TREES OVER TIME: Part Seven - Decline & Death

Death – now there’s a pretty depressing topic for an article, you may be thinking - but indulge me. In researching this article, I came across several magazines dedicated solely to the topic of ‘death’ – of which Funeral Magazine, with its motto “thinking outside the box”, was probably my favourite! If I ever find myself thinking inside such a box, though, I hope I had the foresight to have my mobile phone on me… and some signal!

What constitutes a ‘natural death’ is difficult to define – for us humans, and for trees. Mostly, we get old and are ‘finished off’ with something we might categorise as ‘a cause of death’. It’s probably quite ‘natural’ to die from cancer, flu or heart failure (if you’re an old human) or from fungal decay (if you’re an old tree) – as those causes of death have been around for a very long time. In comparison, being killed by a high-speed train, or, for trees, being killed by the construction of a track for such a train, is a modern, unnatural phenomenon.

For urban trees, only a few very lucky individuals get to be old and experience that type of ‘natural death’. A major challenge in urban forestry and for the tree care industry is the prevention of early mortality to tree stock and what I tend to call ‘early onset decay’ in trees, where decay starts abnormally early in a tree’s life cycle because of physiology stress and/or mechanical injuries.

Everything comes to an end - but can we prolong that period of happiness and togetherness, when it comes to trees growing in our towns and cities? With care, I’m sure we can: but my ‘Trees over Time’ (ToT) images in this seventh article are mostly going to show cases where lack of care is the self-evident problem. I thought I would theme this article using the meme of the four horsemen of the apocalypse: possibly because, as I have been writing it, my partner has been watching ‘Good Omens’ on the BBC, distracting me somewhat. 

Apocalypse, not now but later 

In the absence of a lethal dose of poison, pathogen, pest and road salt, and if they can get overlooked by the tree inspector too, many trees will exhibit a long period of decline before their demise. Only repeated visits can, however, determine that a downward spiral in tree condition is occurring, as a tree can exhibit poor condition in one growing season only to improve in the years after that. Drought damage is the most obvious example of this effect but there are many other factors that can cause a similar ‘roller-coaster ride’ in a tree’s physiological condition from year-to-year. Figures 2 & 3 show trees entering a downward spiral towards death – over a protracted period – from which they are unlikely to recover. 

Figure 2: Decline in condition of a common laburnum (Laburnum anagyroides Medik.) over thirteen years in a small front garden space. Note the loss of foliage density, foliage lustre, some branch death and some changes to the hardscaping around the tree. Small-growing ornamentals often do not live a long life compared with other tree species, especially in more stressful urban settings.

Figure 3: A young Norway maple (Acer platanoides L.) planted in a grassed area at the edge of a village car park, with substantial dieback – which has only increased in extent eleven years later. The first puzzle is ‘why is this tree dying back?’ – but when you observe the excess wetness of the ground here for most of the year, the primary cause becomes obvious. The second puzzle is ‘why this young tree doesn’t just give up and die?’: but that’s trees for you: they are real ‘triers’ – their main goals are to achieve good longevity and potentially a long period of reproduction – nothing switches off those ‘desires’ in a young tree, unless it dies.

Young trees may seem easy to kill to us humans, yet, often they are not. Given how many native and naturalised trees species in the UK are prone to re-sprouting and being tolerant of coppicing, it can take a fair bit of effort to kill a young tree by solely mechanical means, if it’s too large to uproot it. If you are familiar with the way Rasputin the ‘mad monk’ was finished off, it’s a bit like that – time-consuming and somehow demeaning and inhumane! Even in highly adverse conditions, young trees cling to life tenaciously via a highly evolved set of self-regulatory mechanisms. This explains why you’ll regularly get to see the dismal half-dead car park trees that carry on living for maybe a decade or more in an out-of-town retail centre near you (Fig. 4).

