Dear Jennifer,
I was reading your blogs criticising the misrepresentation of the facts surrounding the Murray river floodplains and death of river red gums. I own a property on the Murray river floodplains, downstream of Echuca. My property has river red gum wetlands that have quite naturally not recieved any flooding since 1995.
For the last 15 years my red gum wetland and many other red gum wetlands in the region have suffered massive decline in tree health and in some instances all of the trees have been killed. It is changing the look of the landscape and is quite obviously a regional catastrophe.
But what is the cause? Ask any of the experts and they insist it is “drought”, but in my district the average rain for the past 15 years has only been slightly below the long term average and in reality the redgums have probably had as much flooding as they ever did in dry periods.
The actual cause of the tree death is something much more cute and cuddly, common brush-tailed possum’s. Brush-tailed possums are abundant in these hollow redgums. At times I have spotted up to 15 mature possums in one tree. Each summer the trees grow a few leaves and then for the remainder of the year the possums strip them clean. The trees can only take about three years of this kind of constant bombardment before they die. From the 200 large trees within my wetland at least 75% have died in the last 10 years, and the remainder are in poor health.
Prior to European settlement in the area, the local Aboriginals heavilly utilized brush-tailed possums for food, clothing etcetera. So much so that one of the early pastoralists in the area referred to them as the “possum-eaters”.
As an experiment I possum guarded a number of random trees last November.
The following photograph I took this morning of one of the possum- guarded trees. The trees in the photograph were all in similar health at the time of guarding last November.
Possum attack is a widespread problem in the Murray flood plains now that possums are unable to be utilized and managed, and probably explains a lot of the premature death of red gums that people are witnessing in this natural dry period.
Regards,
Michael O’Brien
******
Note from Jeff Yugovic, added 13th December, 2015
“Although my work is widely accepted by the general public and many practical conservationists, I am being ignored by academia and am regarded as a heretic by some ratbag ‘conservationists’.
My discussion paper is online and is updated periodically:
http://www.spiffa.org/do-ecosystems-need-top-predators.html ”
This paper quotes the above blog post.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Spot on Michael,
Aborigines were top predators. In Western Australia fox-baiting has led to local overpopulation of some ground dwelling animals such as woylies and quenda (bandicoots). I suspect they need culling, before vegetation is permanently damaged. That will cause a furor with the Walt Disney school of conservation.
Now that is what is really called stirring the possum 🙂
Point! Michael.
Interesting.
Brush-tailed possums are extinct from large areas of their former range, especially in the arid zone, but are prolific in other areas, including some urban environments.
If it is true that brush-tailed possums are killing significant numbers of trees they should be culled.
As regards the woylie, one of the two subspecies is extinct and numbers are way down on what prior to Eurpean settlement:
“Evidence from Aboriginal people and early explorer records suggest that woylies were once widespread and abundant across Australia south of the tropics, including the central deserts in central Western Australia and into the southern region of the Northern Territory. Woylie numbers and geographic range have decreased dramatically during this century. By 1975 there were only three known natural populations remaining at Dryandra Woodlands, Tutanning Nature Reserve, Perup Nature Reserve and surrounding areas. It had disappeared from central Australia by 1960. Woylies have been established by translocation at Batalling Forest, Boyagin Nature Reserve, Julimar Forest, Lake
Magenta Nature Reserve, and Peron Peninsula at Shark Bay, and more recently, Kalbarri National Park. Woylies have also been translocated to a number of sites in the northern and southern Jarrah forests of Western Australia, and to sites in South Australia and New South Wales.”
http://66.102.7.104/search?q=cache:vqd7xImiq0QJ:www.calm.wa.gov.au/plants_animals/pdf_files/sp_woylie.pdf+woylie+extinct&hl=en&gl=au&ct=clnk&cd=1&client=firefox-a
The quenda’s story is similar:
“The Southern Brown Bandicoot is widely distributed along the fringe of southern and eastern Australia and in Tasmania, though has declined in from some areas of Western Australia, South Australia, New South Wales and Victoria. The Western Australian subspecies, the Quenda, formerly occurred throughout the high rainfall areas of the southwest, south coast and southern wheatbelt region, however this distribution has declined rapidly since the 1960s. The species persists in the southwest corner of Western Australia, including the Swan Coastal Plain, where it has benefited from broadscale fox control.”
http://www.awc.org.au/wildlifeprofiles.asp?WID=598
If these species now exist in excessive numbers at certain locations, I think new populations should be established in areas where they are locally extinct using translocated animals.
