Models for Forest Growth and Mortality: Linking Demography to Competition and Climate

• Author / Creator

  Dawson, Andria E

• The Earth’s forests are of great economic, ecological, and social importance, and
  sustaining them is paramount for mitigating climate change. To successfully sus-
  tain forests we must understand their internal demographic dynamics and their
  relationship to climate. In this thesis, I developed methods for investigating forest
  dynamics and understanding their relationship to climate. I applied these methods
  to data from the Alberta boreal forest and the oak forests of the Eastern United
  States. First, dendrochronological methods were used to develop a retrospective
  data set from the Alberta mixedwood boreal. This data was used to estimate white
  spruce mortality and construct mortality models based on either recent growth or
  competition. Both models classify dead or live spruce with 75% accuracy, indi-
  cating the potential of using more easily available competition data. Second, I
  developed a quantitative approach for predicting Alberta mixedwood demogra-
  phy as a function of tree size and competition predictors using a size-structured
  integral projection model (IPM). Two models were defined, one with competitive
  structure, and one without. Model projections were tested using independent data,
  and results show that the IPM with competitive structure better predicts annual
  size distribution. Implementation of the IPM presents technical challenges: IPMs
  must be numerically discretized, and the choice of integration scheme may lead to
  accuracy or efficiency loss. I analyzed several quadrature schemes for representa-
  tive IPMs in the third part of the thesis. Results show that the midpoint method is
  often sufficient, but an Adjusted Gauss-Legendre method leads to higher accuracy.
  In the final part of the thesis I considered how climate is related to annual growth
  of chestnut oak in the the Eastern United States. Previously, trees growing in
  closed-canopy forests were not thought to produce ring-widths useable in climate
  reconstruction. However, by employing more advanced mathematical tools I used
  a network of oak forests to identify a strong enough precipitation signal to extend
  the current meteorological record back 150 years. My thesis illustrates the im-
  portance of careful model formulation, implementation and validation in resolving
  climate and competition effects in forest dynamics.

• Subjects / Keywords

  • Models
  • Competition
  • Forests
  • Demography

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3CR5NP9X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.