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Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 31 Aug 2013, 13:42
by Sciethe
Giant wild yews at Merrow Down.JPG
Giant wild yews at Merrow Down.JPG (53.92 KiB) Viewed 10364 times

Taught from the earliest age to discover the reason for information being presented before trying to assess its worth, I’d like to first mention what’s in this seminar and why. I’ll look at an aspect of ancient yew protection, attempt to raise the profile of the Ancient Yew Group and its work to people who care about trees (you I hope), and implicitly explore the broader value of science and scepticism in Druidry exemplified by a personal fascination with the Practical Earthy Middlemarch where reason and spiritual love for nature collide. My mind and soul constantly seek that complex paradoxical and beautiful land - I feel happy among the boiling interfaces where desire meets fact, and solid scientific reality is found to be the stuff of profound spiritual visions. Mind and soul are there united, and in harmony. Why else would a science grad. choose to make a living as a gardener?

The important point here is that it is perfectly possible to help drive an apparently dry scientific conservation project forward with Druidic passion, and I’d like to show the way that science is the chief element of my druidic path - I see it as a form of spiritual expression like poetry or ritual; it can be lived in that way. So here for your perusal is my exemplar, a glance at the close anatomy of the science needed to support a campaign.


It’s the first question most people ask when confronted with a really big yew tree. “What’s green and stands on one leg for a thousand years?” The second question is invariably “how old is this thing anyway?” The first question is perennial, and older than Stonehenge, but science has been sporadically asking the second question for only about two centuries since the Swiss botanist Augustine De Candolle began studying the annual rings of the yew and tried to come up with an answer. It’s an answer which I started seeking when I first became aware of these amazing beings while standing in a Grove of vast yews at Newlands Corner. I got reading (thanks Steve) and looking around, and discovered that no-one really had a credible answer to the ages of these trees, also that none of them were adequately protected.

The scientific view of the maximum age that a yew can reach has been swinging wildly up and down between infinity and 800 years ever since De Candolle’s first efforts. Seemingly the entire problem is well beyond the understanding of conventional science; at least affordable conventional science: the study of ancient trees is not an area of research which draws massive funding. When I appeared on the scene the academic vacuum that existed in the UK around the subject of yew was hosting an aging debate between (mainly) esotericists from various camps; the commonest tools of choice appeared to be distressingly inaccurate dowsing, and asking the trees themselves. Answers of 2,000, 5,000, 9,000 and even 19,000 years were mooted for actually quite “ordinary” specimens. Very surprisingly (sic) no competent arborist or official organisation wanted to have anything to do with it, there being a very few brave and honourable exceptions. The situation impacted severely on the possibilities for protection of the irreplaceable older trees.

Feeling the need for answers, and confronted with this mess, I reasoned that where science fails amateur shoestring empiricism can be our friend. I also had the empowering gift of having no particular academic credibility to loose. That was the beginning of a long journey. Quite a few long journeys, actually- there were a hell of a lot of yews to visit.

Now, onward to my own view of yew aging and how it is possible to circumvent the need for complex mathematical formulae or modern scientific equipment in the quest for good solid answers that get accepted. This last point is the more international “gift” of this piece which also holds for Druids in Australia and the USA for example, where there are virtually no Taxus baccata L., but there are other things which need protection. Perhaps the Ancient Yew Group can provide a useful model.

First, data gathering- knowledge is power


Dull, dull, dull. Not so; fascinating. Trunk girth has been my measure of choice. The beauty of using girth is that historically many yews have been measured in this way, and quite a few old references still exist scattered about in odd bits of literature. If it’s possible to find the tree and re-measure it then it is easy to get a very good idea of how fast it has been growing since the previous measure. Height is no use, old yews collapse and re-grow, and height is also rather harder to measure, particularly in woodland. A collected historical stream of girth references can be built up for some individual trees, and many have now been gathered like this one:
Brockenhurst ref stream.jpg
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Maybe, like me, you are stunned at the new picture the data immediately gives us of the growth history of the Brockenhurst tree, and the really good part is that having gathered this information it’s obvious that the older it gets, the more valuable it becomes. Imagine what this information will mean in a few centuries time. The oldest set of clearly genuine, continuous and undisputed records is for the Crowhurst churchyard yew in Surrey (not the equally wonderful but less certainly documented yew at Crowhurst church in Sussex) which has many contemporary written references to its girth which go back to 1630. It hasn’t changed very much in size since then.

