inclusions

[tree79]

Hi all

 

I have a mature cedrus with a included Co dom stem

 

Just wondering if tthere's any information or research on how safe inclusions are, and probability of failure?

 

 

Many thanks

Tree

[daltontrees]

Good luck pinning that answer down. Mature Cedar are notoriously self-destructive, even without inclusions. I'd say wind exposure is the key factor but there have got to be many factors. And probability of failure will increase with wind speed. Why do you specifically need a probability of failure? Do you mean literally 1 in X chance numerical probability?

[tree79]

Yes not an easy question.

Just wondered if there was any information on inclusions in general. But have been looking at cedar, I don't see any reaction wood or signs of cracks.

How do you risk assess this?

Or is that the million dollar question

[daltontrees]

Yes not an easy question.

Just wondered if there was any information on inclusions in general. But have been looking at cedar, I don't see any reaction wood or signs of cracks.

How do you risk assess this?

Or is that the million dollar question

 

Lonsdale addresses the generalities in Tree Hazard Assessment and Management s. 5.2.1.2 but in the end he says only that "A visual inspection by an experienced person can help to decide whether the area of bark-to-bark contact is geat enogh to pose a hazard". When doing QTRA assessments I have to put a range of probabilities of failure on compression forks regularly. Hard as this may seem, if you think in orders of magnitude of probability it is good enough, but it has taken years of call-outs to storm breakages and surveying thousands of trees that have obviously stood up to those same storms to get an idea of what is an acceptable fork and what is not.

 

Mattheck and Breloer in The Body Language of Trees, your best chance of an overall biomechanical and numeric approach to assessing strength, do not even try to quantify strength. There are intersting comments about 'cupboard door failures' which are a reminder that the alignment of the bark inclusion in a fork relative to wind loads can be significant. Thus it is perhaps more likely that in southwesterly winds a north-south inclusion is more likely to fail than a northwedst-southeast inclusion. But only if the tree has not adapted to endemic south westerlies.

 

That book also suggests that forks with leaning codominant stems are more likely to be weak by the jacking open of compression forks due to annual wood increments in the fork itself.

 

I was up a beech today, c. 25m high with a deep pocket included fork near the base. While thinning the smaller (400mm dia at the base) crown at a height of about 15 metres, and anchored on it and the main substem, I witnessed to my great alarm the substem moving perhaps 300mm awy from and towards the main stem only under my body weight (c. 70kg). Yet it was protected from wind by an adjacent tree and the fork was almost perfectly sw-ne. The tree had to be 150 years old and had probably had this inclusion for 130 of those.

 

In short, there's no rule. But I have a feeling that in the same position with similar dimensions a Norway Maple or a Cedar would have failed 50 years ago. On the same site there were 2 other beech I had climbed past huge compression fork tear wounds in a similar orientation, one was very exposed, the other had been exposed at maturity to fresh loads by the removal of adjacent trees. Yet no 'cupboard door' effect as the substems must have been enormous with so much dead weight that sudden failure led to instant vertical drop of the limbs with oddly minimal tearing beneath. Both trees were thinned by me, and I had little concern for the wound position being weak. n the contrary the reaction wood around the wounds was fabulous, if a little ramshorned.

[Kveldssanger]

Lonsdale addresses the generalities in Tree Hazard Assessment and Management s. 5.2.1.2 but in the end he says only that "A visual inspection by an experienced person can help to decide whether the area of bark-to-bark contact is geat enogh to pose a hazard". When doing QTRA assessments I have to put a range of probabilities of failure on compression forks regularly. Hard as this may seem, if you think in orders of magnitude of probability it is good enough, but it has taken years of call-outs to storm breakages and surveying thousands of trees that have obviously stood up to those same storms to get an idea of what is an acceptable fork and what is not.

 

Mattheck and Breloer in The Body Language of Trees, your best chance of an overall biomechanical and numeric approach to assessing strength, do not even try to quantify strength. There are intersting comments about 'cupboard door failures' which are a reminder that the alignment of the bark inclusion in a fork relative to wind loads can be significant. Thus it is perhaps more likely that in southwesterly winds a north-south inclusion is more likely to fail than a northwedst-southeast inclusion. But only if the tree has not adapted to endemic south westerlies.

 

That book also suggests that forks with leaning codominant stems are more likely to be weak by the jacking open of compression forks due to annual wood increments in the fork itself.

 

I was up a beech today, c. 25m high with a deep pocket included fork near the base. While thinning the smaller (400mm dia at the base) crown at a height of about 15 metres, and anchored on it and the main substem, I witnessed to my great alarm the substem moving perhaps 300mm awy from and towards the main stem only under my body weight (c. 70kg). Yet it was protected from wind by an adjacent tree and the fork was almost perfectly sw-ne. The tree had to be 150 years old and had probably had this inclusion for 130 of those.

