Pruning Guidebook Guidebook

Introduction

Purpose

This guidebook will assist forestry practitioners in meeting the requirements of the Forest Practices Code with respect to the use of pruning to meet forest health, wildlife, and high timber value objectives.

Guidelines are enclosed in text boxes throughout this guide. Guidelines cover the selection of suitable stands, and pruning methods and techniques.

For further information about this guide please contact the B.C. Ministry of Forests.

Benefits of pruning

Pruning is the removal of branches from the stem of a tree to promote the production of knot-free or clear wood.

Pruning improves stand and forest values by:

reducing the size of the knotty core and increasing clear wood production
improving wood quality of some species by speeding the change from lower value juvenile wood to higher value mature wood
increasing the log and lumber value by increasing the proportion of clear wood produced
reducing stem taper
reducing the impact of white pine blister rust.

Pruning is one component in a complete program of forest management. Limited financial resources and the prolonged time the investment must be carried require that management needs and objectives be clearly identified. In addition, thorough consideration of biological factors surrounding the pruning treatment will ensure that the desired effect is obtained. Consideration of operational factors helps to guarantee that the treatment will be cost-effective and that the resulting timber can be harvested and transported to a processing facility for an acceptable price. Economic factors involved in deciding whether or not to prune are discussed in the section on Economics.

Authority

Operational Planning Regulation

Pruning done under a silviculture prescription

A person who is required to establish a free growing stand on an area under prescription must specify a pruning treatment, including any slash disposal methods, if

(a) control of white pine blister rust is necessary to achieve a healthy, free growing stand within the free growing assessment period specified in the prescription, or

(b) stand densities that are at least 30% lower than the minimum stocking levels for that biogeoclimatic ecosystem set out in the Ministry of Forests’ publication “Establishment to Free Growing Guidebook”, as amended from time to time, are required to achieve wildlife habitat management objectives approved for the area in the forest development plan that applies to the area under the prescription.

Scope of stand management prescriptions

The Operational Planning Regulation gives five points that a person preparing a stand management prescription must do to meet the required scope of a stand management prescription.

(a) consider the result of any free growing survey carried out on the area,

(b) ensure that the prescription is adequate to achieve the future stand condition specified in the prescription,

(c) ensure that the prescription is adequate to achieve continued growth of species that are ecologically suited for the area,

(d) ensure that the prescription facilitates the protection of the soil on the area, and

(e) describe any actions required to achieve known landscape level objectives for stand structure and species composition.

Content of stand management prescriptions

Stand management prescription contents pertinent to pruning are listed below. For details on preparing a SMP see the Stand Management Prescription Guidebook.

A person preparing a stand management prescription must, for the area under the prescription, ensure that the prescription:

contains a reasonable evaluation of any forest health factors that exist currently in the area or that may reasonably be expected to occur in the area before the harvest of the next crop and describes the actions that are proposed to deal with those factors,
sets out the actions that are proposed to abate fire hazards,
sets out the target future stand condition and proposed treatments, including spacing, pruning and fertilizing and the objectives of those treatments,
sets out the stand tending treatment requirements.

Silviculture Practices Regulation

Reports

Obligation of major license holder under stand management prescription

A holder of a major license who carries out a silviculture treatment specified in a stand management prescription must prepare a report that
(a) contains a summary of the silviculture treatments performed on the free growing stand on the area during the period beginning 2 weeks before the last report and ending 2 weeks before the current report’s submission date under subsection (2), and
(b) specifies whether the silviculture treatment was carried out to fulfill the requirements of a management plan or an agreement under the Forest Act.
A person required to prepare a report under subsection (1) must ensure that the report
(a) is signed and sealed by a professional forester, and
(b) is submitted each year to the district manager on April 15, July 31, October 31 and January 15.
The chief forester may specify the form and content of a report under subsection (1).

Pruning required by legislation

The Silviculture Practices Regulation (see previous section) outlines two cases where pruning is a free growing obligation.

Pruning white pine

Western white pine is often considered a ghost tree when it occurs at levels of a few trees per hectare. These ghost trees are most often left uncut at the spacing stage, and are not counted in the silviculture survey. They are left as potential sources of rust resistance. When western white pine are considered crop trees and counted as a component of the stand, they must normally be pruned as a free growing requirement. Western white pine grown from resistant seed may not require pruning (see Pine Stem Rust Management in B.C. Guidebook).

Pruning western white pine is done:

to directly remove inoculum from infected trees (threatening cankers)
to reduce potential infection sites for future white pine blister rust cankers
to increase the amount of clear bole wood in the tree.

Care must be taken to remove the lower whorl which may be buried. A silviculture prescription must include first lift pruning in order to consider western white pine as a free growing component of the stand. Pruning western white pine is a two-lift system. The first lift is done when the trees are 2.5 to 4 m tall to a lift height of 1.3 m (breast height). The second lift should be done when trees are greater than 5 m. The second lift pruning for white pine is generally considered an incremental treatment and is planned using a stand management prescription. Second lift height must be a minimum of 2.5 m and leave 50% remaining live crown. Refer to the Pine Stem Rust Management in B.C. Guidebook for more information on pruning to reduce the affects of white pine blister rust (Cronartium ribicola).

Guideline

In order to consider a western white pine crop tree as a free growing stem, it normally must be pruned.

Pruning and wildlife habitat management

The greatest increase in understorey vegetation is created by spacing to lower stocking levels. The understorey plant species which will increase in abundance will depend on the ecosystem association. Increased forage may be necessary in a particular ecosystem for one or more wildlife species. Spacing can be prescribed to meet such wildlife habitat objectives specified in higher level plans. Spacing for these purposes can bring densities significantly lower than the minimum stocking level specified for that ecosystem in the Establishment to Free Growing Guidebook. This wide spacing results in larger branch size that can decrease the total value of lumber obtained from the stand.

Where special management areas for wildlife habitat are required in a silviculture prescription, (e.g., deer, elk, and grizzly bear), pruning must be included in the prescription if spacing densities are at least 30% lower than the minimum stocking level. Pruning is required as a free growing obligation in these areas to maintain wood quality. Guidelines for maintaining grizzly bear habitat are in Guidelines for Integrating Grizzly Bear Habitat and Silviculture in Coastal British Columbia.

Guideline

Important wildlife habitat with stand densities that are 70% or less of the minimum stocking level must be pruned to meet free growing obligations.

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