Background - Silvicultural Terms in Canada







Second Edition (revised)



Industry, Economics and
Programs Branch
Canadian Forest Service
Natural Resources Canada




Ottawa, 1995
(Internet 1999)






©Minister of Natural Resources Canada 1995
ISBN 0-662-61680-4
Cat. no. Fo42-170/1995

Copies of this publication may be obtained free of charge from:

Natural Resources Canada
Canadian Forest Service
Industry, Economics and Programs Directorate
580 Booth St. 7th Floor
Ottawa, Ontario
K1A 0E4

Phone: (613) 947-9065
Fax: (613) 947-9020

A microfiche edition of this publication may be purchased from:

Micromedia Ltd.
165 Hôtel-de-Ville St.
Hull, Quebec
J8X 3X2

2nd Edition compiled by François Sauvageau, ing.f.

Canadian Cataloguing in Publication Data

Main entry under title:

Silvicultural terms in Canada

Second edition

Text in English and French with French text on inverted pages.
Title on added t.p.: Terminologie de la sylviculture au Canada.
Prev. publ.: Canada. Forestry Canada.
Science and Sustainable Development Directorate, 1992.
ISBN 0-662-61680-4
Cat. no. Fo42-170/1995

1. Forests and forestry — Canada — Terminology.
I. Canadian Forest Service. Policy, Economics and International Affairs Directorate.

SD126.S28 1995     634.9'5'03      C95-980098-0E






Part I  Canadian Silvicultural Practices: An Overview

            Historical Development

            Basic Silvicultural Practices
                Ecological Classification
                Securing Natural Regeneration
                Use of Artificial Regeneration

            Intensive Silvicultural Practices
                Precommercial Thinning (PCT)
                Commercial Thinning (CT)
                Pruning and Shearing
                Timber Stand Improvement (TSI)
                Fertilizing and Drainage

            Special Silvicultural Practices
                Seed Orchard Management
                Nursery Management
                Recreation and Landscape Silviculture

            Silvicultural Surveys and Stand-History Record Keeping

            Preparation of Silvicultural Prescriptions




    This second version of Silvicultural Terms in Canada represents an enlarged version of the first edition coordinated by Brian Haddon. Many terms used in the Canadian forestry context have been added to the content of the first edition, to encompass all the standard fields of silvicultural practice. Detailed reviews were kindly provided by silvicultural specialists accross Canada. Special thanks are extended to Jim Ball, Lisa Buse, Rob Cameron, Bob Currell, S.W.J. Dominy, Willard H. Fogal, Andrew Grauman, Richard H. Kendall, Janet Lane, Victor Lieffers, R.L. Macnaughton, Michael D. Meagher, E.K. Morgenstern, Donald N. Nixon, G.R. Powell, Jim Richardson, Victor G. Smith, W.M. Stiell, Roy F. Sutton, Brad Sutherland, Al Todd, Jim Wood, and Christopher W. Yeatman for their contributions to the English text, and Jean-Marie Binot, Jean-Louis Brown, Sophie Calmé, René Doucet, Alain Fortin, Jean-Guy Ruel, and Réjean Talbot, for the French text.








    Silvicultural practices in Canada have been developed in response to local or regional needs. Understandably, the terminology used to describe these practices in different parts of the country tends to have local and regional variations. Presentation of a clear picture of silviculture in Canada, based on statistics aggregated from various sources and jurisdictions, requires consistency in the use and meaning of terms describing silvicultural activities. The intent of this publication is to provide a basis for adoption by the Canadian forestry community of a common silvicultural terminology.

    Specialized aspects of silviculture, such as tree breeding techniques, are beyond the scope of this publication. This second edition of Silvicultural Terms in Canada is not meant to be definitive, nor will it be all-inclusive. Several definitions in the Glossary include reference to regional variations in the meaning and usage of certain terms.

