(Second attempt at posting a long reply…the software is annoying logging me out and loosing the post!)
Since hardly anyone will know why this system was installed into this tree (by me) I will explain a little.
The tree is a veteran Eucalyptus tereticornis, about 4m from the sealed entrance road to a skate park and dog walking area near the little town of Nerang SE Qld.
Council decided they were going to extend the skate park facilities more concrete forms for people to do their thing.
The y planned to have the concrete forms some 2m off the tree on the opposite side to the road. Fortunately the company I work for became involved and we eventually persuaded council to alter things slightly. (Believe me this is not easy to do as any who have worked with councils will attest)
During the lead in to the construction the tree lost a 350mm limb, the limb had extensive decay through the tension wood from a past injury (amongst other factors) which had been hidden by an epiphyte and large volume of leaf debris.
Not surprisingly there was a lot of pressure to dramatically reduce the tree on the side of the skate park. Now this is a 150yr+ old Euc with reduced vigor about to be exposed to construction impacts. The last thing it needed or could sustain would be the reduction in photosynthetic capacity.
Together with another Arb firm we removed all the mistletoe and large diameter deadwood from the area above the proposed new skate ramps. The tree was closely inspected from branch tips back to main stems, all unions looked at.
This tree has been lopped back at least once in the last 50yrs, and although occluded and the regrowth wrapped in many years of wood growth the branch architecture reflects that cutting history.
Hollowing in the limbs and stems of Eucs (and all trees) is a perfectly normal process that reflects the tree’s age and its past encounters with external forces (man made and natural). This tree has numerous hollows in major limbs.
Many of you that do install static cabling would (I am sure) have looked at this tree if asked to quote to install bracing and laughed saying there was absolutely no need. You’d be right IMO, however intervention was what was demanded by the tree owner (council).
The system of fall arrest was installed in the branches and limbs above the new park, the synthetic ropes will snare branches that might fail and otherwise impact the structure below. We have had some wild winds and weather since the system was installed and no branches have yet failed (we did not expect they would nothing to do with the presence of the ropes btw) doubtless we will get a storm bad enough or a freak wind that will break parts of this tree at some time and then the system will have to be replaced.
This system (and therefore the tree) is inspected annually and after any major storms, the health and structure of the tree is monitored which would not have happened otherwise…these are good outcomes IMO.
Cabling of any kind is just a tool an option amongst many that should be considered when it comes to individual trees. Each of you would have had other ideas other solutions to this particular problem. To rule out dynamic cabling by pontificating on high is just plain silly.
I know that the legal environment in the USA is different to ours and that is something that holds your attention as business operators, I have no experience of your legal system so cannot make meaningful comment about its specifics.
There are some pictures of the tree for context amongst these in this album;
http://picasaweb.google.com/freeman.sd/TerraARK# it also contains pics of my final contract climbing job, same tree.
Sean