NRN's Long Read for New Year 2021
Since time immemorial trees have been significant for humankind: the tree of Good and Evil in the garden of Eden, the Sycamore tree in Jericho that Zaccharias climbed so he could see Jesus, the Bhodi tree where the Buddha attained enlightenment, the Ankerwycke Yew tree on Runnymede, which is the last surviving witness of King John’s signing of the Magna Carta, Newton’s Apple tree still growing at Woolsthorpe Manor, and of course, the now ubiquitous Christmas tree, a fir tree laden with decorations and underlain with presents.
Of all the many poems inspired by tree, one of the most memorable is Joyce Kilmer’s, which begins, ‘I think I shall never see/A poem lovely as a tree’…and ends, ’Poems are made by fools like me/But only God can make a tree.’ The words were set to music and sung by the likes of Paul Robeson, Mario Lanza, and Peggy Page – but of course that was aeons before you were born!
Age before Beauty
Trees impress us not just because they create woodlands and forests, but because of their size and their longevity relative to other living things. Giant sequoias reach over 250 ft in height and have a circumference exceeding 100 ft. The oldest known living tree is a Great Basin bristlecone pine in California, which recently celebrated its 4852nd birthday. A Mediterranean cypress in Arbaku, Iran, may be as old. The oldest intentionally planted tree is a sapling from the Bhodi tree, planted in 245 BCE by Sanghamitra, daughter the Emperor Akosha. We now learn from our resident tree expert, Sarah Couch, that the UK is relatively well-endowed with ancient trees compared to other European countries.
It is because trees have such long lives that they have become a means of memorialising people and events. Eynsham has its own Peace Oak, planted in 1919 to commemorate the first anniversary of the armistice of 11 November 1918.
Still Missing-in-Action are a dozen veteran mulberry trees, which Rupert Boulting says date from Eynsham’s dim and distant past. If you know the whereabouts of any of these veterans, please let us know so we can put Rupert out of his mystery.
The Peace Oak, Eynsham, planted in 1919 to commemorate the armistice that ended the Great War.
Stop me and buy one
The commercial value of trees is universally appreciated. Indeed, perhaps the still most influential book on trees in the English language is John Evelyn’s Sylva: A Discourse of Forest-Trees, first published in 1664, and written partly out of concern that deforestation was a risk to the security of the British Fleet. He railed against those who treated trees like weeds and his defence of alders has a contemporary relevance, particularly for us who live along the riverside:
'There are a sort of husbands who take excessive pains in stubbing up their alders, where-ever they meet them in the boggie places of their grounds, with the same indignation as one would extirpate the most pernicious of weeds; and when they have finished, know not how to convert their best lands to more profit than this (seeming despicable) plant might lead them to, were it rightly understood. Besides, the shadow of this tree, does feed and nourish the very grass which grows under it; and being set, and well plashed, is an excellent defence to the banks of rivers; so as I wonder it is not more practis’d about the Thames, to fortifie, and prevent the mouldring of the walls, and the violent weather they are exposed to.'
If we go further back to 1086 and the Domesday Book, we find that about 15% of England was wooded but this percentage declined inexorably to its lowest point just after the Great War when only 5% of England was under trees. This nadir prompted the creation of the Forestry Commission to promote afforestation amongst landowners. A century later, the percentage is rising towards 10% but only 2.4% of all forests are classified as ‘ancient woodland’ - the type of woodland that John Evelyn might have walked through. Despite the accelerated afforestation through most of the 20th century (and continuing) England’s total forested area is still only a fraction of that found in most European countries.
This month, in his Reith Lecture entitled ‘How we get what we value’, former Bank of England Governor, Mark Carney posed the question: ‘Why do the financial markets rate Amazon as one of the world’s most valuable companies, but the value of the vast region of the Amazon appears on no ledger, until it is stripped of its foliage and converted into farmland?’ At our local level, we are all finding, again and again, that our invaluable natural world is being disposed of because it doesn’t have a line in the ledger, and so it vanishes despite the best efforts of our community to attest its worth.
Photons for synthesis
It is only very recently that the value of trees (beyond their traditional utility as a source of fuel, building material or food) is starting to be appreciated, chiefly because of the scientific evidence about the effects of rising concentrations of ‘greenhouse gases’ on global warming.