And here’s the Farringdon yew in Hampshire, pictured below. 10 yards- yes, yards in girth and which is currently growing at about 1 mm in girth each year. It has been doing so since its records began over two centuries ago. The more closely it is studied the more impossible it becomes that this tree is much less than 2,000 years old. No-one knows the real age. It is essentially unchanged since Gilbert White gave a brief description in 1781.
Farringdon yew.JPG
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One still and warm (and sober) summer night when I visited the tree with two friends it was making a clearly audible slow pulsing sound; all three of us could easily hear it. This blew me away both as a Druid and a scientist. I can’t explain it in either capacity, nor will I try, but simply stand shocked and amazed and relay the fact. It’s data of a sort, though not the sort needed for campaigning.

Fancy doing a bit of this?

We need more of the measurement records; a reference in history can save a threatened tree- it’s surprising how many really important specimens are threatened. Find such a reference and you’ve got pure gold. All sorts of publications from Victorian county guides, old transactions of historical and archaeological societies to parish records have been productive. Find an old tree measure, and a re-measure can be done. Then the tree has a history.

If you go out with a tape measure think historically, it’s worth taking really good measures that can be repeated in the future. You made the effort to get to that point after all, it would be a shame to hurry or spoil things at the last hurdle. Yew trunks vary in girth at different heights from the ground, so a good repeatable measure also includes the level above ground that the tree was girthed at, and preferably a written description of the tape-run around the trunk. Even better, make a photographic record as well. Check for old data to see whether a previous effort can be repeated too. We usually measure to the nearest centimetre or inch. Imagine your descendants three hundred years from now wondering at the forethought that went into your work, and copying your action to find a small but significant truth.

The things that you commit to paper regarding such an immortal being as a yew become a legacy, in making that record you celebrate yourself as an ancestor, and quietly launch a boat that will outlast you into the river of time.

There are now well over a hundred of these “reference streams” in existence, and the great and ancient trees that have them are pretty safe from felling simply because of this history. Histories are collated and kept by the Ancient Yew Group, credited to the researcher, and kindly backed up by the Tree Register of the British Isles. All the historic reference streams like the one for Brockenhurst above will appear on the AYG site when I’ve finished with them, although all the yews which have been measured in the last two decades will have their own long measurement histories as time rolls on.

Measuring at West Tisted.jpg
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A high accuracy measurement study, West Tisted, Hampshire, UK, 2013. First measured almost a hundred years ago, the girth is now 6662mm at 4 feet from ground level, the lowest of five repeated measures. We’ve found that the simple act of measuring an aspect of nature, then cataloguing and maintaining a public database about it is an enormously powerful campaigning tool.

Felled yews.

Autopsy time. In the past I’ve really had to bite my tongue and get on with my work, although there was quite a fracas with the Forestry Commission in the 1990s over yew felling at Alice Holt Forestry Research Station right on the Hampshire/Surrey border (the yews are in Hampshire, the Research Station is three or four hundred yards away in Surrey). You run out of tongue to bite sometimes.
Cherkley bole.jpg
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The pictured yew was felled in the 1980s at Cherkley Court in Surrey, a private estate. The story I was told is that a lot of the old yews here were harvested to provide veneer for the Japanese furniture market. The bottom fell out of the trade and the wood was left. I could have cried when I saw this bole rotting away- but instead got on with measuring and counting. Result: 15 feet 11 inches (485cm) at the minimum girth near ground, and over 20 feet at the widest point. The age was 601 years minimum -confirmed by hours of painstaking ring counts and reconstruction (you can see the cleaned lines on the cut where the counts were done), but the tree was likely very slightly older than 601 years because you can’t necessarily see every ring on rotting wood in field work conditions. Close to correct though.

One can fairly surmise that the felled yew probably started growing shortly after a lot of farmland went back to the wild after the Black Death of 1347, there being very few people left to farm and keep land clear of woods and overgrowth in some districts. Quite a lot of our old wild yews date from that period and there is another rarer wild cohort which apparently grew up following localised devastation after the Norman invasion. The oldest Newlands Corner yews seem to me to date from then. This Cherkley Court felling is a perfect example of the insane destruction of a fantastic piece of living history, and all perfectly legal too.

Shocking examples like this are now part of the armoury of the Ancient Yew Group in pressing for changes in national, local and ecclesiastical law. Blanket protection is the aim for yews like this, as already exists in parts of Europe, and my view is that fines for destruction of ancient yews should be introduced which at least reflect their amenity value as calculated on a Forestry Commission approved scale of capital worth; see the CAVAT system:

We will be pushing for this. Using this system the felled yew at Cherkley Court would probably have been “worth” over half a million pounds. Some of our most ancient yews could certainly top two million, although the published version of the CAVAT system runs out of zeroes well before that. Quite a deterrent compared with the £20,000-ish fine for ignoring a Tree Preservation Order. It is important that all the yews which belong on the AYG site are registered there; this action does enhance protection, even more so in future if we can get the Judiciary to accept CAVAT as the basis for fines.

If you know of a yew with the “AVN” provenance described below that’s not on the database then do E-mail the AYG site with details. There are examples of old yews across Europe to the Far East as well as in the UK. And if you find a felled yew, now you know what to do. Describe the location, count the rings, measure the girth - accurately, without exaggeration. At least it’s then one more arrow in the quiver for those that try to protect, a voice for the tree if you like.

Planting Dates.

And then, more happily, there are the yews, still growing, which have a known planting date. These make very useful contributions to data as well. It’s simple in theory, find an old reference to a yew being planted, find the site, and that you have the correct tree (the hard bit) then measure the girth. A simple calculation gives the growth rate from planting. Planted avenues of yews are great for this because you get a statistical sample and it’s obvious which ones they are. DO let me know if you find an old yew avenue with a definite planting date!

Westborne ave quote.JPG
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Sussex County Magazine 1939

Graphic statistics

That briefly summarises the kinds of information needed to get a really good empirically generated graph of growth rate, virtually no funky science needed, just carefully thought out method, grinding amounts of book research and accurate fieldwork. No-one can really argue because nothing particularly complicated has been done. From 180 ring-counted and girthed yew stumps and 50 planting dated individuals we got a graph like this:
Graph AYG yew.jpg
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From the graph (extrapolated using the growth rates we get from the reference streams- I don’t propose to expand on that here) it seems that an 800 year old yew is typically somewhat less than 7 metres in girth, but typically is the word, yews vary massively in their growth rates and patterns. They are a great deal more reactive to morphological and environmental factors than oaks (simplification), which yield a much smoother graph and can be individually aged quite effectively. It seems that yews are also genetically very variable in their growth rate which adds to the chaos. So the graph gives us an average age for yews of a given girth, with a possible deviation from norm so large that it is almost useless for finding the provenance of any individual specimen. Only the mean values from large same-age populations like avenues can be effectively read off the graph.

That’s troublesome, because the idea is to age and thus protect individual yews. The girth data for 42 yews planted at the same time at Monnington Walk (an avenue in Hereford) is an illustration of the problematic variation, the narrowest trunk was about 5 feet girth, the fattest was nearly 15 feet. The average was 10 feet or so. These yews were all 370 years old when they were measured. Not helpful.

What to do? Thought about this for a bit, and decided there were two ways to go.

Way 1: Ancient Veteran and Notable- AVN

Many irreplaceable yews were being felled and mutilated, so in a considerable hurry to get an answer that could be used by my (non-Druid) AYG colleagues to enhance the value of the database, write, and lobby various organisations “The AVN Protocols” were devised. They allow for variations in the form of the yew (morphology) and represent minimums in all respects in order to produce a credible age category for individual yews. Particularly important, AVN gives the minimum age a yew could be for its girth, decided by reading off on a bell curve the value which gives a 90% chance that any yew exceeds the target age. So we’ve ended up with a statistically valid three tier system which is also designed to link with the Ancient Tree Hunt categories*:

Ancient yews, which are definitely OVER 800 years old and with no upper age limit, minimum girth 7.0m
Veteran yews which are definitely OVER 500 years old and probably under 1,200, minimum girth 4.9m
Notable yews which are definitely OVER 300 years old and probably under 700, minimum girth 3.7m


Also an additional category within Ancient without a specific age grouping because this as yet remains uncertain: Exceptional yews which exceed 9m girth, although this category is potentially open to other smaller yew types proved very old indeed such as the amazing ancient cliff bonsai yews found in the north of the UK and the like of the extraordinary Ninefield yew whose massive stem now consists only of roots that once grew down from the branch bases inside the ancient trunk. (*!*) How old is THAT?

Assessing AVN - There are pros and cons: quick to apply and easy to analyse statistically for the thousands of yews collected by colleagues on the database, the AVN system allows for yews which were once big but have broken up, are slow-growing, a funny shape etc.; this system is conservative and so acceptable to mainstream forestry and arboriculture, and therefore useful for campaigning. On the other hand the AVN protocol system, while accurate in the sense that it only allows yews of sufficient age to be included in their right age categories, can be critiqued for the underestimation of actual tree age; for putting all old yews into three rather broad categories only; and for ignoring younger yews entirely. Yews which are slow growing and therefore small girthed can be missed too, but that is not the fault of the AVN system which allows for this possibility.

AVN Protocols are at: ... ndson/3/39

Way 2: Individual reporting
Merrow bulging yew.JPG
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Veteran wild yew 500-1,200 years old deep in woods at Merrow Down

An obvious ideal solution is the careful description of every individual tree. This work is in hand, but is going to take ages. The problem is that there are only a handful of committed people all with day jobs to do it, and over 2,000 widely scattered trees which need at least two days spent on each of them. The other issue with complex individual reports is that they are very difficult to collate as a body of information, and hard - given the variety in the subject matter perhaps impossible - to analyse statistically. Here’s one report that includes an aging attempt: ... Sussex.pdf

So, an insight into the value of empirical fieldwork as a means of protection, and particularly valuable I think, a message to Druids of all nations, not just the UK and Europe: you don’t have to be Albert Einstein and Niels Bohr rolled into one to get a scientifically accepted result. Any tree lover with good school results in science and maths could have done the same. There’s so much out there waiting to be recorded for the purposes of protection, and all it takes to make a start is a reasonable grasp of what you’re trying to achieve, a knowledge of what the establishment are likely to accept, some like-minded friends with complementary skills, tape measure, pencil, notebook. This for me is my major work as an Ovate-Druid.

Royal Forestry Society paper
The stop press is that the AVN Protocol system has been written up as part of a paper by Dr. A. K. Moir et. al. and has been published in the QJF, the journal of the Royal Forestry Society. There’s no higher forestry authority in British academia.

The exceptional yew trees of England, Scotland and Wales by Andy Moir, Toby Hindson, Tim Hills and Richard Haddlesey (2013):
SUMMARY: While English yew Taxus baccata L. has become extinct or rare in many parts of Europe, Britain contains a large population of very large and old yew. We analysed 2,760 records of live yew trees to document this unique population and categorise by girth: 717 Veteran (5-6.99m), 204 Ancient (7-8.99m) and 55 Exceptional (≥9m) yew trees. Individual trees are mapped, and both areas and habitats of the highest proportions are detailed. The loss of 223 notable trees from churchyards highlights a need for better safeguarding a unique habitat of the world’s largest yew trees.

The Royal Forestry Society has unusually and very kindly given permission for the paper to be put on the AYG website, it can be found here: ... wales/3/68

And lastly…

So that’s a very brief overview of one Druid‘s specialist niche part in the campaign for protection of our oldest and perhaps most sacred trees. I’ll say again as a parting word; no very special skills to start with on my part. No previous organisation, just a fortunate collaboration between like minds with different but complementary attributes and talents, and extremely importantly for me, a very strong discipline to put aside spiritual matters in the actual work. The work is science; solid simple science. The reason (in my case) for the work is spiritual. The obvious advantage is that the work is then suitable for scrutiny by serious scientists and government. Influencing the administration is after all the object.

My job here is done if one single Druid goes out with a tape measure and camera to record some of the vital data the AYG still need, or adapts the above model and begins a similar pressure group anywhere in the world to record, analyse and protect some part of the biosphere. I also hope that where this kind of work is seen as Druidic in character, then greater understanding of what Druids are will be propagated among those who may not yet understand the true meaning and value of Druidism.

I do hope that this inspires.


Copyright T. Hindson 2013

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 03 Sep 2013, 22:06
by Bracken
Oh my goodness, this is a brilliant seminar, Sciethe. Definitely one for the Ovates. I'm going to advertise it.
Thank you so much. [And I really feel like I got to know you a bit more. :) ]

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 04 Sep 2013, 11:50
by DaRC
A wonderful seminar :applause: for one of my favourite trees. Congratulations on all your and your colleagues work.

I also googled Merrow Down from your pic and came across this lovely Kipling poem which seems relevant to Druidry...

Chapeau :tiphat:

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 05 Sep 2013, 23:43
by Sciethe
Thanks Bracken, glad you like it. You're right, there's quite a lot of me in it. Luckily I gave up wondering when I'd ever develop a personality years ago, and started doing things like this instead... :grin:
DaRC wrote:A wonderful seminar :applause: for one of my favourite trees. Congratulations on all your and your colleagues work.
I also googled Merrow Down from your pic and came across this lovely Kipling poem which seems relevant to Druidry...

Chapeau :tiphat:
You have excellent taste in trees DaRC. :) Good poem, and the Phoenicians do seem to have used the route across Merrow Down, at least that's the myth/folklore. I like the way Kipling populates the Down. I do something a bit like that myself.


Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 06 Sep 2013, 21:50
by Catafonia
Wonderful post. I've just been 'informed' that my tree for the Ovate grade is the yew - and the nearest ones are in a graveyard half an hour away (so far as I know) - so I'll be skulking round graves for the foreseeable future. But your report has inspired me to visit them, ask about their history and measure them - and to 'seek out new yew life, to boldly measure' etc. I live in an area where trees - and nature - are taken for granted so starting to identify and measure yews and give them a history people might be able to relate to in years to come is a wonderful way of applying my Ovate experience.

Thank you
If you are lost,just ask the way

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 07 Sep 2013, 22:10
by Sciethe
Catafonia wrote:Wonderful post. I've just been 'informed' that my tree for the Ovate grade is the yew - and the nearest ones are in a graveyard half an hour away (so far as I know) - so I'll be skulking round graves for the foreseeable future. But your report has inspired me to visit them, ask about their history and measure them - and to 'seek out new yew life, to boldly measure' etc. I live in an area where trees - and nature - are taken for granted so starting to identify and measure yews and give them a history people might be able to relate to in years to come is a wonderful way of applying my Ovate experience.
Excellent news Catafonia,
glad to be of service. I hope you and the yews get a lot out of this.
Watch out for twigs, getting one in the eye really hurts!
I don't know if you've found the AYG Gazetteer, you can search the whole country for known old ones at:
Any questions can of course be posted here. I don't mind being PM'd on this subject either.
Big blessings,

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 03 Nov 2013, 20:13
by mistletoeoak
Just catching up, sorry for only just reading this! Fascinating :) I am a voluntary tree surveyor with the TCV and there is something about the yew trees. My village one has been dated and certified etc etc and it is mahusive, gave up with tape measures and resorted to lengths of rope to measure the girth. I still find it overpowering and feel slightly wary when approaching. I have another 30+ to log and survey, so many out there just not on paper yet. Anyone in Kent have a look at free training :grin:
Lisa (mistletoeoak)

Re: Sepember Seminar- Yews, Science and Campaigning- Sciethe

Posted: 14 Dec 2013, 13:44
by Sciethe
Thanks for that link Mistleoak,
Excellent work going on, and for those with time to spend volunteering a great thing to do to make a real difference. :D