Friday, March 24, 2006

Whats wrong with the Qld forestry code of practice (3)

Part 2 Exposing the over-inflated need for HBTs (Continued)

11. No assessment has been made of species propensity to co-occupy different hollows in the same tree on the same day or the resulting sensitivity to HBT needs.

Wormington (p147) reports that in up to 16% of observations, two different species co-occupied a HBT on the same day. And this was in a drought year with reduced animal densities. It is a behaviour that is more likely to take place in good seasons when the animal density is higher and the demand for hollows is greater. It is clearly another strategy through which animals ensure that any short term contraction in HBT supply does not lead to species collapse.

12. They fail to consider the “musical chairs effect” in the provision of den diversity.

Much has been made of the Greater Glider’s supposed need to occupy many hollows but they can still only occupy one hollow at a time. It is true that animals do use a number of hollows within their range but this does not mean there must be a surplus over actual usage. And there is no evidence that this usage must be exclusive over time.

Arboreal mammals achieve the variation in den sites in the same way that children in a game of musical chairs enjoy variation in sitting location. And unlike in the game, if the number of chairs is equal to or exceeds the number of participants then the game can go on indefinitely and produce no losers.

To further punish the analogy, in the forest habitat game, some chairs are for big people and some are for small people but some chairs can also sit two people of different sizes. Indeed, a whole family can sit on one chair and in these circumstances having too many chairs may actually inhibit access to the table where the cake and candles are.

13. Wormington’s estimations of age at which species form hollows appears inconsistent with observed evidence.

Wormington (p108) provides estimates of the age at which various species will form hollows. His Figure 6.6 appears to have used the aggregated PAI data from the DPIF permanent plots to justify result that most private forest owners would regard as absurd.

His Table 6.8 (p109) suggests, for example, that >50% of stems will have hollows when Eucalyptus citriodora (Lemon Scented Gum) reach 61cm DBH. This may or may not be the case in private forests but the suggestion that the tree would have to be 220 years old to reach that DBH is far from the case in private forests.

The estimate is at substantial variance with the 15 year old example of this species in my own front yard that is already 43cm DBH. And to suggest that this tree will need another 205 years to achieve a DBH of 61 cm is to seriously test the credibility of the claimant.

It is possible that growth rates in a publicly owned forest, with a history of negligent and culpable mismanagement of a valuable asset, may achieve highly degraded growth rates. This would be especially so if the stand had an over burden of non-contributive stems, and understorey competition that impaired the growth of the stem in question. It would also be true if the tree was the only good nosh in the paddock and it was continually over-grazed by four legged caterpillars.

But what is absolutely clear is the fact that the estimates of time taken for new HBTs to form in public forests are totally inappropriate for use in private forests. Indeed, photographic records are available that are fully capable of establishing that new HBTs can be created within the time it takes for most dead stags to collapse. That is, within 60 years.

There is no evidence to suggest that there is any significant gap between the rate at which stags become non-contributive as HBTs and the rate at which new contributive HBTs can be recruited. Consequently, the need for any recruitment HBTs should not exceed the existing number of dead stags that contribute to any retained HBT requirement.

14. No attempt has been made to determine the full cost of HBT retention.

The cost of a recruitment habitat tree is not it’s stumpage value. Many private forestry uses are in association with the small (formerly) licensed mills and many others are in association with on-site portable milling. Other forests that are not directly associated with portable milling retain an indirect association through contract milling and a complex network of barter deals based on full retail value of sawn timber.

So even if there was a pretext for only using stumpage value to measure the costs of Code of Practice prescriptions in public sector forests, this is totally inappropriate for private forestry.

A typical recruitment habitat tree of 60cm DBH is likely to have a round wood volume of 3m3 each. This would produce 1.5m3 of sawn timber with a minimum value of $800/m3 or $1,200 each. So 11 such recruitment trees in a hectare of young remnant would amount to $13,200 in foregone income from profits and personal exertion per hectare.
If these proceeds were paid against a typical mortgage at 6.5% interest then annual savings of $858 per hectare will accrue to the beneficiary for the term of the loan. And the net present value of such a foregone saving is 10.5 times the annual benefit, or $9009 per hectare.

And to this must be added the value of timber that may have grown where the recruitment HBTs have occupied space or for which the harvest date has been postponed due to impaired growth rates. At a loss of only 2m3 in annual growth/ha this amounts to an additional $800 per hectare with a net present value of about $4,000. This puts the total cost of an 11 recruitment habitat tree prescription at $26,200/ha. And we don’t even get a tax credit for it.

15. There has been no examination of alternatives to HBTs where none exist.

The forest and wood products industry employs an extraordinary range of tools, techniques and technologies to produce an even greater range of products. Trees are specifically grown for specialised uses from cricket bats to masts. Wood is sawn, split, shaven, carved and chipped. It is dried, moulded, bent, glued, nailed, bolted, coopered, laminated and, recently, micro-waved and resin impregnated. It is painted, impregnated, coated and reconstituted.

It produces paper, cardboard, fibreboard, plywood, laminated veneers, mouldings, structural timber, beams and planking. It produced one of the best fighter planes of its time, the Japanese Zero, the 3000 tonne ships of Ming Admiral Cheng Ho, railway carriages, trucks, buggies, drays and wheelbarrows that built nations. It produces windmills, windlasses, propellers, pumps, cranes, boxes and furniture. It produces newspapers, chip wrappers, books, packages, tetra packs and tubing. It produces an outstanding array of dwellings from kennels, cages, barns, stables, cabins, houses, apartments, castles, churches and parliaments.

All these splendid transformations for the betterment of mankind and his environment begin in a forest. They are anticipated by, and dependent on, an on-going forestry purpose. But not one of these century old and even millennia old technologies has been considered as a means through which the dwelling needs of wildlife can be met in those very same forests.

A private forest owner with few HBTs left after historical compulsory clearing must set aside up to 11 perfectly good sawlogs/ha to wait, dumbly and inefficiently, for up to a century, until age, termites and pure chance can provide a service that his wildlife dependents are supposed to be in urgent of need right now.

In a landscape that has been extensively modified by man, it seems the only creatures that are to be excluded from enjoying any benefit from man’s intellect are the creatures that can be adversely affected by his actions. But even this exclusion is a selective one based on discrimination by occupational class.

As the brochure (34) says, “The Land for Wildlife program is proudly co-ordinated by the Queensland Government, Environmental Protection Agency & Queensland Parks and Wildlife Service”. It is also supported by the Natural Heritage Trust through the Bushcare program, Greening Australia and 61 local councils, funded by 14 councils in SE Queensland.

Land for Wildlife Note 19 (35) is specifically titled, “Nest boxes for native wildlife”. It recognises that HBTs can, and have been, depleted and states that “nest boxes can help species survive by providing artificial hollows for breeding and shelter”. A number of references are also provided as well as links to the web sites of nest box makers such as The Australian Nest Box Company (37).

This company sells a range of boxes for the large Possums, smaller Gliders and many bird species with prices ranging from $35 for kits and up to $95 for fully assembled and painted products. They highlight the preferences of various species, advise on multiple users, occupancy rates etc, and include a trap for feral pests like the Indian Myna. And their major customers appear to be local councils throughout the country who have allocated significant budgets for this purpose.

So if these measures are not effective, then why are they spending this money? The aim of the program is obviously to provide hollows for the period it takes for HBTs to form in forests where they are not present. These community owned forests do not have an on-going forestry purpose so there is no foregone production or economic loss that may result from waiting for a perfectly good tree to form hollows.

This is not the case with existing forestry uses. The cost of providing hollows by entirely natural means is very significant and this significance places a burden on any regulatory process to assess alternatives for that delivery.

And if a legal obligation exists for forest owners to provide housing for dependent wildlife households, one must ask, why is such a long delay in delivery of this obligation regarded as acceptable? And one must also ask, if this obligation applies to the owners of native forest without HBTs then why does it not also apply to the owners of plantations without HBTs. Are they not also subject to the environmental duty of care?

Clearly, artificial nest boxes can provide for the housing needs of all dependent wildlife. And despite the relative immaturity of this industry sector, they have already demonstrated the capacity to address this environmental need for a fraction of the cost of the prescribed natural alternative.

It must also be stated that far superior options with lower costs, cheaper and more efficient installation and relocation, easier inspection and maintenance and enhanced resistance to fire and harvest damage have already been tested and found to be preferred by wildlife over most natural hollows. But this intellectual property will remain suppressed until the socio-legal treatment of forest owners returns to accepted community benchmarks.


The sum of the above mentioned errors and omissions leaves little room for doubt that the need for the current HBT retention prescriptions has been based on partial and fragmentary statements of fact, false assumptions and questionable conclusions from selected primary data.

The natural climatic and seasonal range of variation in animal density has not even been studied properly, let alone understood. This ignorance has been exacerbated by an ‘in full knowledge’ failure to consider the extent to which arboreal mammals form family groups to co-occupy nest hollows with resulting over estimation of hollow needs.

