Whispers from the Ghosting Trees
A guest post by Gail Zawacki, who blogs at Wit’s End.
While we hustle busily through the necessities of our lives, wrapped up in our daily preoccupations – our obligations to our families, our jobs, and our dreams – at the same time all around the world, trees are silently expiring. For those who take the time to look, we can see that the forests are being transformed before our helpless and incredulous gaze into spectral mausoleums, as even the most ancient living wood is consumed by a raging tsunami of pathogens unprecedented in scale and virulence. What has instigated this global explosion of lethal insects, disease and fungus, which is decimating swathes of trees across ravines and mountains, invading city streets and wilderness, rampaging through parks and suburban backyards? What would we hear the trees saying if we understood the language of their injured foliage, if we could discern the message in their tortured splintered branches?
Only the latest in a long tradition of foresters, scientists, and ecologists, I am merely an amateur and a gardener doing what I can to warn society that there is a longstanding trend under way that is ominously accelerating. Until very recently impaired tree health was generally regarded as a regional, episodic problem mostly attributable to acid rain from sulfur dioxide. Now, new satellite technology has revealed that precursors of ozone – reactive nitrogen and methane pollution – travel across continents and oceans, and the toxic reach extends into the most remote and rural places. What was once slow and localized and species-specific has become terrifyingly fast, ubiquitous and indiscriminate.
Is it merely a colossal coincidence that all over the world, within the past few decades and at a hugely accelerating rate, trees are dying? If it’s not a coincidence, what is the underlying factor? Fair warning – this post will be a long explanation as to how there is an underlying factor, and why it is pollution. One of the strongest and most persuasive evidence for me has been the visible damage to foliage and needles that became virtually universal several years ago. Serious, terminal damage can occur in roots before any of the classic symptoms appear on leaves…so the fact that by the end of the summer growing season, it is just about impossible to find a single leaf on a tree, bush, garden produce or ornamental flowering plant that ISN’T visibly injured indicates the extent to which the problem has intensified. Just about any link to my blog will include photos of typical leaf damage.
The fearsome question – What would a world without trees be like? – can be an intimidatingly complex and nightmarish topic. I have broken it down into sections, each with many links for corroboration. Any requests for clarification will be gladly answered, and corrections appreciated. To a certain extent this is a synopsis of my book from last spring, Pillage, Plunder & Pollute, LLC, which can be downloaded for for free – except that I have incorporated the latest references for this guest post. Just like permafrost and Arctic ice are melting from climate change faster than predicted by models, the empirical evidence of tree death continues in an avalanche. Throughout, I have tried to be true and accurate. Following is a list of the sections, for ease of access.
- Shifting Baselines
- Scientific Evidence that Trees are Dying across Species, Ages and Locations
- Ozone is Toxic
- Proof that Ozone Predisposes Pathogen Attacks
- Ozone Pollution is Inexorably Worsening
- Annual Agricultural Crops
- What is to be Done?
There is a long history of studying the mechanisms by which pollution damages plantlife, dating back to at least the 17th century. A sampling can be found on the DeadTrees…DyingForests webpage, taken from Imperial College Professor J.N. Bell’s compendium “Air Pollution and Plant Life” (2nd edition, published in 2002):
“In 1661, the English diarist, John Evelyn, published his famous treatise, Fumifugium: Or the Inconvenience of the Aer and Smoake of London Dissipated, in which he described the contemporary air pollution problems in the English capital, making recommendations for their amelioration.”
“Fumifugium contains graphic descriptions of effects on vegetation, such as ‘…Our Anemonies and many other choycest Flowers, will by no Industry be made to blow in London or the Precincts of it, unless they be raised on a Hot-bed and governed with extraordinary Artifice to accelerate their springing; imparting a bitter and ungrateful Tast to those few wretched Fruits, which never arriving to their desired maturity, seem, like the Apples of Sodome, to fall even to dust, when they are but touched.’”
“Fascinatingly, Evelyn also describes what can be described as the first experiment, albeit inadvertent, on air pollution impacts on plants, when coal smoke was eliminated in London one summer as a result of the English Civil War stopping the coastal trade concerned, with him noting how the trees produced unprecedented quantities of high quality fruit.”
