One for Neville

The day before I left for Deventer was pretty busy, getting all sorts of things sorted, packing the ETCC gear I have stored at my place – the normal sort of last minute rushing around.

That evening I had everything packed up, when the phone rang around eight pm. It was one of the property managers for the church, who we work for, sounding a bit flustered, telling me that an old Robinia we were due to prune the following week had dropped a limb, could I go and have a look. Okay, I said, thinking to myself, how bad can it be.

Now just to give you an understanding… this tree is in the garden of the vicarage in the old part of Basel, which towers over the old town and a very steep road down to the middle bridge, which crosses the river Rhine. It must be about a 20m drop from the terrace where the tree is standing.

I called the vicar’s wife, who sounded equally flustered, telling me the fire brigade were on site and the police had closed off the road down below. Egad! I though, this sounds rather serious, so off I went – after all, I had plenty of gear in the vehicle! Arriving on site I was greeted by a rather surreal scene: The vicar, his wife and his four kids were in the middle of dinner in the garden, fire men were milling around the garden and one of the town arborists had also joined the party. In the midst of all this the Robinia, which by that time had dropped a sizeable limb, which initially had been suspended from a strip of live wood, now balanced rather precariously on the parapet of the wall, above the old town buildings below, held in place, thanks to a chimney it had partially pushed over.

Umm. Yesss…

Time for plan… E. Or F. This no longer looked like a case of securing it and coming back later, rather more like getting it down ASAP. So I got myself up the tree, secured the limb upwards with a mechanical advantage system, braced it sideways to keep it stable, then balanced out very gingerly, tied into the Robinia, to reduce the limb branch by branch, passing them back into the garden. Then we straightened out the chimney, which weighed about 80kg. Next I cleaned down the roof, removing the bits of concrete the chimney had shed, as well as branches. Some of the tiles date back to the middle ages, so I was stepping veeeery gingerly.

By about nine thirty we were done. And I was soaked, as it was a very warm evening… still, everybody seemed happy.

We went back two weeks later, now it was time to decide what to do with the tree. It must be a good 160 to 170 years old, loads of die-back and cracks galore. Put it this way, with your normal VTA you would be struggling – and seen from a pure risk assessment point of view, you might well condemn the tree straight out. But having said that, it is so beautiful, every crack you look at is filled with bat droppings and insects of all kinds of description, it really reminded me of Neville Fay talking about arc trees, which help preserve and carry species through time. With this in mind, I was determined to preserve the tree. I requested a meeting with the owner of the tree and the city tree officer, explaining what we intended to do and why, how we intended to manage the risk the tree poses and how we intended to mitigate the residual risk. They were good with all this, so we went ahead.

We reduced the tree all around by a good third, with a focus on retaining as much foliage in the lower part as possible. The tree was so wobbly initially, that I have to say I had my doubts whether we would be able to get it sufficiently stable. My main focus was to ensure that it could not tumble over the wall, that in case of a failure, damage would be limited to the garden. Once we had reduced a good lot of weight off the top and the ends, the tree felt a lot more stable, for good measure we added in four and seven ton bracing between the main limbs.

Et voilà, job done.

Walked away from this one with a sense of satisfaction of having preserved an important piece of habitat in a part of town which has few such trees. Sometimes it is worth removing the liability and risk blinkers we sometimes seem to rely overly upon – and consider other factors. This is not to say that risk was not considered. In this case, it was managed by communicating the limits of what is achievable and by getting the tree owner to accept a degree of risk that there may be further failures in the future, but limiting the physical space in which these can occur. Also we defined a short inspection interval to monitor the tree closely. The tree was pruned back very hard and braced. This would seem to me to be a pretty comprehensive package in terms of managing the risks posed by the tree.

Removing a tree is not the only way to mitigate risk – and we have to be aware of the fact that when we do so, we are always also removing habitat.