A 30 minute drive from Ashburton, Alford Forest is a special mix of New Zealand nature.

Water falls from Mt Alford and pools at the bottom, blending dry beech forests with swampland kahikatea trees.

But a slow growing pest is disrupting the forest’s balance.

Holly, the spiky-leaved, bright red berry Christmas plant, has spread through the area. It began with one plant, bought by settlers who built a nearby homestead in 1878.

A farmer who descends from those settlers, Dan Symons, said several foreign species had been brought to the homestead.

“Laurel was bought over, and sycamore as well.”

“The bird were indiscriminate, they didn’t worry about boundaries, they just went and shat them seeds out where they pleased.”

Symons said Environment Canterbury came to him “a number of years ago,” and identified the holly tree. In 1994, through the QEII trust, a covenant was made to protect around 10 acres of land around the homestead.

The covenant will protect those ten acres from certain actions, like forest burning or swamp draining, forever.

Symons received funding from ECan to deal with the holly, and this year, received a biodiversity grant from the Ashburton District Council, to fund eradication of the pest.

“The problem with holly,” he said, “while it's very tasty for birds, it creates their own dense thickets in which nothing else grows. It's a takeover tree, it will take over the bush if left alone.”

“They’re very hard to get rid of, and the seeds have a long viability.”

Symons has removed holly from his personal garden and around the homestead, but bigger trees have been contracted out by the council.

ECan Land Management and Biodiversity Officer Jess Cochrane said the foreign plants outcompete with our native flora.

“It’s a very shade tolerant plant, so it will grow under the forest canopy.”

“In a forest ecosystem, you’ve got trees that die and then new ones come away. But when you’ve got holly in the understory, those new ones can’t come away, and the forest can’t regenerate.”

She said Mid Canterbury was one of the region’s most depleted biodiversity areas, so the pockets that exist, like Alford forest, need to be looked after.

“We want to get rid of it so forests can do their thing, and be a really good home for birds and lizards and insects.”

The plants are managed in several ways; some are chopped down and their stumps smothered with herbicide, and others are drilled into and injected into.

QEII trust representative Alice Shanks said holly was an unforgiving plant.

“We’ve been working on the holly since 2014 - for ten years. It’s a marathon.”

“Two volunteers took 12 hours to cut down all the stems on a holly one time. And six months later, it rooted again.

She said the blackbirds and kererū which occupied the forest had spread holly berries a huge distance.

“Down in Ashburton, I’ve sighted a holly 1.25 kilometres away from a known tree. Those birds are not working for us!”

The resilience of the plant and abundance of its seeds make it a challenge to eradicate, but work has to continue, she said.

“We can’t stop now or all the previous funding goes to waste.”

Shanks said the presence of kahikatea in Mid Canterbury was rare, and that it was important to ensure that they stayed to support the forest for decades to come.

She said the funds from the councils and support of the landowner were proof of how collaboration can restore our native wildlife.

- Anisha Satya