So… Brooklyn. Got back from NY on Friday after a really interesting few days in Brooklyn’s Green Wood cemetery.

As I wrote in the last post, Phil approached me about the possibility of doing something there together about working with over-mature tree populations. And by golly, does Green Wood have one! Coming from Europe it is intriguing to see trees in this condition, it almost feels as though the urban forest in Europe is sanitised to a higher degree, many of the trees we discussed in Green Wood would probably have been removed here a long time ago. I write this not as a judgement, but merely as an observation – both routes have their pros and cons.

Assessing the condition of the trees was certainly challenging, forcing you to really think out of the box, and to be very honest with yourself regarding what you can make a founded call on – and what not. A broad range of fungi is rampant in the cemetery, affecting trees to a greater or lesser degree. There is an active interest to expand the focus of Green Wood, which was founded in 1838, which makes it one of the earliest “rural cemeteries”, away from being viewed only as a burial site, towards a more diverse perspective, taking into account a wide range of ecological and environmental factors. This obviously shifts the focus regarding how trees are viewed, the value which is assessed to them and the care they receive.

On the first day we were very graciously welcomed by Joseph Charap, the Director of Horticulture and Curator of Green Wood, who then promptly took us for a spin, discussing a number of trees. It was very interesting how the trees I initially thought would never work ended up being viable for retrenching, where as there were others which I thought would be fine, but turned out to be beyond the point where we could do anything viable with them.

The actual work of retrenching these veteran trees was challenging. From the point of view of what you do to them, how much you can remove and where to make cuts, as well as from a technical, climbing point of view. As the beeches we were working on were all affected by phytophtera and hypoxylon, we were forced to err on the side of caution regarding anchor point selection. These lower anchor points in turn made for flat line angles, so I ended up using re-directs, multiple anchor points or v-rigs. Also, lots of use of the lanyard on the various attachment points.

One of the challenges when doing this kind of work is not to smash up all the regrowth you are trying to keep in the lower canopy, so this was one of the points we were keen to explore further. There was some cut and chuck, but also rigging in the periphery of the canopy, using 12mm rigging lines, which are light and no too much hassle to move around, slide lines and also working with DMM’s new Offya trolley. All of these options allowed us to really move sections of canopy well away, and also to avoid targets on the ground.

A big thank you goes out to Jairo, Cipriano, Julian and Sanchez for their support and help during the pruning and also on the workshop day.

The workshop day started up a bit overcast and damp, but quickly cleared. We had a good crowd of people from private companies as well as municipal organisations. The whole event was lively and interactive, touching upon many aspects of managing and working with over-mature trees. The setting in the Green Wood chapel was rather interesting and unique. Apparently the architect responsible for the buildings in that area also designed New York’s Central Station.

Something like this takes a lot of planning and the logistics can be slightly daunting. I ended up taking two 32kg bags and one weighing in at 23kg. This was topped on the way back, because I had forgotten I would have to pack the Offya also, so that meant a fourth bag.

I ended up stranded in the departures hall with all these heavy bag, feeling a bit like a beached whale – luckily some kind soul from American Airlines took mercy on me and gave me a hand. Otherwise I would probably still be there now!

A big thank you to Tony, who joined us to do some filming on one of the days (footage to follow in due courses), Rachel, for being good company, Phil for letting me part of this – and Joe for his gracious hospitality– and his dry whit!

Should you be in New York, do not miss checking out Green Wood cemetery.


I find it fascinating how a shift of perspective can totally change the picture of something which is in itself deeply familiar.

Take monitoring for Asian Longhorn Beetle for instance… in this case your perspective shifts from the macro to the micro scale. Trees are large structures, but here you are looking for things the size of a corn of rice. And suddenly you notice aspects of a tree you had never noticed before, despite having climbed past them many times, such as small blemishes or bore holes.

Yesterday was a similar insight working in Brooklyn’s Green-Wood cemetery with Phil Kelley. The question here is what to do with an over-mature tree population. The cemetery is very interested in retaining these trees, many of which have historical or emotional significance and as such qualify as heritage trees. Yet at the same time, many of them are not in a good condition, populated by a plethora of fungi and a whole host of structural defects.

The shift in perspective here for me was that here is a case where the tree owner realises that their trees have problems but wants to keep them regardless. Oftentimes this will be the point where a tree is removed. I am very glad that in this case the owner is taking a different approach. We are looking at retrenching the trees, inducing their old-age shape with a reduced crown mass, reduced lever arms and the overall weight of the structure. As this is not an everyday set of parameters, you are forced to really think out of the box, considering what you know and what you do not, what you can back up with your risk assessment and an approach based upon due diligence.

What yesterday showed clearly is that the tree you are working with needs a certain level of vitality to be able to handle the intervention, if this is not the case, removing crown mass and causing wounds will likely be detrimental and not lead to the desired effect. The first tree we worked on however was bushing up nicely from the inside, offering plenty of regrowth to prune the canopy back to, the end effect being a much more compact tree than the large structure with lots of dead limbs  we started with.

Neville Faye talks about how trees grow for three hundred years, live for three hundred years – and finally die for three hundred years. It is very satisfactory to be able to be part of such a process and it will be highly interesting to see how the trees here in Green-Wood respond to the pruning being done this week.


Planning ahead

As the year slowly draws towards an end, I look back on a very busy year. Lots of interesting, exciting and inspiring events and meetings with tree people from all over the world.

Mind you, we are not quite there yet, there are still a couple to go. Next week I will be joining Phil Kelley in Brooklyn’s Green-Wood Cemetery to do some work on an alignment of oak trees which are dying back. The plan is to retrench them and finish off the week with a workshop on how the work was planned and executed. I am very excited with the prospect of using DMM’s new Offya rigging trolley for at least part of this work, which involves moving large bits of dead wood over the cemetery’s historical headstones – without causing damage. We will be combing this with Teufelberger’s arborWINCH line, a light-weight, Dyneema-core rigging line which allows very precise technical rigging.

For me part of the planning process involves envisaging the set-up allowing for most versatility and flexibility… I find it easiest to do this by actually sketching it out.

By the way, before anyone can comment on it: the reason I am incorporating Axis swivels into the rig is that the pieces, as Phil described them to me, are bulky and cumbersome – but not very heavy. Obviously, for heavy-duty rigging I would look for a different solution with a higher breaking strength, allowing for a higher safety margin.

In this case the matter is further complicated by the fact that the gear has to be taking either by me or Phil on the plane. The concepts of travelling light and arborist gear clash somewhat, as I have commented on numerous times in the past.

The thought behind the rig sketched out above is that both options allow lengths of rope to be hung off the Rigging Hub. These can be used to spider leg pieces to keep them in orientation whilst rigging them down. Also it should allow us to run a lighter trolley, as otherwise you need a a fair bit of weight on the winching pulley to lower it down to the climber. This way, the climber can simply catch hold of the line and pull the pulley down to himself.

It will be interesting to see how all of this planning stands up to reality.

I will also be shipping gear today for a workshop the following week in Helsinki, Finnland. I have been looking forwards to this event, as similar to the event in Brooklyn, it will feature topics I have not visited in a while, such as an overview and applications of the equipment we have been involved in developing, or working with cranes – as well as new questions, such as “A brief overview of current of how European legislation affects training standards and trends in equipment and techniques in tree care”. Hmmm, right. Let me think about that for a moment… Also, on the Friday there will be the Christmas party of SPY, the Finnish arborist association, which should be a blast.

I would like to thank all of you who have enabled or facilitated an event or workshop in the course of this year. All of this would not be possible without the time and effort you invest into making these things happen. I enjoy and value the opportunity they offer to meet and interact with arborists from many different areas and regions.

Brave little pulley

I came across this Hitch Climber pulley during a recent training course…

It is safe to say that I have never seen damage this extensive on one of these pulleys. What you cannot tell from the photos is that one of the side plates is also severely deformed and the rivet is damaged. It is safe to say that this pulley was not a million miles from failing.

The person using it was blissfully oblivious to all this. They had to rig a tree up a hill and he simply used what he had to hand, realising that it was maybe not the best of ideas, yet lacking options decided, to go with this plan. The steel cable they were using obviously chewed away quite a bit of the sheave, once they finished there must have been a fair old pile of aluminium shavings under the pulley!

Yet still this plucky little Hitch Climber soldiers on! In many ways this made me think of Reverend Awdry’s Thomas the Tank Engine… therefore I declare that henceforth the Hitch Climber pulley shall be known as the Thomas the Tank Engine of the pulley world! 😊

Or, easier in shorthand: TTTEOTPW! (just got to remember that now 😳)

Trip to Israel

I was invited to speak in Israel, which happened a couple of weeks ago.

It is noticeable how it is nowadays rare to go somewhere and encounter an “isolated” community. It has become very easy to link into a global network of discussion and exchange of information via the internet or the various social media platforms. Yet at the same time, every region presents its own specific problems and challenges which people are confronted with – the same is true of the Israeli arborist community.

The workshop days took place in Hazore’a, south of Haifa, which is a secular kibbutz founded in the mid thirties. Today it is a thriving community of 450 people living and working together, swarming with kids and surrounded by beautiful park-like grounds. I was intrigued by the mixture of southern European and  north African vegetation, familiar yet at the same time very different. Oh, and of course the ubiquitous Eucalyptus, originally planted to drain swampy areas. I was humbled by the kind and generous hospitality offered by Dror, a very central person in the Israeli arborist community and Ran of Hazore’a. The group I was working with was obviously very switched on and brought a lot of experience to the table.

There was the usual mix of techniques and approaches to working in and on trees… there were some specific challenges though. Working in full chainsaw protection during a Middle Eastern summer in 50°C certainly sounds challenging in the extreme. The industry is very weakly regulated, allowing for all sorts of cowboy operators to put financial pressure on people trying to do the right thing by investing in training and professionalism by doing work at absurdly low prices (ok, this is sadly not a Israel-specific issue). Tree structures are problematic. Canary palms are suffering from an infestation of a beetle which came in from Lebanon and has moved all the way to the south of the country, internally hollowing out the palms causing damage you cannot see from the outside, causing potential failure when someone climbs on the tree – and of course killing the trees.

Be that as it may, the two workshop days were interesting and fun, flying by in a blur, including a social evening between with families and all.

Dror then took the time to show us around the country, which was amazing. I have never been to a place which I have found challenging on so many levels. Israel feels like a country made up of fragments: you look at one and think you have understood something, to then turn around, look at the next and realise you have understood nothing at all. It is breathtakingly beautiful, moving and interesting, but also crass, upsetting and wrong – all at the same time. Very intense.

Travelling down to the Dead Sea through the desert of Juda was spectacular as you are travelling through an area seeped in history, sunset in the desert over the Dead Sea must be one of the most beautiful things I have ever seen.

Jerusalem on the other hand I found puzzling and slightly bizarre.

It seemed to me that many, many people there are on a voyage of personal spiritual fulfilment, regardless of their creed, and that you might think that this would have a unifying effect – which of course it does not. What you choose to believe in is something deeply personal and is not something I would want to lumber others with – let alone impose on them. This is not what seems to be going on in Jerusalem.

Travelling this country makes you very aware of the depth of complexity to the issues this region is battling with. They have affected many generations and have caused a lot of grief and hatred over the years. Call me naive, but I found it encouraging to hear people from both sides of the – literal – fence say that most people just want to get on with life, and that the only parties interested in perpetuating this momentary situation of conflict are the extremists on both sides. Hopefully in the years to come, voices of reason will be the ones increasingly heard.

Thank you to all who made this trip possible, especially Dror who went above and beyond what I would ever expect of a host. It is certainly one that I will be taking lasting memories away from…


Life is fragile.

Once again this was driven home to me after a strenuous day of making sure people were behaving in a safe fashion and not inadvertently doing anything dangerous during a level 2 training course, when upon arriving home I received some very bad news: A friend had a very serious accident on a building site yesterday when a dumper truck he was driving broke through the roof they were working on – resulting in a seven meter fall.

This is the kind of thing that could so easily kill you. In the blink of an eye.

Luckily here this was not the case, he survived, albeit seriously injured.

All it takes is that one element you are not anticipating or which catches you unaware: a structurally weakened beam, a defect on a limb, a suspended dead piece of canopy, a live wire you thought was isolated, a moment of inattention. Ultimately, it does not matter whether you are top of your game, world-champion tree climber or whatever – or the farmer from the next village or working for a facility management company. Okay, your level of competence may have a degree of influence on the odds, yet no one is safe from falling prey to bad luck, a bad call or simply an oversight.

There is something numbing, raw and frightening about the helplessness you experience when things like this happen to someone in your immediate surroundings. Not something I will ever get used to or am prepared to get used to.

This one goes out to Roman, heal fast and well.

Be safe – and mindful – out there.



Really chuffed to see a number of projects we have been working on finally being shown in public at the DMM booth at the A+A work safety show in Dusseldorf!

The Hitch Climber pulley was due an up-date. I cannot help but feel very attached to this plucky little pulley, as it was one of the first treemagineers products back in 2006, so I am very pleased with this face lift. But of course it is more than mere cosmetics: you can now attach textiles into the rounded holes, the flaring on the fairleads are finally the way we always wanted them to be, the whole thing is beefed up and at an MBS of 44 kN it is not exaggeration to call it pretty sturdy. It also boasts an updated axle with high-efficiency roller bearings… not to mention the becket version!

Then the PerfectO locking carabiners… if you love the Ultra Os (like I do), yet are concerned about build height or length of an assembly, these will make you very happy. They share key features of the Ultra O, symmetrical shape, reversibility solid breaking strength, a choice of three locking mechanisms… yet boast 15mm less length! Happy days.