A fundamental failure has occurred, to consider the ways in which species adjust their ranges, family size and reproductive behaviour to cope with climate based population peaks and troughs and the resulting changes to the relative supply of Habitat Trees.

A fundamental failure has also occurred, to recognise a clearly inelastic relationship between HBTs and species diversity and density over the ‘whole number’ portion of the graphs the relevant ‘experts’ have been studying. This has obscured the actual point of potential species collapse which most likely exists in the fractional scale between zero HBTs/ha and 0.5 HBTs/ha.

There has also been a fundamental perceptual problem in the minds of the people responsible for examining this issue. They have assumed that the survival of species is contingent on their capacity to maximise population in good seasons. This is the only time when anything approaching a shortage of HBTs would be evident.

But the overwhelming evidence indicates that they have got it the wrong way round. Species survival depends primarily on their capacity to survive on the minimal food resources in a bad season. It is this surviving remnant that determines the size of a good season population surge. But there is no shortage of available hollows for a depleted dry season population.

The current departmental position is the ecological equivalent of suggesting that the survival of starving Africans in a famine is dependent on them maximising their birth rate in good seasons. It is the very opposite of the inescapable truth and as equally dangerous.

The detailed modelling of Wormington’s actual plot samples that is attached to this paper is fully capable of advising the policy process on the actual need for retained HBTs under the Code. It is also capable of examining the sensitivity of various levels of HBT retention to both underestimation of populations and actual population changes. And the proper use of such a model, once available, would appear to be a minimum requirement for satisfying the Minister’s general duty of care.

The detriment that forest owners may suffer from the negligent investigation of the need for, and utility of, the habitat tree prescriptions under the code is very significant and entirely foreseeable.

We urge the Minister for Natural Resources, Mines and Energy, and The Premier of Queensland, to take all reasonable and practicable steps to ensure that any detriment that private forest owners may suffer is minimised. For the harm that forest owners may suffer from misapplication of measures is not quarantined from the broader community.

Many forest owners are starting to question whether the community this Minister represents is still worth them donating their time to causes like the rural fire service. They often form the core expertise of such groups and risk their life on-call and often leave their own family vulnerable while they protect the wider community. And they could not help but notice that nowhere, in either the Vegetation Management Act 1999 or in this Code, is there even the slightest provision, or trace of any obligation on the Minister’s part, to maintain what used to be called the cardinal principle of forest management. That is, there appears to be not the slightest desire, on the part of the community this government represents, to ensure that their forest is capable of producing timber in perpetuity.

It would appear, from the matters raised in this paper, that the social contract between the community and private forest owners has been abrogated. And in this circumstance, forest owners have a duty to themselves and their families to reassess the nature and content of any contributions that they have been making to a community that no longer treats them equally before the law.

To paraphrase ‘70’s rock group ‘The Eagles”, in their classic, “The Last Resort”,

“They will provide the grand design, of what is yours and what is mine.
Then try to make a new frontier, by driving families out of here.
They called it sustainable, I don’t know why.
If they call something sustainable, then kiss it all good-by”.

Ian Mott
Secretary, The Landholders Institute Inc.
PO Box 5375 Manly Qld 4179
Ph. (07) 38930612


1 Ratnapala, S. Vegetation Management In Qld, IPA Review 12/2004 (p10) See
2 Judicial Review Act 1991 See
3 Public Sector Ethics Act 1994 See
4 Criminal Code Act 1899 See
5 Code applying to a forest practice on freehold land. See
6 Qld DNRM, Habitat Tree Technical Advisory Group, Managing Habitat Trees in Qld Forests, 4/1998 Lamb. D, Loyn. R, Smith. A, & Wilkinson. G.
7 Op. cit. (p38)
8 Qld Herbarium. “Coreveg” unpublished data set for normal height & canopy cover.
9 Smith. C & Lees, N. 1998, Density and distribution of habitat trees required to support viable populations of hollow dependent species, Qld DNRM.
10 Ross, Y. 1998, Hollow bearing trees in native forest permanent inventory plots in SEQ. Qld DNRM.
11 Wormington, K. 2003. The habitat requirements of arboreal marsupials in the dry sclerophyll forests of SEQ. PhD. Thesis, University of Qld.
12 Ibid.
13 Ibid. Appendix I (p21)
14 Ibid. (p6)
15 Op. cit (p6)
16 Op. cit Fig 5a & 5b (p56)
17 Op. cit (p20)
18 Ibid. (p20)
19 Strahan, R. Ed. 1995. The Mammals of Australia, Aust. Museum/Reed (p264)
20 Op. cit (p26)
21 Op. cit (p271)
22 Op. cit (p22)
23 Op. cit
24 Op. cit Table 3a & 3b, (p47)
25 Op. cit Table 5. and Figs 2a to 4b (p52)
26 Op. cit (p24)
27 Smith, A. & Lindenmayer, D. 1998 Tree hollow requirements of Leadbeaters Possum and other possums and gliders in timber production ash forests of the Vic. Central Highlands Aust. Wildl. Res. 15: (p347-362)
28 Op. cit (p52-56)
29 Op. cit (p22)
30 Op. cit Smith & Lees Fig 5a & 5b (p56)
31 Ibid.
32 Op. cit HTTAG (p23)
33 Op. cit Strahan (p263)
34 Land for Wildlife program. 2003 Qld Government, Environment Protection Agency.
35 Op. cit Land for Wildlife Note 19
36 The Australian Nest Box Company. See

Whats wrong with the Qld forestry code of practice (2)

Part 2: Exposing the over-inflated need for HBTs.

The excessive prescription outlined above can only seek justification with an over-inflated need for that prescription. And the DNRM responded accordingly. Foremost amongst recent efforts has been the very same Habitat Tree Technical Advisory Group as mentioned above.

The primary inputs for their work came from then QDNR’s Resource Science Centre with papers by Smith and Lees (9), called Density and distribution of habitat trees required to support viable populations of hollow dependent species, and by Ross (10) on Hollow bearing trees in native forest permanent inventory plots in SEQ.

More recently, this has been followed by a doctoral thesis by Wormington(11), under the supervision of the same D. Lamb above, on The habitat requirements of arboreal marsupials in the dry sclerophyll forests of SEQ. The unpublished paper was quoted by the HTTAG.

And the body of these works have the following flaws which, consequently, amount to flaws in the policy development process;

1. None of the reports distinguish between hollow use and hollow dependence.

Many species that use tree hollows also use other forms of shelter and many are very adept at either building their own nests or using the nests of others. These are not “hollow dependent species.” Analysis of a core requirement for tree hollows must address partial dependence to focus on the extent to which species must have tree hollows to maintain their life cycles.

Of the arboreal mammals listed as hollow dependent, the Brushtail, the Mountain Brushtail, the Ringtail, the Sugar and Squirrel Gliders (essentially the one species as they interbreed with viable progeny) are known to use many other forms of shelter for some of the time. Feathertails rarely use hollows >6cm, use curled bark and nest in grass trees.

2. They all assume some minimal number of hollows will produce species collapse.

The evidence from suburbia, orchards and regrowth forests proves that this is simply not true. Contrary to the efforts of the department to suggest otherwise, these areas produce surpluses of what has always been the primary determinant of species density and richness, food.

My suburban roof top is routinely the venue for noisy fighting and fornication of two so-called hollow dependent species (Ringtail and Brushtail Possums) that not only maintain their prefix, “Common”, but do so in densities well above those exhibited by forests under the so-called “protection” of the public sector. Their home range is less than half a hectare. They are outnumbered by feline predators but have been fruitful and have multiplied without a single hollow bearing tree. They have built one nest in my Macadamia tree, another in my Bamboo but, like students in a well misspent youth, sleep in a number of beds of opportunity.

The point at which these animals might experience ‘species collapse’ is obviously less than zero HBTs/ha.

A number of Foresters with experience predating the “habitat tree fetish” have observed that the greatest concentrations of Yellow Bellied Gliders were found in “extensively modified coupes”. This term generally meant no retained non-commercial stems and certainly no retained hollow bearing trees. They did, however, produce widely spaced stems with increased soil moisture reserves, improved and extended microbial soil fertility, more nutritious sap, bud and leaf material, for a greater part of the year, in vigorously growing stems that the Gliders simply knew as food.

Wormington(12) makes it very clear that population density is highly dependent on the nutritional value of eucalypts. And in the case of silviculturally neglected publicly owned Dry Sclerophyll forest this means the extent of E. citriodora in the stand. The results from private regrowth or remnant that has been well spaced, with weed control and Super-phosphate treatment is likely to be quite different.

3. No surveys of sites without HBTs have been done to test the ‘species collapse’ theory.

If the species collapse theory has any basis in fact then forest stands without HBTs will have no arboreal mammals present. For these sites will have fallen below this theoretical threshold, whatever it is. But whenever it is suggested that such a survey should be conducted to clarify the matter we have always been told of the difficulty in gaining access to the private forest sites that are assumed to be the only places such a survey could take place.

But this is not the case. A close examination of the 390 Permanent Inventory Plots data used by Ross (13) reveals that there is an abundance of sites without HBTs in the public forest estate that could settle this question if the political and departmental will to do so was present. But one could be excused for not realising this fact.

