Regeneration Cutting Methods FRST 211

Additional Reading: Smith et al The practice of silviculture: applied forest ecology. Chapters Klinka and Varga. Select CD.

Silviculture system: A program of treatments for a whole rotation. Pre-harvest prescription Regeneration cutting method Harvest system Site preparation Regeneration Post-regeneration treatments Brushing Spacing Pruning Fertilization Thinning Pre-commercial thinning Selected to address objectives and constraints for the site.

Regeneration cutting methods Silvicultural systems are named after the method of regeneration cutting by which a stand is replaced. 1.Clearcutting 2.Group selection 3.Single-tree selection 4.Shelterwood systems 5.Seed tree 5 main systems Each system has several variations depending on management objectives and site features Naming of each method should be regarded as ‘descriptive’ not ‘prescriptive’

Removes an entire stand of trees from >1 hectare, and >2 tree heights in width, in a single harvesting operation. A new, even-aged crop is obtained either by planting, natural or advance regeneration, and/or direct seeding. Clearcut System >1 ha >2 tree heights in width >50% open area climate (not influenced by edge) Can include green tree or patch retention

Clearcuts vary in size and shape

Clearcut with reserves Commonly around 8-10% of block is left as reserve area

Bowron River Valley Clearcuts Response to large spruce bark beetle outbreak 1980’s 80km SE of Prince George 48,000 ha harvested 3,000 ha were burned Replanting Operation 70% Interior spruce 28% Lodgepolepine 2% Douglas Fir Mid 1980’s $870M generated from this area $27M was returned to the province as stumpage and taxes

Bowron River Valley Clearcuts Recovery… 2008 image Google Earth

Bowron River Valley Clearcuts Recovery… Large area of young plantations

Clayquot Sound: The War of the Woods (1994) Large progressive clearcuts resulting from road building policies Large public protests forced government and forest companies to use alternative harvesting methods

Greater social and scientific constraints Greater governance by higher level plans and regulations Focused more on what we leave behind Attempt to manage under guiding principle of ‘range of natural variability’ Most sites (on coast) now harvested with “variable retention” systems Recent changes in approach to forest management

Borrows aspects of both even-aged and uneven-aged regeneration cutting systems. –Minimum of 50% of cutblock within the ‘forest influence’ or one tree length from an edge. –Irregular boundaries and the retention of dispersed trees or groups provide ‘forest influence’ –Regeneration in open areas usually even-aged arising from either natural seed or planting. Variable Retention Fundamental management objectives -Reduce ecological impact of harvesting by retaining elements of stand and forest structure -Reduce aesthetic impact of harvesting to gain public acceptance

Aggregate Retention

Dispersed Retention

Selected trees or tree groups left during harvest to provide a seed source for natural regeneration. After natural regeneration is achieved, the seed trees may or may not be removed. Seed Tree System Used with shade intolerant/exposure tolerant species Timing of cut and site preparation as important as spatial configuration produces single or multiple species, single or double cohort stands

Mature trees removed in a series of cuts to achieve a new single or double cohort stand under the shelter of remaining trees. Removes successive components of the existing stand. Regeneration may be planted, natural, or advance. Shelterwood Systems Intent of these cuttings is to: provide shelter provide seeds for natural regeneration provide for volume increments of retained mature trees

May be a series of cuts over years Seed cut: allows for regen to establish Release cut: releases established regeneration Used for shade tolerant/protection requiring species preparatory cut seed cut final release cut release cut Uniform shelterwood

Small openings are created in the stand such that the adjacent trees shelter the new regeneration. The size or density of leave-tree groups decrease through one or more future stand harvests, until the mature overstorey has been completely removed. Regeneration methods may include natural and/or artificial regeneration. Group Shelterwood System May create single cohort or multi-cohort stands

A series of progressive, linear cuts in narrow successive strips. oriented to minimize wind damage to residual stand (In windthrow-prone areas). oriented to take advantage of shading (In areas subjected to drought stress) Strip Shelterwood System

Cut strips to minimize damage and enhance seed fall (seed rain) First cut makes windward edge prone to windthrow Orient cut to take advantage of natural protection (e.g., topography) to windward edge Windward edge becomes increasingly windfirm with time Seed fall is greatest on leeward edge and decreases with distance from edge Windward and leeward edges provide shelter for new stand Width of strips balances seed rain, shelter & resource availability for new regen (<2 TH) In subsequent cuts, cut strips in lee of prevailing wind Cut windfirm edge last Strip Shelterwood systems in windthrow-prone stands Wind, seedfall cut shelter Managing windthrow and seed fall

E-W Strip shelterwood cutting to produce multi-cohort stands Orient strips to minimize limitations to regeneration In a climate where growing season water deficits limit regeneration, shading on south edge of opening enhances water availability during summer drought Orient strips E-W to maximize shaded edges In subsequent cuts, cut N edge of opening so that established stand protects new stand In a climate where cold temperatures and late snow lie limit regeneration, insolation on north edge of opening warm soils and extend length of growing season Orient strips to maximize warm edges Managing resource limitations South edge of openingNorth edge of opening

Different species in overstory Overstory provides protection to regeneration Overtory can be from original stand or established after a cut Nurse tree shelterwood

Harvesting timber at specified repeated intervals Harvesting single scattered individuals or small groups of individual trees Encouraging relatively frequent establishment of regeneration in canopy gaps Encouraging and maintaining an uneven canopy and an uneven-aged stand structure Selection systems (Uneven-aged management)

Small gaps with removal of single trees or very small groups Cutting cycle 1-10 years (or longer) Appropriate for shade tolerant species Single tree selection

Group selection Removes trees in defined groups to create stand openings <2 tree heights wide Creates multi cohort stands Works for shade tolerant to moderately shade tolerant species

Openings < 1 hectare in size Creates distinct even-aged stands by planting, seeding or advance regeneration. (could be considered uneven-aged depending on scale) Does not depend on shelter incidentally provided by the surrounding uncut stand. Patch Cut System ha <50% open area climate Can include green tree retention

Sicamous Creek Silviculture systems trial