Figure 4: I have a large collection of photos of inadequate tree provision in commercial car parks – it’s an odd obsession but I feel I want to hold someone to account for these poor plantings that duped people into accepting the planning applications. After all, we all get to see these dismal scenes in the many retail parks built in the UK. This common cherry (Prunus avium L.) has almost certainly been planted in a very limited soil volume of very low quality. It hangs on in there, though – somewhat spoiling my attempts at ‘retail therapy’ month upon month, year upon year. 

The First Horseman: Climate Change 

Obviously, I chose to live in the North-West, so I can’t be whinging and moaning about the seemingly ceaseless rainfall, the moss and mould-inducing dampness, the chronic flooding and the cascading condensation that develops on my windows overnight – well, not on a good day.

Only two decades ago, there was speculative talk about how climate change might bring to England the climate associated with southern France. This was a very misleading explanation of what polluting the atmosphere would entail, as was the term ‘global warming’, which, to someone in Lancashire in the mid ‘90s, probably sounded quite nice! Rather than inheriting a stable climate from a lower latitude, no biome is staying as it was – higher instances of extreme weather are a key problem which comes with the climate change that rapid fossil fuel consumption is causing (National Academies of Sciences, Engineering and Medicine, 2016).

Climate change makes it harder to make tree selections – Lancashire’s not going to be the Loire Valley of the 1990s, it’s going to be more frequently pounded by heavy rain, storms and extremes of temperature that its residents (including the trees) may not be fully acclimated to. Bitter winds and low temperature events are still likely to occur – so tender species are still at risk of death by our local fluctuating weather too. Figures 5 and 6 show a couple of speculative ‘Loire Valley’ plantings that haven’t worked out well this far north. 

Figure 5: Severe decline of an almond tree (Prunus dulcis (Mill.) Webb), planted in Cheshire as a roadside tree. This choice is just not likely to work in the North West of England – it’s too damp, wet and cold, which induces the defoliating and disfiguring disease ‘peach leaf curl’ (Taphrina deformans), a common cause of decline and death in this species – particularly where there are also other stressors (such as the grass competition in this case – and, at a guess, the occasional strimmer wound). It’s such a mismatch to try to grow such trees in a climate that doesn’t suit them, when there are plenty of better choices to adorn this grass verge.

Figure 6: A grove of tree ferns (Dicksonia antarctica Labill.) that was a beautiful feature – but have mostly died off in this botanical garden setting over ten years. It’s quite common to think that a dip in the landscape will provide shelter for such tender plants, only to find you have planted them in a ‘frost hollow’ that finishes them off!

The Second Horseman: Plague and Pestilence 

If climate change represents the first horseman of the apocalypse to our trees, then it rides side-by-side with the second: imported pests and diseases. The spread of these blights, moths and other ne’er-do-wells is accompanied by a rise in the stress levels in our trees due to adverse weather – and, especially drought years and mild winter temperatures. Some already naturalised tree-damaging agents are also becoming more common tree killers for the same reasons.

My second ToT article was on pests and diseases, so, to avoid repetition, I just want to emphasise the major tree killing going on up here by bleeding cankers – often Phytophthora-related diseases. It is really becoming difficult to justify the planting of an ever-increasing list of trees and shrubs – alder, beech, birch, elm, holly, larch, lime, juniper, oak – are all prone to bleeding or defoliation up here, despite some having native status. Figure 7 is an example of the direct killing one can get to see from this modern ‘plague’.

Figure 7: Death of a previously healthy alder (Alnus glutinosa (L.) Gaertn.) from alder disease (Phytophthora alni), with a decline in the crown of this tree evident from c. 2015 and it having to be removed early in 2018. In my local area, losses of alder trees have been high –new losses associated with recent incidents of flooding which have, presumably, vectored this pathogen to new victims. This specific tree death is a little unusual, in my experience, for the tree was very much divorced from any water sources and foot traffic. Although Myerscough has many alder trees that have died on its campus, we still retain a few alders, mostly growing in urban-like conditions, away from groundwater that would more readily allow the transmission of this pathogen.