    Silvicultural practices and terminology are constantly evolving. Comments and suggestions for improvement to this publication are welcome. Please address them to:

Natural Resources Canada
Canadian Forest Service
Industry, Economics and Programs Directorate
Sir William Logan Building, 7th floor
Ottawa, Ontario
K1A 0E4




Part I

Canadian Silvicultural Practices:
An Overview

    The purpose of Part I is to provide an overview of silvicultural practices in Canada and to explain the context in which silvicultural terms are used. Canadian silvicultural practices should be considered against a background of diminishing virgin forests and the expanding world need for all kinds of forest products and benefits. Three things are evident: first, it is becoming necessary to grow timber rather than find it; second, silviculture needs to be intensified; and third, it is necessary to learn how to accommodate the demands for different uses made of the forest.

    A forest stand can be made to increase its timber yield by:

Changing the stand density and structure.
  • Increasing the net balance of photosynthesis to respiration by crop trees and the forest stand as a whole.
  • Making genetic improvement in the tree species grown.
  • Eliminating forest-floor vegetation that competes with trees and thus detracts from wood production.
  • Using new or different species, strains, or races of trees on particular areas to give greater total wood production or improved quality and stem form.

Ways of changing forest site productivity to increase wood yields are:

  • Restoring lost productivity of abused sites by protection from fire, grazing, and abnormal erosion and by the use of species adapted to the soil and climate.
  • Improving the productivity of the site by cultivation, fertilizing, or irrigation.

          These ways of increasing wood yield are stand-level actions, that is, actions taken to change the structure and dynamics of individual forest stands. Forests are composed of many individual stands, usually grouped into a forest management unit for planning purposes. Forest management involves actions at the level of the whole forest management unit: protection; forest renewal and stand tending; determining the size, location, and scheduling of harvests; and multiple-use planning.

          Silviculture is not forest management. Silviculture consists of actions taken at the level of individual stands to renew and enhance the forest crop to meet stand management objectives for timber, wildlife, recreation, landscape design, preservation, and water yield.


Historical Development

    From 1910 to 1950 Canadian silviculture was primarily concerned with planting trees on prairie farms and abandoned farmland in eastern Canada. Unassisted natural regeneration was relied on in the logging of public forests. In the 1950–1970 period much effort was put into ways to assist the natural regeneration process by modifications to the cutting patterns, scarification, and preparation of ecologically based natural regeneration prescriptions. Some planting and tree-improvement programs were started in this period. Between 1970 and 1980 emphasis was placed on quality planting and dealing with not satisfactorily restocked (NSR) lands, including expanded use of herbicides (Weetman 1982).

        The period 1980–1990 has seen further expansion of planting programs to cover over 25% of the approximately 900 000 ha of annual cutover (Kuhnke 1989). The distinction is made in some provinces between basic obligatory regeneration silvicultural practices required of licensees to reach free-from-noncrop-competition (free-to-grow) status and incremental or intensive silvicultural practices to improve and accelerate stand performance.

        Initially, most silvicultural programs were implemented by government agencies. During the 1980s the silvicultural contracting industry expanded rapidly as government programs were privatized. Increasing emphasis is now placed on customizing and designing silvicultural and forest management programs to forest age-class structures to ensure continuity of wood flows. By 1990, most surplus allowable cut in the provinces had been taken up by new industrial expansion. Although most logging operations are still cutting, and will continue to cut, old-growth virgin timber, the end of this supply is now approaching. The emphasis of silvicultural practices has shifted from almost total concern over successful regeneration to a more balanced and designed program of regeneration and stand-tending actions, based on preharvest silvicultural prescriptions. This shift in emphasis has focused attention to precommercial thinning, pruning, tree improvement, commercial thinning, and fertilizing to produce quality stands in the time frame imposed by declining old-growth reserves.

        As public concern about the appearance and environmental effects of clearcutting (the dominant harvesting practice) mount, increasingly attempts are made in silvicultural prescriptions to use appropriate alternative harvesting systems that meet multiple land-use constraints imposed by public demands, the concerns of wildlife, recreation, and watershed managers, and the mandatory requirement for successful regeneration.