Carbon dioxide (CO2) levels are rising relentlessly and in 2020 reached their highest level in 800 000 years (417 parts per million). Trees, through their photosynthesis and growth, seem to offer the best natural means of extracting atmospheric CO2 and storing the carbon as constituents of wood, like cellulose. A study published last year in Science Magazine attracted widespread media attention, because its authors estimated that the Earth currently has 0.9 billion hectares that are suitable for planting forests, which could store 205 gigatonnes of carbon and thus largely mitigate present CO2 emissions.1 The study’s conclusion: that tree-planting offers the most effective solution to global warming does need some qualification, however, as the authors themselves admitted when there was strong criticism from their peers about some of their claims. One should also recognise that trees store 80% of their carbon in the trunk and canopy, so when trees burn or get diseased and are cut down, most of the carbon they have stored is released again. As we’ve all read in recent headlines, man-made and naturally occurring forest fires are increasing in extent and frequency2 as is the spread of diseases.
Really renewable, or renewable – really?
The use of wood as biomass for burning once seemed attractive as an infinitely renewable energy source. However, the CO2 emissions problem has shown up the real cost to the planet, as the gains in carbon capture by trees are nullified on burning, unless one straps on carbon capture technology. Forest fires may not be common in the UK, but wood is burned on a huge scale, because many former coal-fired power stations were converted to wood-pellet fuel. Drax in North Yorkshire, produces around 12% of the UK’s total electricity and is the world’s largest biomass-fired power station. It is no source of pride that the UK is a world-beater in wood pellet import – 8.5 million metric tons (from the USA and Canada), with additional cumulative costs to the environment from obtaining the raw material, manufacturing the pellets, transporting the pellets by land and sea to North Yorkshire. Drax burns most of the UK’s wood pellet imports3 - around 7 million metric tons each year.
Burning a renewable resource for energy seems preferable to burning fossil fuels mined in Russia or elsewhere, but the problem is that it takes minutes to incinerate a tree and decades to grow one. The sop often proffered is that biomass is carbon-neutral, unlike coal, oil or gas, because you spend only what you have saved. But, in the end, it is our continued reliance of carbon-based energy production, including biomass boilers that we need to address. As we have seen, the UK cannot produce nearly enough renewable biomass to meet its own requirements and thus is dependent on massive imports. Furthermore, the burning of biomass has other knock-on effects - particulate pollution, and other polluting gases, on a scale that cannot be mitigated by the present government's goal of planting millions of trees4. Thus, the additional technological solutions, like ‘scrubbers’ to remove pollutants are needed, particularly if we are to have any hope of achieving ‘Net-Zero’ in our carbon budget5.
Eynsham's Biomass Coppice before clear-felling, May 2020. A rare veteran Black Poplar towering above.
It seems a minor footnote to mention here Eynsham’s own biomass fuel copse (which was planted on a once species-rich floodplain meadow – one of the UK’s rarest habitats). It is a monoculture of willow that was clear-felled for the first time this year at the height of the nesting season and was immediately chipped for biomass to warm a local broiler chicken shed, according to the contractor. Lucky chickens! But what a sad, cumulative degradation of a priceless diverse meadow habitat. It’s a case study in how little we still understand the complexity of ecosystems and how good we are at generating unintended consequences by well-intentioned but simplistic interventions.
The story of the Understorey
The understorey of Eynsham’s fuel coppice is another monoculture: nettles have proliferated following the ground disturbance at tree-planting. When we plant trees, we rarely think about the understorey, yet it is one of the features of ancient woodland that we most enjoy, as do the many living things that flourish there. Wytham Wood’s bluebells, dog’s mercury, wood anemone, lily-of-the-valley and other native woodland plants are a spring delight. It was a highly unusual step for the Eynsham Society (far-sighted as ever) to plant bluebells and primroses and other woodland plants in the Millennium Wood, so adding an understorey as another important element in the generating a mosaic of habitats.
Eynsham Society running the community planting of Millennium Wood in 2000.
Size matters
In the accounts of carbon storage, not all trees are equal. A study just published of forests in the Pacific Northwest found that large diameter trees (53cm, or bigger), which formed 3% of the forest, stored disproportionately large amounts of carbon: 42% of all the above ground carbon6. Compared to smaller, younger trees, these veteran trees are more resilient to drought and fire, they provide a microclimate, and they support more biodiversity.
In his classic study published in 19617, Richard Southwood asked the question: why are some trees associated with more insect species than others? His answer was that the abundance of insect species was positively correlated with tree species that had a longer ancestry in the place they were found. Oak, willow, birch, hawthorn, and blackthorn topped his league table and a later study of lichens followed the same pattern8. The inference was that plants and animals that have the longest time of co-evolution will be associated with the highest diversity, and thus more recently-introduced tree species will be associated with fewer insect and lichen species.
