Tag Archives: Great British Trees

An update on Oak and Ash; Soak and Splash

According to the Field Studies Council, these days we don’t usually see Ash trees coming into leaf before Oak trees do.  Using data from the Nature’s Calendar website, the FSC reports that, since 2000, there have only been two years (2010 & 2013) when Ash trees came into leaf before Oak trees did.  There was one year when it was a dead heat (2006).

The FSC goes on:

In the mid to late 1700’s Robert Marsham (sometimes called the Father of Phenology) recorded the timing of spring events, such as the bud burst of common trees, on his estate in Norfolk. In those days it was quite common for Ash trees to come into leaf before Oak trees (1751, 1769, 1778, 1783, 1785, 1786 & 1788) or for the two events to be noted on the same day (1760, 1765, 1766 & 1781). So what’s changed?

One thing that has changed is that, as a result of man-made climate change, springs tend to be warmer now.  The average temperature (Jan – Apr) for the years 1751 – 1787 was 4.7°C, for the years 2000 – 2015 it was 6.3°C.  The only two recent years when Ash came into leaf earliest stand out as ones with cold, late springs. You might remember the long cold winter of 2010 and how the spring of 2013 didn’t seem to start until late April. So how does temperature affect the timing of bud burst in these two tree species?

We can use data from the Met Office’s Hadley Centre to look at this.  The timing of bud burst in Oak is very strongly correlated with temperature.  In warm springs the Oak leaves will burst much earlier than they do in cold springs.  In fact for every extra degree of warmth they come into leaf about 6 days earlier.  The relationship between the timing of bud burst of Ash trees and temperature is much weaker.  So as springs get warmer the Oaks come into leaf earlier and earlier.  Ash trees do too, but not as quickly as do the oaks – they’re being left behind.  So now it’s only in a cold spring that we are likely to see “Ash before Oak”.  As to the whether we get a “splash” or a “soak” well that’s another story altogether.

Indeed it is.  All this was written in 2016, and 2017 certainly wasn’t a cold spring so the early oak makes sense.  But this doesn’t quite explain the time lag this year.

NB, Wharton Trees adds this:

“Both tree species come into leaf around the same time of year – between late March and May.  Oak trees are temperature sensitive; while Ash are influenced by the number of daylight hours they receive.  If spring arrives early with high temperatures in February and March, Oak trees are likely to leaf first.  However, if cold conditions persist into April, Ash will have the advantage (Weather Channel, 2012).”

It’s worth a look at the FSC website on all this because of the graphs it contains.

 

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Oak or Ash: Soak or Splash

The old folk tale has it that:

  • Ash before oak – we’re in for a soak (that is, yet another wet summer)
  • Oak before ash – we’re (only) in for a splash (that is, not as wet a summer as it might have been)

Well, whatever the truth of all this, it’s enough for me to keep as eye on the oak and the ash to see which comes into leaf first.  Then, typically, I forget about it before summer comes and so never really know whether the prediction was up to much.

Not this year, though.  The ash is so far behind the oak where I live (and have visited recently) that it seems that we’re in for a dry summer (relatively speaking).  And the time lag is so pronounced that I’m unlikely to forget it this time.  In fact, it’s so great that it has prompted me to wonder …

[i] is this a local effect or more widespread?

[ii] it is because of the dry winter and spring we have had?

[iii] is it related to ash dieback, or some other noxious pest I’ve not yet heard of yet?

[iv] is it to do with Brexit!

Does anyone know?

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European Tree of the Year

The Welsh entry in the European Tree of the Year poll, the Brimmon Oak, finished in 2nd place, which is the UK’s best ever finish it seems – much better than our Eurovision efforts of late.  The oak tree was only 1,394 votes behind the Polish winner, ‘Oak Jozef’.  This is how we did:

  • 1st – Oak Jósef, Poland – 17,597 votes
  • 2nd – Brimmon Oak, Wales – 16,203 votes
  • 5th – Sycamore Gap tree, England – 7,123 votes
  • 6th – Holm Oak, Northern Ireland – 7,101 votes
  • 8th – Ding Dong Tree, Scotland – 6,327 votes

You can see the full results here.

Becky Speight, Woodland Trust CEO, said:

“The UK is rightly renowned for having some of the best examples of ancient trees in Europe, so it’s good to see them finally achieving recognition in the competition.   There is now an opportunity to secure better protection for them following the publication of the housing white paper and we need the public to help us make it happen.”

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Forest of Avon Veteran Tree Project

Field trees Bitton

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The charity has long been convinced of the importance of field trees to landscape character, biodiversity and to local culture.

Through generous grant funding from The Mercers’ Company, we are launching the Forest of Avon Veteran Tree project, initially focusing on North Somerset and Bath & NE Somerset.

Over the next 18 months we will work with a wide range of partners to record veteran trees, candidate veteran trees (and where different) significant landscape trees in fields and woodlands. Anna Brunton, who will lead on the project, will submit details of unrecorded veteran trees to the Woodland Trust’s Ancient Tree Hunt website, as well as training Tree Wardens and other volunteers to record significant trees.

Anna will also work with farmers and landowners to provide advice on tree conservation and grants. If funding can be found, we hope to deliver a further phase of the project working in South Gloucestershire.

To find out more about the project and how you can get involved, please email Anna or call (0117) 963 3383. We will also Tweet regularly about progress.

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Natural Connections

What do the following have in common?

