Freezing to death in a warming climate : drivers of yellow-cedar decline on Haida Gwaii
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Comeau, Vanessa
issued: 2019-06-20T15:37:41Z
issued: 2019
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The global rise in temperature and associated changes in climate have led to decline of forests around the globe, across multiple species and ecosystems. This includes yellow-cedar (Callitropsis nootkatensis) decline, which is one of the most severe in North America. I found abundant evidence of tree decline and mortality of yellow-cedar on Haida Gwaii across multiple watersheds and over a range of elevations. The decline on Haida Gwaii parallels the broader yellow-cedar decline in terms of spatial distribution, symptoms, magnitude and timing. Nevertheless, the proposed drivers on the mainland may not adequately explain the decline on Haida Gwaii, due to the more temperate climate and lack of persistent snowpack. I investigated several possible drivers both at the local and regional scale. My results are inconsistent with stand dynamics as a driver of elevated decline and mortality. Neither increased competition, nor aging of a cohort explains the decline. Onset of basal area increment decline and mortality have been accumulating over time, with increased rates since the 1980s. Alternatively, the magnitude and timing of the decline is consistent with well-documented multi-decadal variations and long-term directional trends in regional climate. I found patterns of divergent growth and divergent response to climate among yellow-cedars at the same sites. Yellow-cedars affected by decline were decreasing in growth and negatively associated with warmer drier winter conditions. Whereas, yellow-cedars not affected by decline were increasing in growth and positively associated with warmer growing season temperatures. The limiting factors for declining trees, warm dry winter conditions, are consistent with the hypothesis from the mainland that climate warming has led to root freezing. However, compared to drivers of yellow-cedar decline on the mainland, snowpack plays a less important role on Haida Gwaii. Warming temperatures likely have a more direct effect. I propose warme…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/70710
note: FREEZING TO DEATH IN A WARMING CLIMATE: DRIVERS OF YELLOW-CEDAR DECLINE ON HAIDA GWAII by Vanessa Comeau B.Env.Sc., The University of Manitoba, 2014 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) June 2019 © Vanessa Comeau, 2019 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Freezing to death in a warming climate: Drivers of yellow-cedar decline on Haida Gwaii submitted by Vanessa Comeau in partial fulfillment of the requirements for the degree of Master of Science in Forestry Examining Committee: Dr. Lori Daniels, Forestry Supervisor Stefan Zeglen, British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development Supervisory Committee Member Dr. Richard Hamelin, Forestry Supervisory Committee Member Dr. Sean Michaletz, Botany Non-departmental Examiner iii Abstract The global rise in temperature and associated changes in climate have led to decline of forests around the globe, across multiple species and ecosystems. This includes yellow-cedar (Callitropsis nootkatensis) decline, which is one of the most severe in North America. I found abundant evidence of tree decline and mortality of yellow-cedar on Haida Gwaii across multiple watersheds and over a range of elevations. The decline on Haida Gwaii parallels the broader yellow-cedar decline in terms of spatial distribution, symptoms, magnitude and timing. Nevertheless, the proposed drivers on the mainland may not adequately explain the decline on Haida Gwaii, due to the more temperate climate and lack of persistent snowpack. I investigated several possible drivers both at the local and regional scale. My results are inconsistent with stand dynamics as a driver of elevated decline and mortality. Neither increased …
has type: Thesis/Dissertation
date issued: 2019-09
is shown at: 10.14288/1.0379512
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/2429/70710