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South Australian Society of Arboriculture News

South Australian Society of Arboriculture Seminar – Trees and the Law.

The South Australian Society of Arboriculture (SASA) has recently been restarted by chairman Tom Stevens and a small group of other board members who are working hard to help the organisation thrive again. With growing membership numbers and big plans for the future, SASA aims to begin by building trust back within the SA arboriculture industry. Their first initiative was to run a mini seminar on ‘Trees and the Law’ which was delivered by Michael Palamountain on Wednesday May 1, 2019.

The event cost attendees $5 for two-hour seminar, followed by a BBQ and drinks, which was a great opportunity for participants to network in a relaxed environment.

The seminar focussed on managing trees in the urban landscape of metropolitan Adelaide. Arborists and tree contractors must be familiar with how trees are protected under the law. Arborists must be aware of the legal status of trees, what is permitted under the law and when development applications are required. The information covered important legislation based on the Development Act 1993.

This discussion forum provided an opportunity for members to review, discuss and;

  • Understand what legislation applies to trees in metropolitan Adelaide
  • Understand the framework of the legislation
  • Understand what exemptions apply under the legislation
  • Understand what is permitted under the legislation
  • Understand when a development application is required and when tree reports are required
  • Ensure staff/contractors understand when tree works are permitted

After receiving some very positive feedback from attendees, SASA has taken confidence to move forward and continue offering ‘value added’ events to all those interested.

SASA and its members are striving to help the South Australian arboriculture industry be a safe, respected and well-connected network of people that take care of our beautiful trees.

SASA are still looking for more members. To become a member or for more information, please email [email protected] or call Tom on 0478 982 994.

July 17, 2019 / by / in , ,
Climbing Made Easy

This year sees, among other gear innovations for other industries, Petzl adding to and refining their arborist range.

With all the thoughtfulness to ergonomic design, user comfort and safety Petzl have become synonymous of, their new suite of gear caters for both the traditional and Single Rope Technique (SRT) practitioners.

The updated SEQUOIA and SEQUOIA SRT harnesses are built for comfort, with ergonomically shaped padding in the waist-belt and leg-loops for working aloft for extended periods. The two gated attachment points allow easy connection of the ZILLON or MICROFLIP lanyards or the installation of multiple bridges that have full use of their lateral range, increasing mobility. The SRT version is specifically designed with a textile Ventral attachment point for installing the ZIGZAG, ZIGZAG PLUS with CHICANE and KNEE ASCENDER system and a rear buckle to install a chest CROLL integrated in the SECUR shoulder straps.

Conveniently adjustable, the Double Back Plus waist-belt buckles are quick and easy to use. The new FAST LT PLUS, leg-loop buckles ensure security and one-time adjustment for size with a new locking system that limits the risk of accidental opening.

The ZIGZAG and ZIGZAG PLUS mechanical Prusik devices are intuitive to use, mimicking classic Prusik pulley systems, automatically locking on the rope as their friction-chain section extends. Efficient movement is smooth and precise. Rope feed is easily managed by the subtle adjustment of the release-lever. Changes in pressure control the speed of movement.

The large, sealed ball-bearing pulley wheel makes rope tending smooth and easy. The ZIGZAG has a fixed, lower attachment point to ensure proper alignment with the axis of the user. The ZIGZAG PLUS, lower attachment is a high-efficiency swivel ensuring stable and correct positioning of the device and smooth rope-feed.

Both devices can be used on either doubled ropes or in SRT, thanks to the CHICANE auxiliary braking handle and the KNEE ASCENT assemblies. The upper attachment point for the rope end, in double rope use or the CHICANE, in SRT set-up, has a flexible positioning ring that helps keep the connector oriented along its major axis. They also have an auxiliary attachment point for adding a ZILLION lanyard, connecting a second system or the installation of the KNEE ASCENT assembly.

To this suite of gear, Petzl also introduces the CHICANE auxiliary braking handle and the KNEE ASCENT, CLIP and LOOP assemblies. The CHICANE allows the ZIGZAG and ZIGZAG PLUS mechanical Prusiks to be used in Single Rope Technique (SRT). It provides continuous additional braking thanks to the added friction of the two friction pins. Used with the Petzl Am’D or OK carabiners, whose H-shaped cross-section make the CHICANE and both ZIGZAG versions a fully compatible system. This ensures smooth rope glide during ascents, descents and when limb-walking. Its opening side plate makes it easy to install mid-line and its triple-action unlocking mechanism limits the accidental opening of the device.

Last but not at all least, the new KNEE ASCENT assembly is available in a foot-loop version or clip version for boots with integrated clipping point. They make ascending in SRT a breeze. The elasticated upper strap connects directly to the ZIGZAG and ZIGZAG PLUS and CHICANE, raising the whole unit. The integrated CROLL L (large), compatible to ropes 11mm-13mm in diameter, make for comfortable ascent and no back-slipping. The assembly has multiple setting to adjust to users of all shapes and sizes.

