Kahikatea stands undergo ‘WOF’ to get in top shape

Annette and Ken Arnold were the first landowners in the Waikato to do a Kahikatea Green Wheel assessment of a kahikatea stand.

The Arnolds are nothing but passionate about their kahikatea.

Ken Arnold reckons they have the biggest kahikatea in the Waikato, although Annette, his wife, is happy to claim second place, arguing that the tallest (66.5 metres) is in Pirongia Forest Park.

“No, we have to have some claim, it’s 7 metres around the base,” Ken disagrees, good naturedly. “You find another one that’s 7 metres around the base!”

Nonetheless, it’s definitely a big, old tree, reaching about 60 metres in height and estimated to be about 800 years old. And it sticks out among the other kahikatea that make up two close-together stands on their property.

One tree stands out from the rest, reaching 60 metres in height.

“People have said our trees range from about 400 to 800 years old,” says Annette, in wonder of the information. “Why are they still here? How did they survive? I have no idea!

“Precious, precious; that’s what they are, precious.”

The Arnolds are restoring the kahikatea stands on their Ohaupō life-style block, where they have lived for 20 years, and are tracking their restoration efforts using a kahikatea forest fragment health assessment method developed by Waikato Regional Council.

Both stands are fenced off from stock, enabling young plants to regenerate.

The Kahikatea Green Wheel is like a Warrant of Fitness for kahikatea that should be undertaken every five years – it assesses 32 important health features using a five-point rating system so landowners can easily see what is working well and what needs fixing. The health features relate to threats such as pest plants and animals, stock presence, nutrient inputs and drainage; the presence of native plant and animal species; and management regimes in place.

Kahikatea (Dacrycarpus dacrydioides), an ancient podocarp and New Zealand’s tallest native tree, play a crucial role in wetland ecosystems, providing habitat and food for native birds and insects. Before humans arrived, around 189,772 hectares of kahikatea forest grew in the Waikato’s wet areas, beside lakes and swamps and on floodplains. Today there are only around 2760 hectares – a 98.5 per cent decrease – with the remaining trees mostly found in fragments under 5 hectares in size. Without management, these stands are destined to degrade and eventually die.

The council has mapped the region’s kahikatea fragments, including information about their physical condition and links to other natural areas. This information is available online for landowners who may be interested in restoring their stands and tracking their progress as part of the Kahikatea Green Wheel project.

Currently, 29 kahikatea fragments (126 hectares in total) across seven district council areas have been assessed using the Kahikatea Green Wheel – 86 per cent of the assessments are of stands on private land. The site scores range from 11.4 to 28.8, with 35 being the highest possible mark. 

“I was the first landowner to do the Green Wheel in the Waikato,” says Annette, who helped the council to test the assessment in 2019, at the time scoring 13.2 for stand one, the one with the big old kahikatea.

The stand was already fenced when the Arnolds bought the property, but there had been a lot of privet within it, which the couple had cleared over the years.

“I’d pull them out, lop them down, and we’d chainsaw down the really big ones; cleaned the lot up,” says Annette.

“Then I said, ‘I really got to do this other stand before I get too old’.”

Stand two, which had had cattle through it for many years, was fenced off in 2018, and Annette planted 600 or so eco-sourced native plants into the area in that first year.

During COVID-19 lockdowns, the Arnolds also fenced off a wet area next to stand one and planted 100 kahikatea.

“I have planted a total of about 2000 plants now. It’s all kept me busy, but I enjoy it.”

Annette says both stands look so different now, five years later. She has just completed her second kahikatea stand assessment for the first stand, scoring 21.5 out of 35.

The newly fenced second stand was assessed at the same time and scored 22.3.

“I’m very happy with those results because this is a long journey and they will only go up because I’m putting the land under QEII, so that will give me another five points – and the stands will continue to develop.”

The biggest job is hand releasing the young plants from grass and weeds, but Annette also checks traps and bait tunnels for pest animals once a week and a live cage daily.

With the stock out and ongoing pest animal and plant management, native plants are now self-generating. “And I do a bit of seed gathering and tossing seeds around.”

The couple have seen an increase in bird species: “Kākā, more tūi; I saw a falcon; keruru, king fisher, grey warbler, ruru; blue heron have been nesting there in the last couple of years … the European birds are increasing too, and the Australian – the screechy plovers, magpies and rosellas; and we have bats.”

“I would like to come back in 100 years’ time just to have a look.”