For Ross has seriously misreported the proportion of plots without HBTs and when these errors are corrected we get a very different picture of this resource. In her Table 1 (14) the number of plots with hollows present was put at 323 when the actual records in her Appendix 1 came to only251. The number of plots without hollows was put at 67 when the actual records in her Appendix 1 came to 139 such plots. The numbers under the heading “Plot count” did not even add up, although the totals row did. The table below shows the actual area of plots without hollows to be 33.6%.

Table 1. SEQ Permanent Inventory Plots without Hollow Bearing Trees

Revised from Table 1, of Ross; Stand density of trees & stags in SEQ permanent plots
Broad Plot count Plots Plot Hollows present Plot Hollows absent Plot %
forest Hollows Hollows Total fauna area plot size area plot size area without
type present absent survey (ha) 0.5 0.404 (ha) 0.5 0.404 (ha) Hollows
1 38 22 60 35 28.1 31 7 18.3 9 13 9.8 34.7%
2 92 30 122 25 57.6 72 20 44.1 15 15 13.6 23.5%
3 2 2 4 2 1.8 1 1 0.9 1 1 0.9 50.0%
4 82 25 107 23 50.0 61 21 39.0 10 15 11.1 22.1%
5 37 60 97 43.0 27 10 17.5 13 47 25.5 59.2%
Total 251 139 390 85 180.6 With hollows 119.84 Without hollows 60.76 33.6%

Broad Forest Type =

1 Coastal Dry Sclerophyll, 2 Inland Dry Sclerophyll, 3 Coastal Wet Hardwood, 4 Coastal Moist Hardwood, 5 Cypress

The fifth column(sic) lists the number of plots in each broad forest type that are reported to have had fauna surveys conducted on them. Clearly, there is sufficient number of plots without hollows to enable fauna surveys of an equally representative sample of these. And from this we can conclude that either;
a) an executive decision was made to avoid surveying these plots, or
b) a larger survey actually took place but these records have not been used or reported on for political reasons, or
c) the existing survey includes a number of plots without hollows but the results have been aggregated.

The significance of this is in the implications of hollow tree density and animal and species density across the forest estate. For Ross’ Table 2 (15) averages the total number of recorded hollow trees and stags over the total area of plots to give a mean of 10.2/ha. But there are two very distinct forest classes within this set for which the number of HBTs has a major bearing on animal and species density.

For example, when we allocate the 301 recorded hollows in the Coastal Dry Sclerophyll (BFT1) class to the 18.3ha of plot area with hollows we get a mean of 16.45 hollow stems/ha (up from 10.5/ha) in this class and zero in the remainder. The 149 recorded live stems amounts to a mean of 8.14 hollow stems/ha (up from 5.1/ha) in this class. The 166 >10cm hollow trees and stags produce a mean of 9.07/ha (up from 5.9/ha) and the 67 live >10cm hollow trees produce a mean of 3.66/ha (up from 2.3/ha) and zero in the remainder.

Similar results are produced in the other broad forest types with mean hollow stems/ha, on actual sites with hollows, amounting to;

Broad Forest Type All hollows >10cm hollows
Coastal Dry Sclerophyll (BFT1) 6.45/ha, 9.07/ha,
Inland Dry Sclerophyll (BFT2) 12.66/ha, 7.44/ha,
Coastal Moist Hardwood (BFT4) 18.21/ha, 7.13/ha, and
Cypress (BFT5) 17.62/ha 10.74/ha .

And it is worth noting that this number of hollow stems is well into the zone that is apparent in the graphs of Smith & Lees (16) (Fig 5a & 5b p56) where mammal and bird density is in decline. It should also be noted that Wormington,(17) (p20) who measured all hollows not just >10cm ones, found that, “The number of species also declined when the number of hollow bearing trees was >13/ha” (these sites also had low proportions of C. citriodora).

Clearly, fauna surveys of the plots without hollows are no more problematic than the ones that have already been carried out. The absence of data from these plots represents an absence of information that is likely to be highly relevant to the decision on appropriate levels of HBT retention under any Code of Practice.

4. They fail to conduct any research that would assist in identifying the threshold number of HBTs.

Both Smith & Lees and Wormington have speculated that species decline begins when HBTs are less than 4/ha but this is from a very limited sample. Wormington states, (18) (p20) “The maximum number of 5 arboreal species was found at sites with 3.67 to 13 hollow bearing trees/ha and higher proportions of the total stand C. citriodora”.

But examination of the plot records reveal a very limited sample of only 5 of the 38 (or possibly 76) records had five species present. And the composition of the species reveals that the fourth and fifth species at each site were all capable of using other nest sources.
Of the 10 encounters that made up these claimed examples of ‘maximum species diversity’;

3 were Feather tailed Gliders that according to Smith & Lees, make use of curled bark, old birds nests and possum Dreys. Strahan (19) (p264) reports of nests in the dried fronds of our abundant grass-trees, (Xanthorrhoea sp.) “and a wide variety of other niches”.
· 3 were Sugar Gliders that according to Smith & Lees, make use of Blackberry bushes, rock piles and Dreys. And Wormington (20) (p26) has pointed out that, “The density of Sugar Gliders did not appear to be correlated with the density of hollow bearing trees. The sites where Sugar Gliders were present spanned the range of HBTs from 2 to 20/ha. Instead, the density of understorey Acacia influenced the number of encounters with SG.” Absent Acacia, absent ‘maximum species diversity’.
· 2 were Common Ringtail Possums that according to Smith & Lees, make use of dense vegetation, aerial debris, hollow logs (on ground) peeling bark and, of course, possum Dreys. Other sites of relevance to the COP for freehold forests would include, sheds, power boxes, mailboxes, old vehicle panels, empty cans, Banana bunches and termite nests.
· 1 was a Mountain Brushtail that according to Smith & Lees, make use of stumps, logs and burrows and to which Strahan (21) (p271) adds epiphytes.
· 1 was a Squirrel Glider, essentially the same species as the Sugar Glider. Smith & Lees have not recorded other den sites but as they interbreed with Sugar Gliders we can reasonably assume that they are capable of utilising the same alternative den sites.

The species that made up the fourth record on the five plots with four species also came from the above list so there is no basis for concluding that HBTs were essential in achieving more than 3 species per plot. HBTs are merely an association with maximum species diversity, not a pre-condition for it.

And given that there are 139 plots with no HBTs at all then it would seem that there is sufficient scope to create HBTs in some of them (more than 10 plots each), and modify some of the overstocked plots, to provide a sufficient sample of plots with 0.5,1, 2, 3 and 4 HBTs/ha to determine where this threshold might be. But that, of course, might involve an unencumbered departmental whit and the sacrifice of a few sacred cows.

5. No attempt has been made to reconcile the HBT retention prescriptions with the actual animal density and range of densities found in the public forest estate.

The HTTAG (22) carefully avoided this issue by ensuring that this material was embedded in Smith & Lees’ work. Any references that would normally be expected to perform the essential informing role of statements of fact were ‘weaselled’ off to the model so that any resulting misstatements would be less easily traced to the HTTAG. A good example of this tenuously coherent bunkum can be found on p22 and 23 of their report. The clear purpose of technical advisory groups is not to find the truth but, rather, to obscure responsibility for un-truths. And HTTAG appears to be no exception.
Nowhere in the HTTAG terms of reference, and certainly not amongst the 11 “Reporting Requirements” questions that were asked of the group, is the absolutely critical question;
“What is the nature, size and distribution of the actual population we are seeking to provide adequate housing for?”

Question 3 gives the initial appearance of doing this but no such answer is forthcoming. The question goes on to request answers for the 5 broad forest types used by Smith & Lees but the answers from page 20 to 25, and particularly the Table 2 (23) data provided by Smith, uses different descriptions of only 3 types and fewer samples than the actual source material from Smith & Lees(24) (their table 3a & 3b, p47) This does not appear to be designed to inform.

The estimates of bird and mammal density provided by Smith and reproduced by HTTAG appear to be approximately double the numbers used in Smith & Lees’ Table 5. (25) and in their graphs (Figs 2a to 4b p52) This appears to have been done through (26) “our belief that densities of hollow dependent fauna are underestimates.” (p24) HTTAG put the range of mammals as 1.1 to 2.3/ha while the actual recorded average densities of hollow dependent fauna recorded by Smith & Lees was;

Broad Forest Type SG SqG YbG GG CBP MBP CRP All Species
Coastal Dry Sclerophyll 0.30 0.12 0.48 0.12 0.06 0.00 0.00 1.08
Inland Dry Sclerophyll 0.15 0.00 0.26 0.10 0.31 0.00 0.00 0.82
Coastal Wet Hardwood 0.34 0.00 0.00 0.00 0.00 0.00 0.67 1.00
Coastal Moist Hardwood 0.29 0.06 0.22 0.06 0.03 0.06 0.03 0.75 .