“Clearly air quality deteriorated even further over the next 100 years, as a preface to a second edition of Fumifugium, written in 1772 noted ‘It would now puzzle the most skilful gardener to keep fruit trees alive in these places: the complaint at this time would be, not that the trees were without fruit, but that they would not bear even leaves.’”
“This classic acute, or direct, damage to trees appears worldwide, mostly in the immediate or approximate vicinity of pollutant emitters such as fired power plants, heating plants, metal-processing plants, waste incinerators and the ceramics industry. However, in recent decades, the flue gases have been carried to ever more remote places, due to the current practice of building super-high smokestacks.”
“The most curious result obtained appears to me to be that relating to the effect of a highly ozonized atmosphere upon the roots of plants.” – M. Carey Lea, 1864.
Also, this observation from the 19th century:
“To the philosopher, the physician, the meteorologist and the chemist, there is perhaps no subject more attractive than that of ozone.” – C.B Fox, 1873
…likely refers to the almost imponderable complexity of ozone’s formation and degradation, which is rivaled only by its highly reactive effects on all surfaces, living and inanimate. Lungs, leaves, and even rubber, rocks and monuments are all degraded by contact with ozone.
In more recent decades during the era of modern science, warnings that forests are dying from pollution have been denigrated or even vilified…but mostly ignored. If you search hard enough you can locate the earliest permaculture work by George Mollison in Australia, who denounced in exasperation the “phasmid conspiracy to blame the bugs” back in 1981; find a used copy of An Appalachian Tragedy in published in 1995, (photos and passages are excerpted here); or even read this obscure 2006 article from Bangladesh that declares “Depletion of Forest Cover Portends Climatic Disaster”:
“The epidemic of dying trees which has struck the forest resources of the world appears to be quite mysterious. But the most convincing evidence points to air pollution, specially sulfur dioxide and oxides of nitrogen spewed in the air by the ton from electrical generating stations, industrial boilers, smelting plants and automobiles located thousands of miles away. One school of thought points out, by itself sulfur dioxide can sap the vitality of the tree: so can oxides of nitrogen. But the real problem seems to begin when two gases work in combination in the atmosphere. Hurled into the air by tall smokestacks, the substances mix with water vapour to form sulfuric acid and nitric acid known as acid rain and in the presence of sunlight turn into oxidants such as ozone. When these new chemical mixtures fall to earth as snow or rain or float into forests as wind or fog, they can be far more lethal than the ingredients that went into them.”
“Acid rain, in the form of dry particles, snow and fog, attacks a tree on all fronts. Airborne pollution settles first on the highest treetops of the forest crown, which acts as a natural windbreak. Acid precipitation filters down to the soil, eats away at the root system and eventually leaches out key nutrients such as calcium and potassium and mobilises toxic metals like aluminum. Once on a leaf or needle, acid rain disrupts the operation of the stomata, the tiny openings that permit a tree to “breathe.” The process of photosynthesis is thrown off balance, and subtle changes take place in the internal chemistry of the tree that result in discolouration and premature aging. Finally acid rain washes away vital nutrients from the leaves and needles so that the tree slowly starves to death, its respiratory, circulatory and digestive systems being crippled. Much like an AIDS victim whose immune system has broken down, the ailing tree is defenceless against the ravages of nature.”
That link is one of many to be found at Eco-systems.org, an inactive site which has a huge assembly of reports of trees dying from pollution around the world. It includes a 1998 essay, “Tree Death and Forest Decline’, by Paul Donahue. Excerpts follow:
“One criticism often leveled by opponents of stricter air pollution standards is that acid rain or other pollutants don’t kill trees, that they are actually killed by cold winters or by insects or fungus or some such agent. In a sense these critics are correct – it is true that cold or insects or fungus or some other pathogen is often the ultimate cause of tree death rather than pollutants. But one might fairly ask why in the latter part of this century are so many pathogens suddenly having such a tremendous effect on so many species of trees. If just one or two species of trees were suffering a decline in eastern North America, maybe it would be acceptable to simply blame the weather or some pathogen and dismiss the problem as unfortunate but unavoidable. But that is hardly the case. Instead, what we are witnessing across most of eastern North America is a pandemic of tree death.”
“We need to take the wider view and look on these pathogens as representing only the proximate causes of death, and see forest decline and tree death across eastern North America for the pandemic that it is. Our industrial society with its attendant air pollution is slowly killing our forests, as it has the forests of eastern Europe, weakening and stressing trees, and making them more susceptible to cold winters and attack by pathogens.”