Data from the original study of Southwood 1961 redrawn as a histogram
Dead trees are also host to a host of ‘saproxylic’ insects (remember the word for your next scrabble game), i.e. insects who feed on deadwood 9, 10. Indeed, the World Wildlife Fund report of 2004 stated that, ‘Veteran trees, standing dead or dying trees, fallen logs and branches form one of the most important – yet often unrecognised – habitats for European biodiversity’11. Indeed, some of our rarest species depend exclusively on dead wood, so when we remove dead wood we lose these species.
It is no coincidence then, that in February 2020 Eynsham’s NRN initiated a survey to identify all the ‘veteran trees’ in the parish and measure their trunk diameters to estimate their age. The survey was kicked off by members of the Eynsham Morris, please email if you would like to help with this survey. Once the location, species and age of these trees is more widely known, their value will be more appreciated and, hopefully, they will be better managed and protected – and what could be more satisfying than hugging a veteran tree, I hear you say? (Hugging saplings apparently gives nothing like the same oxytocin rush).
Tree hugging, Eynsham style (Veteran oak on the Garden Village Site).
The Japanese practise forest bathing - shinrin-yoku – to ease their stresses and give themselves time and a space to relax. Here, a walk in the woods can do the same – especially if you walk alone (and leave your mobile phone at home).
Paradise lost
Of course, diseases are a perennial natural threat to trees. If the devastation caused by Dutch Elm disease is too far back in history for most of us to remember, we now have on our doorstep ‘Ash dieback’. A group from Oxford University estimated last year that the costs of clean-up and replacement of the dead ash trees in the UK could cost as much as £15 billion12. In case we think this is just nature taking its own course and nothing to do with us humans, ash dieback actually has all the hallmarks of a pandemic. It is caused by a fungus that originated in Asia and spread west, being first detected in Europe in 1992, when ash trees in Poland were found to be infected. Now it is in our own neighbourhood, killing ash trees in Wytham Wood and in-and-around Eynsham. Given that new pests and pathogens are always emerging worldwide, preventing these diseases from gaining a foothold must be a priority, rather than trying to eradicate the pest when it is already here. This means that one of the essentials steps for nature recovery is to curb the global trade in live plants, because this is the most cost-effective means of controlling these devastating pandemics. Sound familiar?
Veteran Ash off the Oxford Road, one of the trees documented by members of the Eynsham Morris as part of NRN's veteran tree survey. Photo by Rupert Boulting
Right tree, right place.
The central tenet of the NRN is that creating a mosaic of different habitats is the best means of achieving sustainable and resilient biodiversity gain. It follows that, ’look before you leap’ and ‘right plant, right place’, are essential guiding principles in planning and assessing the effects of interventions in the long-term. Surveys on the ground are essential - making decisions based only on map data is particularly hazardous, as the Woodland Trust and the Forestry Commission have found to their shame13. These organisations have been responsible for projects where trees were planted in wildflower meadows and, most recently, in peatlands. Both of these endangered habitats are as efficient as trees in storing carbon, and more resilient because they store their carbon beneath ground.
In November, Private Eye reported that the Forestry Commission had admitted to their blunder in allowing commercial trees to be planted on a 4000-year-old peat bog in Cumbria (Private Eye, No 1536). This elicited a reply from the Director of the Forest Services at the Forestry Commission, who confirmed that they had indeed damaged 10 hectares (around 25 acres) of ancient peat bog, but they were ‘taking firm action to ensure that we deliver not only the government’s ambitions to increase tree planting but to restore peat and biodiversity too.’ (Private Eye, No. 1537).
However, even with the potential carbon capture offered by tree planting, we should be aware that there is no gain without pain: in digging the hole to plant our tree, we disturb the soil causing it to release its stored carbon. Thus, the act of tree planting initially puts the CO2 ledger in the red. It then takes time for the released CO2 to be recaptured by the new tree. So paradoxically, the more trees we plant, the bigger the red number in the CO2 ledger, but the hope is that if the trees flourish they will absorb excess CO2 and store its carbon in their wood over a long period.
The NRN might add that the wildflower meadows, wetlands, hedgerows and other habitats that we are all involved in restoring in Eynsham and surrounding parishes are also a means of capturing CO2, often as efficiently as trees14, 15.
Eynsham Society members planting Queen Mother's Clump in Monk's Wood (Fishponds) in 1982. Trees and members now revered veterans!