Basic Silvicultural Practices

Ecological Classification

        Following early unsuccessful attempts with large-scale applications of modified harvesting systems or of simple planting rules to large, ecologically complex forests, it became evident that the biological guidance for successful regeneration must be based on more detailed study of forest ecology. The approach used has been biophysical classification, that is, the classification of forest land on the basis of ground vegetation in relation to a nutrient and moisture regime matrix. These regimes range from dry to wet and from poor to rich.

        The ecosystems or site associations are recognized as operational silvicultural groups in the nutrient–moisture matrix. The matrices are set up for large ecoregions or biogeoclimatic zones representing a recognizable regional relationship between forest cover, climate, and landform. The units recognized are described in terms of typical forest types and associated soil-profile characteristics. Management interpretations, limiting factors, and successional information are also provided; thus, a biological-classification framework, based on natural forest conditions, is the basis for silvicultural practices. Around the classifications are accumulated knowledge and experience on silvicultural successes and failures, and forest-productivity information. This knowledge base is thus called site-specific. It has been found to be an essential framework for silvicultural practice if mistakes are to be avoided and feedback from successes and failures is to be understood and explained.

Securing Natural Regeneration

        All of Canada’s forests originally developed from natural regeneration without human intervention. Fire, blowdown, and insect attack are the usual agencies for mortality of old timber, and the tree species are adapted to regenerate after these disturbances. Harvesting of timber results in some critical changes to seedbed conditions and seed supply that have no natural precedent.

        Observations on the circumstances surrounding successful natural regeneration lead to silvicultural prescriptions designed to provide appropriate seed supply, seedbed, and moisture and vegetative conditions that favor desired tree species.

        The combination of cutting method and other treatments by which a stand is established or renewed is a reproduction method (Smith 1986). The planned program of silvicultural treatments during the life of a stand is a silvicultural system. The following silvicultural systems are used in Canada:

  • clearcutting systems, involving the removal of all trees;
  • shelterwood systems, involving the retention of an overstory of mature trees while an understory of regeneration becomes established; such an understory is called advance growth and often occurs naturally in old forests;
  • seed-tree systems, involving the leaving of a selected number of individual or groups of trees of superior form together with a receptive seedbed;
  • selection systems, involving the maintenance of an uneven-aged and uneven-sized stand structure that is self-regenerating and periodically harvested to remove a portion of the growing stock from trees of all size classes;
  • coppice systems, involving clearcutting but relying on the vegetative propagation of a new crop of trees from stump sprouts or root suckers.

        Each tree and plant species has particular reproduction and growth strategies and characteristics, and this body of knowledge is known as the silvics of the tree species (Fowells 1965; Daniel et al. 1979).

        It is not biologically possible to secure both rapid and abundant natural regeneration in many Canadian forest associations, even when silvicultural systems are carefully prescribed. We continue to harvest large areas of very old overmature forest that are often composed of climax species, ill-adapted to rapid establishment and growth on open cutovers. The extreme age and high incidence of decay and disease in old forests often mandate clearcutting. Clearcuts are initially not beautiful and are subject to much public criticism. Planting such areas is usually required for prompt regeneration. Large areas of poorly stocked cutovers of this type have accumulated in the absence of planting. They are known as backlog and are given high priority for artificial regeneration treatments. The mechanical preparation of improved seedbeds, primarily designed to expose mineral soil and remove vegetative competition, is called scarification. Scarification treatment is a common component of natural regeneration prescriptions.

Use of Artificial Regeneration

        The decision to use artificial means to regenerate forests is taken where:

  • Natural regeneration cannot be reliably secured or is excessively dense, of poor quality, diseased, or of undesirable species.
  • Prompt regeneration is needed with simultaneous control of species and density.
  • The benefits of tree breeding and tree improvement are available in improved nursery stock.
  • Matching species to site and/or planting an exotic species will result in significant gains in production.


        Since such circumstances are common, artificial regeneration has expanded greatly in the 1960–1990 period. Approximately one-third of current cutovers are planted (Kuhnke 1989).

