Hamas big reduction/pruning thread!

[Tony Croft aka hamadryad]

There are those, myself included, who are of the view that pruning being wounding brings on a defense situation, and prepairs the tree, like a boost to its immuno defense.

 

If nothing else smaller wounds and a bit of dead stubs and cut surfaces often allows harmless saprobes to get a foot hold and create a complex and competative decay community that more serious fungi might have trouble penetrating.

 

There is a complex interplay of microbial pioneering going on within a tree.

[Tony Croft aka hamadryad]

I hope youll all give me a chance to at least try and convert you, I make a good argument for its use as I hope i will prove.

 

We all know about a trees life from seed to senesence right? So we are all agreed that as a tree ages, matures and then goes into decline it retrenches if it is lucky and goes on for many more decades or even hundreds if not thousands of years, like a bristlecone pine, or the classic oak.

 

Can we agree on that?

[Dean Lofthouse]

I'm referring to heavy pruning.

 

I read a book somewhere that said something along the lines of an Oak, grows for 400 years, declines for 400 years and rots down over 400 years.

 

"Not if Billy the Tree Surgeon comes along with his 020" I thought to myself

[Tony Croft aka hamadryad]

Going back to the pictorial theme for a mo.....

 

This beech is in a lot of bother, it is a young tree, but already is suffering from advanced Ganoderma decay of the butt/roots and stem up to the union of the two major stem divisions.

 

The tree appears to have got some level of control (compertmentalisation) of the fungal decay and is producing reaction wood and no signs of decline.

 

Careful pruning to reduce transport distances and optimise photo sytnetic area (ramification) will help this tree. However this is only part of the equation.

 

The damged roots a certainly due to machinery/excavation, there is also disturbance to the soil, compaction and removal of some soil. It would certainly improve the trees chances if some decompaction and mulching was carried out in the root zone.

 

The Ivy remove to allow long term assesment of the decy and reaction. The tree is of critical importance to this new biuld and its landscaping design.

 

 

[Tony Croft aka hamadryad]

In the interest of proving my case, that being for the benefit and validity of crown reduction I have been going through my library (rather extensive these days!)

 

I have been surprised by the response to this thread, the negative views toward crown reduction by many favouring the other two options, a thin or a fell.

 

Now excluding the lopping and topping, for that is not what THIS thread is about, this is about the benefits and art of a technique that is quite frankly an underrated, under practiced and widely mal-practiced art.

 

Thinning is in 99% of the situations I’ve witnessed done poorly also, and usually revolves around removing far too much internal frame work, which at some stage will be needed for crown retrenchment or restoration. Not only that, but thinning also creates a situation of pushing the transport networks to the outer edges or periphery of the crown making it hard for a tree to place carbs where they are needed as efficiently as possible.

 

if you have trouble understanding this concept imagine the strain your heart would bear if it was in your foot and had to pump all the way to your head, it wouldn’t make biological sense would it!

 

Before anyone suggests woodland trees have no lower growth, they don’t because i) it is shaded out. ii) it is in competition so doesn’t waste resources on shaded and unproductive parts. iii) has the shelter and support of neighbours to lessen the need for carbs and reaction at lower levels.

 

And if you doubt that go and read "slenderness ratios" and "optimisation" Claus Mattheck!

 

Now the reading I did for this particular post was "principles of tree hazard assessment and management" by Lonsdale, a truly great arboriculturist, which NO ONE would deny!

 

Extract from Page 202 - 203 chapter 6 "Remedial Action"

 

6.4.2.1 Crown thinning

 

Crown thinning can reduce the sail area, while not necessarily having much effect on the overall shape and size of the crown or the tracery of the outer twigs. Its value in mitigating a hazard is, however, more difficult to determine than the effect of shortening the lever arm by crown reduction. The aerodynamic factors of the crown are affected by many factors which vary not only with the characteristics of the tree species concerned, but also with the wind speed. it nevertheless seems reasonable to assume that thinning can reduce the sail area as to place less stress on the main stem and root plate in windy conditions. most of the evidence for such an effect is probably observational, but an experiment involving light crown thinning of F.sylvatica in a forest stand showed that the crown-thinned trees resisted wind throw far better than their unthinned neighbours.

In view of the uncertainty over benefits of thinning for hazard management, it is probably better to combine this treatment with some degree of crown reduction, rather than to use it in isolation. Crown reduction will in any case bring about a diminution of the sail area.

Edited March 15, 2010 by Tony Croft aka hamadryad

[gibbon]

All I said was that I thought you had taken more off than I would have in one hit. There was never the question of whether or not too reduce, rather by how much.

[Tony Croft aka hamadryad]

All I said was that I thought you had taken more off than I would have in one hit. There was never the question of whether or not too reduce, rather by how much.

 

Dont worry Gibbon, thsat post and all above is really for those claiming it is better to fell or thin than to reduce.

[Dean Lofthouse]

Better to fell or reduce than a 70 % reduction

 

We reduce all the time Tony, but I very rarely do more than a 30%

 

All everyone is saying is massive reductions (unless the tree is ailing) are seen as not in the trees best interest

 

I had a chat with an Oak today and asked it's opinion, it was mortified at the prospect of anything more than a light haircut

[educated arborist]

Careful pruning to reduce transport distances and optimise photo sytnetic area (ramification) will help this tree.

 

thin ice, v thin ice. There is a fair amount of conflicting research on this matter, but i post primerily to expand on deans post.

 

90% of the time reductions result in weak unions. The larger the wound-stem ratio diamiter the weaker the union, the wounds really do have to be miniscule to stregthen the tree & some of the reductions in your photos will have inherent weak points needing cyclical pruning to prevent branch failure.

[Tony Croft aka hamadryad]

Better to fell or reduce than a 70 % reduction

 

We reduce all the time Tony, but I very rarely do more than a 30%

 

All everyone is saying is massive reductions (unless the tree is ailing) are seen as not in the trees best interest

 

I had a chat with an Oak today and asked it's opinion, it was mortified at the prospect of anything more than a light haircut

 

 

so are you suggesting that all my work above is 70% reduction? or even 1 of those jobs, none of which are over 40%?

 

Hieght width, v, leaf area is another point.

 

and those guidance notes are as a rule, and flexible in the right circumstances, what a tree can and cannot tolerate is down to the individuals experiance and knowledge. I have only killed two trees, both in the same line of willows that where topped in dry heat and didnt fair well, they didnt actualy die, but died back a long way leaving high stems of dead wood. A lessen i have never repeated since.