But it is at the top of HTTAG p23 where the real smoke and mirrors begins with the quote from Smith & Lindenmayer (27) which says, “the number of arboreal mammals in 3 hectare sample plots has been shown to increase approximately linearly (my emphasis) with both the number of habitat trees and the portion of quarter hectare sub-plots with habitat trees.”

This approximate linearity appears to be a new synonym for the more familiar term, “barely linear” or almost linear but not quite. And the term means nothing without information on the actual elasticity, or slope, (the degree of change in one variable caused by another variable) of this approximately linear relationship. Smith & Lees graphs (28) and, from memory Smith & Lindenmayers, reveal a linearity that is at first barely elastic (a very gentle upward slope) followed by a majority of zero elasticity (i.e., horizontal) and ultimately to negative elasticity (a downward slope indicating that more HBTs mean fewer mammals).

And in every other field of science this is generally regarded as indicating that the two elements are unrelated. This is especially the case when small samples are also involved. So the linear models that predicted that maximum arboreal mammal density occurs when there are 6 HBTs per hectare have modelled a relationship that barely exists.

As the HTTAG states (29) (p22)

“The concept of maximum habitat tree density is based on an assumption that the density of hollow dependent fauna increases with the density of tree hollows then plateaus once a level (maximum habitat tree density) has been reached above which populations are no longer limited by hollows, but by other habitat factors such as a shortage of food.”

One can have no problem with this. And one must agree with the next sentence by HTTAG that calls for “analysing the empirical relationships between the observed density of hollow dependent fauna and the density of tree hollows in a wide range of forest types”. The problem is that they are yet to do so.

The relationship is likely to exist but if it does exist it will take the form of a steep slope. And in the absence of a steep, elastic slope, one can only conclude that they have been modelling in the parts of the curve where the relationship does not exist. That is, they have been modelling in units that are too large to detect the change.

Smith & Lees (30) (Fig 5a & 5b p56) have modelled in units of 2 HBTs from 2,4,6 & 8 etc, and this precludes the possibility of detecting significant slope changes between zero and the first record at 2. And a simple examination of one of the mammals concerned will reveal why the relationship is not present in the modelling and why the outputs from the modelling are pure bunkum.

Yellow Bellied Gliders, for example, have a home range from 30 to 70ha. So in a theoretical forest where only YBGs existed, the point at which one house is provided to one household would be somewhere between 0.033 and 0.014 HBTs/ha. So any issues about how many hollows are needed by each household will only be resolved by a capacity to model in units as small as 0.01 of a habitat tree.

For birds, the demands on the accuracy of the model are even greater. The Powerful Owl has a home range from 300 to 1500ha so the point at which one house is provided to one Powerful Owl household is somewhere between 0.0033 and 0.0006 HBTs. So the number of hollows required by the full suite of hollow nesting species will only be resolved by a capacity to model in units as small as one divided by the largest home range (in hectares).

6. No attempt has been made to incorporate the most basic of demographic tools, the known data on species households and breeding cycles, to determine the actual number of hollow dependent households per hectare.

It is on this issue that we regret to advise that all of the main publicly funded inputs to this policy process appear to have made serious misrepresentations of fact to this policy process.

Smith & Lees (31) have attempted to calculate two equations for the HTTAG;
Equation 1 - Hollows required per hectare for each individual of each species, and
Equation 2 – Hollows required per hectare for all individuals of all species on the land unit.

In the course of doing so they have made the following extraordinary statements under the headings of “assumptions” but which read more like rationalisations. They said,
· “Owing to simplicity of calculation, time constraints and our belief that densities of hollow dependent fauna are underestimates, we calculated hollow requirements based on the assumption that all species were solitary. Clearly this is not the case for communal nesting species, such as the Yellow-Bellied Glider (and Sugar Gliders, Squirrel Gliders, Feathertails and, to a lesser extent, the Brushtails and Ringtails). Equation 1 below will need to be modified when recognition is made (does this mean when the scam is uncovered?) of communal nesting or that one tree with multiple hollows may be used by a number of species simultaneously.”
· “Figures used for home range size and the number of hollows occupied per home range are independent of habitat type due to the limited information available.”

Armed with this blank cheque Equation 1 was determined as;

No hollows required/ha = No hollows used per individual per home range / home range size (ha)

That is, what they use is assumed to be what they must have. The number of hollows/ha for each species is then multiplied in Equation 2 by the average density of each species/ha and added up to get what is claimed to be the total requirement for hollows/ha. But this is also subject to the following assumptions or rationalisations;

“This is a cautious approach to cater for known inadequacies in sampling techniques and the possibility that wildlife densities are underestimated.”

· “Individual tree hollows are rarely shared between species
· Trees are rarely shared by individuals of the same or different species, despite the number of hollows they contain.”

And they then state, “In reality these assumptions are not necessarily true, but provide for a precautionary approach and simplicity in Equation 2 below.”

So we have a doubling of the initial input of estimated animal density as shown in point 5 above, followed by an assumption that all species were solitary in Equation 1 that clearly overstates the hollow needs of some species by a factor of 5 or more, followed by an assumption that no trees are shared in Equation 2 that also overstates hollow needs by a factor equal to the number of species present. They have adjusted for the perceived underestimate of numbers at every step in the process and have justified it under “a precautionary approach”.

This may not have been a problem if HTTAG had not then stated (32) (p23) that;

“Maximum habitat tree densities required by these groups have been estimated theoretically from their natural density in forest habitats after taking into account a range of factors (my emphasis) such as;
· Nest group size, or the average number of individuals occupying each hollow;
· Species territoriality and the ability to co-occupy hollows in the same tree or different trees in the same cluster;
· Species requirements for multiple hollows within their home range if any;
· Competition between and within species for access to hollows of different size and type; and
· The average numbers of useable hollows per tree.”

To this one can only say, these theoretical estimates have not taken nest group size into account very well. The “not necessarily true” assumptions used by Smith & Lees have not been properly modified for incorporation into the calculation. Indeed, Equation 2, with its incorporation of the actual density/ha of each species has been abandoned.

It was replaced by a generality, a rule of thumb that has supposedly been derived from the above mentioned modelling (of the inelastic portion of the curve). HTTAG said;

“These models can be used to derive a rule of thumb which states that 1.2 habitat trees are required for every arboreal mammal species present(including Antechinus) or 2 habitat trees are required for every large hollow using possum and glider present (excluding Antechinus, Acrobates (Feathertail) and Cercartetus (Pygmy Possum).”

And it is here where the logic stumbles into a worm hole and leaps to hyper space, perchance to orbit around the “Klingon Home World”, when HTTAG goes on to state,

“Thus, in a forest with the potential (my emphasis) to support 2 large possums and gliders per hectare, the maximum habitat tree density (for arboreal mammals only) should be 4 habitat trees per hectare.”

This is the last sign of the already tenuous relationship of HTTAG with actual animal density per hectare. In a single paragraph they have switched from actual animals present to potential animals and those partially present animals have become whole ones needing 2 HBTs each.

So the mere potential for the presence of one Yellow Bellied Glider that dens with its family unit on one or two HBTs somewhere on the surrounding 70 hectares, is assumed to require 2 HBTs on every one of those surrounding 70 hectares. An actual presence of 1/70th of an animal/ha (0.0143) has been “taken into account” as a whole animal on each hectare.

The fact that the HTTAG had full access to the work of Smith & Lees, and can reasonably be expected to have read and understand the significance of the assumptions to the role of animal density in hollow use, then there are grounds to conclude that the above statement is a false and misleading misstatement of fact, that appears to have been made with a knowledge of its untruth.

HTTAG had been properly informed of the significance of actual animal density and the relevance of family unit size. And they chose to ignore the issue.