The Third Horseman: Landscape Design & Development 

Although one might think the process should be simple, determining the cause of death of a tree can be complex as, very often, several factors conspire to kill a tree. However, one can find plenty of examples where the death of a planted tree was “designed in” at the planning stage. Figures 8 & 9 show death and decline that have been induced by poor site planning and ‘wrong plant, wrong place’. 

Figure 8: Severe decline of a silver weeping willow-leaved pear (Pyrus salicifolia ‘Pendula’) in a park. Although the two images are taken from different perspectives, one can see that i) the tree casts a shadow in the former image (where the tree is healthy) but does not cast a shadow in the latter image, even though the photograph was taken in the same season at roughly the same time of day; ii) that a neighbouring tree (Acer davidii cultivar) has over-topped this tree, shading it out. Indeed, another neighbouring tree (Davidia involucrata Baill.) has also overshadowed this unlucky Pyrus. Being a silver-leaved cultivar with little shade tolerance, the spacing of these two larger trees so close to this weeping ornamental pre-set the inevitable death of this tree. In which case, the death of this tree was unwittingly planned by the landscape designer around thirty years ago. This pear has now been felled and removed.

Figure 9: Slow death of a rowan (Sorbus aucuparia L.) in a confined tree pit. Ever since one of my connections on LinkedIn, Oliver Stutter, pointed out how poorly the pinnate-leaved Sorbus species often perform in ‘standard’ tree pits, I’ve noticed this to be the case in many further instances. Two years on, and the dead tree is still there, right next to the entrance to the pizza restaurant it is supposed to adorn. If that company did some research, they would find that a live and healthy tree growing by their front door would bring in a lot more custom. So rarely do we see such pro-active landscaping by these franchise companies, though: As with Figure 4, I despair that there isn’t a greening movement that can take over these neglected urban plantings and re-plant them for the good of all. Further to the “guerrilla gardening” movement, I feel we should develop a guerrilla urban forestry movement too.

Making a photographic record of many sites, I have ended up with a dire number of ToT images where trees have been damaged or removed due to development, of which a couple of examples are shown in figures 10 & 11. 

Figure 10: Killing a tree takes some effort – but some developers and site designers seem to have taken this up as a regular pastime that they engage in. Note that this oak tree (Quercus robur L.) had already been topped when this industrial estate was built on the farmland it was growing on. Note the severe crown decline in the latter image, taken ten years later. Note the rather surprising and sudden appearance of a car park, within less than a metre of the base of the trunk of this tree – well, surprising and sudden from the oak tree’s perspective, at least – but I’ve seen such ‘tree ignorance’ so often that I’m rarely surprised by it these days. Without the planning control from local authorities, this sort of thing would happen all the time: with our current planning control system, it’s still far too common, in my experience.

Figure 11: An avenue of globose maples (Acer platanoides ‘Globosum’) in Manchester, England – and their destruction for the purposes of an urban redesign of this space. The churn-over of central urban sites often leaves very few trees to become mature in the hardscape, in contrast to urban parks and gardens. In one local city (founded in the 12th Century) where I was a tree officer, the oldest street tree was (pathetically) a cherry plum (Prunus cerasifera ‘Pissardii’) from the 1960s, which was removed during my short period of employment. The tree-equivalent of the film ‘Logan’s Run’, I suppose – as so few modern plantings in the urban hardscape get beyond thirty years of age before the site is re-designed.

As an advocate for trees, the recent loss of two mature oak trees local to me, both well over two hundred years of age, was a real blow. The trees had plenty of decades left in them – they were removed, ostensibly, because they were inconveniently situated in the middle of a new housing development, which would have meant giving up two or more profitable plots per tree. An arboricultural report condemned them for their previous limb-shedding scars, which one would expect to find on many open-grown oak trees at that age class.

When I made local efforts to save them, the planners didn’t want to know, the councillors I contacted did not get back to me and even the local media did not end up covering the case. This, despite the irreparable loss of highly prominent and beautiful trees that one could never replace in even one’s children’s lifetimes. Figure 12 shows one of the two oak trees lost in this case. These choices are being made on a daily basis on many housing projects – where I live, it’s nearly always the trees that are coming off worse. More fool the developer: planning the new houses around a green area with this oak as its centrepiece would undoubtedly have improved the price per unit of these shoddy, cardboardy, plastic-front-door executive houses that they are building supposedly to solve our housing crisis.

Figure 12: If there is a ‘housing crisis’ in the UK, why does the solution near me seem to be the building of ‘executive homes’ on many greenfield sites? It makes no sense, unless you are looking for house builders to make very high profits at the expense of the loss of open countryside: it’s not housing for anyone in need. The arboricultural cost for the development of this particular site was the felling of two mature oak trees (Quercus x rosacea), very visually prominent to all users of a main trunk road, of good health and structure for their age – irreplaceable landscape heritage. For non-substantiated and spurious reasons, the trees were felled, the space they occupied used for building plots. Ah – the banality of evil.

The Fourth Horseman: Excessive Risk Management 

Contrasting with the slow deaths shown in figures 2 and 3 of this article, surely a quick mercy killing with a chainsaw is preferable in the case of a terminally ill tree or one destined for structural failure in the foreseeable future? Many of my old images are of structurally compromised trees or weakened components of trees, so my ToT images have recorded a lot of tree removals for risk management purposes. 

We all have an internal subjective gauge as to what level of risk we’d think acceptable from trees – and, unfortunately, those gauges are not centrally calibrated nor fully logical, so people will very often disagree as to the risks posed by a tree on a specific site. Personally, I can understand the need to remediate or remove a cracked tree or cracked part of a tree when it is found in a well-used area of a public park, even though that part of the park is unlikely to be occupied during a storm (Fig. 13). However, when decaying veteran trees have little risk of reaching a target of any consequence, surely they should be left as valuable habitat features. Figure 14 shows the removal of two such trees in northern Lancashire – the change in the local landscape is radical, as these old trees were the only ones of any prominence for several miles. Hollow though their trunks were, they were too set-back from the road to have been a significant risk to traffic – their only other targets being a drystone wall and the occasional sheep. For this latter case, the balance of risks against benefits was greatly misjudged, in my (subjective) opinion.

Figure 13: A silver maple (Acer saccharinum L.) where the first bark-included branch junction has split and the crack has developed down from it into the tree’s stem. I was really enjoying time-lapsing this particular specimen, situated in a public park, as on each revisit the crack had propagated further down the stem, with signs of some compensatory growth at three different stages along the crack. So, it was cracking, stabilising slightly, cracking further, re-stabilising, and so on. The parks department have now curtailed my fun, though, by felling this tree – presumably for risk management purposes. I don’t blame them: I would probably have done the same. The alternative of putting in metalwork or bracing the tree wouldn’t really match up with the limited importance of this tree in its setting.

Figure 14: Two beautiful veteran ash trees (Fraxinus excelsior L.) – and the view “gained” when those trees are annihilated. What a very sad – and unnecessary – loss to this landscape. Both trees had hollow lower stems but were substantially set back away from the road. Such trees are priceless for their value as habitat, as well as their contribution to the landscape. This is an example where excessive worry about what are, in reality, low-level risks can really cause poor decisions and the associated irreparable loss.

Towns Paved with Good Intentions 

Having worked for three very contrasting local authorities earlier in my career, the extent of tree planting provision on public ground was either a) negligible, b) insufficient or c) a healthily sustainable amount per annum. Fortunately, I got out of being a tree officer (TO) before successive cuts were made to council budgets (Harris, 2020), as, for many TOs, it must be hard to manage an urban forest with little to no funds for renewal of the assets therewithin.