        Use of artificial regeneration requires the following:

Seed supply

        Seed collections must be made either from natural untreated stands, selected natural stands dedicated to seed production (seed production areas), or plantations of families of selected trees planted in orchards and subject to irrigation and fertilizing to induce flower production (first-generation seed orchards). Following cross-pollination between families and progeny, test seed orchards are rogued to leave orchards composed of trees of proven genetically superior performance (second-generation seed orchards).

        Tree species vary in their seed production patterns and seed storage and germination requirements (USDA 1974). Forest tree seed is usually labeled by seed zones and location and there are generally rules controlling the use of seed outside its zone or elevation range.

        Forest tree seed is usually stored in large central seed banks under refrigeration, with enough storage to provide many years of demand for each species. Some species and seed zones are in short supply. Large amounts of first-generation seed-orchard seed will not generally be available until at least the year 2000.

        Some species, notably black spruce and jack pine, produce large quantities of seed in cones stored on trees for many years. Collection of their cones is easy, and this leads to large reserves of inexpensive seed in storage. This seed is used in direct seeding, from aircraft or ground (for example, snowmobiles, all-terrain vehicles), usually on scarified cutovers. Direct seeding relies on large quantities of tree seed, and thus on inexpensive tree seed. For this reason direct seeding is mainly limited to these two species.

        Cone collections are often made from trees felled in logging operations. Access to cones in standing trees is gained through tree climbing, ladders, and lifting devices. Cone rakes are sometimes used in difficult terrain.

        Seed collected from different parts of the range of a tree species is tested for suitability at different locations in provenance trials. Seed from certain provenances is in short supply. Some provenances of British Columbia seed, notably Douglas-fir, Sitka spruce, grand fir, and lodgepole pine, are famous or infamous in Europe for their superior or inferior characteristics. Historical lack of control over seed supply and subsequent poor plantation performance gave rise to the current tight restrictions and government control on seed collection and storage and allocation on Crown lands in Canada.

Nursery practices

        Seedlots of species selected as suitable for specific forested sites are sent to forest nurseries for the production of planting stock. Originally, most planting stock was produced in bare-root nurseries, where the seed was sown on raised beds, covered with protective grit or sand, grown for one or two years, and then either outplanted in the forest, or transplanted in the nursery for a year or two to grow bigger before outplanting.

        Currently, most nursery stock is raised in containers in greenhouses under more controlled temperature and moisture conditions and is irrigated with standardized nutrient solutions. Container seedings grow faster, are more uniform, and are often cheaper to produce; however, they are often less able to compete after outplanting than bare-root stock. The stock type is usually ordered and custom grown one to three years in advance of outplanting. Current Canadian production is approaching one billion seedlings per year, grown in government and private nurseries. Much planting stock is held in cold storage following lifting, then trucked various distances to planting sites. Over 95% of the production is conifer, two-thirds pine and spruce species. There is a limited production of poplar raised from cuttings.

Site preparation

        Physical disturbance of the forest floor to create improved seedbeds for natural regeneration is called scarification. Site preparation practices are used to make the task of planting easier and to aid plantation survival and growth. The practices consist of the mechanical actions of ploughing, discing, trenching, crushing, and slash piling; the use of chemicals, usually herbicides, to kill or suppress competing vegetation; and prescribed burns to remove slash and woody debris, set back competing vegetation, provide ash as fertilizer, and increase nutrient mobilization and availability through increased soil temperatures. Such site preparation techniques are often essential for plantation establishment on richer sites, that is, very fertile soils prone to rapid brush and grass invasion. There has been rapid development of a wide variety of mechanized site-preparation equipment, aided by the availability and development of specialized prime movers for logging (wheeled skidders, specialized tracked tractors, and new types of forwarders and backhoes).

        The use of prescribed burning has expanded rapidly following the development of fire ignition systems from helicopters and the scientific calculation of burning indices, slash loadings, and rates of fire spread. Site-preparation practices are a particular necessity in Canadian conifer silviculture because of the many unusable small trees, rotten trees, and noncommercial trees in the virgin old-growth forests that are being cut today; the need to improve soil temperatures in northern forests with thick humus layers; vegetative competition on clearcut areas; and the large volumes of slash.

