Revegetating creeks and reducing rats

REVEG HELPS TO REDUCE RAT PROBLEMS

DECEMBER 2022

Riverside revegetation projects in the Wet Tropics are proving to be a win-win – they can solve rat problems for cane farmers while also stabilising river banks and improving the quality of water flowing to the Great Barrier Reef.

Growers and researchers have reported a 70 to 100 per cent reduction in rat numbers after tree planting initiatives on land between cane crops and waterways. And growers who are involved say crop damage from rats becomes largely a thing of the past.

Here are three examples:

Frank Gatti, Woopen Creek near Innisfail

A dramatic decrease in rats was a major benefit of cane farmers Frank and Stephen Gatti’s revegetation project. The Gattis revegetated 3.5 kilometres – a 30-40m strip between cane and creek – as part of a trial in partnership with the Bureau of Sugar Experimental Station and Queensland Parks and Wildlife 25 years ago.

The intention was to reduce rat numbers – and it worked.  After 12 months an 80 per cent reduction in the rat population was recorded.

“There was no grass for the rats anymore,’’ Frank said.  “We left some sections with grass initially for the trial.  As part of the trial, rats were captured in the grass areas but there was virtually nil capture of rats where we had revegetated. We have virtually eliminated them.”

Before the revegetation project, rats would usually decimate more than 20 metres of cane either side of a creek in the lead-up to harvesting season.

“We started with a bare creek bank and grass,’’ Frank said. “Now we’ve got full cover. The rats have been replaced by scrub hens and owls and the creek bank is more stable.”

The Gattis planted native trees and say the local varieties have proved themselves over time, with a strong showing from quondongs, Leichardt trees and river cherries. Redgums and mahoganies were destroyed by Cyclone Larry in 2006 whereas the endemic varieties shed limbs but survived.  The Gattis began with nursery supplies but later moved to propagating their own seedlings.

“We planted 1 to 2 metres apart with sacrificial trees in between like bleeding hearts – fast-growing pioneer plants that shade out the weeds, get their roots in the ground fast and make it easier for the other trees to grow.”

The rat numbers began declining once the grass was eliminated. Frank said it was important not to leave grass in between the plantings. He said the project was labour-intensive for the first few years but the benefits were well worth the effort. These days he makes sure there are no overhanging branches that would cause problems for harvesters and the rest of the revegetation site doesn’t need to be maintained.

“There were challenges along the way and there was a cost in creating the revegetation site, but the benefits have well outweighed that outlay. Some people worry that trees will shade the cane but you’ve got to weigh up is whether you’re prepared to put up with the rats or some shade. Once the rats chop into the cane it doesn’t grow anymore and you lose CCS.”

“I would recommend revegetation to other growers as a way to reduce rat problems.”

Lawrence Di Bella, Ingham

Ingham cane farmer Lawrence DiBella says 70 per cent of his rat problems ended after he revegetated land bordering the Herbert River.

“We used to lose 20 to 50 metres of cane every year on our riverbank country,’’ he said. “Over the years we have taken the guinea grass out by revegetating the riverbank area.  It keeps the grass species down and we don’t have the problem we had.”

The Lawrence family began their revegetation project in 1994 after visiting a trial revegetation site on Woopen Creek grower Frank Gatti’s land and hearing about his results.

They now have about 1.5 kilometres of riverbank land under trees, varying from 10 to 40m in thickness depending on the area.

Lawrence said he learnt by trial and error that endemic species were the best because they could withstand cyclones and flooding better than natives from outside the local area. His plantings feature Queensland maples, black bean trees and bleeding hearts. In the wetter areas, he has melaleucas and the Leichhardt tree.

The benefits are four-fold – the revegetation project has reduced the rat population, created a buffer for flood debris so it no longer ends up in his cane crop, encouraged native wildlife such as sea eagles and owls which eat rats, and improved the amenity of his property.

The DiBellas have their own nursery for propagating trees grown from seeds collected on their land.

“We’ve been revegetating gradually – we pick smaller manageable areas,’’ he says. “It’s important to keep the sites weed-free for three years. If you do it properly you create a thick stand of trees like a rainforest.

“Every few years we get up in a cherry picker and remove branches for the elevators on the cane harvesters but the sites are largely maintenance-free after the early years. Some years we still get rat damage but now it’s just the occasional year not every year.

“Rat issues are now due to specific cane varieties and some seasonal conditions. It is important to have an integrated pest management approach involving keeping the cane crop weed-free, rat baiting when required and managing the harbourage areas.”

Brice Henry, Tully

Grassland has successfully been transformed into rainforest on canegrower Brice Henry’s Tully farm.

The resulting reduction in rat numbers and cane damage is significant.

The Henrys agreed to be part of a local council-run revegetation program more than 30 years ago where a team came onto properties and undertook both the plantings and the initial maintenance work.

The trees they planted are now up to 12 metres high and the rainforest area has multiplied thanks to seeds coming in with bird populations.

Brice says he had a bad rat problem before the revegetation project along Weis Creek. “We’d lose cane on both sides of the creek. Towards the end of the season the rats were getting about half of what was left.  We’d burn the grass out but we’d still have a rat problem.”

About 3 kilometres of creek-side land has been revegetated from the base of the waterway in a strip of 20 to 30 metres.  Species include quondong, palms and cottonwood.

Brice says the project has also stopped any re-growth of pest plants hymenacne and para grass.

There was a noticeable drop in rat numbers within four to five years, and the last 15 to 20 years have been almost rat-free on the Henry’s farm.

“There is maintenance involved but there are big pluses. I get the trees trimmed back every couple of years for the harvest season and I needed to spray a bit around the plants initially.  The benefits have outweighed any costs or time outlays. The reduction in rats and hymenachne are two pluses and another is the safety aspect.  The trees keep tractors away from the edge of creek banks. Also, the area helps to filter any run-off during times of flooding.”

Benefits for the environment

Watercourses that are revegetated are much healthier, with habitat for beneficial birds and animals, and with shade helping to remove choking grass and sediment build-up. This improves water quality and allows clean-flowing water to provide diverse habitats in our farming landscape and in our Reef catchments.

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