“A good analogy can be made between acid rain and AIDS. You don’t die from the HIV virus, you die of the diseases you contract because of your depressed immune system. The same holds true of atmospheric pollutants and trees. It is often not the pollutants that kill the trees but the insects, viruses, fungi, or bacteria that attack once the trees’ overly-stressed immune systems are weakened.”
2. Shifting Baselines
It’s only natural to recoil from the horrifying suspicion that we are destroying our only home, Earth. The pernicious implications for climate, our food supply, and the habitat for so many of our fellow creatures, are soul-crushing to contemplate. As the health of trees is gradually degraded, our reluctance to accept industrial civilization and overpopulation as the fundamental cause is enabled by the phenomena of shifting baselines. Over time our perception of what is normal changes, as we gradually forget how robust and vigorous trees once, and not so very long ago, either. If you’re not familiar with the concept of shifting baselines you could watch Daniel Pauly give a TED talk about how our expectations for life in the sea have been eroded as fishstocks have been exploited over time. This concept has been extended to other perceptions, as described here:
“Papworth et al. (2009) have recently addressed this knowledge gap by defining two kinds of shifting baselines:
general amnesia (‘… individuals setting their perceptions from their own experience, and failing to pass their experience on to future generations’) and
personal amnesia (‘… individuals updating their own perception of normality; so that even those who experienced different previous conditions believe that current conditions are the same as past conditions’)
…Humans inevitably have short memories when it comes to environmental degradation, suggesting that real-world biodiversity declines are probably far worse than many realize.”
The same principle holds for forests. Certainly within my recent memory the world was verdant. It has taken far less than one generation for us to accept it as barren and depauperate wasteland. Just as the once teeming life in the sea is being systematically destroyed through overfishing and acidification, in a perfect parallel to bleaching of corals – which represent the foundation of the oceanic ecosystem – their terrestrial equivalent, forests, are being rendered into a skeletal purgatory.
Trees are intrinsically amazingly strong. They have to be, because their lifespan often should be hundreds and even thousands of years. Individuals cannot pick up and leave when the weather is adverse; through evolution they developed the ability to store enormous amounts of energy to enable them to survive seasons and even years of extremes of temperature and precipitation. Here are some reminders:
The roots of this tree, located in Kalaloch, Washington cling to eroded cliffs.
The tree above is one of a row in Basking Ridge, New Jersey, that have enveloped an old iron fence.
The bicycle was “lost” by a young boy who didn’t like it, in 1954 in Vashon, Washington.
Often foresters will claim that trees are dying because they are overcrowded, but old photographs of virgin forests prove otherwise. These chestnuts from the early 20th century thrived in extremely close quarters
A collection of photos of old trees can be viewed here. Luckily the loggers of old liked to take pictures of the trees before they cut them down, and no wonder. They were magnificent and profoundly humbling. There is almost no forest left to remind us of what once covered the entire US east of the Mississippi, Europe and even the Middle East. Impressively, long after clearcutting, many family farms were abandoned as we turned to industrial agriculture and the fields became filled with vigorous secondary growth. Those forests are not yet mature, one reason many foresters refuse to believe forests are in danger.
Historical notes from this New Zealand photo: “A 30 foot kauri log, 18 feet in girth ready for trucking after being hauled out of the bush near Piha. It will provide 6,000 super feet of timber. This will be used in the construction of a new 48 feet A class keel yacht for Messrs N. H. and J. H. Newcombe of Auckland, former owners of the B class yacht ‘Lady Wilma’. (J. T. Diamond).”
Trees were once so strong that a large section of them could be chopped out and the loggers had no fear of being accidentally crushed.
Another photo of this popular pose is from a story in the Smithsonian about Sequoias.
A particularly terrific book about the innate majesty of trees from 1996 is Meetings With Remarkable Trees by Thomas Pakenham, who has photographed many of the oldest specimens in the UK. Not only are they testimony to the natural longevity of trees, but quite a few of them were imported long ago from exotic locations around the world, as enthusiastic gardeners brought them to thrive in the mild climate in gardens, parks, arboretums and grand estates. This is an important point as shall be noted later, when we get to the multiple threats to trees in the British Isles, being largely blamed on invasive species. These two are just a couple of examples from the book; more can be seen at this post.