 

In short, there's no rule. But I have a feeling that in the same position with similar dimensions a Norway Maple or a Cedar would have failed 50 years ago. On the same site there were 2 other beech I had climbed past huge compression fork tear wounds in a similar orientation, one was very exposed, the other had been exposed at maturity to fresh loads by the removal of adjacent trees. Yet no 'cupboard door' effect as the substems must have been enormous with so much dead weight that sudden failure led to instant vertical drop of the limbs with oddly minimal tearing beneath. Both trees were thinned by me, and I had little concern for the wound position being weak. n the contrary the reaction wood around the wounds was fabulous, if a little ramshorned.

 

Fantastic post. Really useful information here.

[Mark J]

It depends where it is and what the wind can get up to. There was a mature Cedrus libani at my college in a courtyard. It was fine until it was just big enough for the eddying effects of the wind in the courtyard cause catastrophic failure.

 

Could you brace it to mitigate any perceived risk?

[tree79]

Lonsdale addresses the generalities in Tree Hazard Assessment and Management s. 5.2.1.2 but in the end he says only that "A visual inspection by an experienced person can help to decide whether the area of bark-to-bark contact is geat enogh to pose a hazard". When doing QTRA assessments I have to put a range of probabilities of failure on compression forks regularly. Hard as this may seem, if you think in orders of magnitude of probability it is good enough, but it has taken years of call-outs to storm breakages and surveying thousands of trees that have obviously stood up to those same storms to get an idea of what is an acceptable fork and what is not.

 

Mattheck and Breloer in The Body Language of Trees, your best chance of an overall biomechanical and numeric approach to assessing strength, do not even try to quantify strength. There are intersting comments about 'cupboard door failures' which are a reminder that the alignment of the bark inclusion in a fork relative to wind loads can be significant. Thus it is perhaps more likely that in southwesterly winds a north-south inclusion is more likely to fail than a northwedst-southeast inclusion. But only if the tree has not adapted to endemic south westerlies.

 

That book also suggests that forks with leaning codominant stems are more likely to be weak by the jacking open of compression forks due to annual wood increments in the fork itself.

 

I was up a beech today, c. 25m high with a deep pocket included fork near the base. While thinning the smaller (400mm dia at the base) crown at a height of about 15 metres, and anchored on it and the main substem, I witnessed to my great alarm the substem moving perhaps 300mm awy from and towards the main stem only under my body weight (c. 70kg). Yet it was protected from wind by an adjacent tree and the fork was almost perfectly sw-ne. The tree had to be 150 years old and had probably had this inclusion for 130 of those.

 

In short, there's no rule. But I have a feeling that in the same position with similar dimensions a Norway Maple or a Cedar would have failed 50 years ago. On the same site there were 2 other beech I had climbed past huge compression fork tear wounds in a similar orientation, one was very exposed, the other had been exposed at maturity to fresh loads by the removal of adjacent trees. Yet no 'cupboard door' effect as the substems must have been enormous with so much dead weight that sudden failure led to instant vertical drop of the limbs with oddly minimal tearing beneath. Both trees were thinned by me, and I had little concern for the wound position being weak. n the contrary the reaction wood around the wounds was fabulous, if a little ramshorned.

 

That's really helpful, I have seen a fair few included union fail over the years, but more on board leaves.

many thanks

 

tree

[tree79]

Yes not an easy question.

Just wondered if there was any information on inclusions in general. But have been looking at cedar, I don't see any reaction wood or signs of cracks.

How do you risk assess this?

Or is that the million dollar question

 

 

 

Ive add a photo of the union, I don't see any reaction wood or signs of cracks/splits in the bark, but this is a typical cedar long weighted branches.

Could you use a non invasive rigid brace?

Edited June 29, 2016 by tree79

[Gary Prentice]

Fantastic post. Really useful information here.

 

My thoughts as I was reading too.

 

 

 

Ive add a photo of the union, I don't see any reaction wood or signs of cracks/splits in the bark, but this is a typical cedar long weighted branches.

Could you use a non invasive rigid brace?

 

Thirty years ago we would have put a rod or two through that, without a second thought! I actually remember doing a maple which was starting to crack and fail, only to return a few weeks later after the Great Storm because the whole tree had uprooted.

 

IIRC, there is an American site that has recorded failures (reported by arbs/forest services/etc) by species, which gives some indication of the relative frequency of the different types of failure. Unfortunately I don't have a link but I think David Humphries may have supplied it to me originally.

[timbernut]

What sort of cedar is it? I'm by no means an expert but I have worked on several cedrus atlantica which have had failed included unions and they seem to have a high failure rate.

In fact there's one with are cent wound near the entrance to the farm were working on at the moment.

Just my tuppence worth😃