The Offya trolley system offers loads of variations for rigging highlines. This has evolved again since we demoed its use at the Climbers’ Forum in April, looking absolutely stunning now. Combined with the Deviant attachment/ anchor point this will be a great tool for that one specific rigging job which would otherwise have been a nightmare.

Chris, Elliot and the team at DMM have done fantastic work on all of this kit, a big thank you to all of them for providing us with this fantastic gear to play with at work…


What forces can a body sustain?

In the last blog post on the [slaice] rope terminations I wrote that the forces being discussed were well above anything a human body could sustain without suffering injury. This statement of course begs clarification…

Quite a bit of research has gone into this matter, dating back to studies investigating injuries paratroopers were suffering back in WW2 when their parachutes deployed, seeking to better understand the mechanisms involved and prevent people from getting hurt. Also there is the research looking at injuries suffered by drives and passengers in car accidents, this is about impacts rather than falls, but of course there are parallels when it comes to the mechanisms involved.

In case of a fall, it is not necessarily the landing that will hurt you, but rather the deceleration.

Impact with a hard, immovable object (e.g. the ground and/ or structure) is one instance of deceleration, but falling into your climbing systems can equally lead to injuries caused by rapid deceleration.  Considering that we are all ultimately naught more than sacks of skin filled with bones and squishy bits and bobs, we do not suffer deceleration well – as the momentum of the squishy stuff wants to carry on moving it at the same speed. Sudden deceleration can therefore lead to significant internal injuries, such as haemorrhaging.

When using work positioning systems, European legislation requires that the Maximum Arrest Force (MAF) shall be limited below 6 kN (≈600 kg), for the US and Canada it is 8 kN (≈800 kg). During any activity liable to generate a MAF higher than that, the person shall be protected from a fall by use of a fall arrest system.

So far, so good. But of course this is not the whole story.

What is critical is how the force is exerted upon the body. A number of organisations and researchers have done work investigating this matter.

NCAP, of the crash test dummy fame, an organisation whose aim is to improve safety in cars, for instance, have shown significant spinal deformation as from side impact forces of 350 kg on upwards.

Also, the Mägdefrau report (“Human Bodies in Falls”) and Andrew Sulowski (“How Good is the 8kN Maximum Arrest Force Limit in Industrial Fall Arrest Systems?”) looked into the matter of how the direction of fall has an influence upon the severity of injuries sustained. When comparing X-, Y-, and Z-axis falls, both studies conclude that there are significant differences.

A +Z-axis fall could happen when a person is secured to a back up device on a ladder attached to a sternal attachment point on the harness. In this fall orientation, the resulting force compresses the spine. From a constructive point of view, the spine is well able to do so, with plenty of muscles and vertebrae to dampen the force.

A +Y-axis fall could happen as a result of attaching a lanyard to the same side D-rings of a harness (not recommended practice). The spine is less well equipped to deal with this kind of force – a shearing force across the spine. Yet there are large muscle groups to either side of the spine in the abdominal region which will help to dampen the force.

A +X-axis fall will occur when ventrally attached to a work positioning systems, e.g. when using a sit or work positioning harness. Our body struggles to handle this kind of fall, as there significant leverage exerted over the lower back in a whiplash motion in a direction lacking in structural stability (muscular or skeletal).

These mechanisms are reflected by the findings of both Mägdefrau and Sulowski.

As you can see in the chart above, whilst all six falls generated similar peak forces, falls one to four would have fractured a real person’s spine (a humanoid dummy was used for the tests, of course), falls five and six caused no visible damage. The difference between the falls? Falls one to four used a sit harness (resulting in a +X-axis fall), five and six a full body harness (resulting in a +Z-axis fall).

It is worth noting that the forces recored above are well below the 6 or 8 kN limit defined by legislation.

Sulowski’s findings are similar to those described in the Magdefrau report, where only in the instance of a +X-axis fall did the fall protection effectively limit the MAF to below 6 kN.

So what is the conclusion? Use fall arrest systems, attached sternally to our work positioning systems to ensure a +X-axis fall?

The answer to that is obviously no.

As we are working in work positioning systems these should by definition not generate a MAF, as the aim is to prevent a fall from occurring in the first place. I do however think these are interesting figures to have in the back of ones mind, as they allow you to put other values in perspective, for instance when discussing MBS for personal protective equipment which are double, tripple or even quadruple the forces discussed above. Incorporating robust safety margins and allowing for wear and tear is all very well, but we must remember that the human body is fragile and likely to be the weak link in the chain.

Well, that, and the anchor points we select in trees – but that is a whole different story.