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Developing stand management prescriptions to maintain suitable habitat for Mountain Caribou
Klenner, Walt
Mitigating forest management impacts and assisting in the recovery of mountain caribou populations will require comprehensive analyses of various forest management activities on critical stand and landscape-level attributes for caribou. The amount and distribution of early seral forest conditions (ages 1-100) has been identified as the main causal mechanism in mountain caribou population (adult female survival) decline (Wittmer et al. 2005). The main shortcoming of early seral conditions (primarily age 1-40) is likely that these promote the growth of shrubs and browse for other ungulates (moose and deer), which consequently increase the number and proximity of predators in caribou habitat. Increased predator numbers in the proximity of caribou are believed to increase the likelihood of predators encountering caribou, possibly leading to higher predation rates (Wittmer et al. 2005, Stotyn et al. 2005). In addition, loss of winter habitat through logging reduces the availability of suitable habitat attributes, particularly lichen forage associated with old forests (Stevenson et al. 2001). Furthermore, roads constructed to access timber may exacerbate the problem by increasing the potential risk of disturbance, harassment, and predation. In the Headwaters Forest District, the Mountain Caribou Sub-committee of the Kamloops Land and Resource Management Plan identified the objective to maintain a minimum of 40% of capable winter habitats in suitable condition in all core caribou winter areas distributed in a way that minimizes interspersion of early seral habitat. The subsequent retention strategy developed by Furk and Lewis (2005) identified suitable habitats for retention based on existing models that use slope, stand age and leading tree species targeting attributes such as high lichen loading associated with these forest conditions. However, the strategy also recognized that caribou used many stands that did not fit the model, including partial cuts and younger mature (aged 80-140 years) forests. The suitability of these forests and their contribution to the recovery of caribou habitat within landscapes over time will largely influence future access to timber and sustainability or recovery of caribou habitat on the landscape. Thus, the objective to maintain 40% of capable winter habitat in suitable condition over time requires knowledge of how suitable habitat can be maintained, recruited from younger forests through time, or through stand-level treatments (i.e. partial cutting, thinning and spacing treatments). In particular, managers require better understanding of how habitat suitability changes through time so that the spatial and temporal placement of future cutting treatments on the landbase can be optimized to sustain existing suitable habitats and recruit optimal caribou habitat (landscape recovery) while providing access to timber. Our approach to address this knowledge gap is to use the stand model TASS (Tree and Stand Simulator)(Mitchell 1975) and an arboreal lichen model (Klenner et al. 2004) to identify general trends in the likely lichen response to a range of natural stand conditions and partial-cut harvesting options. A preliminary version of the lichen model was developed to work with TASS outputs to quantitatively assess relative amounts of available lichen forage for caribou under various stand-level management prescriptions by tracking changes in lichen growth and relative composition within an individual tree canopy over time in response to changes in available substrate and local climate. In addition, stand and local tree environment outputs derived from TASS can be used to understand changes of stand-level attributes and environmental conditions (e.g. ground-level light conditions) that promote browse for other ungulates. Because the models work at the individual tree level, they can measure responses to very specific stand-level disturbances such as insect mortality and wind-throw or ...
Report Number
Final Report
ESSF Stand Structure (Presentation)

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