Assessing the structural condition of a beech

[Paul Barton]

Great post and good discussion. Tight forks in Beech are difficult to assess I think.

 

Here's a link to the presentation that Duncan Slater gave at the 2011 AA conference. See slides 18-20 in particular - the slimming down of the stem below the union can indicate a weaker fork and the tree you have posted about seems to have a narrow taper below the three-way union.

 

http://www.trees.org.uk/aa/documents/amenitydocs/aa_amenityconf_mon7_Duncan_Slater_2011.pptx

 

If the cost-benefits analysis allow, a reduction and some bracing may be the way to go.

 

Ed Gilman also talks/writes about structural pruning to suppress the growth of branches and stems. Perhaps a reduction of one of the more diagonal stems could over time suppress it so that a more vertical stem becomes dominant, therefore improving the diameter ratio between the stems.

[Paul Barton]

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

 

Cobra bracing is dynamic polypropylene rope. Why do you have a preference for steel?

[jacquemontii]

Interested in opinions regarding this branch union on a mature beech (approx. age 200 years old - based on the formula of John White’s ‘Estimating the Age of Large and Veteran Trees in Britain’).

The union contains water, which can be seen leaking from a small visible section of included bark on one side. Would it be correct that if it contains water then the majority of the hollow remains sealed against decay, aside from the small included section? There appears to be plenty of slight bulge formations around the union which suggest extra wood laid down to strengthen (optimised).

As seen in the photo, the tree appears to still be in good vitality, with all past pruning wounds well occluded. There is a cavity further along the branch, again with healthy looking wound wood forming to the edges (although beech does not compartmentalise decay too well?)

In terms of context the tree is located in a private garden and the branch has a spread of about 9m and overhangs the boundary wall and a minor public lane.

(there are no obvious signs of any fungi – don’t be fooled by the photo with the bird feeders, which at a glance look a bit like fungal brackets!).

In terms of a conclusion based on a visual inspection, I would suggest this is a potential defect, but it looks ok at the moment, and would recommend further regular monitoring to check for signs of any splitting in the union (particularly after any storms). Would there be any merit in some light pruning to reduce the load, whilst maintaining the aesthetic balance of the branch? Or would this in effect weaken the branch, reducing the energy mass of an old tree?

[treeseer]

Paul, let's consider:

 

Movement is likely to worsen the condition of the fork. Several here have (correctly I think) noted this.

 

Dynamic bracing material is designed to allow movement.

Static bracing material (steel) is designed to limit movement.

 

Which material best suits this splitting fork?

 

Beyond this are other factors:

steel lasts 30+ years with little or no maintenance

steel requires a 1/4" hole for a 3/16" cable that will provide 9000# of support

 

O and I agree with 10 Bears; calling for a fell seems ridiculous.

Edited January 7, 2016 by treeseer

[tree79]

Interesting post.

 

Not sure I would crown reduce, may be crown thinning instead, I would of suggested flexi bracing but again interesting comment with the use of steel, would it not still be a flexi brace though unless install as a rigid system using a steel rod?

 

what about if the tree was inspected and defects recorded, no work assigned and just a re inspection date assign (say 1 year).

Would this be enough to satisfy your duty of care needs?

[arb culture]

I was starting to get a bit concerned by some of the responses on here, so I thought I'd add:

 

"Examples of trees with a high risk of this type of failure include various species of willow and poplar, horse chestnut, beech, ash and true cedars."

 

Taken from,

http://www.forestry.gov.uk/pdf/fcpg13.pdf/$file/fcpg13.pdf

 

Just in the last two weeks I've been to see and prepare reports on three different beech trees which have failed, and which I suspect looked similar to the second example tree in this thread before they did fail. I can't really comment on the first tree, because I can't tell what's going on just from the photo.

 

The other thing that strikes me about this thread is this:

 

What does the client want?

 

Maybe they are loaded, love the tree and are willing to spend money on it, but perhaps they hate the tree and just want it gone, or perhaps they are (like most clients) somewhere in the middle.

 

As for how this relates to the PTI assessment - from my experience they are more interested in your observation skills and reasoning than in any specific set of recommendations.

 

You seem to be on the right tracks Jacquemontii, so even if I don't necessarily agree with your recommendations, I'd suggest that if it's something you want to do, you are probably ready to do the PTI assessment. Good luck with it

[treeseer]

The notion that reducing a branch or tree inevitably weakens it is an unproven theory. Photosynthesis is far too complex to reduce it to 'number of leaves = amount of photosynthesis'. Proper reduction often leads to rejuvenation, as shown so well on this forum.

 

"would it not still be a flexi brace though unless install as a rigid system using a steel rod?" Excellent question. Yes of course there is always movement from wind, even with a steel cable. This can be minimized by using more than one, or in extreme cases by adding a rod, as you describe.

There is however NOT movement from stretching and springing back. Dynamic cable is properly specified to allow this dynamic movement, which of course is good, when the forks are not cracking.

[treeseer]

Rejuvenation of a tree’s physiology slows down its aging clock.

This is best seen in trees that grow on stressful environments, like

mountaintops. Among trees, some adversity can promote longevity.

Recovery from damage enhances dignity in veteran trees, as they

demonstrate endurance.

 

“Pruning does it by inducing the growth

of younger meristems, shortening the internal transport path, and

balancing shoot load and activity with limited root activity and

support. In trees, physiological and developmental aging operate

independently.

They can be simultaneously embryonic and senile,

resulting in a form of ecological immortality.

It is this potential for

immortality that makes trees so fascinating to work with.”

Peter del Tredici of Harvard

University (Cambridge, MA),

[jacquemontii]

Thanks Treeseer, some good pointers, but what about the species characteristics of beech?

 

With reference to 'Ancient and other veteran trees: further guidance':

In a table of Species characteristics to take into account before pruning, beech is described as relatively likely to die back after severe cutting, since it often tends to produce relatively few epicormic shoots. Also, its lack of durable heartwood often leads to excessive development of decay.

 

I know in this instance we're not advocating "severe cutting", but presumably these species characteristics are pertinent?

[jacquemontii]

I was starting to get a bit concerned by some of the responses on here, so I thought I'd add:

 

"Examples of trees with a high risk of this type of failure include various species of willow and poplar, horse chestnut, beech, ash and true cedars."

 

Taken from,

http://www.forestry.gov.uk/pdf/fcpg13.pdf/$file/fcpg13.pdf

 

Just in the last two weeks I've been to see and prepare reports on three different beech trees which have failed, and which I suspect looked similar to the second example tree in this thread before they did fail. I can't really comment on the first tree, because I can't tell what's going on just from the photo.

 

The other thing that strikes me about this thread is this:

 

What does the client want?

 

Maybe they are loaded, love the tree and are willing to spend money on it, but perhaps they hate the tree and just want it gone, or perhaps they are (like most clients) somewhere in the middle.

 

As for how this relates to the PTI assessment - from my experience they are more interested in your observation skills and reasoning than in any specific set of recommendations.

 

You seem to be on the right tracks Jacquemontii, so even if I don't necessarily agree with your recommendations, I'd suggest that if it's something you want to do, you are probably ready to do the PTI assessment. Good luck with it

 

Thanks for the encouraging response Arb culture, and indeed to all others who have taken the time to respond on this, it really is very helpful to get all this input!