Some months ago I received a note from a forester about dieback in native Australian forests, following is an edited version:
“There is a very large and growing forest health issue particularly in the dryer forest types. Die back known by a variety of names from Bell Bird Dieback to Mundulla yellows is affecting thousands of hectares of native forest and appears to have the potential to affect thousands more.
It is a little talked about issue but it covers all land tenures public forest and national park and private property.
Based on observation by forest managers an hypothesis has been put forward that dieback is the result of changed fire regimes. In particular reduced incidence of low intensity burns has promoted changes in soil chemistry and moisture levels that have promoted antagonistic conditions to over storey eucalypts resulting in dieback and ecological change. Parallels can be drawn with the US Pacific North West and the forest health problems being documented there after 70 years of fire exclusion as a result of the overly successful ‘Smokey the bear’ campaign.”
This morning I received a note from David Ward. The following has been edited slightly:
“There is an article (Jay Withgott ‘Fighting Sudden Oak Death with Fire?’, Science Aug 2004 Vol.305 p.1101) which decribes how California oaks are dying from Phytophthora ramorum.
Two researchers (Moritz & Odion,’Prescribed Fire & Natural Disturbance’, Science Dec 2004, Vol. 306, p.1680) have found that there is some association between this pathogen and long fire exclusion. The researchers caution that there is not yet a demonstrated causal relationship, and that prescribed fire may have a different effect from natural fire. However, the article may be of interest to Australian researchers, and land owners.
… Some local WA Nyoongar Elders have said that, in their view, traditional summer burning, on dry soil, prevented the fungal diseases which we see now. At the same time, summer burning promoted other fungi, some of which were good tucker.”
This afternoon, Vic Jurskis send me a copy of his recent paper titled ‘Eucalypt decline in Australia, and general concept of tree decline and dieback’, Forest Ecology and Management, Volume 215 (205) pages 1-20 (available online at www.sciencedirect.com for $30).
The paper includes the following comments under a heading ‘Implications for Management’:
“Considerable resources are being devoted to research of contributing factors in tree decline but
few corrective actions are being applied in eucalypt forests other than quarantine and hygiene measures to restrict the spread of Phytophthora .… Prescribed burning appears to be the only silvicultural practice that can have widespread application in conservation reserves and
timber producing forests. Passive management of nature reserves in Australia has failed to maintain healthy ecosystems, especially in the case of the grassy forests that were most depleted by clearing for
agriculture and are now mostly declining in health and changing in structure.To conserve healthy dry and moist eucalypt forests it will be necessary to restore more natural outputs of nitrogen and moisture by using frequent low intensity fire and/or grazing. Ecological burning
regimes should be integrated with hazard reduction burning to protect forest health as well as social and economic values.”
David Ward also commented that it would be “valuable to get views from other parts of Australia on this topic”.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
What amazes me is how little we know from science about managing our eucalypt forests. With all our modern gear we can’t keep the more open woodlands going it seems.
Two things are wrong, researchers are not looking far enough back, to times before English grasses and weeds were sown everywhere and we don’t have a bunch of kids running around bare foot with a handful of fire sticks any more, keeping their pathways clean.
I suspect their fires left the majority of trunks and logs untouched and avoided a subsequent leaf fall.
Risk management for them was all about minding your feet, before and after the fire.
IMHO our foresters should try it with the old ways first.
The Commonwealth EPBC Act lists Phytophthora cinnamomi as a ‘key threatening process’ throughout Australia. It mentions fire in an unsuccessful management trial in WA. http://www.deh.gov.au/biodiversity/threatened/publications/tap/phytophthora/index.html.
Over 200 patches of rainforest dieback have been found in the Wet Tropics WHA – mostly in wet notophyll vine forests above 700m on acid volcanic soils (14% of the World Heritage Area). Fire is prohibited in WTWHA rainforest.
I have heard tourism lobbyists argue that its threats are overstated to close access to higher altitude sites, which are both valued for rare mammal sightings but also are almost sacrosanct to conservation scientists because of their restricted habitat values.
Phosphite has been successfully used to control phytophthera in some situations.
The subject is of international concern hence a whole conference devoted to the subject.
http://wwwscience.murdoch.edu.au/conf/phytophthora/prog.html
This is interesting; phytophthera may be cyclical, once it colonises an area it exhausts its food supply and dies back allowing regeneration of prior sp;
Regeneration of Vegetation in the Brisbane Ranges After Fire and Infestation by Phytophthora cinnamomi
P Dawson, G Weste and D Ashton
Abstract
The distribution, population density and regeneration of some prominent spp. of understorey and overstorey (dominant Eucalyptus spp.) were monitored over a period of 20 yr in seasonally well drained dry sclerophyll forest. Changes varied with susceptibility to the pathogen and to fire. Changes in spp. composition and crown density of the overstorey were attributed to fire. Population density, basal area and crown cover of the Eucalyptus spp. which were associated with the pathogen, also declined in 1962-82.