The importance of afforestation has been long appreciated: Here is Dr. Atrov in Uncle Vanya Act 1, by Anton Chekov back in 1897:
'But when I walk past our village woodlands which I’ve saved from the axe or hear the rustle of my own saplings, planted with my own hands, I feel I too have some control over the climate and that if man is happy a thousand years from now I’ll have done a bit towards it myself.'
Riches in Heaven (and Earth)
‘Men become wise just as they become rich, more by what they save than by what they receive’ said Wilbur Wright. Although there is energy and enthusiasm to plant millions of trees in the UK - and the political, social, psychological and financial means to do so – we need to put a similar energy and money into saving the trees we already have, especially the veterans. The Sheffield City Council’s tree-felling war with its citizens is well-publicized and the Ombudsman found they were indeed at fault16, but it is dispiriting to learn that extensive tree-felling has been going on in our own backyard. In July 2020, on behalf of our NRN, Oxfordshire County Councillor Charles Mathew asked the County Council how many trees they had felled over the past 5 years and how many they had replanted? The County Council reported that it had felled 2297 trees along the highway, and had replanted 75. It stated: “Currently there is no budget allocation for tree planting. The only tree-related budget is for Highway Tree Maintenance.” i.e. felling.
Councils should be particularly active in promoting afforestation in towns and cities for the benefits of air quality alone. Eynsham lies next to one of the busiest main roads in Oxfordshire and if that’s not enough, we have a Toll Bridge, where pollutant-emitting slow moving traffic queues form twice a day. Urban trees absorb particulates and volatile pollutants, so improving air quality where most needed17, 18. They also absorb sound and heat, but perhaps less well-known is that urban trees can have a role in crime prevention.
Long Mead Orchard with veteran ash and newly planted understorey of snakeshead fritillary. One day its 60 varieties of historic apples and pears might mitigate some of the pollution created by the Toll Bridge queue
Crime and Punishment
A study in Portland Oregon found there was a strong negative correlation between the number of trees planted and the number of violent crimes19. Whether this finding is generalisable awaits further research, but anyone who has walked through a leafy town centre appreciates the benefits to all our senses, including our sense of well-being. Given our outdoor experiences during the pandemic, perhaps we now see urban trees in a more holistic way, valuing their cumulative functions – ‘ecosystem services’ in the current jargon – that contribute synergistically to overall benefits to human health and well-being, as well as to the biodiversity of our urban spaces.
Conduit Lane. Veteran trees hosting clumps of mistletoe.
Various tree-owners, whether they be public organisations or private citizens, have for various reasons taken a chainsaw to their mature trees and not replaced them. While the cost of maintaining trees is usually in the simplistic ledger-domain, Mark Carney reminds us that trees (in the Amazon or elsewhere) embody intangible assets and their total value cannot be written down as a simple number in a ledger. By force of habit we are too ready to remove an unwanted, diseased, or damaged tree, casually supposing it is ‘renewable’. If we come to appreciate their intangible value, it is no longer the first option to take a chainsaw to an ailing tree, rather than nurturing it, or tending its wounds. More than this, trees, by their longevity, can have a very personal value to someone quite unknown to us, possibly someone not yet born. Even if it grows from our own garden, ‘our’ tree is also part of a wider townscape, so it may be loved by a neighbour - or used as a landmark by many town folk who pass by, as well as likely being a haven for wildlife.
Veteran Apple Tree in Back Lane, Eynsham
Thus we would be wise to be cautious in ridding ourselves of a tree, particularly as it may outlast our own lifetime. And think of the trees themselves - doesn’t every tree aspire to be amongst Britain’s oldest, like the Fortingall Yew in Perthshire (2000 – 3000 years old), or even the relative whippersnapper like the 1500-year-old yew at Much Marcle (albeit older than the 13th century church in whose grounds it grows)?
These veterans may not always be beautiful or elegant (though stag oaks can be majestic), but we admire them as landmarks that have been nurtured and admired by generation after generation. The yew at Much Marcle has just been pruned for the first time in many years; 6 tons of deadwood and collapsed branches were removed and is now good to delight passersby for another 1500 years.
In his poem, ‘Binsey Poplars, felled 1879’, Gerard Manley Hopkins’ reminds us how the felling of trees can lead to the instant loss of a long-loved landscape:
O if we but knew what we doWhen we delve or hew —
Hack and rack the growing green!
...After-comers cannot guess the beauty been.
Ten or twelve, only ten or twelve
Strokes of havoc unselve
The sweet especial scene...
Worse than the destruction of individual veteran trees, is the destruction of whole woodlands in the name of ‘progress’ and ‘development’. When the Woodland Trust reports that 1225 ancient woodlands are currently under threat of destruction from ‘development’, then the current well-meaning drive to plant new trees does seem Alice-in-Wonderland. We become rich by what we save, not by what we destroy and then play a losing game of catch-up to ‘restore’.
