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Topic

Forest Stand Hydrological Recovery of Snow Accumulation and Ablation Investigated Using Simultaneous Localization and Mapping (SLAM) Enabled LiDAR

Department of Geography

Date & location

• Tuesday, December 3, 2024

• 9:00 A.M.

• David Turpin Building

• Room B255

Reviewers

Supervisory Committee

• Dr. Daniel Peters, Department of Geography, University of Victoria (Co-Supervisor)

• Dr. Olaf Niemann, Department of Geography, UVic (Co-Supervisor) 

External Examiner

• Dr. Ed. Nissen, School of Earth and Ocean Sciences, University of Victoria 

Chair of Oral Examination

• Dr. Sonya Bird, School of Languages, Linguistics and Cultures, UVic 

Abstract

Forest – snow interactions were investigated using fine-resolution mobile terrestrial LiDAR scans carried out in four stands representing increasing forest maturity ranging from a recently replanted clearcut to a mature forest in the interior cedar – hemlock bio geoclimatic zone of the southern Selkirk Mountain range in British Columbia, Canada. Gridded models representing peak snow depth and average daily ablation were used to perform power analyses to investigate how sampling intensity impacts stand-level averages. These models were further used to determine the point sampling distances, or gridded model resolutions required to identify measured between-stand differences and within stand-variability of the snowpack. The return of snow accumulation and ablation processes in regenerating forests to pre-disturbance conditions, collectively referred to as hydrological recovery, has been investigated in past decades through manual snow surveys in adjacent open, juvenile, and mature stands. The outcomes of such studies provide a general understanding of hydrological recovery but lack transferability to areas where stand structure and terrain conditions differ from the reference sites. The application of mobile terrestrial LiDAR used here investigated peak snow water equivalent (SWE) and ablation rates beneath regenerating trees in a space-for-time substitution study design which provided new insights on the process of hydrological recovery in snowmelt forests of British Columbia, Canada. Outcomes of this study better quantify the influence of tree growth on peak SWE and ablation rate at both the tree and stand level for north aspect mixed conifer stands. Recovery of these two processes differ with recovery of Peak SWE beginning when the trees in a stand reach 3 meters in height and recovery of ablation rates beginning once trees reach 5 meters in height. Additionally, the process of negative ablation recovery in early juvenile stands reported in previous studies is herein clearly observed, providing an improved understanding of forest canopy effects on hydrological recovery in juvenile stands. The methods used in this study increase transferability of outcomes to stands where canopy characteristics (i.e., height, crown cover, and heterogeneity) are not represented in reference sites.