Assessing the structural condition of a beech

[jacquemontii]

Would appreciate some insight from those experienced in Visual Tree Assessment. I’m doing some personal study with a view to taking the Professional Tree Inspection. I have a theoretical question based on a beech tree I recently discovered.

 

The tree forks into 3 stems from 2m high. The trunk appears to have developed a natural lean to the east, with corrective vertical growth in the stems above.

 

The second photo shows some detail of the east side of the trunk (compression side). There appears to be evidence of what I think may be beech bark disease (dark stains, cracking peeling bark and white material that could be Cryptococcus colonies).

 

However, Cryptococcus aside, what really concerns me is the included bark and compression fork union. The line which appears to continue below the union to near the base of the trunk is a cracking of the bark, with occasional glimpses beneath of what appears to be an occluding crack?

 

Would this indicate an underlying crack developing due to the weight of the crown compressing the leaning stem? Is it common for beech to fail under these conditions? What remedial measures would be appropriate in this instance?

 

I realise its difficult to offer opinions based on a few photos, but any pointers would be gratefully received.

[Paul Melarange]

However, Cryptococcus aside, what really concerns me is the included bark and compression fork union. The line which appears to continue below the union to near the base of the trunk is a cracking of the bark, with occasional glimpses beneath of what appears to be an occluding crack?

 

Would this indicate an underlying crack developing due to the weight of the crown compressing the leaning stem? Is it common for beech to fail under these conditions? What remedial measures would be appropriate in this instance?

 

I realise its difficult to offer opinions based on a few photos, but any pointers would be gratefully received.

 

You are right, the acute stem unions are likely to be the point that this tree fails (caveat - based on the photos only). However, I have often found this type of failure to be progressive (so happens over a period of time, worsened each time there is a significant wind event). With this in mind monitoring trees with these type of defects is always a good idea. So re-inspection yearly and after gale force winds (assuming there is a significant target!).

 

If it is the intention to retain the tree as long as possible, you could carry out some crown reduction combined with installation of a flexible bracing system.

 

You have to consider the cost v benefit at the end if the day. Is it worthy of all that additional cost for works & monitoring? If it's not got any significant ecological value or visual amenity, then maybe not?!

[10 Bears]

Good points Paul - but I believe the main event here is that this an internal rib formation. Jacquemontii's comments that this appears to be a longitudinal crack that is attempting to occlude match the rib idea well.

 

Simply put, its not a death nell for the tree and yes it does confirm that there is an internal partial failure there is most likely going to be enough sound wood to support the tree - even with the damage, for a long time to come (unusual wind/storm events excepted). Hopefully the occlusion will continue to the point that the rib becomes 'blunt-nosed' and the associated strength loss from the crack is remediated by the occlusion. If still a 'sharp-nosed' rib - the crack still extends to the outside so may re-open in certain circumstances - again unusual winds etc. I don't believe it is common for Beech to fail with these types of injuries ie not without other complications.

 

Otherwise, remedial action as described above - crown reduction and bracing is the best course of action.

 

Jacquemontii - good post by the way. Please pose more questions like this to help with your course prep. I'm sure there will be several offers of help.

[Gary Prentice]

From the PTI point of view, there's a target, you can't guarantee that failure won't occur within the inspection period due to the fault - so felling would probably have to be your recommendation.

 

If you can reason your opinion you can't be wrong really.

 

But then again, with eight arbs in the room on the recent course, at times we had more than eight opinions:biggrin:

[10 Bears]

I've never done the PTI course Gary, but I'm interested to read your opinion in this regard. Dont take my comments the wrong way, I will take it that your comments are from the perspective of what you have been told on the PTI course, I am just somewhat surprised by the PTI logic.

 

To my view, suggesting that this tree will need to be felled due to this relatively minor damage as you cannot guarantee that it won't fail within the re-inspection period is ridiculous. No-one can guarantee the non-failure of trees within re-inspection periods as simply there is a safety factor within all mechanical structures, which if exceeded will lead to catastrophic failure of the structure. Personally I don't have a crystal ball so cannot guarantee that safety factor won't be exceeded within a re-inspection period of a year, hence by that reasoning I can't give a guarantee. Do you follow the reasoning?

 

This would then mean that any tree with any kind of fault would need to be felled as soon as it gets inspected! Obviously I am taking this to the extreme here, but the PTI reasoning you suggest must surely be incorrect, or at least mis-applied in this case.

 

You also say there is a target - OK a path is there yes, but doesn't target type, target population and occupancy of target area all contribute to an estimation of risk exposure for the potential target area? Again, is this not an oversimplification of the PTI method to say yes there is a target so there is immediately a problem that must be remedied? From my view, there is a hierarchy of targets based on the aforementioned variables. Yes all trees have the potential to fall over, and by that logic there is always a target - but as I'm sure you would agree some targets are significantly more worthy of protection than others.

 

I hope your review was just a quick comment and not a true reflection of the PTI approach, but we will see. Just have to wait for the other 5 arbs to enter this room and see how the opinions differ!

[Gary Prentice]

I'm going to have to stop commenting using my phone, as I don't get the depth into the answer that it requires.

 

I'll reply later, from a proper keyboard, in more depth

[10 Bears]

Sure, no problem. Telling me you answered from your phone (as I am now), probably tells me all I need to know! Still, not having done the PTI, I would still like to hear your thoughts.

[john p]

Having no academic/pti training as such that tree looks like trouble! 20% reduction, wang a bit of cobra bracing up and jobs a good un

[MATTMOSS]

Good thought provoking thread.

I don't have anything more to add than what has already been said really, the tree doesn't look the best structurally but very reasonable physiologically.

I suggest the target frequency would play a big part of deciding what remedial action to take here, if any at present.

[treeseer]

20% reduction, wang a bit of cobra bracing up and jobs a good un"

 

good post; if the 20% is specced to reduce sprawl and strain, and the bracing could be steel, i agree.