Erosion to resilience: Kānuka at the heart of change

When Cyclone Gabrielle tore its way through parts of the North Island three years ago, Fonterra farmers Trevor and Angela Corbin lost a large piece of their land to the elements.

The Corbins used to utilise their back hills to carry sheep to make a bit of extra income out of steep, grassy land that wasn’t cattle friendly. But then Gabrielle hit – and took approximately half of their back hills with it.

Trevor says they used satellite imagery to show what the farm looked like before and then after the cyclone as a tool to assess the damage.

“They ascertained how much grass or land was lost, or how much scarring there was – and about 46-47% of the hill area was just dirt,” he says. “It was quite devastating from the point of view of using it.”

Tackling future erosion

The couple weren’t the only ones who saw large areas of land eroded in the cyclone – the rivers of Hawke’s Bay were inundated with sediment and debris.

To help encourage future erosion control, the local council looked at subsidies for landowners to plant out erosion damaged or erosion-contributing land.

After speaking to Hawke’s Bay Regional Council, the Corbins discovered their land qualified for the programme and decided planting on their farm’s back hills made good economic and environmental sense for them and for future generations using the land.

Balanced Forestry was contracted to plant 60 hectares of the farm in trees.

The Corbins considered their options and decided kānuka was a good low-cost, low-input solution.

But there were other reasons for choosing kānuka.

“The hill already had kānuka growing on it naturally. About 15-20 years ago, we would try and chop it out and it just kept regenerating, because it’s pretty hardy,” Trevor says.

A neighbouring farmer had already decided to let a similar piece of land regenerate naturally in kānuka some 25 years ago – and not one piece of his land disappeared in the cyclone, he says.

“That tells you how effective kānuka is in erosion control. So, that was the decision – to plant kānuka because it was the easiest thing, cheapest option, and also probably the most appropriate considering it grows there naturally.”

The Corbins had 67,000 kānuka trees planted on their farm. A survey of the area eight months later found there was around an 84% plant survival rate, suggesting the plants were taking hold – and well on their way to creating land that will be more resilient to future weather events.

Wider advantages of planting

While Trevor and Angela’s situation was extreme, planting can bring plenty of benefits for other farms too, says Charlotte Rutherford, the Co-op’s Director of Sustainability.

"Every farm is different, but it’s worth exploring how planting could work for yours and connecting with experts like local catchment groups or specialist consultants to help,” Charlotte says.

“Prioritising native species for riparian zones, steep slopes and erosion-prone areas is key to supporting New Zealand’s ecosystems. Planting can stabilise soil, protect waterways, provide shade and shelter for livestock, and deliver benefits that strengthen both your farm and the environment.”

How to make on-farm planting work for you

1) Create a strategy: Think about any areas of your farm that might be erosion-prone or unproductive, whether certain areas have adequate shade or shelter, and if there are opportunities to improve on-farm biodiversity. Where you can, include native plants and trees in your planting projects.

2) Create a plan: Put together a plan that lists what you’ll be planting, where and why. Investigate what funding might be available in your area to help reduce costs.

Speak with your Sustainable Dairying Advisor about what species of plant would be good for your farm – but try to choose plants, seedlings and seeds produced from trees already growing successfully in your region. Consider also that different types of planting have varying requirements. If you have little or no experience with planting, consider talking to a planting project management provider. Search online or contact your regional council for options.

3) Protect your plants: If you do decide to plant out areas of your farm, protect them as they mature to prevent weeds or other competing vegetation from overtaking their space. Get a pest management strategy in place too – your regional council can help with locally-focused information, tips and tools for dealing with plant and animal pests.

Find out more about the benefits of on-farm planting on the Farm Source website, and talk with your local council to discuss the best approach to planting on your farm or call your Farmer Support Team on 0800 65 65 68 for more options.