Lunar Thorn  Selenia lunularia
Privet Hawk-moth  Sphinx ligustri
Ash Bud Moth  Prays fraxinella
Brick  Agrochola circellaris
Mottled Beauty  Alcis repandata
Lilac Beauty  Apeira syringaria
Twin-spotted Quaker  Orthosia munda
Brown Oak Tortrix  Archips crataegana
Variegated Golden Tortrix  Archips xylosteana
Centre-barred Sallow  Atethmia centrago
Tawny Pinion  Lithophane semibrunnea
Ash-bark Knot-horn  Euzophera pinguis
Ash Pug  Eupithecia innotata f. fraxinata
November Moth  Epirrita dilutata
Dusky Thorn  Ennomos fuscantaria
Coronet  Craniophora ligustri
Privet Twist  Clepsis consimilana
Common Slender  Caloptilia syringella
Feathered Slender  Caloptilia cuculipennella
Brown Ash Ermel  Zelleria hepariella

Although it sounds a bit like an Oxbridge entry exam question, the clues are in the English names … They are all moths – ones native to the UK.  More than that, they are the moths that use the Ash as a foodstuff.  This picture is of the Dusky Thorn.  The Wildlife Trusts say that at least 60 of the rarest insect species in Britain have an association with ash – mostly rare beetles and flies.

The Wildlife Trusts website has an informative section on the Ash and Ash dieback, which is where this detail comes from.

 

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Problems of the Plane Tree

The Arboricultural Association website has a link to a story in the Telegraph about problems with the Plane tree across parts of the continent.  The article says that it’s only a matter of time before plane tree wilt (canker stain) reaches Britain.  The disease is currently spreading north through France and is reported to have reached Paris.  It has already wrecked parts of the Canal du Midi in southern France.

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What are your elms like this summer?

It seems to have been a bad summer for the elm across southern England.  Wherever there is elm, there are the tell-tale signs of attack by the elm bark beetle with shriveled brown leaves and bent-over branches standing out against the green hedge background.  From being green and healthy-looking in May and June, during July and August the elm gradually fell victim to the fungus the beetle carries.

To try to stop the fungus spreading, the tree blocks the vessels within the wood that carry water and nutrient, causing tissues to die.  So, just when the elm was fighting back, it’s had another knock, and the cycle of attack – recovery – attack – recovery … continues.  Curiously, however, as Mark Cocker has pointed out in his Spectator review of Fiona Stafford’s book: The Long, Long Life of Trees, this is not so much a story of decline, as one of survival.  Thankfully, we have not seen the last of the elm, although the industrial use of elm is not what it was at its height.  Elm wood is strong, durable and resistant to water.  Traditionally it was used to make furniture, floorboards, boats, wheel hubs, water pipes, troughs, coffins and lavatory seats.  Odd then, perhaps, that it has a reputation for not generating much heat as this old rhyme reminds us:

Apple wood will scent your room,
with incense-like perfume;
Oak and maple, if dry and old,
keep away the winter’s cold;
Ash wood wet or ash wood dry,
a king will warm his slippers by; but
Elm burns like the graveyard mould,
even the very flames are cold!

 

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Using citizen science to find disease-resistant ash trees

The Guardian website has an article about a new scheme starting today to identify trees that are resistant to ash dieback disease.

From today, members of the public will be able to go to the Living Ash Project and request tags to mark ash trees, and provide details of the trees on the website.  People will then be able to monitor the health of those trees and report those that do not succumb to dieback.  The aim is to find at least 400 resistant ash trees from which cuttings will be taken in order to create a new generation of healthy trees.

The aim of the AshTag project is to take cuttings from resilient trees in the hope of creating a healthy generation of ash trees.  Gabriel Hemery, chief executive of the Sylva Foundation, one of the promoters of the AshTag project, said:

“Last month scientists announced they had identified one ash tree that appeared to be resistant to the fungus that causes dieback. We want to find more trees like this. Then we can create stock to replace affected ash trees.”

The Forest of Avon Trust hopes that lots of people in our area will join in this project.

 

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A year in the life of an oak

Have you seen the BBC’s 90 minute programme about a 400 year old oak tree over a 12 month period?  It was first shown in 2015, and was on BBC 4 again last night – and is now available on iPlayer for a month.

The programme aimed to provide insights into the life of the oak.  Filmed over a year, it illustrated the transformations the oak goes through to meet the challenges of the transitions between the seasons.  What was particularly fascinating was how technology was able to show the oak in novel ways.

There is much to admire in this film, and a lot to learn.  Although it was about an oak tree near Oxford, on land owned by the University, it was, of course, about oak trees everywhere in the country, and it could be that the next time you see an oak in the Forest of Avon, or near where you live, you will look at it differently.

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Do you know your trees?

The Forestry Commission has an on-line tree name trail which starts with leaf shape.  In setting out its top tips for identifying tree types, the Commission says:

Trees can be divided into two main groups: those with flattened, wide leaves (broadleaved or deciduous trees) and those that have needle-like leaves (conifers).

Most broadleaved trees lose their leaves in the winter but most conifers (evergreen trees) keep their leaves.  It is helpful to also look at other features such as the tree shape, bark, buds flowers (all trees have them in some form, mostly in Spring and Summer), fruit and seeds (mostly in late Summer and Autumn).

All sound advice, no doubt.  But this is a peculiar time to identify trees as, on many species, the leaves are only just emerging, and their (later) distinctive shapes can be hard to discern.  That means it’s a time of year when other features (bark, shape, buds and flowers) make their strongest contribution to identification.

Although walking round the Forest of Avon is always a joy, April and May are particularly wonderful months to see trees in their glory.

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