Another common excuse for trees to be dying of late is that they are on poor soil, or shallow bedrock, a concept defied by these yew trees.
There is a saying “…as sturdy as an oak”, and it’s easy to see why.
We once thought of trees as solid as rocks. We weren’t afraid of climbing in them, building treehouses in them, or having branches overhang our roofs.
And yet in hurricane Sandy, just one power company alone in New Jersey had to take down 65,000 trees or branches fallen on power lines. Most of the people killed in that storm died not because of the flooding along the coast, but because trees fell on them directly, or on their cars or on their houses.
The New York Times reported that perceptions of trees have changed following Irene, Sandy, and lesser meteorological events, in a classic example of shifting baselines. The article chronicles the fact that people have come to fear trees. It’s easily overlooked that neither Sandy nor Irene had exceptional winds; both were mainly rain and flood events. And yet incalculable numbers of trees came down. The most important point and one that is easily verified by looking at photos in the media is that many of the trees that fell in those storms were visibly rotting – and remember that trees can be weak and dying BEFORE rot is visible. For those who are gluttons for dying tree porn, I have posted many photos demonstrating this from New Jersey – after – Sandy to California. Following are a few others. The first three are from Connecticut.
The picture below is from Louisiana.
This photo is from Philadelphia.
The tree below crushed a car in Winnipeg.
This tree smashed a house in Ohio.
Just for fun I took two new pictures over last weekend, down the road from Wit’s End. The house above belongs (or once did) to one of the Toll Brothers – of McMansion subdivision infamy. And just beyond the treeline below is Donald Trump’s National Golf Course in Bedminster. Ozone is no respecter of financial wealth. Estates that once were private can now be seen from the road, as the hedgerows and trees are lost.
One article reports that it’s not at all merely in our imagination that there are more power lines down, with more frequent and longer outages. By far, the major reason is trees falling on them:
“It’s not just a feeling: Power outages have become normal in the United States. Last month’s heat and derecho storms that left more than 300,000 people in the Mid-Atlantic states without power (some for as long as a week) are part of a larger trend. In 2008, according to the Eaton Blackout Tracker, there were 2,169 power outages in the U.S. affecting 25 million people. In 2011, there were more than 3,000 outages affecting 41.8 million people.”
“According to Eaton, the majority of power outages in the U.S. are caused by weather, in particular storms blowing trees on the lines, and heat waves that overwhelm the carrying capacity of the system.”
For MunichRe’s graph on insurance claims from thunderstorm damage –the majority of which is due to falling trees – they had to expand the perimeters, the jump in 2011 was so high compared to previous years.
Is that due to wind? Some perhaps, there’s no question storms are more intense due to climate change. But a remarkable number of trees are falling even when there is no wind, or in winds they once withstood. Long ago Leonardo daVinci discovered that trees are designed to withstand high winds.
3. Scientific Evidence that Trees are Dying – Across Species, Ages and Locations
When I first noticed that trees are dying – in 2008 – I started trying to learn why. At that time it was not generally acknowledged that there is a global decline, in fact the idea typically met with derision. Now, in just the few years since, the data has caught up with the real world and many studies have emerged indicating that forests are, indeed, dying off on every continent. The most recent study published in Science Magazine, which received quite a bit of attention in the press – Global Decline in Large Old Trees – focused on old trees because they hold a vital niche in the forest ecosystem, sequestering substantial amounts of carbon and providing unique and irreplaceable habitat for other species.
However according to other studies, it’s not just old trees that are dying, a point unfortunate when overlooked, since it indicates that the fundamental, paramount reason is different than the limited influences cited in that study.
In an interview on NPR last month, a former nurseryman explained why he has turned to cloning ancient trees. He said, “…we’ve been in the shade tree business in northern Michigan for several generations. And 20 years ago, our trees that we were growing for the cities and nurseries started to die and we didn’t know why. Well, after a couple of years and a lot of research, we found out it was due in large part to the decline in air quality.”
But there is far more extensive research than a few anecdotal observations. A series of articles following With Death of Forests, a Loss of Key Climate Protectors in the New York Times in 2011 began to expose the grim situation to the public.
