Advice on how to deal with windthrow of trees on your property

Posted 17 June 2022

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Parts of the North-West Tasmania were thrashed with fatal gale force winds over the June long weekend resulting in thousands of fallen trees and extensive damage to privately-owned plantations and native forests.

Known in forestry terms as ‘windthrow’, trees are uprooted, broken, snapped and overthrown by fierce winds and storms.

Unfortunately, these events are the responsibility of mother nature and can occur in any forested area throughout the world including urban areas and involves extensive clean ups, loss and destruction.

In response to this recent event, Private Forests Tasmania has compiled information for affected landowners and are available to discuss your personal situation further should you require specific advice.

It is important to note the immediate safety evaluation of affected trees within your property, access roads, homes, outbuildings and to livestock. Should you notice unstable trees or down powerlines, please contact the SES immediately on 132 500 or consult a private Tree Arborist to assist with removal of storm affected trees threatening homes and outbuildings.

If your matter is less urgent, you may require the services of a consulting forester who can provide critical technical assistance in all phases of your forest management.

Affected areas should be identified and monitored with appropriate remedial treatment techniques being identified and implemented where necessary.

For example:

1. Edge stabilisation (see below);

2. Re-evaluate the wind risk of the remaining trees and decide to:

• clearfall,
• salvage windthrow or leave the windthrow; or
• if windthrow occurs along a boundary, do not salvage and create a similar new boundary.

3. Retain windthrow as a windfirm buffer or create a new windfirm

Edge Stabilisation

1. Edge feathering will reduce wind-loading on boundary trees. Trees in the edge buffer should be removed in the following order of preference:

• Unsound trees with a large crown, including: diseased, deformed, forked, scarred, root rot infested etc.
• Trees with asymmetric or stilt roots.
• Trees on unstable substrates, e.g. rocky knolls, large boulders, poorly drained depressions, etc.
• Tall non-veteran trees, especially with above features or large crowns.

2. Residual trees should be left in the following order of preference:

• Sound, well-rooted veterans.
• Sound trees (strong roots and good taper) with relatively small, open crowns.
• Sound hung-up trees, where safety is not comprised.

3. Stem removal should not exceed 15-20% of the trees in a strip 20-30m from the boundary (not recommended at all in single-story, dense stands).

4. Topping and/or pruning of vulnerable trees may be necessary along boundaries to protect critical areas eg. reserves, wildlife habitat, etc.

5. 20-30% crown reduction appears to reduce wind risk.

6. Combination of edge-feathering, topping and pruning should be effective in high-risk areas.

Should you be considering the need to engage a consulting forester, please see ‘Why do I need a Consulting Forester and how do I choose’.

Additional information is available on our website including ‘Forest and wind risk in Tasmania – guidelines book’ and the ‘Wind Risk Calculator tool’ which is available under our TOOLS tab.

Please phone us on 1300 661 009 for any additional information.