Removing branches

[Ivan Owen]

So i'd been under the impression that removing a live, healthy limb from a tree is a cardinal sin until recently, when my boss (Who genuinely knows his stuff) informed me that it could 'potentially' extend the life of the tree by up to 150 years.

So what's the general verdict? Is he right or wrong?

Note that he was referring to a limb around wrist thickness.

 

[santaman2000]

Think about your garden. Do you prune anything there? As far as wild trees in the forest I suppose it would depend on how well you know the species and how it should be pruned. As for just how long it extends the life (if it does) it would also probably depend on what the average lifespan already is for the individual species.

I have the oaks in my front and back yards pruned back several feet every other year before hurricane season. I would wait longer but by the second year the branches are always grown back over my roof.

 

[Callum]

Hi Ivan

I think your boss is being a bit simplistic. Some of the oldest trees in the country are often pollards (i.e. they have been manged using a system of specialist pruning, usually to provide food for cattle or materials for basket making etc.) At other times when a tree is structurally unsound for what ever reason then correct pruning practice can help rebalance the trees structure and prevent collapse.

In most cases pruning branches is of no benefit to the tree becasue they have evolved the ability to self optimise. Pruning wounds can create an opportunity for pathogens to bypass the trees defences.

I think we have to be sensible though- if it is essential for someone to prune a branch for a bushcraft purpose they should make sure the cut is in the right place and that they are aware that they are probably not doing the tree any good, that way people don't do it without good reason.

Callum

 

[forestwalker]

I've been told, by a forestry person, that as long as one does not damage the bark of the trunk, and leave a short stump the tree should generally take no harm, perhaps even benefit from it.

 

[Callum]

How would the tree benefit from having a healthy branch removed? the tree has expended energy to grow the branch and has done it in reaction to a large number of environmental factors so that it can benefit from the energy produced (photosynthesis) from the leaves.

You can improve the value of the timber produced by pruning but this is a benefit to the forester rather than the tree and a skilled arborist can carryout remedial pruning to improve the structure of a tree but in the context of bushcraft this is not what most people are doing.

There is a zone of wood in the branch collar that is adapted to compartmentalise effectively in reaction to a wound and the tree produces anti fungal and bacterial compounds but pruning a branch still increases the chance of infection by invasive pathogens.

Also some trees should only be pruned at certain times of the year (e.g. Prunus sp, Walnut etc)

Callum

 

[Retired Member southey]

Ah, but does the energy produced buy the branch sustain more than the branch itself?

 

[Callum]

Hi Southey

Yes it does- The carbohydrates produced in the leaves are transported throughout the tree, just as water,nutrients and minerals absorbed by the roots end up in the leaves.

I'm not totally against pruning branches to use in bushcraft because using and learning about trees is probably the best way of conserving them. If more people were out there practising responsible bushcraft in the outdoors I think we would be in a much better situation as far as the environment is concerned.

I do think it's important to recognise that we are rarely benefiting the tree by pruning it (and there is some chance that we may cause some harm). That we should prune in a way which causes the tree as little damage as possible and to only do it when neccessary.

From reading the posts on this site i think that most people are already doing what I'm suggesting.

Callum

 

[blacktimberwolf]

Can't see how removing a healthy limb can be benificial to the tree.

 

[treelore]

Hi all,

This is a cracking thread, all the answers are right…. But here’s my penny’s worth


The general rule is if a tree limb is healthy then it’s best not to touch it. Yes removing a limb can increase the life span of a tree, but it can also reduce it, either by a bad pruning cut, die back, fugal infection or even shock in some cases and many other causes. The size of a pruning cut, species of tree and time of year all have affects on the tree as well. There is no easy answer to this, but if the limb/branch is needed, everything is taken into account and the process is done the correct way then the tree(s) should be fine. (Coppicing can some times be a better option, but that’s a whole different matter).


Pollarding, coppicing, limb removal and even tearing a limb from a tree (veteran) can all increase the life plan of a tree, but with everything it’s a calculated gable. But with the right knowledge, tools and in cases training you can stack the odds in your favour.

Forestwalker, your forester friend is right it can benefit the tree, but also the forester as he is producing a "woodland" tree for timber.

Ivan your boss is right to a point, but I’m sorry to say it’s also not a straight forward one.


I think the real answer people should ask them selves is do they really need the limb/branch?


All the best


Treelore

Arborist and Forester

 

[Ivan Owen]

Keep the knowledge coming guys this is very interesting stuff. Tearing? Your gonna have to explain that one treelore.

It seems clear to me that there are different 'rules' for foresters; it'd be interesting to hear more about it? Details of how/where to cut etc.

 

[Callum]

Hi Ivan

I think I've managed to insert an image which shows the basics of target pruning above. Try googling Alex Shigo he's the guy who came up with the idea of modern pruning.

Tree lore is probably the one to talk to about forestry, I work on the arb side of things.

Hope that helps

Callum

 

[calibanzwei]

Great thread - ties in nicely with my college course

 

[treelore]

nice one callum, spot on diagram and yes Alex Shigo is the forward thinker in all matter tree related. lol callum i studied arboriculture and then forestry a couple of years latter, doing woodland management and ecology this September, are you a tree worker too ?

calibanzwei what are you doing at college ?