For the record, the reported range of sizes of family units of the relevant arboreal mammals are;
Feathertail Glider – Strahan(33) (p263) advises groups up to 16 in the wild and 22 in captivity and reports that captive breeding will not take place if they are maintained in pairs but breeding will take place in a larger social group. Smith & Lees (p32) cite Agnew 1996 as claiming den sizes of only 1 to 6 animals. For this analysis we will assume a mean grouping of 8 per den.
Sugar Glider – Strahan (p230) advises groups of up to 7 adults and their young of the season (2 per female, and 2 litters in a good year) in one nest with adolescents dispersing into smaller transient groups when 7 to 10 months old. Some are members of 2 groups with high mortality in 1st year of independence. Smith & Lees cite Quinn 1995 and Suckling 1984 as claiming den sizes of 2 to 7 animals. Wormington also cites Quinn’s 7 adults in 4 age classes (3 M, 4 F) and, presumably the current years offspring. For this analysis we will assume a mean grouping of only 5 per den.
Squirrel Glider - Strahan (p234) advises “Typically, a family group comprises one mature male (2+yrs), one or more adult females and their associated offspring of the season. Occasionally one or more young males (>2 years old) may also be associated with a group of up to 10 animals, including as many as 5 adults.” He also advises that SqG and SG breeding times and growth and development are “strikingly similar” i.e., 2 young per female and 2 litters in a good year. Smith & Lees cite Goldingay & Possingham as indicating den sizes of 2 to 9 animals. Wormington (p167) also cites Quinn as indicating an average of 2.9 animals per den. For this analysis we will assume a mean grouping of 2.9 per den.
Yellow Bellied Glider - Strahan (p230) advises, “In the northern part (of its range, i.e., Qld) a male may associate with 2 or 3 adult females and up to 3 young.” He also indicates travel distances of 2 km per night which would appear to be inconsistent with home ranges of 30 to 70 ha. Smith & Lees cite Henry & Craig 1984 as indicating den size of 1 or 2 animals while Wormington (p167) suggests the high den numbers are only in North Qld. For this analysis we will assume a mean grouping of 5 per den.
Greater Glider - Strahan (p240) describes it as “essentially solitary” But then states, “Males and females normally share a den from the onset of the breeding season until the young emerge from the pouch (4mths) and become independent at 9 months. Smith & Lees and Wormington (p166) appear to assume they are continually solitary. For this analysis we will assume a mean grouping of 1.5 animals per household or den, consistent with 4 months with male & female in one den, 4 months with male in one of a number of dens and female and young in another and 4 months of male, female and adolescent in solitary dens.
Common Brushtail Possum - Strahan (p273) makes no reference to den size, nor does Smith & Lees. For this analysis we will assume the same mean grouping of 1.5 animals per household as described for the Greater Glider above.
Mountain Brushtail Possum - Strahan (p271) makes no reference to den size but indicates that young are suckled for 9 to 11 months with a degree of pairing between male and female. Smith & Lees (p32) also provide no indication of den size. For this analysis we will assume a mean den size of 1.75 animals. This is based on 6 months of male and female in one den, and 6 months of solitary male and female with young. (i.e., 0.5x 2 + 0.5 x (1 + 2)/2 = 1.75).
Common Ringtail Possum - Strahan (p254) makes no reference to den size but advise that the pair bond carries over into the following season. Two young are born to established pairs with a second litter in a good year. Smith & Lees (p32) cite Thomson & Owen 1964 indicating up to 8 animals per den. This would be consistent with 2 parents, 2 litters of the current year and 2 semi-detached adolescents. For this analysis we will assume a mean den size of only 4 animals.

These assumed mean den sizes are applied to the reported mean animal density records of Smith & Lees Table 5 (p49) and the actual site density records of Wormington (p19) in the attached spreadsheets. These spreadsheets adjust for den size and an assumed 50% propensity of some species to use other nest sites. They provide the number of dependent animal households/ha on each of the 38 sites and show the number of HBTs that are available to each dependent household on each site.

Additional sheets model the consequences of a lower number of HBTs/ha (down to 0.5 HBTs/ha) on each of the sites. This enables the impact of any hollow shortages to be assessed at both site and landscape scale.

7. Smith & Lees extrapolated to two totally improbable extremes of HBT need to make the DNRM preferred prescription appear reasonable.

No discussion on the science behind the DNRM prescriptions can take place without specific critique of the extraordinary mathematical acrobatics that have gone into Smith & Lees’ Tables 4, 5 and 6 (p48-50). This was an attempt at reconciling species known range of hollow use with the known variation in home range sizes. And a very poor attempt it was.

Table 4 recognised that the calculation of Hollows Required/ha, in Equation 1 above, involved two variables, hollows used and home range size. This used the data on home range size in Table 2a (p32) and the number of reported hollows used from the same table.

For example, Sugar Gliders have been reported to use from 1 to 5 hollows and have home ranges from 0.5ha to 7.1ha. So the lowest number of dens (1) was divided by the largest home range (7.1ha) to get the number 0.14 hollows/ha as the minimum in the range. Then the largest number of dens (5) was divided by the smallest home range (0.5ha) to get the number 10 hollows/ha as the maximum in the range. And it was between these two numbers that the actual need for hollows may be found.

The problem with this is that these are two highly improbable extremes. It is like looking for the definition of a reasonable man by reference to Hitler and Stalin. We all agree that the answer is somewhere in the middle but we are none the wiser from examining the extremes.

The greatest number of hollows used is most likely to be found on the largest hame range, not the smallest. The least number of hollows used is most likely to be on the smallest home range because the food supply is sufficient to justify a higher density of animals and they are willing to compromise on housing to enjoy the benefits of the abundant food supply.

The smallest home range of 0.5ha has a radius of only 40 metres so the den is only one jump from shelter from anywhere in the territory. The largest home range of 7.1ha has a radius of 150 metres in which five hollows spaced along a 90 metre radius within the territory would be 100 metres apart (113m on arc) and ensure that no part of the territory is more than a 50 metre jump from shelter.

Apply the same analysis to 5 dens on 0.5ha and we get a rather silly scenario where no part of the range is more than 15 metres from a hollow. This situation in a mature forest would negate the need for gliding altogether. Animals could jump from one tree to another as possums do. The maximum number of hollows on the minimum range is an absurd extreme.

But that didn’t slow Smith & Lees. Their Table 5 (p49) proceeded to do the same calculation for each species in each broad forest type and then sum these values as an overall requirement per hectare. Column 6 multiplied the maximum hollows by the maximum animal density to get 13.3 hollows/ha for Sugar Gliders and a total of 41.17 hollows/ha for all the arboreal mammals in Coastal Dry Sclerophyll. The minimum number of hollows multiplied by the maximum animal density came to only 0.8 hollows/ha for all species in the same forest type.

But once suitably gobsmacked by the 41.17 hollows/ha number, the reader was then well primed to accept the almost equally unreasonable calculation in Column 7. This multiplied the maximum hollows/ha (10 for SG) by the mean animal density (0.3/ha) to produce a requirement for 3 hollow/ha for Sugar Gliders and 7.24hollows/ha for all arboreal mammals in the forest type. The minimum requirement multiplied by the mean animal density came to only 0.14 hollows/ha for all species in the forest type.

Obviously, 7.24 hollows/ha is certainly less unreasonable than 41 hollows/ha but this still does not bestow any legitimacy to the number. A highly improbable hypothetical extreme is still being applied to the mean animal density. But this did not prevent Smith & Lees from reflecting on how these results coincided with the HBT retention targets under the Code of Practice. And having arrived at any sort of figure that could plausibly support the established departmental position, the brain appears to have shut down and gone home.

But before doing so there was one last (the fourth) opportunity for incorporating the above mentioned “precautionary approach.” Smith & Lees (p50) state,

“On the basis of the precautionary principle, and consistent with the uncertainty inherent in dealing with this type of data (in this way) it might be prudent (sensu Gibbons and Lindenmayer 1996, 1997a and b) to choose maximum values to insert into the formulae we outlined in section2.3.2, so that maximum numbers of hollows are retained.”

No attempt was made to multiply a mean value by another mean value to get a most probable and realistic picture. If we know that the median density of Sugar Gliders in Coastal Dry Sclerophyll is 0.3/ha then we can reasonably conclude that the mean home range of an assumed solitary animal is 3.3ha. A circular territory this size would have a radius of 102 metres and it would take only 3 dens on a 50 metre radius to ensure that most of the territory was less than 50 metres from shelter.

And multiplying this mean (3 dens) by the mean animal density (0.3) gives a most probable hollow requirement for Sugar Gliders of 0.9 hollows/ha. But even this is not good enough as it still assumes they are solitary animals which they are not. It also still assumes that any values less than the mean will lead to, or are symptomatic of, species collapse.

8. They fail to consider how these species are known to respond to either short-term or long-term overpopulation or housing shortage.

Neither Smith & Lees nor Wormington have described the climatic conditions that were present during their fauna surveys. Both stressed their belief that the recorded data represents a significant underestimate of numbers and have incorporated “precautionary approaches” to the basic records. Smith & Lees’ efforts are mentioned above.

Wormington’s efforts in this respect was to only analyse the highest of the two records taken for each of his 38 sites. And his belief that this selected class, with 73% of all encounters, is the “true picture” is so strong that he has refused to provide me with the other data sets unless he had prior agreement to his vetting of any conclusions.

But the true picture is more complex still. Wormington’s (p16) surveys took place between August 1997 and September 1998. This was an extreme El Nino period with an extended dry period in 1996 as well. Both the forest and the wildlife within had shut down into survival mode. The trees had shed leaves and had released toxins into their remaining foliage to make it less digestible. Soil microbial activity was impaired by moisture deficit, producing lower nitrogen levels and less nutritious sap and leaf matter. And this had serious consequences for all arboreal fauna. And their density adjusted accordingly.

So if there has been any time in the past few decades when species were close to “species collapse”, it was when the survey took place. It would seem trite but apparently necessary to state that species collapse is highly unlikely in a run of good seasons.

This data is shown in the attached spreadsheet, [2 sample Data]. The average animal density over the 38 plots and two surveys was only 0.189/ha, just more than a sixth of the 1.08 animals/ha recorded by the DNRM sample in Smith & Lees. (Assuming the DNRM sample area really was only 3ha as stated, with any sightings beyond 100m radius being excluded).

