IN 1999 when Michelle (Woo Wei) Richards was living in the forest near Toonumbar National Park on the Richmond Range, she would wake up before day break to hear the dawn chorus.
As light slowly crept into the forest landscape, all of the forest-dwelling birds would begin to sing in the new day. Then she noticed the native bell miner birds were beginning to dominate the landscape, calling out with their distinct bell-like chime. At the same time Woo Wei noticed some of the eucalypts in the surrounding sclerophyll forest were beginning to lose their leaves and die.
“There are so many bell miners now that their call is no longer a romantic tinkling, it’s a deafening chaos,” Woo Wei said. “Now when I look at some forest areas there all of the trees are dead.”
As the forest dieback spread throughout the area, Woo Wei and other concerned landowners began to investigate the link between bell miners and the dieback. They discovered the dieback problem was first noticed on the NSW central coast in the 1950s and was now spreading at an alarming rate through coastal eucalypt forests from Queensland to Victoria, causing impacts on biodiversity and the productive capacity of forests.
“As forest health declines, stressed trees are attacked by the tree lice of Australian forests: small-bodied insects called psyllids,” Woo Wei said.
Psyllids feed on the leaves and tips of eucalypt species, sucking the sap from a tree until the exhausted tree can’t pull moisture into its leaves and slowly dies. There are more than 100 different species of psyllids and they all exude a protective sugary coating called a ‘lerp’ that native bell miner birds love to eat. Aboriginal people also collected lerps for food and the name ‘lerp’ comes from an Aboriginal word meaning sugar.
“In healthy, well-managed forests, the psyllid populations work to its benefit: attacking stressed trees on the edges of rainforest gullies, helping the rainforest in the gullies spread outward, creating a natural breathing border between wet and dryer forests and countering the spread of bushfires through the area,” Woo Wei said. “Now, the natural controls that restrict over-population of psyllids are missing because of over-logging, inappropriate burning and species changing practices over the past 50 years which have disturbed the forests’ biological systems. We need better forest management practices if we want to control the problem.”
After encouraging the National Parks & Wildlife Service to take action, in 2001 the Bell Miner Associated Dieback (BMAD) working group was formed. Landowners, representatives of conservation and industry groups, and government agencies including Forests NSW and the Department of Environment, Climate Change and Water began to work together on how to better understand BMAD.
As a conservationist representing the North East Forest Alliance (NEFA) Woo Wei became a member of the BMAD working group. In 2004 she received a Heritage volunteer award for an outstanding contribution to heritage conservation in NSW for working on the dieback problem. After years of watching the complex dieback syndrome in the Toonumbar area Woo Wei describes it as a “cascading chain of effects and problems” caused by a loss of psyllid controls and forest health and vigour.
“There is a suite of inappropriate forest management practices that include prolonged inappropriate fire, logging or grazing regimes that result in a varying suite of forest structural changes, including overly dense understorey growth, as often lantana takes over,” Woo Wei said. “Eucalypts can become stressed for a variety of reasons, mostly to do with water and nutrients. Eucalypts that are adapted to grow in soils with low nutrient levels become stressed when lantana releases high nutrient loads and competes with them for water. Stressed trees attract psyllids and in this past drought I saw a lot of trees die.”
Woo Wei has seen clouds of psyllids take wing in a forest and move to other trees. In some areas the plant community has changed to non-local species and these trees may be prone to water stress.
“The first trees that are affected by psyllids are grey gums, then flooded gums, ironbark, blue gum and spotted gum,” Woo Wei said. “It’s a smorgasbord for the psyllids; they are eating the most tasty species first. One stress effects another and as soon as the canopy is reduced, more light gets in and lantana takes off further and competes with the trees.”
With a dense understorey of lantana to live in and plenty of lerps to eat, the aggressive bell miners then colonise an area of forest and drive away other small birds. Jim Morrison, chairman of the BMAD working group, said an experiment conducted last year showed that bell miners would eat only the lerps, with an 80% survival rate for the psyllids, while noisy miners ate both the lerp and the psyllid.
