Adaptive Management Projects

Project Summary: Alternative Silvicultural Systems

A number of trials throughout B.C. are looking at the feasibility (both economic and practical) and ecological merits of alternative silvicultural systems. These trials, such as the one summarized below, are providing information about stand level impacts, but uncertainty remains about impacts (and feasibility) at larger scales, and in other ecosystems and terrain. These questions could be addressed by applying adaptive management - where management plans are designed to compare alternatives and test hypotheses about responses at the landscape scale.

Management Issue (Quesnel Highlands ESSFwc3 project)

How can managers maintain habitat for caribou and extract timber economically, as well as address a range of other concerns?

Mountain caribou depend on the arboreal lichens found in stands with old-growth characteristics. Clearcutting would remove lichens for decades, reducing the amount of habitat suitable for caribou. As an interim measure, managers in the Horsefly Forest District have defined a "caribou line", above which no logging will occur.

There are also concerns about the effects of clearcutting in high elevation forests on visual aesthetics, regeneration, water quality, and biological diversity. Site preparation and artificial regeneration typically required after clearcutting have a number of undesirable effects, including smoke emission, herbicide use, and site degradation.

Group selection has been suggested as a way of maintaining old-growth characteristics at the stand-level and supporting the continued growth of lichen, while still allowing for some timber extraction. It may also address the issues of aesthetics, regeneration, and other environmental impacts.

Management Strategy:
Researchers are testing three different group selection systems that vary in the size of openings (0.3ha, 0.13 ha, and 1.00 ha) used to remove 30% of the volume. Treatments and a control are each applied over about 15 ha at three different sites in the ESSFwc3.

A number of regeneration methods are also being tested within each harvesting treatment.

Researchers are monitoring a range of indicators to address specific questions about responses at the stand level (e.g., growth rate of selected species of lichen, soil temperature, snow accumulation and melt).

Preliminary results are favourable: lichens are growing well in the partial cuts, and have been subject to little wind-scouring, and there have been few problems with windthrow.

Limitations of stand level trials:
While trials of this size can detect responses at the stand level (e.g., lichen growth, snow melt) they cannot answer questions about effects at the landscape level. Partial cutting may allow for adequate lichen growth in managed stands, but will caribou use watersheds made up of partially cut stands? How will road access provided by logging affect caribou populations? Some cumulative and emergent impacts may become apparent only when treatments are applied at large scales.

While this trial will provide information about the value and feasibility of group selection in high elevation ESSF forests, can these results be generalized to other biogeoclimatic subzones or to other terrain?

Applying adaptive management:
Replicated treatments could be applied over larger areas (e.g., subdrainages) and in more forest types and terrain. Managers could evaluate those treatments that have the most potential (based on results from stand level trials). In some cases, it may be informative to implement treatments that will discriminate between alternative hypotheses about landscape level responses.

Even where it isn't possible to find replicate landscapes, the "best" treatments (based on stand level results) could still be applied and monitored.

These large scale management experiments need not involve the same intensity and detail of monitoring used in the stand level trials. Managers could focus on those indicators most closely linked to management objectives (e.g., caribou populations).

In Plum Creek in the U.S.A., and in the Vernon Small Business Enterprise Program, managers have noted the benefit of trying new forest practices in a significant way, rather than just trying a few isolated experiments.

References:

Forest Sciences, B.C. Ministry of Forests, Cariboo Forest Region. 1992. Group selection system for high elevation forests (ESSFwc3) to maintain caribou habitat in the Cariboo Forest Region: Working plan. (EP 1104). Harold Armledder, Forest Sciences Section, Cariboo Forest Region. Personal communication, July, 1995.

Zielke, K. 1993. Environmental Forestry: Plum Creek Timber Company's approach to forest management. B.C. Ministry of Forests, Silviculture Branch and Forestry Canada. 21pp.

Peter Bradford, Silviculture Branch, B.C. Ministry of Forests. The Vernon Small Business Enterprise Program. Draft document, July, 1995. 5pp.