The unfortunate end-result of this can be a town or city that is ‘paved with good intentions.’ It’s common practice to get tree pits capped over temporarily when a tree dies – to avoid trip claims – but with the intention to put a tree back in there when funds become available. This is one impact of the long-lasting austerity period for local councils, that I can walk and find so many of these capped over tree pits (Fig.s 15 & 16). 

I would also have to add that, very often, these pits are cheaply and poorly devised: many do not provide a good enough growing medium for the intended trees – and this surely adds to the increasing number of empty pits to be found in most towns.

Will we ever fulfil those good intentions? Well, it’s part of our drive in running an Arbor Day in the UK that we’d like to see more of these pits opened again for community tree planting – I’m ever the optimist… 

Figure 15: An upright Malus (probably Malus tschonoskii Schneid.) – the only tree on a shopping street in the city of Lancaster, England. On my return to this site, only a capped-over tree pit could be seen – with a bike rack built over the top of it. These sorts of site-by-site losses are part of the reason why our urban forests are mostly in decline in the UK – through non-renewal of tree losses – and from densification of our urban conurbations. Time to speak up that this is not the way in which we want our towns and cities to develop.

Figure 16: A similar issue of a capped-over tree pit on the main shopping street of Lytham, Lancashire – another street paved with ‘good intentions’ – but twelve years on from the death of that initial tree, no good act has occurred – this spot remains treeless. Retrofitting in a better tree pit is not impossible on a site such as this – this high-use site deserves an investment in green infrastructure.

Does the UK need a ‘Dead Tree Awareness Week’? 

There’s a period in late spring/early summer when one can most easily pick out the dead trees in the landscape. However, it’s very clear that most people are not avid observers of trees at all, to the point that they won’t even notice whether large trees in their own garden are alive or dead. I will often come to a site and say “You’ve called me because of the dead tree at the front, right?” – and they’ll say “What dead tree?”. Err… the one you can’t really miss, I would be thinking, whilst biting on my tongue…

Figures 17-19 illustrate three examples where owners (or management companies) have not really been attending to their landscaping… at all…

Perhaps we need a ‘dead tree awareness week’, so that people do get around to replacing the young dead trees to be found on so many new housing and development schemes. I’d be quite happy to serve a ‘Death Notice’ on some local developments, given their highly tokenistic efforts to incorporate trees and greenery. 

Figure 17: Planting of twelve upright hornbeams (Carpinus betulus cv.) occurred after the restructuring of the roundabout interchange between the A6 trunk road and the M55, just north of Preston, Lancashire. Planted in late June, when the road enhancement scheme was finished, all these trees died (unsurprisingly) – and remained on display to several tens of thousands of road users for nearly three years. An exemplar of poor landscaping that all local people should be angry about – but I doubt most even noticed! These twelve trees were planted, too, in compensation for several mature trees that were necessarily felled for reconfiguring this roundabout, so canopy cover has been severely depleted here, despite this attempted planting. On my return – no replacement planting has been done. Such sites are frequently a ‘one-hit-wonder’ and get overlooked for re-afforesting for many decades after a planting attempt like this fails.

Figure 18: Another commercial landscape, and this wild cherry did not establish when planted in a shrub bed at the front of this new supermarket. But, hey, let’s just leave it there, front of house, for a few years, to display how little we care, as a supermarket chain, about the appearance of our site and the appearance of the local area. Note the complete neglect of this bed has also allowed the ingress of a lot of common horsetail (Equisetum arvense L.) – which will now be difficult to eradicate.

Figure 19: A commercial site demonstrating that a ‘Dead Tree Awareness Week’ is much needed. How could this happen at the entrance to a ‘Show Home’?! To add to this advert of not caring for the local urban forest, there are also two dead trees in the back garden of this Show Home. Two years on, I can report that they are all still there! ???♂?