“The psyllid can grow a new covering in 6-8 hours,” Jim said. “The bell miners are allowing the psyllid to proliferate by driving away all the other birds that might kill them.”
Despite this both Jim and Woo Wei agree that the problem is not the birds’ fault; thy are just taking the rap.
“The basis of the problem is declining forest health,” Jim said. “Dieback is a symptom.”
As president of the North Coast Environment Council Jim, along with other conservation groups like NEFA, believes there should be no logging in BMAD-affected forests until a thorough assessment of the problem is completed and a plan developed to
bring forests back to health.
“It’s an issue across three states,” Jim said. “We are a little group in NSW trying to deal with a big issue. It has been declared a key threatening process under the NSW Threatened Species Act and we have thousands of hectares of dead standing trees with lantana in them and no hope of regeneration. It’s out of site out of mind. We need the government to take more action. The Gondwana Rainforest group has given out a grant to address the extent of the problem in the Blue Mountains; below the three sisters there’s a lot of dead canopy.”
The BMAD working group is still trying to achieve appropriate satellite technology mapping of the widespread problem but needs more funding to make it happen.
“We picked out 20,000 hectares of the Richmond Range and borders and went up in a helicopter to map it by GPS,” Jim said. “About 6000 hectares were terminal and another 8000 were badly affected, and since then the problem has expanded. “A lot of people are pointing the finger at National Parks, but on the Richmond Range most of the National Park area with BMAD problems was heavily logged in the 90s and handed over with no money for rehabilitation. NEFA and other groups fought to get those National Parks and they were handed over because of the high biodiversity or arboreal animals like gliders and owls. In 15 years, much of the biodiversity in these areas will be gone.”
Over the past few years the BMAD working group has been conducting trials of forest management methods on private and government lands to see if the bell miner habitat in the understorey can be controlled and if BMAD-affected trees can recover.
“Property owners and National Parks staff have developed techniques to kill lantana so that rainforest can regenerate through the dead weeds,” Woo Wei said. “There is a suite of treatments for different forest types. We need to assess what might be appropriate for each forest type. Depending on the forest type, whether wet or dry sclerophyll forest, lantana removal may best be carried out with a low level herbicide application and the moist species allowed to grow back in the dead lantana. You can’t burn in dry or wet sclerophyll forest with too much fuel load or the fire will burn too hot and kill trees, vines and shrubs.
Treated forested areas can be supplement planted to encourage the local forest community to grow back.
“National Parks and the working group trialled lantana removal at Sheep Station Creek and eventually the problem disappeared. We know it can work, now we need to roll it out and we need appropriate political response.”
If the future of our eucalypt forests is to change for the better, Woo Wei and Jim believe appropriate forest maintenance is necessary, including changes to logging practices.
“We have been unsuccessfully trying to get Forestry NSW to assess an area of forest prior to harvesting and record if it is dieback affected,” Jim said. “Affected forests especially need to be treated carefully. The problem is that NSW Forests log compartments, move on and don’t have the resources for rehabilitating them. We need to see mandatory rehabilitation of forests after every logging operation to address weed problems until the regenerated canopy is established.
“I’m a landholder myself and I can see no problem with sustainable timber harvesting. But what I’m seeing happen is unsustainable and we need to see a reduction in timber quotas. Forestry log an area and just move on. It’s like they think the forest is the magic pudding and we can take whatever we want and don’t put anything back.”
Monoculture plantations have also been devastated by the psyllid insect. Plantations designated for the eucalypt plantation program announced by Bob Carr in 1998 have now been replaced by exotic pine plantations.
“Mixed species plantations may help,” Woo Wei said. “We need to promote and respect natural systems and health processes to control psyllids. We need a gradual transition to repair stressed, unhealthy forests. Sometimes this means re-establishing a fully developed canopy, middle storey and not-overly dense understorey.
“We are facing the total collapse of our eastern seaboard hardwood forests. We need to change our forestry management practices now.”
The problem of BMAD is now officially called ‘Forest eucalypt dieback associated with over-abundant psyllids and bell miners’. If you would like more information, you can visit the website www.bmad.com.au