Virtually all current orthodox articles and studies blame climate change or alien species. When I first realized that that trees are dying, I assumed it must be from drought from climate change. It wasn’t until 2009 when I was closely observing plants that I realized that is an explanation that simply doesn’t satisfy the empirical evidence, which is that the leaves of young trees being watered, aquatic plants, and even tropical ornamentals in the summer grown in pots exhibit identical damage to older trees regardless of location. Nevertheless following are some of the studies because, regardless of the source of stress, they do demonstrate a perilous decline worldwide.
Four studies indicating widespread tree decline are linked in this post. The first, How the Big Trees in Trouble, How the Mighty Are Falling, is a survey of the literature focused on old trees but the next, Widespread Increase in Tree Mortality in the Western US makes clear trees of all ages are dying prematurely. Finally, two studies, slightly different versions by the same lead author Dr. Peng, found tree mortality across the boreal forest of Canada even eliminating sites with insects. The first is titled A drought-induced pervasive increase in tree mortality across Canada’s boreal forests while the second, essentially the same investigation, was amended to read Regional drought-induced reduction in the biomass carbon sink of Canada’s boreal forests. Dr. Wofsy of Harvard objected to the characterization of eastern forests being in decline and so the second paper, with a very different perspective, was subsequently published listing Wofsy as editor. Such is the prejudice among academics, and rather amusing too if you want to read up on the incident at Wit’s End.
An article in Nature proclaims, Dying Aspen Sound Alarm for World’s Forests, while another, Global Convergence in the Vulnerability of Forests to Drought, sees vulnerability to drought lurking everywhere.
Black walnuts have earned devoted websites due to their threatened status, from Tennessee, North Caroling and Georgia. One of them says: “Thousand Cankers Disease (TCD) poses a serious problem to the health of the black walnut tree. Walnut trees are important because of their nut crop and the desired wood for various products. TCD is a progressive disease that kills a tree within two to three years after initial infection. The disease-causing fungus, Geosmithia, is transmitted by a small twig beetle. Branches and trunk tissue are killed by repeated infections by the fungus, as the beetles carry the fungus into new bark cambium tissue.”
An extensive list of threatened forests, Climate-induced forest dieback: an escalating global phenomenon? available from the UN Food and Agriculture Organization is based on an oft-cited 2010 paper, A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. The introduction at least nods in the right direction: “Furthermore, forests are subject to many other human in?uences such as increased ground-level ozone and deposition.” but then quickly squelches any such component as pertinent – they cite papers linking drought to forest dieback from the beginning of the last century and then say, scornfully:
“Furthermore, the overwrought perception of unprecedented forest decline and impending death due to air pollution in central Europe (where it was referred to as ‘Waldsterben’) and eastern North America that received much attention in the 1980s provides a cautionary example of exaggerated claims of widespread forest health risk in the absence of adequate evidence (Skelly and Innes, 1994).”
This is particularly absurd considering that the entire point of their paper is to document
“global” decline! The authors ask, rhetorically:
“So are recent occurrences of die-off simply well-documented examples of a natural phenomenon linked to climate variability, or is global climate change driving increases in forest mortality?”
They should ask – Or are recent occurrences of die-off simply well-documented examples of a continuation of the die-off that began decades ago due to pollution and has lately grotesquely accelerated? This is a question they don’t even ask, let alone answer, although somehow this slips in:
“…Based on the decline spiral model (Manion, 1991; Manion and Lachance, 1992), drought can operate as a trigger (‘‘inciting factor’’) that may ultimately lead to mortality in trees that are already under stress (by ‘predisposing factors’ such as old age, poor site conditions and air pollution) and succumb to subsequent stem and root damage by biotic agents (‘contributing factors’ such as wood-boring insects and fungal pathogens).”
…and then is promptly ignored in favor of drought, in section 4.1.
However, since we can easily show that trees that aren’t old, or in poor site conditions, are dying off, that kind of leaves air pollution as the remaining “predisposing factor” doesn’t it? …leading them to succumb to “subsequent” damage by biotic agents. Exactly. It’s there, sleeping, in their own paper.
