51:34Z
issued: 2019
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Accurate historical reconstructions of disturbance regimes are necessary because current approaches toward more sustainable forest practices attempt to model forest management after historical disturbance regimes and recovery processes. Using dendrochronological analyses, I characterized both the historical fire regime and outbreaks of western spruce budworm (Choristoneura occidentalis Freeman) within a dry mixed-conifer forest to assess whether contemporary regimes are outside the historical range of variation. By determining the degree of change between the historical fire regime and the current, I provide insight into the potential consequences that fire suppression has had on resilience to fire and budworm. Historical fires burned in 23 different years from 1619 to 1943 with a mean interval of 15 years. Beginning in the later part of the 19th century fire patterns changed, such that the current fire-free period drastically exceeds the historical maximum fire-free intervals at all but 1 plot. Fire scars and post-fire cohorts varied among plots and indicated fires burned at mixed severities through time and space. Eight western spruce budworm outbreaks initiated between 1800 and 2001 with mean a mean duration of 14 years and mean return interval of 29 years. Outbreaks of a range of durations, frequencies, and severities were well represented throughout the record with no discernable trend in time. There was no significant difference between the number and timing of infestations initiating in plot canopies or subcanopies. The simple linear regression analyses determined plot-level subcanopy tree density (R² = 0.02; p = 0.43,) and the ratio of subcanopy to canopy tree densities (R² = 0.02; p = 0.48) to be poor predictors of severity during the outbreak from 2001 to 2011. It is strongly suspected that in the absence of fire in the 20th century, the forest has become denser and has lost a substantial degree of structural diversity. In addition, accumulations of ladder…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/69755
note: HISTORICAL AND CONTEMPORARY DISTURBANCE REGIMES IN CENTRAL INTERIOR DRY FORESTS OF BRITISH COLUMBIA by Wesley Brookes B.Sc.F., The University of British Columbia, 2013 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2019 © Wesley Brookes, 2019 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: Historical and contemporary disturbance regimes in central interior dry forests of British Columbia Submitted by Wesley Brookes in partial fulfillment of the requirements for the degree of Master of Science in Forestry. Examining Committee: Dr. Lori Daniels, Forestry Co-supervisor Dr. Allan Carroll, Forestry Co-supervisor Dr. Bianca Eskelson, Forestry Supervisory Committee Member Dr. Nicholas Coops, Forestry Additional Examiner Dr. Dominik Roeser, Forestry Additional Examiner iii Abstract Accurate historical reconstructions of disturbance regimes are necessary because current approaches toward more sustainable forest practices attempt to model forest management after historical disturbance regimes and recovery processes. Using dendrochronological analyses, I characterized both the historical fire regime and outbreaks of western spruce budworm (Choristoneura occidentalis Freeman) within a dry mixed-conifer forest to assess whether contemporary regimes are outside the historical range of variation. By determining the degree of change between the historical fire regime and the current, I provide insight into the potential consequences that fire suppression has had on resilience to fire and budworm. Historical fires burned in 23 different years from 1619 to 1943 with a mean interval of 15 years. Beginning in the later part of the 19th century fire patterns changed, such that the current fire-free period drasti…
has type: Thesis/Dissertation
date issued: 2019-05
is shown at: 10.14288/1.0378281
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/69755