Identifying and Assessing the Yield Implications of Forest Canopy Gaps in Forest Management Using Full Feature LiDAR

  • Author / Creator
    Jensen, Daniel E
  • Gaps in the forest canopy are common in boreal aspen, spruce and mixedwood stands and can negatively affect forest volume. Data from four Alberta Vegetation Inventory (AVI) polygons, two aspen (Populus tremuloides) and two white spruce (Picea glauca), were analysed to determine how forest volume is affected by the presence of forest canopy gaps and to determine if this approach could be used to reconcile stand volumes estimated by growth models with volumes obtained from ground samples. LiDAR point clouds were processed to create canopy height models (CHMs) for each polygon to differentiate canopy cover from canopy gaps. Strong curvilinear relationships were found between LiDAR gap area and expanded gap area measured in the stands (R2 > 0.90). Based on the estimated expanded gap areas, the potential volume loss due to gaps in each polygon was assessed. Potential polygon volume was estimated by determining the average tree occupancy area for canopy trees within fully stocked areas of each polygon and then estimating the “missing” volume based on the number of trees required to fill the gaps. By comparing the estimates of volume lost to gaps to the potential polygon volume when the gaps were filled, it was shown that gaps affect volume by upwards of 18%. However, the effect of gaps on volume was variable between polygons. Lastly, the CHMs were combined with wet areas maps depicting depth to water index. Estimates of the effects of hydrology on gap size and frequency were calculated with results showing that gaps are larger and more frequent in poorly drained soils than they are in well drained soils.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • 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.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Renewable Resources
  • Specialization
    • Forest Biology and Management
  • Supervisor / co-supervisor and their department(s)
    • Bokalo, Mike (Renewable Resources)
    • Comeau, Phil (Renewable Resources)
  • Examining committee members and their departments
    • Nielsen, Scott (Renewable Resources)
    • Armstrong, Glen (Renewable Resources)
    • White, Barry (Alberta Environment and Sustainable Resource Development)