Ivan, tearing is where you just rip the limb off the tree using a winch and your wagon, this is done on veterian trees and you need to be trained in the process.... this is one of the things i do for the FC, but the Arborist side of me thinks WHAT THE HELL lol...

if you need to know anything just yell

all the best

Treelore

 

[Ivan Owen]

Cheers guys; what's a veterian tree?

I'm hoping to run an orchard and do some coppicing/pollarding some day. When i know my stuff.

Did some work with a tree surgeon a while back but he wasn't interested in teaching me anything so it's good to hear this stuff!

 

[bushcraftbob]

Great thread this be! Treelore - How does "tearing" benefit these veterans?

 

[santaman2000]

Some of the most exasperating pruning is done by Christmas tree farmers. Not only do they need frequent pruning but in addition to taking care to preserve the tree's health they have to have the skill of a Bonzai artist to obtain the desired shape. Very profitable business though.

 

[Callum]

Hi Treelore

I'm an arb consultant. Most of the work i do is for construction companies (BS:5837) as well as H&S surveys. The veteran tree management stuff is fascinating although I've never had the chance to get involved myself.

Ivan. A veteran tree is a tree which has reached a size or stage of development which is unusual for the species, they can be hundreds or even thousands of years old. The thing with these trees is that in terms of providing niche habitats for other species they are unique and also very rare. The habitat one of these trees can provide to rare species is the one of the most important factors when deciding how each tree should be managed.

Because of this, veteran trees need specialist management techniques which often go against the type of thing which is usually recomended. e.g. instead of target pruning, they may leave a stub and carve groves into it to mimic a natural branch failure. This allows organisms which have evolved specifically to live on the ends of broken branches to colonise the wood.

The woodland trust has quite a lot of information on their website.

Callum

 

[treelore]

i hope that answers your qustion on veteran trees..could`nt put it better my selve callum. I forgot to add the other day that if a tree has a “weak union” (the join were the branch meets the main stem) can also be a good reason for removal. This is done to stop the limb from snapping out and leaving a large wound and possibly letting disease and decay into the main stem, but again only if it will benefit the tree or for public safety.


In woodland or forestry management trees that are of no timber, historic or cultural value can be left to fail (limb to snap) to provide habitat for invertebrates, birds, fungus and bats.


All the best

Treelore

 

[robin wood]

Just to chip in a couple of points that may be of interest.

Why should cutting prolong a trees life? Well every year a tree has to completely cover it's entire surface area with at least one cell thick of new growth. For the first 150 years or so that is no problem at all. at around 150yrs depending on species the crown of the tree reaches the maximum size the structure can support so from then on we have an ever increasing surface area to cover with new wood but the energy input is static so the layers (growth rings get thinner as the tree goes say 250-350. Then it gets to the stage where it struggles to put that layer over the increased surface and different trees react in different ways. Oak tends to have strong epicormic buds even in the old bark so it can shed a big limb and regrow from the main trunk, beech has few epicormic buds and does not shoot again from old bark so at 300 yrs or so in a dry summer it just dies off.

Pollarding effectively does the same job an oak often does naturally but in a more controlled manner so on a rotation the branches are removed and left to regrow. Now the tree has a much smaller crown to generate energy but also a very small surface area to cover so it works out OK again.

Last thing is that folk found that a naturally shed or windblown branch would tend to regrow from the stub far better than a clean chainsaw cut. It is 20 years since I was in veteran tree management with the National Trust but back then we were experimenting with various options eg controlled ripping to leave a shattered stub, cutting with axes or chopping at the cut to expose more surface area at the edge of the cut, cutting v notches around the cut again to increase surface of cut for potential regrowth etc. Generally trees regrow and seal off the wound of a small cut easily but anything over wrist size is more hit and miss depoending on species, location, genetics (some trees have more epicormic buds than others) etc.

 

[demographic]

Just to chip in a couple of points that may be of interest.

Why should cutting prolong a trees life? Well every year a tree has to completely cover it's entire surface area with at least one cell thick of new growth. For the first 150 years or so that is no problem at all. at around 150yrs depending on species the crown of the tree reaches the maximum size the structure can support so from then on we have an ever increasing surface area to cover with new wood but the energy input is static so the layers (growth rings get thinner as the tree goes say 250-350. Then it gets to the stage where it struggles to put that layer over the increased surface and different trees react in different ways. Oak tends to have strong epicormic buds even in the old bark so it can shed a big limb and regrow from the main trunk, beech has few epicormic buds and does not shoot again from old bark so at 300 yrs or so in a dry summer it just dies off.

Pollarding effectively does the same job an oak often does naturally but in a more controlled manner so on a rotation the branches are removed and left to regrow. Now the tree has a much smaller crown to generate energy but also a very small surface area to cover so it works out OK again.

Last thing is that folk found that a naturally shed or windblown branch would tend to regrow from the stub far better than a clean chainsaw cut. It is 20 years since I was in veteran tree management with the National Trust but back then we were experimenting with various options eg controlled ripping to leave a shattered stub, cutting with axes or chopping at the cut to expose more surface area at the edge of the cut, cutting v notches around the cut again to increase surface of cut for potential regrowth etc. Generally trees regrow and seal off the wound of a small cut easily but anything over wrist size is more hit and miss depoending on species, location, genetics (some trees have more epicormic buds than others) etc.

Interesting stuff, thanks.