Clearly the MDBC were correct to state that their “understanding of the response of River Red Gum communities to drought and variation in natural river flow is still in its infancy….”
Dieback can be due to any number of factors acting in concert or independantly, from the SA Dept Environment and Heritage “Dieback in Native Vegetation in the South Australian Murray-Darling Basin”
……………………………
VISIBLE factors include:
+ Insect attack
+ Witches’ broom
+ Mistletoe and Dodder-laurel infestation
UNDERLYING factors include:
+ Native vegetation fragmentation and isolation
+ Lack of available soil moisture
+ Waterlogging
+ Increase in soil salinity
+ Increase in soil nutrients
+ Loss of understorey
+ Soil compaction
+ Mundulla Yellows
+ Plant pathogens – organisms that cause plant disease
+ Other factors
Ultimately, tree death occurs when the stressed plants are no longer able to withstand the combined effects of these factors.
…………………………..
Dieback is also occurring in the Hunter Valley, from aerial photographs some of the river red gums have been dieing back since the 1950’s. It has been noticed that in some areas land use changes (grazing) have occurred alongside tree recovery – whether dieback is directly related to the loss of native shrub and grass within the immediate vicinity remains to be established.
Dieback around Armidale was studied and whilst the results were inconclusive they did note that “Diebacks are worldwide and have various origins and etiologies (Mueller- Dombois 1986, 1987). The Australian dieback is particularly severe and directly related to land use changes and insect outbreaks.”
http://www.canopymeg.com/PDFs/papers/0029.pdf
http://www.hcr.cma.nsw.gov.au/factsheets/land_and_veg/dieback_results.pdf
Dieback can be due to any number of factors acting in concert or independantly, from the SA Dept Environment and Heritage “Dieback in Native Vegetation in the South Australian Murray-Darling Basin”
……………………………
VISIBLE factors include:
+ Insect attack
+ Witches’ broom
+ Mistletoe and Dodder-laurel infestation
———————————————
“Insect attack” is the other common deparmental response when I point out the problems.
Funnily enough I don’t think my pieces of tin stopped the beetles, moths and butterflies. I remember the good old days when there was some insect life in the redgums, now they don’t get a sniff of them.
Yes rog. Tree dieback can be caused by lots of things. What is impressive about the above photo is the result of controlling one of those things, possums, on one tree for one season. Have our cute furry friends been underestimated?
Michael, what is the material around the trunk of the tree, which is obviously the possum barrier, and how much did it cost? Can it be permanent, or is it a degradable material? I am interested in the short and long term economics of humane possum control.
From memory, possum were introduced into New Zealand and are now/were once considered a serious alien pest species. Again from memory, control in New Zealand forests involved baiting with poisons.
You can see how dieback is a useful political tool, without proper analysis it can be made to prove anything.
Michael,
I’ll bet the Aborigines you speak of did not only eat possums, but a wide range of bush tucker stimulated by frequent, mild, patchy fire. If they were anything like the Nyoongar of south western Australia, they would have used fire to chase possums out of hollow trees. Eucalypt dieback is not only, or even primarily, due to the factors listed by Rog. Some of us believe the fundamental problem is long exclusion of mild fire. This has affected soil nutrients and pH, seed germination, insects, shading, mistletoes, etc. A recent study even showed an adverse effect on snakes, which used to hide under sunny rocks, now covered by scrub and litter.
Some academics (male) are ideologically opposed to fire (ignis nullius), and are doing their best to discredit ideas about Aboriginal burning. Unfortunately they seem to have the ears of those politicians sensitive to the votes of urban environmental theorists who dislike even small amounts of smoke. You will see outrageous porkies such as “little is known about Aboriginal burning” (Esplin Report on Victorian Bushfires. They should read some of the excellent work on Aboriginal fire and food gathering by female academics, such as Dr Sylvia Hallam of UWA, and Dr Beth Gott of Monash. For a sample see http://www.csu.edu.au/special/bushfire99/pages/gott/
Michael, the community no longer deserves your wetland. They have deprived you of your effective ownership of those trees. They have taken all control over your trees but accept no responsibility for them. They will not listen to even the most rudimentary common sense from landowners but will leap to attention at any gonzo claim by an urban daytripper.