This entire suite of gear shows Petzl’s detailed understanding of the working arborist and their ever-changing work environment. Not all trees are the same as not all arborists, but in this range Petzl has catered for the traditionalist and SRT climber equally.

For further information on availability in your state, contact your local, independent Arborist equipment supplier or Spelean directly, for whom that might be, where you are.

June 3, 2019 / by / in , , ,
Major Mitchell’s Hollows

Artificial formation of tree cavities – part 2

A manual of techniques to create simulated natural cavities in Slender Cypress Pine (Callitris gracilis murrayensis): for use by Major Mitchell’s Cockatoo (Lophochroa leadbeateri leadbeateri).

Cavity creation techniques

As the decision matrix illustrates there are several techniques available depending upon the size of the tree and the state of any cavities in the tree. Each of the four techniques for creating a cavity ready to use by MMC are described in full detail with images to illustrate each of the key steps in sequence.


Excavation involves the creation of an entirely new cavity. This technique is generally only suited to dead wood as it involves removal of a face plate which would cause extensive damage to sapwood if undertaken on a living tree. Also in some dead trees it may be necessary to remove some of the canopy to reduce wind drag in order to increase the longevity of the remaining trunk and cavity (Figure 9). In some cases a natural scar may already exist following the loss of a branch exposing the heartwood. The resulting scar may be used as an entry point to excavate a new cavity.

The first step is to use a chainsaw to cut out a face plate. This is best done by first cutting two cross cuts ~70 cm apart and not more than ¼ the diameter of the tree at the height of the cuts. Then make two longitudinal cuts with the chainsaw bar held at a 900 angle for each on either side of the face plate starting one at a time from just below one end of the top cut and continuing down to the lower cut. Repeat this on the other side. The angling and depth of the longitudinal cuts should allow the cuts to meet in the middle of the trunk all the way along the cuts (Figure 10). The face plate should naturally fall loose once the final cut is complete. The face plate should be set aside for further work later.

Once the face plate is removed, use a chainsaw to make a series of long, deep vertical, parallel cuts into the exposed heartwood (Figure 11). The cavity walls being created should be ≥10 cm thick. Furthermore, check the required blade depth to ensure that no holes are made through to the other side of the tree trunk. This is critical as large parrots, such as Galahs, will chew-out and enlarge even the smallest of holes until they have created a further entrance-sized opening (Hurley, 2009).

Following the chainsaw cuts the resulting slabs can either be prised-out with a pinch bar or horizontal cross cuts can be made to further speed up the removal of the bulk of the trunk’s heartwood (Figure 12). Then use the Arbortech© to clean out the trunk cavity and form contours to the desired dimensions. It is important to leave some rough surfaces or small grooves in the walls of the cavity to provide climbing holds for birds to easily enter and exit the cavity.

If the height of the hole left by the face plate does not match the desired cavity depth it is relatively straightforward to use the Arbortech© to deepen the cavity in the tree trunk. The measurements provided for this dimension should be regarded as a minimum as cavities up to 1.8m deep have been used successfully by MMC at Pine Plains (Hurley, 2006a).

Figure 3: Decision matrix for the selection of the appropriate technique in simulated cavity formation in Slender Callitris Pine (Callitris gracilis murrayensis). Diamonds are decision points and light teal boxes are actions. The dark decision strips represent recording and monitoring activities

It is critical that the proposed nest chamber floor is relatively flat with minimum diameters of 18cm x 19cm. In addition to cavity depth, this is the single most important aspect of the SNC construction (Korpimäki & Higgins, 1985).

Smaller nest chambers will either deter MMC from nesting in them or limit the clutch size laid. A nest chamber with a larger diameter may be used by MMC and may be excavated if the trunk diameter is of sufficient size to accommodate it.

Now, the inside face of the face plate must be carved-out so it has internal concave contours to match the curvature of the cavity being carved from the inside of the tree trunk. The cavity entrance can also be carved from the face plate (Figure 13-14). These carving tasks are best done with an Arbortech© blade attached to an angle grinder.

Refitting the face plate is a critical stage for long-term viability of SNCs. Gaps and/or air flow between the remaining trunk cavity walls and the face plate must be eliminated. The kerf width from the chainsaw creates a 1cm gap between the face plate and cavity walls and requires in-filling. Use plywood strips cut to suit or Callitris lengths custom made to fit each joining surface of the face plate.

Regardless of which timber is used, these infill or caulking strips should be glued and tacked to the joint edges of the trunk and then trimmed with the Arbortech© so that they sit flush with both the external and internal contours of the trunk and cavity. The contouring of theses strips will help to camouflage them from the prying beaks of Galahs and other cockatoos. A standard builder’s glue can be used to bulk up any minor cracks between the jointed surfaces. Tech screws may also be used to strengthen the join between face plate and tree.

