UBC Theses and Dissertations
Strategy to convert an even-aged stratified stand to an uneven-aged mixed species stand English, Denise Lynn-Al
This thesis is the initial step of a long term study to evaluate and monitor a selection silviculture system applied to a 38.9 hectares private woodlot in the Golden moist-warm variant, of the Interior Cedar Hemlock (ICHmw1) zone. It establishes the selection silviculture parameters designed to convert an even-aged stratified mixed species stand composed of trembling aspen (Populus tremuloides Michx), paper birch (Betula papyrifera Marsh), Engelmann spruce (Picea engelmannii Parry ex Engelm), Douglas-fir (Psuedotsuga menziessii (Mirg.) Franco var. glaucd), lodgepole pine (Pinus contorata Dougla. ex. Loud var. latifolia) and subalpine fir (Abies lasiocarpa (Hook.) Nutt. var. lasiocarpd) into an uneven-aged mixed species stand over twenty years. A selection criteria for advanced regeneration and a tree classification method for crop trees were developed. In addition, the study includes a review of literature relevant to developing and executing a selection silviculture system for a mixed species stand. The literature review identified two important issues concerning uneven-aged management. First, long-term, site specific research is necessary to provide information on mixedwood, including deciduous species, selection silviculture systems in British Columbia. Second, the complexity of mixed species, uneven-aged stands excludes the use of existing yield tables, stand density diagrams and SI curves in the development of a mixedwood selection silviculture system. The advanced regeneration selection process, and classification for trees greater than 10 cm, builds upon existing information and data collection methods currently in place. The advance regeneration process and tree classification system will be used for the study site, but can also be used in the development of selection silviculture prescriptions in the Interior Cedar Hemlock zone. The landowner's preference to maintain high forest cover on the site for aesthetic and wildlife reasons was the basis for investigating a selection silviculture system. Selective harvesting of the 75-year-old stand over the past 27 years, and the stratified stand structure of the stand, has resulted in the stand having a reverse J-shaped diameter distribution suitable for a selection silviculture system. Analysis, of the original stand structure and the Prognosis modeling of possible stand treatment, assisted the author in developing a selection silviculture system. The above criteria, knowledge relevant to uneven-aged management, specifically the 'BDq' method, and results of analysis were amalgamated to formulate a management plan for the study site. The planned initial residual basal area for the study site is 24 m2 per hectare. The cutting cycle is five years. The target stand structure chosen for the study site has an initial "q" value of 1.5 for diameter classes greater than 15 cm. The target species composition maintains all of the six existing species as a component of the stand. The above parameters result in a predicted average annual increment for the stand of 3.8 m3/ha/year over the next twenty years.
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