Planting methods

        Of all the silvicultural practices, the task of planting approximately a billion trees per year is the least mechanized. Careful planting on the appropriate microsite is very important; this can really only be done well by hand, in spite of many expensive attempts to develop mechanized planting machines. Over a million person days of work per year are required. Manual planting is a major source of annual income to the reforestation contracting industry.

        Not only must seedlot and species be custom selected for each planting site, but so must the planting-stock type, that is, its age, size, and whether it is bare-root or container, and if container, of what container size and type and whether the type is compatible with the treatment used.

        Planting is usually done in early spring following snowmelt and is subject to rigorous quality checks and inspections. Payment is usually on a piecework basis. The work is physically demanding and is usually carried out by young people using tools such as planting mattocks or shovels for bare-root stock or planting tubes for container stock.

Vegetation management practices

        Experience has shown that planting must be followed by tending practices to ensure free-growing trees, that is, trees free enough of competition and with adequate supply of moisture and nutrients to ensure continued survival and height growth. Achievement of free-from-noncrop-competition status is a mandatory basic silvicultural requirement for licensees on Crown lands in some provinces. Vegetation management practices include those of site preparation before and after planting and also following natural regeneration germination (Walstad and Kuch 1987). Release of trees from competing vegetation (weeds) uses chemical methods (usually selective herbicides with and without fertilizers), manual methods (hand slashing, pulling, and thinning with chain and brush saws), and biological methods (cattle, sheep, goat, and deer grazing).

        The objective of free-from-noncrop-competition status is to ensure a new forest crop of reliable and predictable stand development, low in risk and with calculable dimensions, product values, and yields.

        Basic silvicultural practices are regarded as the minimal performance needed on public lands to ensure that the productivity of the new crop of trees will be as good as or exceed that of the original stand.

        Provincial forest service policies seek to assign to each Canadian generation a limited equity in forest resource property and to pass it undamaged from generation to generation. Basic silvicultural practices are seen to satisfy this ethical responsibility.

Intensive Silvicultural Practices

        After a new crop of trees has been established and reaches a free-growing condition, the future timber and other resource values of the forest stand can be further enhanced by intensive silvicultural practices.

Precommercial Thinning (PCT)

        Any given stand has a limited capability to produce an annual volume of timber, when the site is fully occupied by trees; precommercial thinning accentuates the volume production on fewer trees and trees of desired species. It is usually done manually using brush and chain saws or mechanically with tractor-mounted flails or saws. PCT homogenizes the stand, increases mean tree size, and lowers the age at which the stand can be harvested. The practice is difficult to mechanize and is very expensive; more than one person-day per hectare is commonly required. In spite of its high cost, this practice is common. Accelerated harvest of younger stands often allows for accelerated harvest of older overmature stands in a forest management unit, thus yielding more than enough revenue to pay for a PCT program. PCT also reduces logging costs and increases product values. Wildlife habitat and landscape values are often improved. Without PCT treatment, stands on lower-fertility sites may never be operable. Stands may be left at final crop density or may be designed to allow for one or more commercial thinnings.

        The practice is called precommercial since it is done shortly after crown closure, the time at which the available crown space has become fully occupied. The trees are relatively small and there is no market for the cut trees.

Commercial Thinning (CT)

        Up to 30% of the total volume production in a stand can be lost due to competition-induced mortality (smaller trees in dense stands die because there is not enough growing space for all of them). Commercial thinning attempts to recover this mortality loss and to provide early income from a stand by harvesting trees big enough to have product value. In practice, it is almost impossible to recover all potential loss through mortality because repeated light thinnings are necessary if residual stand volumes sufficient to maintain stand growth rates are left after each thinning.

        Because of present Canadian market conditions and the high logging cost of thinnings, most of the repeated light thinnings desired are unmarketable and too expensive; even a single thinning may not be economical. Commercial thinnings are more likely to be economical if the stand has had density control at establishment or by subsequent precommercial thinnings. Currently, very little commercial thinning is done in Canada, primarily due to unsuitable stand densities and species, high logging costs, and low stumpage values.

Pruning and Shearing

        After stands have been reduced in density to the point where valuable final crop trees can be identified at an early age, pruning is possible. Pruning increases the value of individual trees by prematurely removing the lower branches so that clear wood, free of knots, is laid down around an unpruned knotty core. Several valuable tree species have branches that do not rot off readily and remain persistently on the tree even after death due to shading.

        Dead and live branches are cut off flush with the trunk using manual handsaws; mechanization is very difficult. Repeated prunings are needed to maintain a cylindrical knotty core and yet not remove too much live crown.

        Pruning is very expensive; for it to be economical the increase in stumpage value of clear timber over knotty timber must be great and the stand must have been thinned. Since these conditions are rare in Canada, pruning is little practised. As more and more PCT-treated stands accumulate and as supplies of clear old-growth timber diminish, pruning will become more economically attractive. The practice requires a 20- or 30-year lead time before clear wood in sufficient quantities is produced by a tree. The most common species pruned are white pine and Douglas-fir.

        Shearing is the practice used in Christmas tree culture: a shaping of the form of the tree to make it more saleable. It is usually done with sharp knife blades. Pine trees are treated while in candle, that is, while the leaders are growing. Other conifers are treated after bud formation.

Timber Stand Improvement (TSI)

        Timber stand improvement — cutting down or poisoning all deformed and unwanted trees within older stands — is usually done in previously untended hardwood stands containing valuable trees mixed with less valuable ones. It is usually a noncommercial practice, in that no revenue is generated, although some fuelwood may be produced. The objective is to concentrate the growing capacity of the site on the most valuable trees, without excessive growing-stock reduction and loss of growth. Eastern Canada has very extensive areas of tolerant hardwood forests, often previously subjected to cuttings that removed the most valuable trees and left the least valuable. Such stands are of low quality and should be treated by TSI practices. Currently, TSI is little practised because of the high cost and lack of immediate return.

Fertilizing and Drainage

        The growth rates of individual trees and stands can be increased by providing additional supplies of limiting nutrient elements. In contrast to agricultural crops, forest ecosystems recycle nutrients; however, many forest stands are mainly limited by their nutrient supply, rather than by their climate, temperature, or moisture regime.

        Granular fertilizers are spread by helicopter on designated forest stands, an expensive practice. Because of the high cost of the extra fertilizer-grown wood, the fertilized trees must be final crop (the stand thinned to final crop density) and the stumpage values high. In addition, there may need to be a shortage of stand volumes in certain forest age classes in a management unit. It is essential that the forest stand be known to be responsive to such treatment.

        Most stands are fertilized after crown closure, usually at final crop density. Some fertilizing at the time of planting or immediately after planting is also done. To be successful, vegetation management is required, together with accurate diagnostic tests of regeneration nutrient status.

        Drainage of forest sites, especially organic soils, has a great potential to improve stand growth. Although it is widely practised in the boreal forests of Finland, where timber and growing sites are in short supply, it is used only experimentally in Canada, usually in black spruce muskeg conditions. The practice requires large forest ploughs or specially designed backhoes. The distance and depth of drainage ditches must be carefully matched to the organic matter classification and hydrological characteristics.

Special Silvicultural Practices

        Most of the previous intensive silvicultural practices are used to enhance timber production. In addition, there are cultural practices designed to attain other objectives.

Seed Orchard Management

        Designed to maximize cone production, the practices involved in seed orchard management are drainage to control soil moisture; standpipe mist irrigation to delay bud formation until local pollen sources have gone; repeated nitrogen fertilizing and basal scarring to stimulate female flower bud formation; radical top shearing for convenience of cone picking; and cross-pollination breeding and progeny testing followed by roguing.