Remember to use a standard angle grinder blade to grind off or disfigure the tech screw heads, then paint them matt black and grey. This last action is recommended so as to not to attract undue attention from people or predators. The external surfaces of the caulking strips must also be painted a mottled matt dark-grey and black to protect from the weather. Alternatively thick strips of bark may be attached using silicone glue to cover the caulking strips. Once the face plate has been reattached, fine Callitris wood chips must be placed in the base of the new cavity. One or two handfuls is enough (Figure 15). Following this the face plate should be camouflaged with bark from the same tree the work is being done. Entrances should look as natural as possible Initially allow a half to one full day (4-8 hours) for the excavation of new cavities. With experience a team of two chainsaw operators will be able to an average excavate two cavities per day.


Cavity formation is normally associated with older mature or senescent trees (Gibbons & Lindenmayer, 2002). It is estimated that Slender Cypress Pine do not reach a sufficient size to support a cavity suitable for MMC (i.e. 50cm DBH) until trees are >80 years of age (Gibson et al. , 2008). A variety of methods involving the exposure of heartwood and manipulation of tree health have been proposed to accelerate cavity development (Gibbons & Lindenmayer, 2002).

The exposure of heartwood provides an entrance for fungi, bacteria and saprophytic insects which cause decay and, in conjunction with the trees adaptive growth response, leads to cavity formation (Mattheck & Breloer, 1997; and Lonsdale, 1999; and Taylor et al., 2002). The rate at which wounding techniques are able to accelerate the processes of natural cavity formation is on a temporal scale unsuited to the rapid provision of cavities for threatened species recovery (i.e. formation will take place over decades). Cavity augmentation involves accelerating the formation of a cavity or improving the function of an existing cavity. Accelerating cavity formation for this purpose is based on many of the techniques required to excavate a cavity in a tree without an existing cavity.

In addition to accelerating cavity formation, cavity augmentation also involves making improvements to an existing cavity. This may be as simple as enlarging the entrance to an existing cavity or may involve more extensive works to enlarge the internal dimensions of a small cavity. Furthermore, augmentation often is in the form of inserting carved timber sections to deflect rainwater from flowing into a cavity or repairing cracks in cavity walls.

The primary augmentation process involves mechanically removing the decay and heartwood associated with wounds caused by natural processes. A pre-existing scar, revealing advanced rotting of the heartwood is slightly enlarged to allow use of Arbortech blades to excavate the rotten timber (Figure 18A and B). Once the rot has been removed to sufficient dimensions for an SNC a face plate is carved from a single piece of timber and glued and screwed in place (Figure 18C).

Augmentation can also include modifications to an existing cavity to improve cavity function. These may be in the form of simply enlarging the entrance or other features of a cavity to suitable dimensions (Figure 19). In some cases augmentation may involve strategically placing a plug of timber to block water from flooding into a cavity(Figure 20 and Figure 21).

Ironbark Environmental Arboriculture Pty Ltd is an interdisciplinary company with expertise in arboriculture, ecology and wildlife conservation. In 2014, in partnership with DELWP, they pioneered the use of chainsaw-carved hollows for threatened species conservation with their work on the Major Mitchell’s Cockatoo. Since this time they have completed a range of targeted hollow creation projects in urban and forest environments, including Musk Lorikeets in the City of Melbourne and Brush-tailed Phascogales in Box-Ironbark forests of Central Victoria.


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Hurley, V.G. (2009) A report on installing nest boxes and repair of degraded nest hollows in Callitris Pine for use by Major Mitchell’s Cockatoo (Lophochroa leadbeateri) in Pine Plains, Wyperfeld National Park. Unpublished report prepared by the Department of Sustainability and Environment for the Mallee Catchment Management Authority, Mildura.

Hurley, V.G. (2011) Results from the 2010 breeding survey of Major Mitchell’s Cockatoo (Lophocroa l. leadbeateri) Pine Plains, Wyperfeld NP. Department of Sustainability and Environment, Mildura.

Hurley, V.G. & Harris, G.J. (2014) Simulating natural cavities in Slender Cypress Pine (Callitris gracilis murrayensis) for use by Major Mitchell’s Cockatoo (Lophochroa leadbeateri leadbeateri). Department of Environment and Primary Industries, Mildura. Kenyon, P. & Kenyon, P. (2010) Pruning for habitat workshop.

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Hurley, V.G. & Harris, G.J., (2015) A manual of techniques to create simulated natural cavities in Slender Cypress Pine (Callitris gracilis murrayensis) for use by Major Mitchell’s Cockatoo (Lophochroa leadbeateri leadbeateri). A report to the Department of Environment, Land Water and Planning, Melbourne.

For more information please send an email to Grant Harris at [email protected] or visit the website

October 22, 2018 / by / in ,