Both distribution and population density of Xanthorrhoea australis and Isopogon ceratophyllus declined markedly following the spread of infestation, whereas those of Hakea sericea and Lepidosperma semiteres increased. Regeneration of X. australis but not of I. Ceratophyllus was observed in certain areas of the infested plots 12-20 years after infection. This is the first record of such regeneration. It is postulated that a bush fire in 1967 both stimulated X. australis seed production and reduced further an already declining pathogen inoculum density.
Australian Journal of Botany 33(1) 15 – 26
Full text doi:10.1071/BT9850015
Thanks Rog,
I will follow up on Dawson et al.
I have read the paper by Vic Jurskis and I have spent a day in the wandoo forest with Vic. He is that unusual type of modern research scientist: one who actually spends a lot of time in the bush, with his eyes open. Everything I see on my trips around Australian forests supports his findings.
The wandoo forest is a textbook case of mismanagement leading to forest health problems. I knew this forest well in the early 1960s, when I was part of the team which was type-mapping the area. This involved days and weeks of walking through the bush, so my experience was first-hand. In those days the wandoo forest was open and grassy. Fire occurred frequently, usually about once every 3 or 4 yrs, as a result either of lightning, deliberate ignition by beekeepers and hunters or escapes from clearing burns on the new farms in the Talbot Brook area. Becvause of their frequency, the fires were not intense, and the local foresters were happy to let them trickle around all summer. It was a very healthy and beautiful forest, park-like, and with abundant wildlife.
From about the mid-1960s, fire was progressively withdrawn from this bush. The law required the department to suppress wildfires ASAP. The department did have a policy of prescribed burning, but this was related to fuel accumulation rates, and as this dryland forest accumulates fuel only slowly, the burns went out to 12 years or more, in some places 20. Burning to reduce fuels to aid fire suppession is a good thing, but we now know it is not enough. We need burning for ecological reasons as well, and the ecology, it turns out, requires more frequent, not less frequent fire.
The wandoo forest today is very sick. Trees have serious crown decline or are dead. The whole place looks tatty. The open grassy understorey has filled up with woody shrubs and species like parrot bush and rock sheoak which do not like frequent mild fire, but can expand rapidly in long periods free from fire. This situation has been exacerbated in many places by the dense regeneration which came away in the wake of logging operations, and by a general decline in rainfall in southwestern WA since the mid-1970s.
The poor old wandoo now finds itself in a situation where rainfall is lower, but it has an understorey of dense shrubland which (a) prevents recharge of soil water; and (b) utilises soil water itself. Whats more, most of the area has recently been made a National Park, so the regrowth stands cannot be thinned.
Here we have a forest health problem which could be fixed at very low cost. What is needed is a regime of frequent, mild fires accompanied by a commercial thinning of overstocked regrowth forests to reduce tree numbers. Neither of these things will happen. They are opposed by the conservationists. Meanwhile, a lot of effort is being put into getting the agency bureaucrats in ome decent trials. I am not optimistic.
So unless we get a return to above average rainfall, and this is said by the experts to be unlikely due to climate change, this lovely forests appears to be on track for massive ecological change, basically at our own hands.
Roger,
Vic Jurskis’ observations in the eastern states ring a bell for me in Western Australia. I have seen patches of very sick, long unburnt jarrah, but it is not Phytophthora, because the banksias are thriving. Amphion block, near Dwellingup, unburnt since 1931, is converting to a banksia woodland, with sick and dying jarrah poking up through it. The dying tuart forest is similar, except that the understory there is dense peppermint.
After the big Karagullen (WA) fire (summer 2004/5) I spoke to old residents, who described the wandoo forest up to about 1960 exactly as you do – grassy, with frequent (2-4 year) mild fire. They say the jarrah forest was burnt every 3-4 years. In both cases, the frequency of fire in the landscape matrix protected many small fire refuges, which are now destroyed by large, uncontrollable fires.
I have also talked to old residents of the kwongan bush, near Dongara and Eneabba, north of Perth. There, botanists want to impose a blanket minimum interval of 12-16 years between fires, based on a ‘mathematical model’. The local residents are bemused – they remember when that area was open and grassy, with patches of banksia heath. It was mildly burnt every 2-5 years in winter. Now it is tall, woody, dense banksia heath, and burns uncontrollably in summer, at unpredictable intervals, up to twenty years in places.
Some practical CALM field staff see the damage by big fires, and are interested in the local history. CALM policy, shaped by the academics of the WA Conservation Commission, seems to be based on the prolix publications of academics.