Veteran Walnut Tree in Station Road, Eynsham, lost in 2020. Photo by Sue Chapman.
Sadly, even here in the heart of Eynsham we have seen landmark trees felled in 2020 – one just recently in Conduit Lane, which, like the clear-felling of the fuel copse, caused a ripple of concern right across the NRN. Expert gardener and Chair of Eynsham Society, Eleanor Chance, who witnessed the felling, was of the opinion that it could have been pollarded rather than razed to the ground. A more sophisticated approach, i.e. mitigating the safety risk of falling trees and balancing it with the health risk of removing veteran trees in their entirety is something that NRN is eager to explore. Various members have been in discussion with our Councillors about drawing on the skills of our local experts to initiate a more joined-up and consultative approach to managing our local environment, and one that starts to shake off 20th century habits of leaping to total destruction before looking at what is being lost.
Majestic Copper Beech in Newland Street, Eynsham, lost in 2020. Photo by Sue Chapman
If we in the NRN adopt as our New Year’s resolution the doctors’ injunction, ‘first, do no harm’, then we can at least halt the destruction of what we already have. This seems the best foundation on which to build our NRN efforts for nature recovery over the coming decade. If you have experience relating to trees and would like to contribute to NRN’s conservation and advisory work please let us know.
Kevan AC Martin
1. Bastin JF, Finegold Y, Garcia C, Mollicone D, Rezende M, Routh D, Zohner CM, Crowther TW. (2019) The Global tree restoration potential. Science 365: 76-79
But see also: https://science.sciencemag.org/content/368/6494/eabc8905
2. https://www.nytimes.com/2020/12/28/opinion/climate-change-earth.html?action=click&module=Opinion&pgtype=Homepage
3. http://biomassmagazine.com/articles/16876/uk-wood-pellet-market-past-present-and-future
4. Cannell MGR (1999) Growing trees to sequester carbon in the UK. Answers to some common questions. Forestry 72: 237-247.
5. The Sixth Carbon Budget. The UKs path to Net Zero. Committee on Climate Change, Dec. 2020
6. Mildrexler DJ, Berner LT, Law BE, Birdsey RA, Moomaw WR. (2020) Large trees dominate carbon storage in forests east of the Cascade Crest in the United States Pacific Northwest. Frontiers in Forests and Global Change. doi.org/10.3389/ffgc.2020.594274
7. Southwood, T.R.E. (1961) The numbers of species of insect associated with various trees. J. Animal Ecology 30: 1-8.
9. Natural England Commissioned Report NECR225a (2016) The role of trees outside woodlands in providing habitat and ecological networks for saproxylic invertebrates
10. Mestre L, Jansson N, Ranius T (2018) Saproxylic diversity and decomposition rate decrease with small-scale isolation of tree hollows. Biological Conservation 227: 226-232.
11. Deadwood – Living Forests (2004) WWWF Report
https://wwfint.awsassets.panda.org/downloads/deadwoodwithnotes.pdf
12. Hill L, Jones G, Atkinson N, Hector A, Hemery G, Brown N. (2019) The £ 15 billion cost of ash dieback in Britain. Current Biology. 29: R315-R3126.
13. anewnatureblog.com/2020/11/06/berrier-farm-under-trees-100-acres-of-peat-bog-heath-and-wildlife-rich-grassland-destroyed-by-tree-planting/
14. Ying Y, Tilman D, Furey G, Lehman C (2019) Soil carbon sequestration accelerated by restoration of grassland biodiversity. Nature Comm. 10: 718. doi.org/10.1038/s41467-019-08636-w
15. Natural England Research Report NERR043 (2012) Carbon storage by habitat: Review of the impact of management decisions and the impact of carbon stores and sources.
16. www.lgo.org.uk/information-centre/news/2020/oct/council-should-apologise-for-tree-controversy-ombudsman-says
17. Urban Air Quality. (2012) Woodland Trust Discussion Paper.
18. Salmond JA, Tadaki M, Vardoulakis S, Arbuthnott K, Coutts A, Demuzere M, Dirks KN, Heaviside C, Lim S, Macintyre H, McInnes RN, Wheeler BW. (2016) Health and climate related ecosystem services provided by street trees in the urban environment. Environ Health. doi: 10.1186/s12940-016-0103-6
19. Burley BA (2018) Green infrastructure and violence: Do new street trees mitigate violent crime? Health and Place 54: 43-49.