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UBC Theses and Dissertations

Object-based image analysis protocol for historic trend analysis of forest structure in cumulative effects assessment of forest biodiversity : a feasibility analysis Gregg, Brandon


This research examined the feasibility of a geomatics solution to establish baseline conditions in forest structure using historical aerial photography and to assess trends in forest structure over time. The Geomatics Feasibility Assessment Framework (GFAF), designed for this research, has 3 components that work in a linear direction to assess conceptual and practical feasibility. Gap/opportunity analysis: Forest biodiversity is linked to the provision of ecosystem services (Millennium Ecosystem Assessment, 2005) and is a value in the Cumulative Effects Framework (CEF). Limitations to forest biodiversity assessment stem from the use of age-based inventories (e.g. VRI) and HRV-derived benchmark conditions. The Historic Aerial Photograph Heterogeneity Analysis (HAPHA) designed by Morgan & Gergel (2010, 2013) was identified as a potential solution. This conclusion is supported by: objective, efficient and reproducible analysis of historic photos using OBIA methods, and; the unique quantification of ecologically relevant metrics (i.e. heterogeneity). Pilot Study Design: A normative research design was constructed for the pilot studies. The design consists of a stratified sampling scheme, a comparative accuracy assessment and, a multi-variate mixed-effects (hierarchical) regression analysis. Based on data requirements of the research design, the GIS-based multi-criteria evaluation identifies two potential study areas: Opax/Isobel silvicultural research sites and Arrowstone Provincial Park. The sites were selected based on distinct anthropogenic and natural disturbance histories, existing data, consistent aerial coverage, and a shared BEC subzone. Cost/Benefit Analysis: Costs were estimated using a bottom-up estimation technique and expert judgement. For a single study area, a pilot study would cost between $13,900 and $21,400. Benefits were estimated through a comparative analysis of relatable research and assigned a likelihood based on a unique set of evaluative criteria and likelihood rubric. The potential benefits of this approach are being able to establish baseline conditions from historical imagery, quantify unique ecologically relevant metrics (i.e. heterogeneity) and identify trends in forest structure over time. Altogether the benefit is a unique assessment of forest structure that can be used to guide forest management activities including, but not limited to, cumulative effects assessment of forest biodiversity. The results indicate the benefits are achievable and pilot studies should be conducted.

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