Thinning is winning for Pilliga’s little creatures

DPI study shows thinning Pilliga cypress pine can restore and improve habitats


Top Stories
Aa

Study shows thinning of cypress pine can restore and improve habitat for native species

Aa
DPI Principal Research Scientist Dr Brad Law said more than 200 species were recorded during the three-year study of the central-western NSW Pilliga forests.

DPI Principal Research Scientist Dr Brad Law said more than 200 species were recorded during the three-year study of the central-western NSW Pilliga forests.

FOR many, cutting down trees probably doesn’t link with helping native species – but a new study in the Pilliga shows if done right, it can boost ecological communities and tree growth. 

The three-year DPI study revealed patchwork thinning of Pilliga cypress pine regrowth not only improves biodiversity, but can restore and improve habitat for native species including microbats, small reptiles, birds and marsupials. 

But land managers should also leave a few hollows and small dead trees to give them more shelter. 

DPI Principal Research Scientist Dr Brad Law said more than 200 species were recorded during the three-year study of the central-western NSW Pilliga forests.

Thinned sections of cypress forest.

Thinned sections of cypress forest.

Boasting more than 535,000 hectares, the Pilliga represents the largest inland woodland in Australia, with cypress pine being a dominant tree species in many areas.

The area comprises a number of State forests and Conservation Reserves. 

Notoriously, the regrowth cypress forests often have a very high density of stems. 

“They lock up and stop growing at 5 metres or so and remain in high density state for decades,” Dr Law said

“You also see it with the Redgum forests along the Murray River. Competition between trees takes a long time to sort itself out.”

“In the study areas in the Pilliga we sometimes found 6000 to 10,000 stems per hectare. That’s very homogeneous and not great for biodiversty.”

Unthinned cypress pine in the Pilliga region is often seen as homogenous and negative for biodiversity and habitat growth. Stems can reach densities of 6000 to 10,000 per hectare. The thinning trial reduced this to 1500 stems per hectare.

Unthinned cypress pine in the Pilliga region is often seen as homogenous and negative for biodiversity and habitat growth. Stems can reach densities of 6000 to 10,000 per hectare. The thinning trial reduced this to 1500 stems per hectare.

The thinning project reduced density four-fold to about 1500 stems per hectare, with taller trees given priority to stay.

“Ones left behind go on to grow more rapidly than was the case otherwise.”

The study found that the main negative outcome of thinning was the loss of small dead trees, which provide hollows for insectivorous bats and reptiles in the forest.

“Radio-tracking showed bats preferentially foraged in recently thinned stands, but avoided roosting there during the day. Even small dead trees can contain hollows and these are key structures to retain during thinning operations,” Dr Law said.

“So I’d say leaving behind a few logs and smaller dead trees is pretty important.” 

The study found that the main negative outcome of thinning was the loss of small dead trees, which provide hollows for insectivorous bats and reptiles in the forest.

The study found that the main negative outcome of thinning was the loss of small dead trees, which provide hollows for insectivorous bats and reptiles in the forest.

Murray River Red Gum stockpile ready to use 

Meanwhile, stockpiled timber from a Murray River Red Gum thinning trial has been distributed to local sawmills to process for firewood. 

The five-year ecological thinning project – unpopular among conservation groups – is taking place across 400ha, or less than 1 per cent, of the 41,601ha Murray Valley National Park, near Deniliquin. 

Murray MP Austin Evans said for 18 months the project’s stockpile of River Red Gum had sat dormant.

Related reading

He said permission was finally granted earlier this month for local millers to process the load, which he said was about 13,000 tonnes. 

 “It’s just been sitting there rotting, it’s good timber,” he said.  

Firewood collection in the National Park requires a licence, with a limit of three tonnes per permit and six tonnes per household per year. 

They will now be able to present to local mills to get their firewood instead of collecting and processing it themselves in the park. 

Earlier, Labor’s ag spokesman Mick Veitch had a crack at Mr Evans’ silence on a 2017 byelection promise to de-gazette the Murray Valley National Park altogether.

Labor created the park in 2010 and said it would fight for its survival.

In September last year when he was on the campaign trail, Mr Evans vowed to lodge a Private Member's Bill in parliament to unlock jobs and investment in the region.

He said he hoped to have something drafted in the coming months, and was currently speaking with his Liberal Party colleagues to gauge their support. 

“Those who I’ve talked to in the Liberals haven’t come out violently against it either, some have even supported the idea,” he said

“So I think it will be a matter of working my way through everyone.

“Legitimately enough, they want to see the bill before they commit one way or another. That’s fair enough.”

Local communities see the timber as a crucial economic resource and say experienced forestry industry operators best knew how to manage it. 

“They need to put it back into forestry hands,” said local sawmiller Chris Crump.

“You don’t go to your dentist to get your car fixed.”

We know the forest. It’s our future. We’ve seen it grow from nothing to what it is now. We’ve grown it and looked after it. We were there when the fires came. We’re not going to destroy it.

“This lock up and leave mentality is not working.”

Aa

From the front page

Sponsored by