Of more interest is the average number of occupied hollows/ha and the number of HBTs for each dependent mammal household, for each of the surveys. For this shows the actual use being made of the HBTs at any given time. Wormington’s sample had a mean of only 0.0736 occupied hollows/ha or 103.6 HBTs for each family that needed one. The DNRM sample had 0.2467 occupied hollows/ha or 43.41 HBTs for every family unit that needed one.

Sheet [7.625 HBT] shows Wormington’s highest data records with plots ranked from highest to lowest animal density. The plot with the highest density, Bau201, had 17 encounters but this was still only 0.708 animals/ha. Each species was divided by its average household size to get a total of 0.249 animal households/ha. After adjusting for partial use by nest builders etc, this amounted to 0.1953 occupied hollows/ha each day. This plot had 6.33 HBT/ha which translated into 32.4 HBT for each mammal household that needed one.

But this was not the plot with the shortest supply of HBTs. This honour went to Plot 7, Mar203, with 11 encounters and only 2.67 HBTs/ha. This was 0.458 animals/ha, 0.2667 animal households/ha, 0.1556 occupied hollows/ha and amounted to 17.2 HBTs for each mammal household that needed one.

At the other extreme was Plot 37, Mtw204, with only one encounter but with 20 HBTs/ha. This was 0.042 animals/ha, 0.0083 animal households/ha, 0.0042 occupied hollows/ha and amounted to a mind bending 4,800 HBTs for each mammal household that needed one. And this was the highest record out of the two for this plot.

In all, 75% of encounters took place on 50% of the plots. And while we do not have access to the lesser record for each plot we can compile an average by deducting the highest record from the total recorded encounters. We know that 252 (73%) of the total 344 encounters were in the highest record set while the missing lowest record set had only 92 encounters (27%). This is broken down in tables 2 and 3 at the bottom of sheet [7.625 HBT].

The highest sample set averaged 6.632 encounters per 24 ha plot with 7.625 HBTs/ha. This was 0.276 animals/ha, 0.1289 animal households/ha, 0.1036 occupied hollows/ha and a mean 73.6 HBTs for each mammal household that needed one.

The same plots, at another time of year when the missing lowest sample was taken, averaged only 2.421 encounters per plot with the same 7.625 HBTs/ha. This sample had only 0.101 animal/ha, 0.0550 animal households/ha, 0.0435 occupied hollows/ha and a mean 175.3 HBTs for each mammal household that needed one.

And this, folks, is a classic example of zero elasticity in the relationship between HBTs and animal density. There was almost a three fold change in animal numbers and zero change in HBTs/ha. More importantly, it is clear that when animals are at their most vulnerable, the last thing they are concerned about is a shortage of hollows.

It should be noted, however, that HBTs/dependent household in this analysis are overstated in bad years and understated in good ones by the use of a single assumed household size. Household size will obviously change with climatic circumstances. So the average household of Sugar Gliders in drought may only be 2 individuals who have not reproduced that season while the average household in a good season may be 8 individuals made up of 2 parents, 2 litters of 2 young each for the season and 2 lingering adolescents.

And if the good season continues into a second year then the adolescents will respond to any localised shortage of HBTs, or any comparative decline in food supply, by seeking a new home range in the less populated parts of the forest or by playing their part in the food supply of an expanding Powerful Owl population. Those who do not adapt, have the adaptation forced upon them by other species who have adapted.

But the analysis of this issue to date has not recognised the capacity of species to respond to change. And this has obscured the fact that, in the forests for which data is available, the only undersupply of HBTs, if any, is a temporary phenomenon, found in good seasons. Arguments for retention of high numbers of HBTs/ha are based on the extremely unrealistic assumption that, in Queensland over the coming decades, the good times will continue uninterrupted.

The element that is responsible for the ten fold variation between Wormington’s lowest sample and the DNRM sample from Smith & Lees is rainfall related food supply. As, indeed, it is for every other native and feral species in Australia. That, folks, is an example of high elasticity (a steep slope) in the relationship. And it is a disgrace that so much resources have been devoted to studying an irrelevant variable.

9. They fail to examine how hollow deprived species collapse might actually happen and this allows the assumption of broad based collapse to remain unchallenged.

It can be argued that a failure to fully exploit a good season can lead to species collapse in a bad season. But this ignores the extent of variation across the forest resource. We know that in Wormington’s highest sample, 50% of the plots had only 25% of the population. And this sparse population operates to protect the inhabitants from predators by expanding the area over which the hunt takes place. Once the target population drops to a certain level then it is the predator’s survival that comes into question.

The predator’s problems are exacerbated by a greatly expanded supply of hollows that can be exploited by the remaining arboreal mammals. It is nature’s magic at play, once again. When a species actually need lots of hollows for survival, there is plenty of them available. When their survival is not under challenge in a good year, there is less available to each one. And in such circumstances they adapt by fitting more of their expanded family into the shelters available and switch to a “safety in numbers” strategy.

It should also be noted that the various anecdotal reports of certain species using large numbers of hollows are likely to be based on seasonal overabundance of HBTs that are created by seasonal population decline. They should never be used as some sort of constant requirement or be applied to the expanded population in a good season.

We also know that animal density remains higher on good quality sites. In Wormington’s highest sample, 75% of the population were found on the better 50% of plots. These sites maintain the best capacity to respond to improved conditions when they arrive but the most potential for density expansion is likely to be found in the lower quadrats.

The current departmental view on HBT requirements assumes a static resource and a uniform response to change. Neither of which is true. The attached spreadsheets enable each plot to be examined for its sensitivity to various assumed HBT retention levels and to various levels of species population.
10. No attempt has been made to determine the sensitivity of species sightings to HBT requirements.

The belief that there are more animals present on a site than those that are encountered is widespread amongst researchers and has some validity, especially for the smaller mammals. So one of the most important tasks for any examination of the need for HBT retention prescriptions is to model for the sensitivity of the stand to various levels of under-reporting.

The attached sheet, [model 1Hbtha] can be used to assess the demand for hollows by any likely under-reported population, for any level of HBT retention. In default form it models the impact on the highest and lowest of Wormington’s samples, the average of the two, and the impact on each plot.

It shows the same reported average of 0.189 animals/ha and 0.0736 occupied hollows/ha which, if only one 1 HBT was retained per hectare, would still mean 13.6 HBTs for each mammal household that needed one. The highest sighting sample still had a mean 9.6 HBTs for each mammal household that needs one. And the lowest sighting sample had a mean of 23 HBTs for each mammal household that needs one.

This would enable an average 13.6 fold population increase to a point where every HBT is occupied, assuming no increase in den size, or co-occupancy of HBT, takes place. And this potential increase would appear to be greater than the 10 fold variation between the reported DNRM population of 1.08 animals/ha and Wormington’s lowest sighting average of 0.101 animals/ha. And this suggest that a level of 1 HBT/ha may be adequate for maintaining species capacity to fully exploit a good season or two.

When 1 HBT/ha was modelled for the range of plots, only 3 plots had less than 4 HBTs for each family that needed one. These 3 plots had the 2nd, 3rd and 4th highest animal density so significant population increase can take place before adolescents need to leave the area.

But this may not be so if there is some serious under-reporting of animals present. This is more likely to occur with the smaller animals, the Sugar, Squirrel and Feathertail Gliders, than the larger species. And this is where the model can assist in understanding the problem.

We can take the average number of sightings in Wormington’s two samples (172) and add an equal number of encounters that are spread between the above mentioned three species. So the sightings of each three would increase by 57/58 to cover an assumed 50% under-reporting. This doubling of encounters would show new values of 59.5 Squirrel Gliders, 76 Sugar Gliders and 62.5 Feathertail Gliders.

This would show a doubling of animal density from 0.189 to 0.337 animals/ha but, due to larger family sizes, average households/ha would only increase from 0.0919 to 0.1339/ha. And because they are all partial users of other nest types, average occupied hollows will only increase from 0.0736 to 0.0946/ha. And each mammal family that needs a hollow will still have 10.6 HBTs each instead of the original 13.6 HBTs each. So the impact of under-estimation of species present has only marginal impact on the actual need for HBTs.

When only 0.5 HBT/ha (1 for 2 ha) was modelled, the average of the two samples still showed 6.8 HBTs for every mammal family that needed one. The highest sighting sample had 4.8 HBTs each while the lowest sighting sample had 11.5 HBTs for each mammal family that needed one.

When 0.5 HBT/ha was modelled for the range of plots, only 3 plots had less than 2 HBTs for each family that needed one. These 3 plots still had the 2nd, 3rd and 4th highest animal density so significant population increase can still take place before adolescents leave the area but the point at which larger families will occur and when co-occupancy of different hollows in the same HBT takes place will be earlier in the climatic cycle.

But this earlier Diaspora of adolescents may actually increase the rate of formation of breeding pairs in the less populated parts of the forest. In so doing it could ultimately lead to a greater capacity to fully exploit a good season.

Continued next post. IM

What's wrong with the Qld Forestry code of Practice?

Briefing to Private Forest Owners, And to the Premier of Queensland,
Ssubmission in respect of the Draft Code Applying to a Native Forest Practice on Freehold Land.
Prepared by Ian Mott, Secretary, The Landholders Institute Inc. 3rd March 2005

“Beware the Ides of March” Said the Oracle to Julius Caesar.

