Paul Barton

Top class reply Julian! One thing about the 'RPA' is that is not intended to necessarily represent the extent of roots. Although I see some logic in the root:shoot ratio theory, it doesn't allow for those roots that perhaps by necessity due to soil conditions, track an awfully long way from the stem in order to exploit available soil moisture. I.e. if the soil in close proximity is moist and nutritious then the tree may have a fairly compact and fibrous root morphology, but if conditions are not so good a tree will throw out exploratory roots for some distance. We've all seen roots tracking under roads and footpaths etc. So if the RPA can't even come close to describing the radial spread of roots, it must be more about a sufficient volume of soil that is required to sustain the tree. As Julian says, this means that soil depth is pretty critical. If the soil is only 50cm deep before rock, then we should all be doubling the radius of RPAs as I recall the BS5837 radial RPA is based on a 1m depth! Going back to the original question, is it reasonable to estimate that a pollarded tree will need less soil volume than a full-crowned tree. Well, yes I think it is but perhaps only temporarily as pollards tend to produce prolific foliage to re-instate the root-shoot ratio. Research in to heavy pruning/pollarding to reduce water demand in subsidence prone areas shows that water uptake is resumed to previous levels in just two-three years after cutting so unless a tree is pollarded very frequently to control it, presumably root activity continues. Julian - your observations about incremental thickening of pollards is very interesting. I don't have any stumps or cross-sections to dispute your point, but I do recall hearing a talk a few years ago from Mr Barrell where he showed some slides of some small pollards in a church yard - the assumption was they were quite young as their stems were slender but when they were felled they were found to be really quite old. Maybe a long-term regime of pollarding does reduce incremental thickening? Or maybe those trees were just growing in poor soils and had somehow struggled on for more than a century!

Look, I'm easily confused at the best of times so don't taunt me with your mind-boggling scenarios!!

I commonly adjust the shape of RPAs due to ground conditions, but rarely reduce the overall size of an RPA due to crown size. I think your logic is pretty sound though - it follows that a small crown will require less moisture and soil nutrition to sustain it, and certainly large anchorage roots will be less than for a full-crowned tree. That said, the opposite thinking prevails when it comes to veteran and ancient trees. These often have small, retrenched crowns but the standing advice from Natural England and the FC is that the RPAs should be enlarged! They're not really comparable situations though

We use ucheck. They seem fine.

If you have a resistance drill (eg Resistograph) of high enough resolution the reading will show annual rings. As long as the drill bit can penetrate the entire radius that could give you useful information.

Nice one Timon. I bet you were praying hard that fell went right ? Respect for telling your inspiring story.

Nice one! Will have a watch.

It’s possible. If there is water and oxygen down there then yes. I’ve heard of instances in London where roots have been found down to around 5 metres.

Superb! Did you choose a high-line because it was easier and cheaper than a MEWP? Or just cos it’s way cooler?!

Sounds like a great opportunity to work in a nice area!

It’s fair enough for the council to ask for a report despite the foundations being outside of notional RPAs - there are plenty of other ways trees can be damaged during construction other than directly by excavating for foundations. Perhaps get some more quotes for the report if £800 seems a bit much for what could be quite a simple report.

These seem great - I’ve looked in to them in the last. The only thing that put me off was relying on wind speed data from a local weather station which could actually be quite different accounting for gusts and shelter. Do you use an anemometer placed nearby? And do you interpret your own data or send it away for analysis? I’m keen to know how ‘user friendly’ these are.

I watched the extended interview on YouTube. He is brilliant!

Interesting post, thanks for sharing David. I don't have any first hand experience with pull-tests, but a few questions! As already asked by Darin above, do you know how the test and interpretation of results accounts for soil and rooting conditions. Obviously the stretch of wood fibres under tension is measurable, but surely the cohesion of fine and structural roots to the soil medium is critical when considering whole tree failure? Are the values provided by the test compared with some kind of benchmark data - e.g. the 'normal' elasticity of Platanus wood? I notice that the tree was a multi-stemmed tree but that the cable was attached to one of the stems rather than linked to all of them. How does the test allow for the flexure of that stem at its junction with the primary trunk? I would have thought that this junction would flex and therefore dissipate some of the load from the base - or would that only be true of a dynamic test rather than a static load? I realise that you were an attendee rather than the demonstrator - but you're about the smartest tree nerd I know so I reckon you'll have something to say in return

FreeAgent - it's excellent. Here's a referral code to get 10% off (for you and for me!): http://fre.ag/434xo4m9

Not great pictures! Possibly a Whitebeam?

Are you a member of the Arb Association? There's a bunch of guidance documents on their website which may be what you are looking for. https://www.trees.org.uk/Help-Advice/Help-for-Arborists

Have you got a link you can share to that?

Well the CAD app would save you having to mark up a paper copy on site but not much else. Just need someone to make a simple app that links a DWG with a survey form.... ArbEvolve looked good but won’t work on Mac’s so won’t work for us.

On an iPad mate. It’s a simple free CAD app called DWG Fastview.

In my experience so far there is no single setup that will do everything that you want - I’m still looking for it! GPS/GIS based systems are great for tree surveys other than BS5837 surveys which are based on topographical plans and need to be presented to clients in common CAD formats. We use a GIS collector system for tree condition surveys but a CAD based app and spreadsheets for BS5837.

...or a Foundation degree, degree or Masters from a University.

I've not heard of this tree so looked it up on t'interweb. It's not Dichrostachys cinerea and it's not Crinodendron hookerianum as that's evergreen! I'm away from home and my ident books at the moment. Can anyone shed light on what the botanical name of this tree is? I recently came across a Halesia carolina (Snowdrop tree) which has similar lanterns on it.

You mean you broke it?!

Hi Dave, My understanding of the legislation is that replacement trees as far as TPOs go, are only on a one for one basis. The wording from s.206 of the TCPA is: If any tree in respect of which a tree preservation order is for the time being in force— (a)is removed, uprooted or destroyed in contravention of the order, or (b)except in the case of a tree to which the order applies as part of a woodland, is removed, uprooted or destroyed or dies at a time when its cutting down or uprooting is authorised only by virtue of section 198(6)(a), it shall be the duty of the owner of the land to plant another tree of an appropriate size and species at the same place as soon as he reasonably can. [emphasis mine].