Farm advice: The impact of weather on farming

John Sheddan, director in Sheddan Pritchard Law, discusses the effects of bad weather and its implications on forestry and farming communities

Our weather is changing and, while some are still arguing about the cause, it’s extremely evident – particularly to insurers – that we’re on the receiving end of some violent extremes in weather. The resulting storms and flooding are creating havoc and damage throughout New Zealand.


Councils and individuals throughout the country must now focus on how to prevent, minimise or, in some cases, mitigate the effects that these weather extremes bring.

This article focuses particularly on forestry, the effects of bad weather, and the implications on all in the forestry and farming communities.

Forest debris

Trees, particularly plantation forests destined for logging, produce branches and debris. Trees and branches that are uprooted or broken by wind (described as ‘windthrow’) create debris that can be washed downhill with heavy rain and can end up in waterways. Due to the nature of the remaining forest, windthrow debris is usually snagged and trapped by the remaining forest.

Plantation tree blocks, however, are usually clear-felled with the larger valuable timber being removed. This smaller debris, termed ‘slash’, remains and the bare land is exposed and open to the elements until replanted.

These exposed sites are vulnerable to water run-off and soil erosion until the replanted forestry regains sufficient maturity for the root and canopy systems to mature to such an extent that they soften, and capture heavy and extreme rainfall.

Storm damage from slash and windthrow

Commonly-planted forests of pinus radiata have a typical harvest age of 25–35 years, and a large number of pine forests planted in the 1990s are now maturing for harvest.

Increasing areas of cleared timber exacerbate the effects of heavy rainfall, erosion, and slash movement. The effects of this have been particularly seen in Tolaga Bay in the Gisborne region.

During a storm in 2018, an estimated one million tonnes of slash was dislodged and washed downstream causing millions of dollars worth of damage. This has had disastrous effects on the region, its industries and residents, as well as the infrastructure and environment on which the region depends. 

The effects of this storm are still being experienced as the region seeks recovery from the ongoing effects and issues arising from it.

This includes liability for this damage being pursued in court; the Gisborne District Council has laid charges against a number of forestry companies for alleged breaches of the Resource Management Act 1991 (RMA). Other affected parties, such as farmers, are also considering bringing further claims if liability is proven.

The charges being argued are that forestry companies discharged contaminants, being soil and slash, onto land or into water in breach of the RMA.

The effects are not limited to plantation trees. In Northern Southland, in 2018 a 50-metre stretch of the Pyramid Bridge was washed away during heavy rainfall when a build-up of windthrow debris was trapped against the bridge by floodwater.

The resulting damage has created burdens and delays for the community. The local rural water scheme was shut down until remedial repairs were completed, there are increased travel times and costs, and delays for emergency services. All these delays will continue until a replacement bridge is constructed in 2020.

Implications for forestry block owners

The implication for farmers and industry operators is whether their actions, or inaction, may have consequences beyond what is normally considered usual.

As well, on 1 May 2018 the National Environmental Standards for Plantation Forestry (NES-PF) came into effect, which creates a single set of rules for forestry activities in New Zealand for forests over one hectare in size. These rules cover eight key activities:

  1. 1Afforestation (planting)
  2. Pruning and thinning
  3. Earthworks
  4. River crossings
  5. Forestry quarrying (quarrying of roading materials)
  6. Harvesting
  7. Land preparation, and
  8. Replanting.

Forestry land is also broken into four colour-coded zones with regards to erosion susceptibility: green, yellow, orange and red. Each colour has attributed different levels of risk.

Due to the risks associated with a particular zone, various considerations and resource consents may be required for harvesting. In particular, red zone land, which is at high risk of erosion and likely to be very steep, will require resource consent to provide mitigation factors to ensure land stability and minimise the risk of any run-off.

Pinus plantations of particular concern

Of particular concern is the nature of pinus plantations. During their first six years of growth, the root systems and the tree canopy are underdeveloped and the soil is susceptible to erosion damage from excessive rainfall.

As a result, the harvesting and replanting of such land must be well-considered. Clear-felling may not be permitted and the replacement forest may have to be planted with trees with longer maturing times; with trees to be harvested selectively. These mitigators will help prevent a situation where land is never totally clear of forest, nor is it exposed to the elements.

As a result of these events and developments, there are implications for those involved in forestry as owners, operators, insurers, and those supporting farming and related industries are all affected by the ongoing implications and risks.

As with health and safety obligations, there are now significant responsibilities and liabilities for all – personally, commercially, or communally – to ensure a viable future for all. Information given in this column should not be a substitute for legal advice.

About John


John Sheddan is a director of Gore law firm, Sheddan Pritchard Law Ltd. He specialises in rural and commercial issues involving rural and residential property sales, business sales, leases, subdivisions, and helping families to plan for the succession of businesses and family farms to future generations.

Sheddan Pritchard Law Ltd is a member of NZ LAW Limited, an association of 53 independent law firms practising in more than 70 locations.

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