My local history is consistently dismissed by some academics as ‘anecdotal’, and snide suggestions have been made that I have led the witnesses. The witnesses are, in fact, stalwart and forthright country folk. Any attempt at leading their opinions would get short shrift from them. Besides, once started on fire history, it can be difficult to get a word in edgeways. They are passionate, and puzzled by CALM’s fire policy in places.
My conclusion is that something is missing in the education of academic biologists. Possibly they are trained, rather than educated. Many do not recognise the value of history in understanding landscape ecology. Nor are their ‘mathematical models’ terribly clever. Models are only as good as the (oft obscure) basic assumptions. Some academic fire ‘experts’, with vast publication lists, are stunningly ignorant of actual fire behaviour. It’s like taking flying lessons from instructors who have never been off the ground.
CALM, and eastern state agencies, need to pay more attention to local history if they really want to understand and conserve the bush. Ecology is not simply a branch of biology, even if some biologists naively think so. It is interdisciplinary. At the landscape scale managers use, history is essential. In the USA this seems to be well understood. As Thomas Swetnam et al. have pointed out, “Scientists and managers alike are increasingly using environmental history as a base datum for understanding and managing ecosystems.” It’s time for some Australian academics to catch up on their reading of history, and help land managers, instead of misleading them.
Ref: Swetnam, T.W., Allen, C.D. and Betancourt, J.L. (1999) Applied historical ecology: using the past to manage for the future. Ecological Applications 9(4) pp. 1189-1206.
Roger & Davey
Although the posts by Rodger and Davey interest me greatly and I probably agree with their thoughts I’m not about to put my guts on these issues up here for others to sniff through. Firstly I don’t work from a science background and secondly others aren’t ready for the alternatives like local practice and old timer’s wisdom etc.
Its suffice to say that in looking forward one hundred years you have to look back at least a hundred years to get a handle on our trees and their habitat decline or development over time. As I have said often enough the evidence lives in the trees and we don’t have to cut them all down to find it Some of these fly by night writers could do with some lessons out in the bush though, with the old time loggers and sawmill operators for starters.
I once watched a saw doctor for hours as he made a large softwood milling operation rise from dubious turnover to substantial profit by merely using a hammer. Similar crafty skill can apply at every stage of our forestry operations including the selection of seed and soils in recovery. But there is no one recipe for success with growing and protecting trees. I reckon it’s as elusive as breeding and training a horse to win the Melbourne cup or becoming a blacksmith by reading through links posted in Jennifers blog on the internet.
While the forestry experts are stuffing round with blue gums and pines everywhere many places including the ACT are loosing forest reds and yellow box etc to all sorts of pressures, including drought, fire and dieback. I write sometimes about honey.
Rosslyn Beeby reminds us again about another issue with her article on Page 4 (Canberra Times March 28th 2006) $3m fire study sees livestock role in Kosciuszko Park (bushfire CRC funded).
Controversy has erupted again over the role of Gary Nairn’s cattlemen in their traditional grazing of the high country versus NSW Parks management and their dependence on decades of research by the alpine ecologist Dr Alex Costin.
Everybody knows my position on science versus practice in these debates (note; here we have the bull by the other foot) however it was myself who pushed others back in 1972 to do the same cattle banning campaign in Victoria but for very different reasons, water retention in the high country versus new dams in the head waters of the Murray.
After one of the worst fire seasons on record wiped out most of the ACT wood reserves in its pine plantations, farm lands and so on, I have asked our government to consider farming all natural resources locked up in our reserves by a new management plan. Namadgi in the ACT is part of the Australian Alps parks system. Our water supply is also the headwaters of the Murrumbidgee.
There is no one recipe for taming the elements.
Bugger, I dont know about the racehorse analogy, all sorts of dodgy tricks are being played courseside, horse owners lose money in fistfulls, they earn it elsewhere. AJC estimate average return 10/15c in the $. Its a passion, sport of kings.
These “forestry experts are stuffing round with blue gums and pines everywhere”, are you talking about the managed investment schemes like Timbercorp who buy and manage their own land, mills, wharves and plant their own timber?
Somewhere along the line reason must prevail.
I have interesting observations and information regarding dieback in north qld.I can be contacted on 0740979339.
Die back in trees is caused by many forms of stress that trees are suffering from.
The idea that people tramping through the forest will spread die back is ludicrous.
Animals have been rushing through the forests for thousands of years…..in which case the
trees should have disappeared long ago.
The clearing of forests has been the major reason for this disaster. There was no problem until
people began wholesale clearing of healthy trees.
The rising of the water table, and the increase in salinity has added to this tragedy.
However it is the wide spread ignorance of the physiology of plant life is perpetuating this
problem.
Healthy trees are aware of human emotions, they are living organisms and they are affected
by the what happens around them, they are far`more sensitive and intelligent than biologists
give them credit for.
Plant biologist perform autopsies on plants ..other than that they are ignorant any thing thing else about them.
Get rid of the chain saws and bulldozers ..and the trees will come back.