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(K)nowledge (K)November – information overload!

Autumn is coming to an end and oh how it reminded us that it can be both warm one moment and then chill us to the bones the next.  As the people of Dumfries & Galloway (and further afield!), huddled around their fires and clasped tight cups of hot tea in the too-soon dark evenings, many tuned into a special series of online talks, (K)nowledge (K)November, presented by D&G Woodlands. These 3 talks hit us with fascinating facts about bats, Ash dieback and Dendrochronolgy.  

Before these talks happened, I like to think our minds resembled a house ready to be inhabited, empty rooms full of potential with maybe the odd dust sheet piled in the corner covering who knows what.  As the talks progressed however these rooms quickly filled up with boxes as we moved the facts and figures in.  At first we had a neat little pile of boxes labelled “bats” but by the end of talk three there were teetering towers of brim-full boxes filling the rooms, some kicked over spilling their contents as we’d stumbled by. 

Now it’s time to unpack these boxes, put the right knowledge in the right drawer so we know where to find it, and display those special facts to wow your friends up on the shelves. 

Talk 1 – Beth Bridge – Bats, Trees and Farms.

Bats get a bad press as they’re often associated with the occult however anything that goes out at night eating over 3000 midges gets my vote!  Here in Scotland we have 10 species of bat, which fall into 3 categories: generalists, open ground specialists and woodland specialists. 

Beth’s PhD study collected audio data of bats in several pastures with and without trees.  The study showed a 40% increase in bat activity in pastures with scattered trees compared to pastures with no trees.  This is likely because the holes and cracks in old trees are perfect for roosting bats during the day, and they host a plethora of tasty insects, perfect bat prey at night.  Beth has now started using thermal cameras to further investigate how bats use landscapes and trees. 

Quick facts to put on your knowledge shelf:

  • Bats do have good eyesight but mostly use echolocation to navigate and socialise.
  • In winter bats enter a state of “torpor” not hibernation.  Shorter periods of inactivity, lowering metabolism and body temperature.
  • Great pest controllers, help to alleviate pest numbers on crops and livestock.
  • Indicators of how “healthy” an ecosystem is.
  • Threats to bats include: woodland fragmentation, clearing of old trees & deadwood, light & noise pollution, pesticides, and windfarm collisions.
  • Conservation of bats: Increasing standing deadwood in woodlands, removal of invasive non-native species such as Rhododendron enabling native species to thrive boosting insect populations, planting hedgerows, boosting dung beetle populations through good cattle diet.

Recording of event is here: https://www.youtube.com/watch?v=KPAV2Uz3_74

Talk 2 – Matt Combes & Simon Jones – Ash dieback: Past, Present and Future.

Ash, Fraxinus excelsior, is both culturally and ecologically important having been used within societies for millennia and hosts 955 species within the UK.  Symptoms of Ash dieback were originally spotted in Poland in the 1990’s, it’s suggested that the pathogen was present within Europe by 1978, but it wasn’t until 2006 that the pathogen was officially identified as Chalara fraxinea. The pathogen has now spread across Europe and was officially detected in Britain in 2012.

Unfortunately, there is no getting away from the fact that there will be a high mortality of Ash.  The spores of the pathogen overwinter in leaf litter, later forming fruiting bodies in spring & summer once air temperatures reach +10°C, spores are then released into the air dispersing within 50m.  These spores land on tree foliage, spreading into the shoots and stem, eventually blocking nutrient transport within the tree causing death.  This can be exacerbated by other pathogens.  But wait there is good news!  There is natural resistance within the UK Ash population however it isn’t as simple as resistant/non-resistant, but rather a spectrum of tolerance to the pathogen. 

Ash borer beetle is a huge problem in North America for their native ash, the pest is currently as far west as Kiev however work is currently underway to identify potential entry points into the UK so swift interventions e.g. biological controls, can be made if it arrives here.

There are many native pathogens that impact many of the trees in the UK, to which our native trees have evolved natural levels of however quickly spreading non-native pathogens hit trees hard.  The global trade of wood and the movement of freight is exasperating the spread of many of these pathogens.  As Ash dieback progresses, a main concern is the risk from the resulting falling deadwood; management should seek to fell diseased trees that pose a risk to public health i.e. roadsides and paths.  Felling operations are recommended while the tree is within class 1 or 2 of the disease as beyond this point felling operations are likely to become more complex and expensive i.e. road closers, heavy machinery use.

Quick facts to put on your knowledge shelf:

  • Resistance in Ash is down to a variety of genetic markers but also environmental factors such as moisture, temperature, soils, microbiome and tree density.
  • Chalara spores cannot survive above 35°C.
  • In the coming decades there is a hope that we be able to plant Chalara tolerant Ash.
  • The progression of Chalara infection in Ash is categorised into 4 classes.  Class 1 having most of the canopy remaining to class 4 where 25%-0% of the canopy remains. Tree health can improve slightly sometimes dependant on environmental conditions, but generally the disease only progresses.
  • Pollarding diseased Ash (monolithing) can help to keep the tree alive as it will send up new growth.
  • Diseased ash that doesn’t pose a risk can be left as this standing deadwood and has a high ecological value.

Recording of event is here: https://youtu.be/TWzxSedSAcU.

Talk 3 – Dr Coralie Mills – Woodland history detectives

Back in 1900 there was only 5% woodland cover in Scotland, nowadays we have up to 19%.  Dumfries & Galloway currently has 31% woodland cover, most of which is conifer forest, 1% of this cover is ancient woodland (at least 250 years old) however it is in poor condition. 

Studying the cultural history of a woodland can greatly help to inform restoration and future management of sites as well as revealing the past uses of a site and re-connecting people and place.  To understand the history of a site a multi-disciplinary approach needs to be made using both field evidence and desk-based research.  Field evidence data can come from; tree forms, species present, and woodland structure, as well as tree ring data (chronology) and woodland archaeology studies.  To compliment this the desk-based research provides information from written records, historic maps, LiDAR, artwork/old photographs and old specialist reports.

During the talk Coralie discussed several fascinating case-studies.  We saw examples of old tree forms such as skirting, displaying historical grazing pressure; as well as preserved structures that have remained hidden under woodlands for centuries such as old dykes, coppice stumps, stony quarries & roads.  Looking at maps from centuries past we are able to see changes in land-use over time.  LiDAR data can also show us hidden structures that are difficult to observe under the dense woodland canopy such as historical drains and wall systems.  This information provides invaluable knowledge on how people used these woodlands in the past and how we can now manage them for the future. 

Quick facts to put on your knowledge shelf:

  • Tree aging via tree girth measurements in Scotland is not reliable.  We have such a variety of growth rates that size isn’t everything!
  • Dendrochronology: Provides tree age and cutting history i.e. pollarding routine and dates of last coppicing cuts.  It can also be used to date timbers in old buildings, to felling year and sometimes to even the season and potentially where the tree was felled.
  • Until 1450 the majority of buildings were built using native oak, after this date we switched to imported oak, and from the 16th century onwards we have moved to building with imported pine.

Resources:

Recording of event is here: https://youtu.be/FV6e2qv9YTw?si=BqZiv2YSgKW4Gf4j.

Many thanks to everyone involved in the events and the funders – particularly The National Lottery Heritage Fund – for supporting them.

Phil Dowling

December 2024