In the last edition of the S&W Report, it was emphasized that when logging in your woodlot one of the key steps in meeting your silviculture objectives and maximizing future financial return is to use logging methods that will minimize damage to the remaining trees.

What can landowners do to prevent tree damage in their woodlot? First, they need to have an appreciation of the problem. Second, they need to have an understanding of how a tree grows and third, they need to implement good forestry practices that will minimize the damage.

The Problem

Bark abrasion is one of the most significant types of damage that can occur during harvest operations. When this type of major damage occurs, it greatly reduces the quality and quantity of future wood products by causing stain or decay in the high-value butt log. In fact, major damage of this type can result in a 50 percent chance of tree mortality.

This type of damage generally occurs during the process of felling trees and during the removal (skidding) of the timber from the woodlot. In both cases, pressure and friction of one tree against another can cause the bark of a standing tree to be peeled off. This removes a layer of growth tissue (cambium) and exposes the underlying wood (xylem) to further invasion of fungi. This may result in decay and stain of the wood, or death of the tree. The incidence and severity of this type of injury varies seasonally in direct relation to the physiological processes in trees.

How Trees Grow

The diameter growth of a tree occurs through the division of cells in the layers of cambium located between the bark and the wood. Warm spring temperatures activate the buds of a tree to produce chemical growth stimulants, which are then distributed to other parts of the tree including the cambium.

The cambium cells are the most active during the spring season when they are fully saturated with auxin. During this stage, the separation of the bark and cambium from the wood occurs more easily than during the dormant period when the cells are dry.

Cambium - the thin layer of reproductive tissues separating the bark and the wood, which, by cell division, forms additional bark and wood cells.

Xylem - the same as wood (characterized by growth rings arranged concentrically around the pith).

Auxin - a substance found in plant sprouts, which can stimulate cell growth in plant tissues.

When preparing your plan you should give consideration to the following details:

Selecting equipment - assess the work to be performed and match the right equipment to the job. In most instances, selecting the smallest piece of equipment that is capable to perform the work will result in leaving a smaller "footprint" in your woodlot.

Timing - woodlot owners are encouraged to give serious consideration to operating outside the "resistance to peeling" season (after August 1) to avoid excessive logging damage to the residual trees stands. This is especially important when working in woodlots containing higher quality timber (i.e. areas managed under the selection and shelterwood systems).

Skid Trails - the number of skid trails is often directly related to the amount of logging damage. Usually, the greater the area covered with skid trails, the greater the logging damage. Therefore, as a good practice the following points should be considered when conducting harvesting operations: