Saskatchewan, like other western jurisdictions, has recently revisited the regeneration assessment standards for its forest industry. Alberta’s Reforestation Standard and Manitoba’s Forest Regeneration Survey Manual were both revised in 2010. While all three standards measure renewal success, they differ in how this is accomplished.
Modelling the Future of Silviculture in Saskatchewan assess compliance with forest cover type transitions
Saskatchewan, like other western jurisdictions, has recently revisited the regeneration assessment standards for its forest industry. Alberta's Reforestation Standard and Manitoba's Forest Regeneration Survey Manual were both revised in 2010. While all three standards measure renewal success, they differ in how this is accomplished.
All regeneration assessment standards aim to provide several sources of information to ensure proper management of the future forest after harvest. Regeneration surveys provide basic information – stocking, survival, growth and species mixtures – to answer the question: is the forest regenerating?
At this basic level, however, there are still unanswered questions that are important to forest sustainability:
• Is the regenerating stand meeting the growth and yield predictions that underlie the timber supply analysis (and thus the allowable harvest)?
• Is a transition in cover type occurring from harvested to regenerated stands on a landscape level?
• Is industry meeting the landscape level renewal commitments in their forest management plans?
In answering these questions, Saskatchewan's approach is to leave the growth and yield analysis within the planning process, while tailoring the regeneration surveys to the issue of cover type transitions and compliance with the forest management planning assumptions. Changes to the Saskatchewan Regeneration Assessment Standard are currently in development. The intent of the changes is to generate cost-effective data that can be used to assess both block and landscape level compliance with forest management plans.
In Saskatchewan, the government requires industry to maintain cover species groups (S, SH, HS, and H) after harvest at the landscape level on each licence, not at the block level. In other words, industry is not required to return a particular hardwood-dominated mixedwood block to that state after harvest, as long this happens for a similar area elsewhere on the licence area. Since most of Saskatchewan's forest harvest is in the aspen-spruce mixedwood, ensuring the stability of cover species groups becomes a bit of an accounting exercise. Mixedwood succession is also an issue; rarely does the stand harvested at age 100 match what is regenerating at age 14.
The proposed changes to the standard will generate data that can be used for licence area
and landscape level analyses. These analyses will asses compliance with forest cover type transitions as described in the forest management plans and associated timber supply models, using modelled predictions of the future cover species groups.
Saskatchewan has been involved in the Western Boreal Growth and Yield Association for many years. One of the products of this effort is the Mixedwood Growth Model (MGM) developed by researchers at the University of Alberta. Details of MGM's recent validation will be published in an upcoming issue of the Forestry Chronicle. Saskatchewan has used MGM to develop matrices, based on regeneration survey density, that predict future cover species groups at various rotation ages. Using the regeneration survey data, these matrices will help determine whether industry is meeting landscape level planning targets in their renewal programs.
Assessing whether industry is meeting its landscape level forest cover type targets will be, for the most part, a GIS exercise. Analysts will overlay harvest depletion areas on the pre-harvest inventory to determine the overall area of the different cover species groups. Polygon by polygon, the species densities from regeneration surveys will be compared with the appropriate MGM matrix, providing a prediction of rotation age cover species group designations for each polygon. Compiling these areas by cover species group and then comparing it to the pre-harvest areas will give an indication of whether the landscape level targets are being met.
Repeated analyses over several years will detect any shifts in cover species groups affecting the approved harvest levels. By studying these trends, the government and industry can develop silvicultural practices to mitigate shifts. For example, if the analysis predicts a drop in hardwood-dominated mixedwoods, silvicultural ground rules can be developed that increase planting or better protect the spruce understory.
The proposed changes to the Regeneration Assessment Standard will have the dual benefit of being results-based and providing the information needed to assess industry's compliance with landscape level forest management planning assumptions. Saskatchewan intends to have the new standard in place in 2011.
David Stevenson, RPF works for the Forest Service Branch at Saskatchewan Ministry of Environment. He can be reached at [email protected]
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