A semi-natural approach to mixedwood management in the prairie provinces

Abstract

The white spruce-aspen mixedwood associations of the prairie Les peuplements mClangCs composCs d'Cpinette blanche et de provinces have a variety of possible compositions ranging from tremble que l'on retrouve dans les provinces des Prairies peuvent pure aspen to pure white spruce to mixtures of the two. Regulations se prksenter sous diverses compositions allant de la tremblaie pure and silvicultural treatments have been largely aimed at promoth la pessibre blanche pure tout en passant par un melange des deux. ing the more commercially valuable white spruce, largely through Les normes et les traitements sylvicoles visaient essentiellement plantation establishment and management. We feel that it is 2 promouvoir la plus grande valeur commerciale de l'kpinette blanche, time to re-evaluate our current management of these mixedprincipalement par voie de crCation de plantation et d'amCnagewoods for the following reasons: 1) Because of competition ment. Nous croyons qu'il est temps de rCCvaluer I'amCnagement from hardwoods and grass, white spruce regeneration has been actuel de ces peuplements mClangCs pour les raisons suivantes: 1) very expensive and only partly successful. 2) Hardwoods are now Parce que la lutte contre la compCtition exercCe par les feuillus et acceptable crop trees; the traditional conifer bias is now inappropriate les graminCes au niveau de la rCg6nCration de 1'Cpinette blanche and there are increasing possibilities for conflict between hards'est avCrCe dispendieuse et partiellement rCussie. 2) Les feuillus wood and softwood users of the same land base.3) The increased sont maintenant des espbces acceptables au niveau de la rCcolte; understanding of forest ecosystems and a strong environmental le biais traditiomel envers les conifres est actuellement inapproprik movement have resulted in demands for management systems that et les possibilitCs de conflits entre les utilisateurs de feuillus et de are ecologically based.rCsineux sur un meme territoire sont de plus en plus fortes. 3) La In future, management systems will likely move away h m expencomprkhension sans cesse plus pousste des 6cosystbmes forestiers sive single species plantation systems and promote more mixed ainsi que les mouvements Ccologiques plus que prCsents ont forests. To retain the white spruce component of these forests, sysentrain6 des demandes pour des systkmes d'amhagement qui reposent tems must be developed that enhance natural regeneration of lower plus sur 1'Ccologie. Dans l'avenir, les systbmes d'amknagement densities of white spruce over a wider area. These must be coudevront vraisemblablement s'kloigner des systkmes o n k u x de planpled with refined harvesting techniques that protect spruce regentation contenant une seule es* et faire une plus grande promotion eration during the harvest of the aspen. Growth and yield moddes peuplements mtlangb. M n de conserver la portion d'kpinette els must accurately reflect the ecology of mixedwoods. Tenure blanche prCsente dans ces peuplements, des systbmes doivent Ctre systems should ...

Early vegetation control for the regeneration of a single-cohort, intimate mixture of white spruce and aspen on upland boreal sites – 10thyear update

“…On the upland sites of the boreal forest, clearcutting is widely used to emulate fire in initiating stand renewal (Lieffers and Beck 1994). Following clearcut harvest, aspen frequently regenerates from root suckering with little or no subsequent silvicultural intervention (Lieffers et al 2003); stocking and density depend on the basal area, distribution and vigour of aspen in the parent stand, and the homogeneity of site conditions across the harvested area (Frey et al 2003, Gradkowski et al 2010.…”

“…Acknowledging the need to produce both aspen and conifer for commercial demand, while maintaining the ecological goods and services provided by mixedwoods, a number of research efforts have been directed towards creating spatial mixtures, through various arrangements of pure groupings of spruce and aspen (Groot et al 1996, Groot 1999, Comeau et al 2005, Man et al 2013, or intimate mixtures (with species separation on the scale of a few metres or less) by using mature or semimature aspen as a shelterwood for the regeneration of a younger age class of spruce (Lieffers and Beck 1994, Lieffers et al 1996, Comeau et al 2004, 2009). These approaches serve various ecological objectives, but share potentially serious operational shortcomings in the spatial and structural complexity of the stands that they create.…”

Ecosystem Responses to Partial Harvesting in Eastern Boreal Mixedwood Stands

“…They represent a transitional, post-fire stand development phase between break-up of an initial cohort of shade intolerant hardwoods and dominance by more tolerant, late-successional species [1,2]. The notion of natural dynamics-inspired silviculture or ecosystem management [3][4][5], notably for boreal mixedwoods [6,7], has progressively gained support in academic, governmental and forest industry communities and is now part of forest regulations in a number of jurisdictions.…”

Mapping conifer understory within boreal mixedwoods from Landsat TM satellite imagery and forest inventory information

“…To achieve sustainable management goals on the landscape, knowledge is required about forest ecosystems within a framework of maintaining and understanding ecological processes such as succession, (Franklin 1997). One example is the movement away from conventional pure plantations to management of mixed woods in boreal forests (Lieffers and Beck 1994 b) 60% deciduous/40% coniferous stand with white spruce in both the overstory and understory. In the boreal forest of western North America, mixedwood forests are found on mesic sites that are dominated by trembling aspen (Populus tremuloides Michx.)…”

“…If sufficient conifer understory exists, then Alberta Land and Forest Services harvesting guidelines ( http://www.gov.ab.ca/env/forests/fmd/manuals/index.html ) require the company with deciduous interests to implement protection strategies that reduce reforestation costs and minimize damage to the understory during removal of the overstory. Information about the understory component is therefore important for spruce management planning (Brace and Bella 1988) because of its contribution to future timber supply (Morgan 1991, Lieffers et al 1996, and has importance in other roles such as habitat diversity (Lieffers and Beck 1994).…”