Nursery Management

        The management of forest-tree nurseries is highly specialized and more akin to agriculture than to silviculture. Every nursery has its own special problems that must be worked out by experimentation. Seedlings that are grown outdoors are usually grown from seed and are bare-root, which means that their roots are separated from the soil when they are transported to the final planting site. However, the reestablisment of contact between roots and soil is so crucial that planting can be done only during those short seasons during which there is rapid root growth. The alternative techniques of growing planting stock from vegetative cuttings or in containers, especially the latter, have known a tremendous increase in recent years.

Recreation and Landscape Silviculture

        TSI, PCT, and CT and vegetation management practices are applied to meet the needs of tourist campers, hikers, and motorists in parks, recreation areas, and commercial timber forests. Landscape design criteria often require a major modification of the cut-block layout and influence the choice of silvicultural system and even of species for planting. Pruning of trees along roadsides in forests provides views into stands. Forests stands are deliberately manipulated by silvicultural practices to improve wildlife habitat. Stand-level practices include PCT, CT, and fertilizing to encourage understory forage production; use of selection silvicultural systems along streams and rivers to protect riparian habitat and keep water temperatures cool; and the retention of snags, dead trees, and wolf trees for nesting. Cutovers, forest meadows, and stands are set on fire to create forage and set back succession. Grass seeding is a common practice on cutovers on open-range situations in western Canada where cattle graze.

Silvicultural Surveys and
Stand-History Record Keeping

        One of the essential features of forestry practice is the planning of silvicultural actions in a way that meets the owners’ stand management objectives. Planning requires excellent record keeping and monitoring of stand performance by surveys. Silvicultural survey practices include those of regeneration and backlog assessment surveys, plantation surveys, and free-from-noncrop-competition surveys. All data are entered into stand-history record-keeping systems, which are in turn components of forest inventory and planning systems.

        Silvicultural surveys of every cutover area are required during a 10- to 40-year period until the new stand has reached crown closure. This means an annual workload of 1–3 million hectares of silvicultural surveys in Canada. These surveys involve fieldwork or the use of remote-sensing techniques. Fieldwork varies from field walk-throughs to the sampling of numerous small, temporary and permanent plots established in grid patterns on cutover areas. The plots are measured for species frequency; tree density and height; occurrence of insect, disease, and other damage; and competing brush invasion.

        Since most commercial forest land in Canada is under lease for timber harvesting with a legal obligation for successful regeneration or free-from-noncrop-competition status, the silvicultural surveys represent inspections of performance. Such inspections are done by provincially licensed or approved silvicultural surveyors in some provinces.

        Stand-history record-keeping practices are usually computer-based storage and retrieval systems on a stand-by-stand basis. These systems are often linked to a geographic information system (GIS) and a broader total forest inventory and planning system. Such systems are maintained and developed by both corporate licensees and provincial governments. Canada has no national system of standhistory record keeping.

Preparation of Silvicultural Prescriptions

        The final major field of silvicultural practices, apart from the business and legal components of silvicultural contracting, which are not considered in this discussion, is that of preparing silvicultural prescriptions.

        This silvicultural practice involves assessing the stand for growing stock, stand structure, species composition, fertility and moisture regime, amount of regeneration, seedbed and seed supply situation, brush invasion, and landscape, recreation, and wildlife habitat values; planning stand establishment and crop tending; writing a detailed prescription; implementing and monitoring the planned actions at the stand level; and determining the impact on forest-level objectives. Such formal analyses and prescriptions are mandatory in some provinces for every cutover area and must be signed by a professional forester (thousands are required every year). They have become necessary because of controversies over the use of forests for multiple purposes, such as timber, recreation, wildlife, landscape scenery, and nature conservation, and because the biological variation and complexity of forests do not allow for standardized successful treatments.

        The stand inventory is related to various feasible stand management alternatives that meet landowners’ objectives and are economical. The best prescription is chosen and a detailed year-by-year plan of implementation is designed with recommendations on costs and details of procedure. The whole procedure is similar to the work done by engineers and architects in design work. The preparation and implementation of a successful silvicultural prescription is the ultimate test of the professionalism and ability of a Canadian silviculturist.