Ministry of Forests

Cariboo Region Research Section


Mountian Caribou in Managed Forests

Preliminary Recomendations for Managers

During winter, the mountain caribou (Rangifer tarandus caribou) of southeastern and east-central British Columbia use mature forests almost exclusively The caribou range over large areas, feeding on the arboreal lichens that are most abundant on old trees. Forest harvesting in mountain caribou habitat is a management concern that has grown as timber supply pressures increase. The Mountain Caribou in Managed Forests (MCMF) program was begun in 1988 to address the question:

Can forest stands be managed, through silvicultural systems and habitat enhancemenr techniques, to sustain both timber harvest and mountain caribou habitat over the long term?

This report synthesizes the best scientific information on caribou/forestrymal1agement available at this time, for the use of resource managers at the landscape and stand levels of planning.

The report focuses mainly on winter ranges because they are the seasonalhabitats where conflict.s with forestry activities are most severe. Mature forests in the Interior Cedar - Hemlock (ICH) and Engelmann Spruce - Subalpine Fir (ESSF) zones are u.sed. Mountain caribou generally use low elevations more in early winter than in late winter; their use of the ICH zone varies geographically. During late winter, open-canopied stands in the upper ESSF are used regularly.

Arboreal lichens are important in the diet of mountain caribou throughoutwinter. caribou browse frequently during early winter, especially on low evergreen shrubs, but as snow depths increase they depend more on arboreal lichens. Key habitatattribute.s of early winter range include: low evergreen shrubs; lichens available as litterfall; on windthrow, and on .standing trees; and a conifer canopy that interceptssnow. Later in winter caribou regularly use open-canopied stands in the upper ESSF.The extra lift provided by a deep, settled snowpack allows the caribou to reach the lichens on the lower branches of trees.

I~lanlling for caribou habitat management at the landscape level must addressthe problems of maintainillg suitable lichen-producing winter ranges, minimizing habitat fragmentation, managing access~ and maintaining habitat separation frompredators. As well, planIlillg must recognize and address the risks of catastrophic events and of faulty assurnptions. An approach to habitat management at the landscape levelis suggested that includes a system of zones to protect seasonal ranges and linkage areas. Forest and access maIlagement strategies dilfer from one zone to another.

At the stand level, a set of management objectives and associated silvicultural strategies for caribou winter ranges have been developed. The combination of objectives that apply to any given site depend on the biogeoclimatic zone and season of use (early winter or late winter) by caribou. For example, amanagement objective that applies in all zor~e/season combinations is to maintain abundant arboreal forage lichens on standing trees. The suggested silvicultural strategy is to limit volume removal to approxirmately 30%, spread over a range ofdiameter classes. A management objectiYe that applies only in early winter range areas is to maintain low shrubs and avoid enhancing forage for moose and deer. The suggested silvicultural strategy is to minimize disturbance to soil and vegetation by winter logging on a protective snowpack, and using only spot scarification.

Forest stands in mountain caribou range can potentially be regenerated witha variety of selection and clearcut silvicultural systems. Uneven-aged silvicultural systems, including the single tree and group selection systems, are most suited to achieving and maintaining the stand characteristics needed by caribou over time.Both single tree and group selection systems are currently being tested in operationalscale research trials. Key management recommendations for stand-level operations are:

Various stand and habitat attributes are monitored in the MCMF experimentalblocks. These features include abundance of arboreal lichens available to caribou, growth rates of the lichens, microclimate in the lower canopy andlor at seedling height, actual use by caribou, snow characteristics, understory vegetation response, regeneration response, blowdown, and habitat attributes for other wildlife species.

In the next 5 - 10 years, significantly more information will be availableabout the short-term effects of various selection systems on cariboll habitat and timber values. Current recommendations may require some modification. However, important questions will remain, and long-term effects will not be known for many decades.Furthermore, even if the impact of selection harvesting on caribou at the individual level is clarified, its impact on caribou at the population level is likely to remain unknown.

Responding to the challenge of integrating resource use and cariboumanagement within portions of mountain caribou habitat will be a long-term process In the short term, silvicultural prescriptions and forestry development should followa conservative management strategy. Adequate monitoring of individual treatments and their effects on the overall resource is an integral component of the management scenario.

Forest stands in mountain caribou range can potentially be regenerated witha variety of selection and clearcut silvicultural systems. Uneven-aged silvicultural systems, including the single tree and group selection systems, are most suited to achieving and maintaining the stand characteristics needed by caribou over time.Both single tree and group selection systems are currently being tested in operationalscale research trials. Key management recommendations for stand-level operations are:

Various stand and habitat attributes are monitored in the MCMF experimentalblocks. These features include abundance of arboreal lichens available to caribou, growth rates of the lichens, microclimate in the lower canopy andlor at seedling height, actual use by caribou, snow characteristics, understory vegetation response, regeneration response, blowdown, and habitat attributes for other wildlife species.

In the next 5 - 10 years, significantly more information will be availableabout the short-term effects of various selection systems on cariboll habitat and timber values. Current recommendations may require some modification. However, important questions will remain, and long-term effects will not be known for many decades.Furthermore, even if the impact of selection harvesting on caribou at the individual level is clarified, impact on caribou at the population level is likely to remain unknown.

Responding to the challenge of integrating resource use and cariboumanagement within portions of mountain caribou habitat will be a long-term process In the short term, silvicultural prescriptions and forestry development should followa conservative management strategy. Adequate monitoring of individual treatments and their effects on the overall resource is an integral component of the management scenario.

 

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