A few of us from AWA Tree Consultants went to the recent ‘Thinking Arbs Day’ at Sherwood Forest Country Park, Mansfield, Nottinghamshire. The event was a guided walk hosted by Nottinghamshire County Council, led by Ancient Tree Forum Founder Ted Green MBE, held in conjunction with the Midlands Branch of the Arboricultural Association. Speakers included- Ted Green, Izi Banton, Luke Steer, Mick Boddy & Reg Harris.
Sherwood Country Park is designated as a National Nature Reserve (the only one in Nottinghamshire), and this is in a large part due to the site having over 1000 ancient oaks, including England’s Tree of the Year, The Major Oak. The site has annual visitor figures of around 350,000 and this year sees the implementation of plans to demolish and relocate the existing visitor centre from under the canopy of several of the ancient oak trees. As such, this band of merrie arborists had more than enough fantastic trees to admire and tricky management decisions to deliberate.
The event was held on a sunny dry Saturday, and this helped gather a good (sell-out) turnout of 60+ tree professionals. What follows are a few notes, photos and thoughts from the day – the excellent speakers covered a lot, so this is only a very sketchy list of what was covered – what struck a chord with me.
After a brief introduction we left the main courtyard of the visitor centre and had a short stroll to the first tree – ‘stumpy’. It was highlighted that the tree had notable short twig-extension. This is generally a sign of stress or decline in a tree, often seen the following year after drought or similar stressor. However, it was suggested that the short twig-extension is likely due the large number of burrs on the old stem (burrs are the distinctive ‘knobbly bits’ on the old tree stems), and as such, the short twig-extension wasn’t an immediate cause for alarm.
Questions as to why and how burrs occur were asked. The consensus was that it’s unclear as to why a burr forms – but they are thought to be a response to an external stressor (possible fungal). This reminded me of Roger Deakin in Wildwood: The burr is like an excrescence of would-be buds rising from somewhere deep inside the tree like a spring… A burr may arise as a reaction to some itch in the tree, a kind of benign wood tumour. There is an outburst of mad cell division, and elephantiasis sets in.
We then walked to the next ancient tree which had recently undergone ‘Haloing’ works. As an ancient tree ‘grows down’ within a woodland environment, they are often overshadowed by dense younger and taller trees. The practice of Haloing involves the removal of the younger competing trees from around the ancient tree.
The discussion focused on the benefits of this work – reducing competition and increasing sunlight to the lower crown. However, it was advised that a ‘little-and-often’ approach was needed as a sudden large increase in sunlight may also damage the ancient trees, via bark scorching. The best way to create this ‘careful exposure’ was discussed, with the pros and cons of felling/coppice which requires ongoing long-term management. Also stem injections or ring-barking was highlighted as a method that provides a slow decline of the surrounding trees and the required gradual exposure, yet this was balanced with management issues of falling trees that could damage people and/or the ancient trees. The question was asked whether haloing is needed for shade tolerant trees, such as Beech?
We then all admired England’s most famous tree, first from behind the visitor fence, before being allowed to get up close and personal, which was worth the cost of the event alone.
The past (mis) management of the tree was highlighted, practices that now would be frowned upon included excessive propping and bracing and fertilising the soil around the tree, “so as to make the leaves nice and green!”. The most recent of which was over-mulching, in an attempt to relieve some of the last 200 years’ worth of ground compaction.
We looked a trial holes dug under the canopy and in the adjacent wood and compared the stark difference in soil compaction. A handy tip was suggested that if a screwdriver can’t easily push through the soil – then neither can a tree root.
In an attempt to improve soil conditions the wood mulch was so liberally applied over the soil around the tree over the last decade, it resulted in a 30cm thick layer of what was termed ‘amorphous organic matter’ – a peat like strata – laying over the compacted layer of sandy soil. Much of this thick layer of peat-like mulch was recently removed, and ongoing management decisions as to how to manage the compaction, and integrate the broken down mulch into the lower soil profile are still to be made. The use of plants with the roots having the ability to break through the compacted soil was mentioned. As was the need for careful thought before anything was implemented. ‘Do no harm’ being at the forefront of all future management decisions. The urge to ‘do-something’ should not always be followed just to satisfy our urge to manage. Does the tree need to be re-vitalized? Perhaps it has learnt to tolerate the 200 years of footfall under its canopy?