They don’t deserve your goodwill because they don’t value either your past efforts as custodian or your future capacity to protect, restore and enhance your own ecosystems. Indeed, they do not see you as having any long term place in your ecosystems.
The only way these people will ever get the message is for you to go on ecological strike. Keep your photos but take down the possum exclusion measures and let the whole lot die.
If you need the ecological services of trees there then there are plenty of exotics to try. But keep some local seeds in a safe place so you can restore it all whenever you are satisfied that “they” can be trusted.
I hope you wont have to wait too long but I suspect that your kids will still have the seeds when they retire.
But it is weekend again and I’m off to spray some more seedlings.
“ecological strike”
is that what the farmers have done in the UK, hence all the empty land?
what would it achieve? Who would bear the brunt of that?
The evil city folk would just import agric needs and buy the vacant land to downshift, build their dream home and telecommute in the increasingly dispersed economy
Good contribution, thanks Michael. Have you attempted to spread the word on the possum hypothesis?
True story – A friend was dining in Victoria Street, Richmond at his favourite restaurant. He knew the proprietor and said to him jokingly ” any possum tonight Ng?” “No” said Ng “…too expensive…”
I tried the smoked stuff that comes out of NZ and it was very good!
Ian Mott posted some dietary requirement levels for grazers of tree leaves such as possums on an earlier thread, noting that they were only achievable with regrowth.
It is well known in rangelands management circles that forage from a plant struggling to re-establish is of high dietary quality but of low yield, and that the plant’s long term survival is not enhanced by grazing at this stage.
At a smaller scale, but similar effect – the gazanias in our garden have been wiped out by mallee ringnecks
Ian,
Gazanias go often feral. The mallee ringnecks have the right idea.
Michael, what is the material around the trunk of the tree, which is obviously the possum barrier, and how much did it cost? Can it be permanent, or is it a degradable material? I am interested in the short and long term economics of humane possum control.
———————————————–
Hi Helen,
The material around the trunk of this tree is piece of rippled sheet metal from an old swimming pool, that I found dumped in the bush.
I have sourced sheet metal from wherever I can find it and have even bought new material for some trees. Given the girth of these ancient trees, this works out very expensive and I think it would cost between $50-$100 to guard a single tree.
You might also question if in fact waiting for the possums to leave their cosy hollows one night and then locking them out in the cold is actually humane?
The sad fact is that this is a naturally isolated redgum wetland, surrounded by natural grassland plains.. When these possum end up killing all their food source (except for the half dozen trees I’ve guarded), they will extinct themselves from my farm.
It is crazy that you can’t capitalise on what is an obvious population imbalance especially when they are so good on the tooth.
I’ll put you in touch with Ng if you like.
Perhaps freeze the possums and then you can pull them out for future use along with the saved seeds?
Steve M.,
You are right, of course, about relocating excess quenda and woylies, but it takes resources. Meanwhile, at Dryandra Woodland, I am told that excess woylies are eating orchid bulbs. What do you want, lots of woylies, or lots of orchids? Could be an academic punchup between botanists and zoologists? In my own semi-rural suburb I have seen up to four quenda rooting up a small lawn, in broad daylight. My own killer tabby cat cowers under the barbeque when marauding quenda (Basil & Barbara) raid her dish. They are specially fond of those little fish flavoured biscuits.
One of the worst attributes of restricted fire regimes is the formation and maintenance of hydrophobic soil layers that seriously impede soil moisture retention.
A good fire fixes this well.
By the way, Michael, there is a good cheap method of solving your possum problem and saving your trees for the cost of only one of your tree barriers.
But this is the kind of knowledge that myself and other disgusted farmers are no longer willing to make public to a community that has trashed the social contract. Please don’t take it personally but when injustice becomes law then opposition becomes a moral duty.
Pity.