Can You Burn Forestry Slash In NZ? (Explained)

The burning of forestry slash after logging operations is a hot topic in New Zealand. Forestry slash refers to the leftover branches, logs and debris after trees have been harvested.

There are differing opinions on whether forestry slash should be allowed to be burned or if other disposal methods should be used instead. This article will break down the debate around burning forestry slash and provide recommendations for sustainable forest management practices.

The Importance of Sustainable Forest Management

New Zealand’s forestry industry provides many economic and environmental benefits to the country. Plantation forests cover around 7% of New Zealand’s total land area, providing vital jobs and export revenue. Our planted forests also play an important role in soil conservation, erosion control, and protecting water quality.

Sustainably managing the full lifecycle of our production forests is crucial to ensure the industry continues providing these benefits over the long-term. This includes sustainable options for disposing of forestry slash after harvest.

The two main schools of thought around dealing with slash are:

  1. Burning it in controlled burns
  2. Alternative disposal methods like wood chipping or on-site debarking

Proponents on both sides argue their method is more sustainable. So what does the evidence actually say?

Is Burning Forestry Slash Sustainable?

Burning forestry slash has traditionally been seen as an economical and effective disposal method. Controlled and well-managed burns clear the land rapidly for replanting and release valuable nutrients like nitrogen and phosphorus back into the soil.

However, burning forestry slash can have negative impacts as well:

  • Smoke pollution – slash burns contribute to New Zealand’s air pollution, especially impacting nearby towns and cities downwind of forestry areas. Smoke is linked to health issues like asthma.
  • Carbon dioxide emissions – burning forestry waste releases stored carbon back into the atmosphere, contributing to climate change. These can be significant emissions given the large volumes of slash generated.
  • Loss of dead wood habitat – the burn sites lose valuable dead wood habitat relied upon by fungi, insects and geckos. Lost long-term carbon storage in the soil.
  • Wildfire risk – improperly managed slash burn-offs can spread into wildfires, especially in hot, dry weather.

Considering these potential negative impacts, there are valid questions around whether the burning of forestry slash can be considered sustainable practice. Alternatives should be explored.

Alternatives to Burning Forestry Slash

Instead of burning forestry slash, New Zealand forest managers have several alternative disposal options:

On-site Debarking & Chipping

  • Chipping slash into bark chip produces mulch for forest floors or can be used for erosion control on slopes.
  • Debarked logs can be left to decay, which returns nutrients and provides dead wood habitat.
  • Enables natural regeneration of native bush at some sites.
  • Reduces carbon lost to burning and smoke pollution is eliminated.

Transport Off-site

  • Transporting slash off-site enables processing into wood pellets, biofuels like wood ethanol, or recycling into fiber board products.
  • No local air pollution or negative impacts on soil health/habitats.
  • Generates additional revenue from the waste resource.

Improved Burn Management

If burning is still required in some locations, negative impacts can be minimized by following best practice burn guidelines:

  • Only burn slash when weather conditions reduce risk of spreads and impacts of smoke plumes.
  • Exclude patches of vegetation from burn areas to retain dead wood habitats.
  • Return ash residue after fires to recycle nutrients.
  • Use slash to stabilise soils and slopes where needed instead of burning.

Many forest managers in NZ are adopting progressive slash management policies, avoiding burning where feasible and mitigating impacts where burning is necessitated.

Case Study: Ernslaw One’s New Approach

Ernslaw One is a major New Zealand forestry company taking a sustainability focused approach to slash management on their sites.

Some key points from Ernslaw’s policies:

  • Default position is to avoid burning slash wherever viable.
  • Sites are assessed to determine best disposal method based on terrain, soil conservation needs, logistics etc.
  • Chipping and debarking machinery used instead of burning on ~85% of sites.
  • Any burns required are done safely under strict smoke and fire risk controls.
  • Continuous monitoring of soil health, carbon emissions and biodiversity to track sustainability performance.

This strategic approach enables Ernslaw One to maximise sustainability while still meeting economic needs, serving as a model for the wider industry.

Key Recommendations for Sustainable Practices

Based on all the evidence, here are some best practice recommendations for sustainably managing forestry slash in NZ:

  • Work to eliminate slash burning completely where feasible. Prioritise chipping, debarking, off-site removal and recycling.
  • If small controlled burns are still required in remote terrain areas, follow stringent controls and monitor sustainability impacts vs alternatives.
  • Invest in specialized debarking/chipping equipment to grind up materials on-site. Look to utilize biomass for revenue generation.
  • Develop progressive slash management policies tailored for each plantation forest site and geography. Regularly review practices.
  • Monitor carbon emissions, biodiversity, soil health and other metrics to compare slash disposal methods and make informed sustainability decisions.
  • Support further research into the quantifiable sustainability impacts of different harvesting slash management techniques in New Zealand forests.

Adopting more sustainable forestry slash disposal policies based on site-specific environmental, economic and social considerations will enable the industry to lead on sustainability and build an enduring renewable economic driver for New Zealand.

Frequently Asked Questions

Can forestry slash be burnt legally in NZ?

Yes, burning of forestry slash is legal with the appropriate resource consent from local councils who consider environmental factors. However, some burning practices could be restricted in future if not demonstrably sustainable.

What are the penalties for illegal forestry burns?

Penalties can include fines, requirement to offset carbon emissions or fund remedial works, and suspension of resource consents where burns breach consent conditions or cause environmental harm.

Do sustainable forestry certifications allow burning?

PEFC and FSC ecological standards require slash burning only occurs where it meets strict criteria. Burning cannot be business-as-usual practice and alternatives must be thoroughly assessed first.

Is transporting slash off-site achievable from remote forest areas?

Transporting slash can be challenging in steep, isolated terrain. New Zealand logging operators are adopting specialised slash removal equipment like debarkers, chippers and barges to remove slash for recycling without needing roads.

Could native trees be replanted on old forestry sites?

Yes, sites can be returned to native forest. Leaving woody debris after harvest enriches soils and enables seeds in the soil to germinate. Destructive burns hinder this regeneration.

In Summary

There are still divided views on whether burning forestry slash should continue as common practice in New Zealand’s plantation forests. However, with increasing adoption of alternative disposal methods, improved practices and monitoring – the industry is working hard to transition towards more demonstrably sustainable models of slash management.

Eliminating largescale slash burns where feasible, while better managing essential burns, will reduce the industry’s impacts – helping sustain a vibrant economic driver that also protects our soils, air, climate and biodiversity.

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