Executive Summary

The Code is not a regulation. It is a 15 page definition in the Vegetation Management Act with 37 prescriptions and none of the protections that are accorded to ordinary members of the community. It has been specifically structured to provide the Minister and the Department with the capacity to exercise power improperly.

The science and policy inputs that have been employed in developing the Code include false and misleading statements of fact and serious omissions of relevant considerations.

These misleading statements appear to have been made with the knowledge of their untruth and with the intention that they be acted upon by both the government and by private forest owners. Both the government and some forest owners have already voluntarily acted upon those misrepresentations to their detriment. And even if they only amount to innocent misrepresentations, they are most certainly negligent ones.

There are three flaws with the HTTAG assessment of the impact of Habitat Tree prescriptions on productive capacity. These flaws obscure the fact that the current prescriptions will effectively extinguish the forestry purpose within two harvest cycles.

There are 15 major points of issue with the science that has provided a tenuous plausibility for the Habitat Tree prescriptions. Foremost among them has been the blatantly false assumption that arboreal mammals do not form family units and the absurd belief that a modelled shortage of hollows for a good season population peak could produce species collapse in a much diminished population in drought.

The detriment that private forest owners may suffer as a result of the negligent consideration of the habitat tree issue is entirely foreseeable and is as high as $26,000 per hectare. And it may not deliver the desired habitat service for up to a century.

We urge the Minister to take all reasonable and practicable steps, including review of the need for, impact of, and alternatives to, habitat tree retention, to minimise any detriment that forest owners may suffer.

This submission includes detailed modelling of the impact of various habitat tree retention levels and seasonal population changes on the supply of tree hollows to the arboreal family units that need them.

We request a meeting with the Minister for Natural Resources and his advisors to demonstrate the model and impart the critical insights that it, alone, will provide.

We also request copies of, and right of reply to, any critiques of, or responses to, this paper that are input to this policy process.

Ian Mott

Habitat Hollow Science

“The world is full of intelligent, highly educated people who lack the ability to think”. Edward De Bono.

Regrettably, this is probably the best spin one could put on the mix of arrogance, voodoo science, rat cunning and substance impaired cognition that now comprises the modus vivendi of Queensland’s Department of Natural Resources, Mines & Energy. And their handling of the Code Applying to a Native Forest Practice on Freehold Land is no exception.

First, as the Director of the Centre for Public, International and Comparative Law at University of Queensland, Professor Suri Ratnapala (1) has pointed out, this and other codes under the Vegetation Management Act are deemed not to be subordinate legislation (s.10(7)). And the Professor has stated, “Since subordinate legislation requires parliamentary approval, the sole purpose of these exclusions is to remove these instruments from parliamentary scrutiny and hence public debate”. See

More importantly, he said, “…these instruments are not generally subject to judicial review”. Nor are they subject to regulatory impact assessment. And the gravity of this is only fully apparent when one examines the nature of the fundamental rights that, till now, have been protected by the Judicial Review Act 1991 (JR Act)(2) and the regulatory review process.

Along with sidestepping the principles of natural justice, procedural fairness, jurisdiction and authority, the Government has carefully and deliberately contrived to gain the capacity to exercise power improperly. The JR Act, through (s.23(a to i)) outlines the meaning of improper exercise of power. And by circumventing these constraints on both Ministerial and administrative authority, Minister Robertson and his department have taken to themselves the capacity to;

(a) take any irrelevant consideration into account in the exercise of their powers.
(b) fail to take any relevant consideration into account in the exercise of their powers.
(c) exercise their powers for purposes other than the purposes for which they were conferred.
(d) exercise their discretionary powers in bad faith.
(e) exercise their personal discretionary power at the direction or behest of another person.
(f) exercise their discretionary power in accordance with a rule or policy without regard for the merits of the particular case.
(g) exercise power in a way that is so unreasonable that no reasonable person could do so.
(h) exercise their power in such a way that the result of the exercise of power is uncertain.
(i) any other exercise of their power in a way that is an abuse of the power.

Examination of just two aspects of the Code applying to a native forest practice on freehold land, as outlined below, appears more than capable of establishing that Minister Robertson and his Department have already stooped to exercising (abusing) “all of the above”.

The interesting issue arising from this situation is whether the Minister, his Director General and all his policy staff and advisers acted lawfully in organising an arrangement and drafting legislation that deliberately, and in a discriminatory fashion, circumvented peoples fundamental legal safeguards. For all of them are bound by the Ethics Principles and Obligations that are set out in the Public Sector Ethics Act 1994 (3) which, under (s.4(1)), “are declared to be fundamental to good public administration”. These obligations include;

Respect for persons.

8.(1) A public official should treat members of the public and other public officials –
(a) honestly and fairly; and
(b) with proper regard for their rights and obligations.


9.(1) In recognition that public office involves a public trust, a public official should seek –
(a) to maintain and enhance public confidence in the integrity of public administration, and
(2) Having regard to the obligation mentioned in subsection (1), a public official –
(a) should not improperly use his or her official powers or position, or allow them to be improperly used; and
(c) should disclose fraud, corruption and maladministration of which the official becomes aware.

Forgive my ignorance, but it was my understanding that having proper regard for a persons rights and obligations has never included working with other persons to develop a back-door means for depriving them of those rights. It was my, possibly mistaken, understanding that working on such arrangements did not constitute ‘consultation’ but, rather, by way of their lack of lawfulness, clearly fell within the spirit, if not the definition, of conspiracy.

And many ordinary men and women could be forgiven for thinking that one of the attributes of the diligent exercise of a Director General or Senior Advisor’s duties would be the ability to recognise that carrying out work for the purpose of circumventing fundamental rights and protections in law;
(a) neither maintains nor enhances confidence in the integrity of administration, and
(b) amounts to allowing improper use of powers, and
(c) could give rise to a perception that maladministration has not been disclosed.

And these apparent multiple breaches of the ethics obligations are not breaches of obscure, isolated or newly established community expectations. Indeed, the Criminal Code Act 1899(4) also has quite a bit to say about community expectations of honesty and integrity in general and the actions of public officials in particular.

There amongst the fraudsters, procurers and abusers are provisions such as (s.92(1)) dealing with public servants doing or directing, in abuse of their authority, any arbitrary act prejudicial to the rights of another (Up to 2 years in prison). There is (s.200) dealing with public servants who, perversely and without lawful excuse omits or refuses to do an act which is his or her duty to do by virtue of their employment (up to 2 years in prison).

And in the case of legislation like the Public Sector Ethics Act that prescribe no specific penalty, there is (s.204) which covers any person, without lawful excuse, the proof of which lies on the person, does any act that they are forbidden to do, or omits to do any act that they are required to do under any statute (Up to 1 year in prison).

So while the process of drawing up legislation and regulations were fully authorised under legislation, it is clearly the community’s fundamental expectation that the processes involved, and the work carried out, must be fully compliant with all existing legislation. And the more conversant reasonable men and women become with the facts in this matter, the more likely they are to conclude that this has not been the case. And this is especially so with the Code applying to a forest practice on freehold land.

Flaws in the Code of Practice

Part 1: The understated impact of excessive HBT retention prescriptions.

The attribute of this code (5) that has the most significant impact on forest owners are the provisions relating to habitat tree retention. The objective of this provision is to ensure that, “Required Outcome (RO2) The wildlife habitat values of the forest stand are maintained”. But this worthy objective comes with Required Practices (RP2 that go far beyond the stated objective. It stipulates that the number of habitat trees (HBTs) and recruitment habitat trees as specified in Table 3 are retained as well as all feed, nest and shelter trees.

The Table gives the impression of being a scaled prescription for forest type but close inspection reveals that most Coastal or Inland Dry Sclerophyll forests have the same prescriptions as those applying to Rainforest due to the listing of shires deemed to be within the “preliminary predicted range of the Greater Glider”. This means that most farmers from Boonah, Goondiwindi and Atherton must satisfy the prescriptions for the wettest forest types.

Furthermore, where the existing forest has less than 6 HBTs then a greater than commensurate number of recruitment trees must be retained up to a total of 11 trees if there are no HBTs present. This clearly passes beyond the meaning of ‘maintaining wildlife habitat values’ to now encompass very significant ‘restoration’ and penalty components.

It looks benign to the ill-informed. But most private remnant forest has been allowed to re-establish on extensively cleared land (often by compulsion) and this means that most private forests will, entirely lawfully, only have 1 or less habitat trees (with at least one 10cm hole) per hectare. These regrowth remnant forests (unlike their market competitors the native species plantations) are being compelled to set aside very significant additional portions of their productive capacity. It is clearly an environmental tax, of an in-kind nature, levied on capital, not income, in a discriminatory manner and for which no credit is given when other taxes are assessed.

It goes far beyond the stated objective of merely maintaining existing habitat values, seeking to restore wildlife habitat values to approach the pre-clearing condition. And the scaled additional recruitment trees, at almost double the replacement rate, will mean, for most remnant forests on private land, the complete extinguishment of the productive capacity of the existing use in as little as 15 years.

