Weed Control Trials: Assessing New Methods for Protect Rainforest

WEED CONTROL TRIALS

PROTECTING RAINFOREST FROM INVASIVE WEEDS

26 JULY 2022

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.”

Removing hiptage in the Daintree

In the Douglas region, the focus was hiptage, a woody vine that can smother rainforests and is found in the Mossman Gorge area. The project gave Douglas Shire Council crews the chance to tackle additional infestation areas across 27 hectares and to trial a new method of weed removal.

“A positrack – a bobcat style machine – with a mulcher attached was used to shatter the stumps and roots of the vine as opposed to cutting the vine by hand or with a chainsaw. It was a much more efficient method timewise and the spraying was more effective too, penetrating the root system better and allowing natural recruitment to be fast-tracked as an alternative to revegetation, which was the original expectation for this site.

Partnerships with councils

“We loved these projects because they could support councils to take on work that they wouldn’t otherwise have been able to do. The first stage of weed management is always the most labour-intensive. Now these sites can be incorporated into the councils’ ongoing work plans.”

These projects are part of a ‘Native Vegetation – Many Hands Make Light Work’ program funded by the Queensland Government’s Natural Resources Investment Program. Monitoring work will continue at the three sites through the program for another six months.