Managing the risk of slash and woody debris discharges from forestry

Authors: Sam Reed
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2025, Issue N.Z.J.For. 70(3) 2025, pp Pages 3 - 7, Nov 2025
Publisher: New Zealand Institute of Forestry

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Abstract: The forestry industry is experiencing massive and rapid change regarding what councils, communities and mana whenua are expecting and accepting for the risk management of slash and woody debris discharges from forest sites. Extreme weather events, the most recent of which was Cyclone Gabrielle, have highlighted a complex legacy problem of landslides and woody debris discharges affecting downstream communities. This paper introduces a proposed approach to assessing and managing these risks, using engineering and GIS assessments and forward planning. It explores legacy issues of land instability, the ‘window of vulnerability’ concept and the evolving regulatory landscape. It also discusses mitigation strategies, considerations for slash trap designs and the importance of transparent, independent, science-backed risk assessments.

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