And it is in the departmental community’s attempts to obscure this fact that the official information dives into the murky end of the pond. The DNRM’s Habitat Tree Technical Advisory Group, (HTTAG) (6) based estimates of the impact on productive capacity on extraordinarily unreasonable, and inappropriate assumptions and plain gonzo science.

To begin, they only analysed for one point in time, not for the reasonably foreseeable future, as they are obliged to do. This enabled the assumption that retained HBTs don’t grow and allowed the implication that recruitment HBTs had the same, or lesser, effect on site occupancy as actual HBTs.

Two scenarios were plotted (7) (p38) which appear to have calculated the proportion of HBT canopy for a range of assumed canopy covers from 100% down to 40%. The first scenario employed “current silvicultural standards” (i.e., the ones that were ignored under the SEQFA) while the second was based on ‘more intensive silvicultural standards”.

The ‘current’ case assumed that each hectare already had 5 unmerchantable trees/ha or 25% of total area and that the HBTs would all come from them first. This would be consistent with an assumed 40% (4000m2/ha) normal canopy cover with each tree covering 200m2, a crown diameter of 16metres, a crown to stem ratio of 15 to 1, and DBH of 1.06 metres. And this enabled them to conclude that retaining 8 HBTs/ha would only require another 3 trees which would only involve a 0% to 15% loss of site occupancy.

The ‘intensive’ case assumed that all large trees were potentially merchantable so all HBTs would need to come from productive stock. It projected a loss of site occupancy of between 14% (for a closed 100% canopy with slightly smaller trees) and 40% (for a 40% canopy).

Three major problems with DNRM modelling

But there are three very significant problems with this modelling. The first is that the on-going productive capacity of a forest is primarily determined by the stems that are retained after a selective harvest, not before it. The essence of native forest harvesting is the removal of mature and undesirable stems so that the remaining (usually 50%) stems can fully utilise the productive capacity, the soil nutrients, water and sunlight, of the site. So any loss of productive capacity must be calculated as a proportion of the remaining canopy cover, not the potential canopy cover. Site occupancy is not a surrogate for productive capacity.

Consequently, a forest that is at full capacity at 80% or 8000m2/ha canopy cover will normally be selectively harvested to produce a retained canopy of 40% or 4000m2/ha. These retained trees will be fully capable of utilising all of the site’s growth potential. And in this circumstance, 8 HBTs of 200m2 each will occupy 1600m2 of canopy and amount to 40% of 4000m2 rather than 20% of 8000m2.

The second significant problem with the modelling is that the stem to crown ratio (1:15) that appears to have been used mostly applies to closed forest ecosystems. The dry sclerophyll RE’s that make up most of the forest resource that is subject to the Code of Practice exhibit larger ratios (up to 1:20). And this has a major bearing on the modelled result.

A tree in a closed forest with a 1.06 metre DBH and a stem to crown ratio of 1:15 will have a crown area of 200m2. But a tree in a natural or man-made open woodland with the same DBH may have a stem to crown ratio of 1:18 and would have a crown area of 286m2.

So in the example given 3 paras above, 8 HBTs of 286m2 each will occupy 2288m2 of canopy, 43% more than the 1600m2 predicted under a 1:15 ratio. Under even more open conditions (i.e., 1:20) the same 1.06 metre DBH would produce a crown area of 353m and eight such trees would cover 2825m2/ha.

And this brings us to the third significant problem with the modelling. Most of the Regional Ecosystems (RE’s) that are subject to the Code of Practice have ‘normal extents’ or normal canopy cover that is less than the minimum 40% cover that was used in the model.

The DNRM/Qld Herbarium’s(8) “Coreveg” data set outlines the deemed canopy cover that has been used to determine the boundaries of each mapped remnant polygon. It is, therefore, the primary determinant of whether forest is deemed to be remnant, and subject to the Code of Practice, or non-remnant, and not subject to the Code.

And farmers all over Queensland would be very surprised to learn that the percentage canopy cover used in the mapping process is often well below the actual canopy cover that is exhibited on the ground by their mapped remnant forest.

For example, inquiries in respect of a polygon mapped as RE 12.11.5a Mixed tall open forest, with mostly Spotted Gum (E. citriodora) and Grey Ironbark (E siderophloia) revealed that the ‘normal’ canopy cover for this RE was only 40% and, consequently, any paddock with more than 20% canopy cover (50% of normal extent) was deemed remnant. This forest was in Brisbane’s East side with annual rainfall of 1250mm so one can reasonably assume that even lower canopy percentages have been used for remnants in dryer parts of the state (i.e., most of it).

The implications of this are that if the ‘coreveg’ percentages are used to determine the applicability of the Code of Practice to a forest then the same percentages must be used as the basis for assessing the impact of HBT retention prescriptions under that same Code. This has clearly not been the case in any known DNRM assessment.

So what does this mean on the ground?

Under a standard 50% harvest of the above mentioned RE 12.11.5a polygon, the canopy would be reduced from a ‘normal extent’ of 4000m2/ha to 2000m2/ha. If six HBTs of 286m2 each, totalling 1716m2 and 2 recruitment trees (sawlogs 60cm DBH, 10.8m crown & 92m2 ea) covering 184m2 for a total of 1900m2 were retained on each hectare then the Code of Practice has occupied 95% of the productive capacity of the site.

And contrary to widely held departmental assumptions, these trees will continue to grow and utilise the productive capacity of the site. Their DBH may not increase by much over the following growth cycle but the same growth increment will be ‘attached’ to the tree in the form of wider upper stem (reduced taper) and larger limbs or in diminished growth through shading. In 20 odd years time the volume and crown area of the retained recruitment stems will have doubled and any residual growth will be in a very slow growing understorey with a lead-time to harvest of such length that it is effectively irrelevant.

At that second harvest only 5 to 10% of standing volume will be harvested. There will be no retained production stems and the retained recruitment and HBT stems will occupy more than 100% of the original productive capacity. The forestry purpose will be completely extinguished and we will still have another 120 years to wait before the recruitment trees form an acceptable hollow.

If there are no HBTs in that forest, due to past lawful clearing or generally accepted forestry practice at the time, then the Code of Practice will require not just the 6 trees needed to produce 6 HBTs in 140 years time. Consistent with normal departmental practice of allowing themselves the extremely liberal margins of error that they would never allow the public to enjoy, a total of 11 recruitment trees (sawlogs) must be retained to cover any anticipated mortality prior to the year 2145 when the first Possum takes up residence.

Assuming these 11 sawlogs are also the only feed or nest trees on site, the total canopy area captured under the code will still amount to 1012m2 or 51% of productive capacity on the day after the first harvest. Over the next cycle these trees will grow to cover 2024m2. (i.e., circa 75cm DBH with less taper) They will enable a 49% harvest at year 20 but after that harvest the Minister’s trees will account for 102% of the retained stand volume and productive capacity. There will be no 3rd harvest in year 40, the forestry purpose will be extinguished and the translation of the homeless fauna’s opinion of the Minister’s environmental credentials would be unprintable.

But even this scenario understates the conditions found in most of the forests in Queensland. Most graziers recognised the contribution that timber could make to their integrated agricultural use. So instead of complete clearing, as their cropping neighbours had done, they maintained artificial open woodland that fluctuated in density below the ‘normal extent’. So while the fully stocked canopy cover may have been 40%, they maintained forest cover between 15% and 30% to promote better pasture growth while maintaining a contributive forest. It is the natural equivalent to the plantation based wide agro-forestry model that is widely promoted in the name of sustainability by governments all over the world.

But this range of forest cover within the existing agricultural use would ensure that it would fall within the remnant threshold in the later half of each harvest cycle. And rest assured, if there was any hint of ambiguity in status, it would be mapped as remnant anyway. Even a regrowth flush after a good wet season would be sufficient to add the paddock to the remnant map. But the Code of Practice makes no allowance for variations in existing use.

In such a case the Code will still require the above mentioned 11 recruitment habitat trees. Their 1012m2 of canopy would occupy 67% of the retained 1500m2 canopy stand on the day after the first harvest. At the second harvest in year 20 only a 32% canopy removal (976m2) will be possible and the Minister’s trees will then occupy 135% of the normal retained area. The forest owner will then have no choice but to watch the Minister’s forest expand at the expense of his grazing operation and abandon any hope of a third harvest.

The existing forestry use will be effectively extinguished by year 20 and over the following 20 years any remaining profits from the grazing operation will be absorbed by higher overheads that had formerly been covered by the forestry element of his use. The grazing operation will shrink and losses will accumulate as the Minister’s trees continue to grow and retake or even exceed the ‘normal extent’ of the RE.

And it is all done in the name of ecologically sustainable land use, one of the main principles of which is, wait for it, intergenerational equity!

Continued next post. IM

Thursday, March 23, 2006

Why Regional Australia Needs Their Own New States.

This was the subject of a recent interview by Michael Duffy on ABC Radio National's 'Counterpoint' programme.
Click here