5th April 2018
ATF Spring Visit to Blenheim
Blenheim Palace was the venue for the Ancient Tree Forum’s 2018 spring field visit, as Jim Mullholland, Training and Technical Officer reports.
After a brief welcome, the day began in earnest, with attendees shepherded into the back of the shoot lorry for transportation to High Park. Upon dismounting from the lorry we gathered beneath a veteran beech tree adjacent to a track. Paul Orsi, our guide for the day, introduced himself, detailing his responsibilities whilst employed by the estate. Although he has now moved on to pastures new, Paul’s knowledge of the estate and its trees was second to none, making him the perfect guide for the day.
After this introduction, Paul regaled us with a story of how, when employed by the estate, he had commissioned a tree safety survey of the tree we had assembled below. The results of this survey were provided a few days before the tour of Britain cycle race; an event that would see a large number of cyclists funnelled beneath the tree as the race passed through the Oxfordshire countryside. Fortunately for Paul the safety survey had highlighted a cause for concern in a large branch that overhung the track, unfortunately for Paul the short time period between the completion of the survey and start of the race left him with a challenge over what to do. In the end Paul was able to find a suitable contractor who was willing to work on a weekend to make the tree safe, enabling him to rest easy as the lycra-clad visitors whizzed through the estate unaware of the problem they had inadvertently caused.
As we began our walk, discussion turned to the presence, or rather absence, of fallen wood. Paul explained the desire from the estate to have grounds that are well looked after; this results in any fallen trees being removed, along with the decaying wood resource they provide. This is a common story, and Ancient Tree Forum supporters are all too aware of the constant battle to educate people on the values of fallen decaying wood. Paul went on to tell us that, with some convincing, the standard approach has now been changed so that only trees visible from the roads are removed. Those that fall within more secluded areas, and lie out of sight, area retained; finally putting to bed the age-old conundrum ‘If a tree falls in the forest, will anybody move it?’
Next, Paul showed us the result of a first staged halo clearance of an oak tree, that had been completed some 10 years before. The aim of this work was to provide more light to the veteran by removing the trees growing into the canopy, both from below and the side. This first phase had removed everything beneath and approximately 1m from the edges of the canopy. The group discussed the response of the tree to this first phase of clearance, when the next phase should be undertaken and the need to manage the re-growth from the first clearance to prevent it growing back up into the canopy.
Continuing our tour, we stopped at the King Oak which was measured giving a girth of 8.89m. Aljos Farjon shared some of the findings of his research into ancient oaks in the UK. With 140 no. 6m+ oak trees, from the 2002 survey, Aljos informed us that Blenheim was the most important site in the UK for ancient oaks. Keith Alexander, Ancient Tree Forum trustee, spoke about the Index of Ecological Continuity, as a means for determining the historic value of sites for saproxylic beetles; the presence of saproxylic beetles can provide evidence of abundant decaying wood habitat, even if it doesn’t persist today.
Emerging from the woodland, we stopped briefly at ‘Bluebell Ride’; a ride providing a vista to the Palace from High Park. Paul explained that there has been a desire to maintain and enhance a view from the Keeper’s cottage to the Palace, as this was considered to be an historic landscape feature. He went onto inform us that with a bit of investigating he found some wartime photographs that show the area covered by trees; confirming that the ride was indeed a modern feature in an historic landscape. Whilst the maintenance of this ride didn’t impact upon any veteran trees, this is a challenge faced by managers where interests in a landscape conflict. A word of caution was offered by Paul for those seeking to restore an area to a perceived ‘historic state’.
In the next section of woodland, we stumbled across what appeared to be our first evidence of pollarding; a wonderful veteran oak with multiple stems arisings from approximately 2m. This was in stark contrast to all of the other veteran oak trees we had seen, which exhibited maiden growth forms. This led attendees to question, was this indeed a pollard, or just a storm damaged tree? It is unlikely that we will ever be able to confirm either way, but was an interesting conversation topic: Are we too quick to read into the body language of trees when considering their history?
Having piled into the lorry, we made one final stop ahead of lunchtime. A cedar of Lebanon known as ‘the Harry Potter tree’. The tree receives it’s name due its appearance in the film Harry Potter and the Order of the Pheonix. Paul instigated a discussion around tree tourism and the management of tree risk. Due to its silver screen credentials, this tree is a popular attraction brining both additional visitors and revenue to the estate each year; a nice example of the economic value of ‘famous trees’. However, an increased footfall coupled with a hollowing stem has caused some concern over risk management. Recently, the estate has invested money into cabling the tree to reduce this risk posed to people. Concerns were raised over the soil compaction caused by increased visitor numbers. It was suggested that increasing the root protection area would be alleviate this compaction and also help manage risk by keeping people further away from the tree.
After lunch we reassembled in the car park, ready for the afternoon’s leg of the tour. We didn’t get too far, about 2 meters, before we stopped at a veteran oak in the car park. Paul informed us how cars used to park all the way around the tree, right up to the trunk. Car parking has now been formalised providing space for the tree roots by removing the tarmac and installing parking barriers at a distance from the tree. The discussion turned to soil compaction once again and suggestions of means of alleviating this were discussed.
Round the corner Paul showed us a mixed aged lime avenue, which made for an interesting discussion. The management of avenues is a complex and divisive topic: Should a uniform age structure be maintained to retain homogeneity? If so, once a single tree dies should the whole lot be replaced? What about the historical and ecological value of those that remain standing? We were pleased to see a wide age range of trees represented within the avenue. Brian Muelaner, Ancient Tree Forum trustee, highlighted that irrespective of the variety ages of trees in an avenue, the avenue still functions along the axis it was designed to be viewed (i.e. down its length). Only when the trees are viewed from a perpendicular angle, is the diversity is noticed. The consensus in the group was that the approach to management provided a range of benefits, not least the retention a number of veteran trees (but we would agree on that!).
Slightly further along the group assembled under a squat oak tree for the obligatory group photograph. Keith Alexander took the opportunity to educate the group on the various beetle exit holes visible in the exposed heartwood. Most noticeable were the exit holes of the deathwatch beetle (Xestobium rufovillosum), a beetle that gets its name due to the noise made when trying to attract a mate. In folklore this was seen as a sign of impending death, and it was common for relatives to keep watch at this time (i.e. a death watch).
Thankfully we all escaped with our lives and the 2018 spring field meeting was undoubtedly a success; the event being, once again, sold out. The Ancient Tree Forum would like to thank Paul Melarange and Kate Crook for organising the field trip, Paul Orsi for performing the role of tour guide, Rachel Brodie and to Blenheim Estate for hosting us.
We look forwarding to seeing you all in June for the summer forum.