What's a 30% reduction to you?

[Tony Croft aka hamadryad]

Figure 6.2 page 198 "tree hazard assesment and managment" Lonsdale

 

This goes a long way into dealing with the complexity of the issues surrounding interpretation of "reduction" I would reccomend anyone who needs a better understanding of this problem read this passage in particular.

 

I would say MOST clients want D of the four sketches in the page mentioned, with B being the better option and C being the happy medium and compromise.

 

This is a good passage to show clients in order to explain the differences in "arborists terminology" as there is a great void between what WE think of as truly representing 30% and what clients EXPECT 30% to be as an outcome.

 

This is a bone of contention and dissagreement best sorted at the quotation stage!

 

When you think of 30% it is to most people almost a third, the public percieve this as you would expect by hieght and spread and they visualise it this way, hence the frequent dissapointments some clients will have with what spec they was quoted for.

[Albedo]

 

This is a bone of contention and dissagreement best sorted at the quotation stage!

 

 

Agree hugely with this statement Hama, I go to great pains to achieve this, and like the client to be there on the day too where possible. Keep meaning to buy a lazer pointer to aid in the explanation, quotation stage.

[MattyF]

30% height or leaf area =to much unless the tree has some serious structural default or has died back by this amount and is or has regenerating a new canopy in wich case the cuts become clear imo.

Its a hard question i used to do it by height but now explain its leaf area... or what ever suits the tree in question best to minimalise re generation.... in some cases regeneration can be a good thing though!

[paradise]

hamadryad could you explain what lonsdale says the ideal is for those of us who don't have the book? Does he say it means leaf area?

 

 

Anyway, I'm glad to see I'm not the only one confused about this

[Tony Croft aka hamadryad]

One thing most guys forget to think about when reducing is eveness of foliage, with great skill and a lot of thought you can reduce a crown considerably whilst retaining an even structured foiliage mass that will generate JUST enough shade to the inner crown to keep regrowth to sensible limits. Most regrowth from reduction is generated as a response to light penetrating the inner structure or scafolds, this is why thinning is so pointless. maintaining as much internal growth as is physicaly possible helps reduce that horrible excurrent regrowth habit of most deciduos trees.

[Tony Croft aka hamadryad]

hamadryad could you explain what lonsdale says the ideal is for those of us who don't have the book? Does he say it means leaf area?

 

 

Anyway, I'm glad to see I'm not the only one confused about this

 

The bottom line is that when we reduce thin lift or whatever, we are removing the trees food production facility. Too much and the tree (understandably0 goes into panic or shock using massive quantities of stroed sugars, sugars that are reserved for a natural catastrophe such as a limb loss or invasive force like fungi. When we reduce heavily we temporarily weaken the trees imunal defence and this is one of the major reasons trees in the urban environment suffer so greatly.

 

Sensitive (leaf area) pruning and smaller wounds is the right approach, but it is ALWAYS a compromise in the urban environment, there is just too little sympathy and empathy for the tree.

[Doug Blease]

Setting that kind of limit makes sense to me because what it kind of does is limit the wound size. A 30% reduction in branch length on a big tree can leave huge wounds, whereas on mature trees (species differences aside) removing 2m would likely leave more or less the same wound size whatever the size of the tree.

 

 

Your absolutely right Paradise. But what it does do is allow the TO to control excessive reductions which had been going on in the area, claiming the "variable" 30% idea.

 

Luckily, with a bit of experience of reducing larger trees for a variety of reasons, you can still interpret what the customer and TO have in mind and agree a consensus.

[paradise]

While googling reductions I came across this, which someone was proud enough of to put on their website:

 

Hunts Tree and Garden Services Ltd

 

Interestingly it was a TPO job so I bet they said it was a 30% reduction.

[Mesterh]

While googling reductions I came across this, which someone was proud enough of to put on their website:

 

Hunts Tree and Garden Services Ltd

 

Interestingly it was a TPO job so I bet they said it was a 30% reduction.

 

Oh dear

[Amelanchier]

I don't see why anyone should be writing a spec that just includes a percentage without explaining it. It takes seconds to describe works accurately - I suspect people either;

1. can't be bothered,
   
2. don't know what they're doing or
   
3. expect to get the work,
   

 

Honestly, if you're going to use a percentage - state what it's a percentage of! Otherwise you might as well say "cut off not too much and not too little."

 

I use the metres from the outer limit of the crown method and often specify a maximum cut diameter as well. Of course, I'm not going to climb the tree with a set of callipers but it communicates my expectations. Everyone can be on the same page.

 

I've often thought we should spec what's going to be left of the tree rather than whats coming off. The cut diameter is part of that but maybe something like;

 

Undertake a crown reduction by the removal of no more than 2m of the outermost canopy back to suitable secondary growth points, leaving minimum crown dimensions of 8m radial spread and 18m overall height at any one point. Resulting pruning cuts must not exceed 150mm in diameter.

 

That took 20 odd seconds to write, its not hard. Just a tiny bit more effort (more so on large numbers of trees!)

 

I know people like a flexible spec so they can make their own judgements when climbing and react to the pruning points - fair enough, there is room for leeway but it fundamentally ties down what the hell is going to happen to the tree.