The ongoing battle with weeds in the Wet Tropics region has led to a three-year project across 40 hectares of land that has trialled different methods on the edges of world heritage rainforest.

Terrain NRM has worked with the Cassowary Coast, Douglas and Tablelands regional councils on projects that are buffering world heritage forest from fire and weeds, and restoring woodland habitat. They have also involved revegetation work.

Project coordinator Chelsy Maloney said the goal was to improve the resilience of big patches of native vegetation by managing emerging threats in smaller patches of neighbouring vegetation.

Restoring fire-damaged rainforest near Silkwood

In the Cassowary Coast region, the focus was a fire-damaged section of rainforest on a council reserve along the edges of world heritage rainforest.

“With the likelihood of more rainforest fires given our changing climate, it’s important to learn how to best restore these areas,’’ Terrain project coordinator Chelsy Maloney said.

“Cassowary Coast Regional Council worked with us on a weed management and revegetation project where we trialled low-cost assisted regeneration to support rainforest restoration. We found that by managing the high threat weeds, more space and less competition was created for natural recruitment and pioneer species. In the short term, the forest condition showed a definite improvement.”

Weeds were managed on 3.5 hectares of world heritage rainforest and a strip of revegetated land along the roadside.

Revegetating woodland understorey near Ravenshoe

In the Tablelands region, an infestation of guinea grass and lantana in council reserve land beside South Cedar Creek at Ravenshoe was the focus.

“In woodlands the canopy can often be intact while the understorey is overtaken by weeds. By managing lantana and guinea grass, we’ve started to see lots of different understory species recruiting across 10 hectares, and an increase in native species overall.

“We also trialled high-density understorey revegetation work on 1.5 hectares in an attempt to out-compete exotic pasture grasses such as guinea grass, and there have so far been really good results.”

Weed warriors are gaining ground on a major threat to the Mossman Gorge area’s world-heritage rainforest.

What is hiptage?

Hiptage is an invasive weed that’s smothering rainforest north of Cairns – and this vine from eastern India and south-east Asia grows so well in the Wet Tropics region that its sheer weight can bring down trees.

Work crews from Douglas Shire Council and the Queensland Parks and Wildlife Service have been targeting the species for almost two decades, with council crews recently extending into new territory for this project thanks to funding from natural resource management organisation Terrain NRM.

Douglas Shire’s Biosecurity Team Leader Brad Everett said crews were hiking up rainforest gullies on a hill known as ‘ground zero’. They take chainsaws, hand saws, secateurs and knapsack sprayers.

“It’s hard work. The whole north side of Butcher’s Hill is infested,’’ he said. “But it’s rewarding work too. We had spots we’d take people, to show them just how bad hiptage gets, where the vine was almost impenetrable.

“Now we go back in there for follow-up work on a biannual basis and there are a few vines and seedlings. The native forest is getting a chance to regenerate and self-seed.”

Where is hiptage found?

Hiptage exists in a 60-hectare section of the Mossman River catchment, with Tara Hills identified as the core infestation area and the gateway for Mossman Gorge National Park infestations.

A major threat to world-heritage rainforest in the Mossman area is sending work crews into the thick of forests.

Crews spent six weeks freeing-up a creek system on a property bordering Mossman National Park in the latest assault on the invasive weed hiptage which is smothering rainforest north of Cairns.

Douglas Shire Council Biosecurity Team Leader Brad Everett said the hiptage incursion was almost impenetrable.

“It’s a really hard, woody vine that grows up trees and smothers them – it gets so heavy it can bring the trees down,’’ he said. “Then it throws roots down and becomes a dense bramble.”

He estimates work crews cut down thousands of mature vines and removed tens of thousands of seedlings during the six-week campaign which is part of a regionwide Native Vegetation Improvement Project funded by Terrain NRM through the Queensland Government’s Natural Resources Investment Program.

“We almost had a monoculture – now the native forest can regenerate and self-seed in this area,’’ Mr Everett said.

Douglas Shire Council and the Queensland Parks and Wildlife Service have been working for more than a decade to contain hiptage in a 60-hectare section of the Mossman River Catchment.

“Over the years we’ve got to the stage where we can walk through sections that were once choked with hiptage and just remove one or two seedlings,’’ Mr Everett said.

“We run aerial surveys and on-ground monitoring each year. The funding from Terrain NRM will also allow us to begin another eradication program in coming months in a different Tara Hills area.”

Terrain NRM’s Tony O’Malley said work was also underway to improve the resilience of big patches of native vegetation on the Tablelands and in the Cassowary Coast region.

“This project has brought councils from across the region together to decide on priority areas of native vegetation where they can make measurable improvements over the next few years through funded on-ground works,” he said.