We then took a short stroll to see a magnificently brutal mix of nature and engineering, as an ancient tree that was splitting in two has been prevented from doing so with steel bracing. This relatively expensive engineering method was debated – with concern being raised that a similar approach to a veteran tree in north Europe ultimately may have contributed to its recent death. Other engineered methods – bolts or straps – were mentioned.
This led to a talk on the ecological value of these trees and how, as well as retaining them for their own arboricultural and heritage value, it is vital to prolong them –by any means necessary – for the invertebrate specialists that are only found in ancient trees. The necessity and difficulty in bridging the gap between old trees and the ancients was made worryingly clear.
The lunch break was followed by a discussion of the upcoming works around the visitor centre. A consortium led by the RSPB has been chosen as the preferred bidder to design, build and operate a new visitor centre and to manage the natural habitats within Sherwood Forest Country Park. The existing visitor centre is on a site that is full of veteran oak trees and must be relocated. The new centre will be on land at Forest Corner, close to Edwinstowe village. The centre cafe is currently flanked by two ancient trees – one of which had limbs leaning on the centre itself.
Concern was raised as to how this would or could be done without harming the trees. The consensus from many of the group was that is was achievable, through the use of a project arboriculturist and careful supervision as part of an arboricultural method statement. Consideration was given to engineering methods available to achieve this, while being mindful of the budgetary and time constraints and as to how the sensitive work could be tendered for and implemented in practical terms.
While fascinating, for some of us this section of the day no doubt felt a bit too much like a day at the office (albeit an extraordinary day). So when the we were given the choice to assess the demolition methods in more detail or to go and look at some more ancient trees, most were happy to do the latter.
The final stroll through the woods highlighted some of the recent veteran tree work, including how and why the practical tree inspections and tree surgery were being undertaken. The benefit and use of the MEWP was detailed, as a way to better understand and get a ‘feel’ for the trees, that can’t be appreciated by a visual assessment from the ground alone. Any pruning is very carefully assessed – and a single pruning cut was debated in detail. With such a precious and limited resource, the stakes are high for any management intervention.
Discussions were had on how branches from veteran trees fail and fall – often from ball-and-joint type sockets. Was this a form of cladoptosis – the regular shedding of branches, akin to leaf shedding, whereby an abscission layer forms, and the branch is shed cleanly?
We marvelled at how a massive deadwood column, hovering over a cracked and hollowing stem, seemed to defy gravity. Which led to questions of risk management and health and safety – with the use of dead-hedging to manage the target being the preferred option.
Following an emotive final talk from Ted Green as to the value of these veterans, and our role as arborists to protect them, many of us had to leave, while some others continued the debate and looked at some more trees.
Overall it was an enjoyable and informative day, and it was good to catch up with like-minded people. The low bright sun made for fantastic viewing of the awesome gnarled tree stems and several times I had to snap myself out of my reverie, to focus on what was being said! On a couple of occasions Ted Green complained at the lack of talking from the group – yet the input that there was from the group was pertinent and interesting. I got the feeling most came to hear the experiences and views of the experts working on these trees (and we’ve all been at similar events when someone in the crowd enjoys the sound of own their own voice – or an argument for arguments sake – too much).
Living in Sheffield we’re only around 50 minutes from the site, and to our shame, it had been too long since the three of us had explored the site. The logistics of the day meant we’d only scratched the surface of the collection of ancient trees, so we promised ourselves to revisit in Spring to undertake some more exploration. As we headed home the lasting impression was that it is comforting to know that this dedicated group of humans are spending so much time and effort safeguarding these remarkable trees.
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