Reincarnation and resurrection 

“Death comes to us all.” Does it really? Many people live on beyond their mortal existence in the memory of others, some become legends that last millennia. Our urban trees can go much further than that – they can be immortal.

If we are serious about having large-growing trees in urban areas, we need to be guardians of the soil: for, without open areas of native soils, the task of growing and keeping such trees is made so much the harder. Figure 20 shows a paradigm of ‘reincarnation’: a tree is necessarily lost from a small public open space, but there has been the foresight to replace it – and over a short period of time. Upon my return, there is another good arboricultural asset developing on the same spot, growing in the conserved soil on this dense housing development. If only I found this ‘ideal’ situation more often! 

Figure 20: The necessary loss of an urban tree should be an opportunity for renewal, regeneration, rejuvenation and, of course, replanting. Here, after some risk management has led to the decline and death of a willow that had been incorporated into a housing scheme, on my return the local council had enacted the planting of an oak (Quercus robur L.) that is already contributing a lot to this public open space (POS). If only this good practice was what I commonly found along my ‘Trees over Time’ journey – but it’s an exception, I’m sorry to report.

I have a fair few photos of ‘bounce-back’ trees in my ToT images – trees that have fallen over but continue to grow, trees that have been felled or snapped but then have resprouted and show the potential to make a decent tree again. The more we ‘tidy up’, the less we’ll get to see of these inspiring efforts by trees for their own resurrection. A rather extreme case of resurrection is provided in Figure 21.

Figure 21: If a tree can dodge Death – it will. This Robinia ‘Pink Cascade’ was planted in an over-wet area of Myerscough College’s gardens, got a bleeding canker, and subsequently died. Or did it? On my revisit, ten years later, the rootstock of this cultivar has proliferated as many, many (unwanted) suckers. Trees like this can be immortal – as can those that resprout at the base of their trunks. Re-wilding the UK should involve giving some areas over to suitable trees species that can layer, sucker and re-sprout to their own content: although, to be clear, I’m not recommending that we establish large thickets of Ailanthus, Rhus or Robinia. This I have seen extensively in my recent visits to Italy – and it marks a terrible take-over of a landscape by naturalised non-native trees.

Much of the ecological crisis that is on-going relates not solely to destruction of previously untouched wilderness but also to excessive ‘tidying up’ of land already under our management. In the past, many B&W films depicted men cutting through overgrown thickets or jungle to reach some kind of ‘El Dorado’: now we need new films, which point out that the thickets and jungle are the real treasures in this world, with all their untouched biodiversity. As well as reducing the use of plastic for any outdoor purposes, we need to think before we start doing any ‘tidying up’ of trees – trying as much as we can to give something back to the environment, rather than processing everything through a chipper. 

Post-mortem 

If you are a fan of these ToT articles (allegedly, a few people are!), and you are thinking that I’ve now covered the topic of ‘death’ so that must mean the end of this series, well, don’t worry – this is not the final curtain. This is the penultimate article I will be producing for the Arb Magazine from ToT images: further to the final one, I hope to put a book together, based on some of the more interesting time-lapses I have captured – as I think this approach can teach quite a few lessons about the care and management of trees, and the link between trees and our increasing need to take up opportunities of environmental restoration. Writing this book will probably be the death of me – but I owe it to the trees I have caught on camera to share their extraordinary life (and death) stories. 

Yours undyingly, Duncan.

*** THIS ARTICLE FIRST APPEARED IN THE 2020 SUMMER EDITION OF THE ARB MAGAZINE, PUBLISHED BY THE ARBORICULTURAL ASSOCIATION ***

References

Harris, J. (2020) Austerity is grinding on – it has cut too deep to ‘level up’; The Guardian, 10th February 2020.

National Academies of Sciences, Engineering and Medicine (2016) Attribution of Extreme Weather Events in the Context of Climate Change. Washington, DC: The National Academies Press.