White spruce advanced regeneration response to Strip Cut Understory Protection harvesting

• Author / Creator

  Krebs,Valerie S

• Understory protection harvesting in boreal mixedwoods, which removes mature trembling aspen (Populus tremuloides Michx.) while leaving advance regeneration of white spruce (Picea glauca (Moench) Voss), is being used in many parts of northern Alberta, Canada. The harvesting system is a step forward in sustainable forest management by maintaining biodiversity within a stand, producing valuable timber, and following natural succession of a boreal mixedwood stand. From a management perspective there is a need for accurate yield estimations for understory protection harvesting sites. In this thesis I focus on the growth of white spruce advanced regeneration following removal of overstory aspen. Data were collected from five understory protection harvesting sites in northern Alberta and dendroecological techniques were used to determine diameter and height growth responses. Mixed effect- and generalized least square models were built to evaluate spruce growth response following understory protection harvesting and to examine the influence of neighboring spruce and aspen and climate on spruce growth. White spruce grew vigorously following removal of overstory aspen. I found a distinct immediate increase in diameter growth in the year following understory protection harvesting and in the following years, while height growth increases showed a delay of 3 to 5 years after release. Moreover intraspecific competition had a strong negative effect on the growth response of released spruce trees, whereas deciduous competition, mainly from aspen trees had less influence. Climate variables showed a weak influence on spruce growth following harvesting. Results from my research demonstrate the importance of including intraspecific competition in growth models. The incorporation of these results into stand growth models, specifically the Mixedwood Growth Model (MGM), will improve yield estimations for released white spruce

• Subjects / Keywords

  • Mixedwood Growth Model
  • White spruce advanced regeneration
  • Effects of competition on spruce growth

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3474704V

• 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.