What has happened here, is that there was a rift many years ago, particularly between those pesky European foresters and the Americans. Those scientists who were warning about pollution killing forests were labeled as heretical by the establishment forestry community. Now, the evidence of global decline is so irrefutable that they have latched on to climate change induced drought and invasive pathogens, rather than go back and confess that the Cassandras were right (as was the original Cassandra). They also are far more likely to claim that species are “shifting” like the birch and spruce in Alaska – “undergoing transition” – rather than dying, and that pathogens are to be blamed, since after all they can be sprayed. What job will there be for foresters when the forest is a desert?
In order to understand this obfuscation – some of which is probably subconscious – it helps to put the US Forest Service into context. Surely it is no surprise anymore that our government is corrupt. Goldman Sachs owns the Federal Reserve Bank, Monsanto owns the USDA…and Georgia Pacific owns the Forest Service which in turn often funds the academic branches of forestry research. Let’s recall who owns the timber giant Georgia Pacific. It’s the Koch brothers. So you won’t find too many foresters admitting that industrial civilization – and the stealth logging, mining, fossil fuel, and other extractive processes and dumping on public lands that support it – is incompatible with a healthy forest or perhaps any forests at all.
It is getting far more difficult to claim forests are healthy with any credibility also some still try. In the spring of 2010 when I wrote to one of the researchers at the Smithsonian Environmental Research Center in Maryland about a paper claiming that trees are growing faster due to increased CO2, he claimed that there was no evidence of the massive die-off I inquired about. So I went there myself…and there were dying trees all over the place. Not only that, but the understory – the lovely native laurels and dogwood – were perishing in droves as well. Scientists at Harvard Forest have told me that area is healthy, even though it’s not, and the same is true for Yale. Both universities have huge plots of forest for study, and they won’t admit they are in dieback, which is why Dr. Peng had to rewrite his paper.
In a preposterous lopsided interpretation, researchers from Yale recently revealed their discovery that methane is being released FROM trees as a new, previously undetected source of a greenhouse gas…when the most significant part of their results is that it indicates trees which are no where near maturity – average 80 to 100 years, and that “appear outwardly healthy” – are actually rotting from fungus to the point that the methane they are releasing is in “flammable concentrations”. Worse, these foresters extrapolate from this that trees all over the world are in the same predicament. One of the researchers I contacted wrote me this:
“The common fungal infection described in the paper could be compared with tooth decay (bacterial), or athletes foot (fungal) infection in humans. It is essentially ubiquitous in the world’s forests. Would you describe an otherwise normal adult with a tooth cavity as being in terminal decline? I would not. Also, I would mention that, while concerning at the extremes, many of the other signs of ‘terminal decline’ you describe above can be the result of normal ecological processes active in all forests.”
Well, since when did tooth decay or athlete’s foot compare to being “…hollowed out by a common fungal infection that slowly eats through the trunk?” Wouldn’t a more appropriate analogy be gangrene, or leprosy…or maybe necrotizing fasciitis? Since when do tooth decay or athlete’s foot fungus ever reach “flammable concentrations”?
Here is what John Skelly, cited in the paper above, wrote to me from retirement in Virginia in August of 2011:
“…I am quite conservative in my estimates of air pollution effects to our forests…productivity is up, planting new trees is excellent, the forests within our state and national parks (except for natural disease and insect outbreaks…many from introduced organisms) are wonderfully healthy but we do indeed have some effects of pollution as well…but certainly not doom and gloom from my perspectives.”
There is no polite way to describe how inaccurate this assessment is so I won’t.
Let us dispense with the drought canard. Obviously, drought, especially extreme drought from climate change, is going to destroy swathes of forest and likely already has. However, that cannot be what is currently driving GLOBAL dieback because not all areas are in drought, and in fact, not all areas have seen more than the most minor changes in temperature. The increase in temperature is heavily skewed towards high latitudes. In fact, climate science clearly predicts that there will be more extremes as the differential between the much faster-warming Arctic and hardly-even-warming-at-all equatorial region causes the jet stream to lag. Dry areas will get drier and wet areas will get wetter – that’s the prediction, and that is what is what has been documented. So places like the UK and northern Europe and Scandinavia and the Northeast US and Canada are getting, if anything, wetter and yet trees are dying just as fast if not faster in those areas.
A December 2012 report from the European Environment Agency, Climate Change, Impacts and Vulnerability in Europe, provides this map which I discuss in greater detail here, but the gist of it follows:
In a BBC video headlined “Fight to Save Britain’s Ash Trees from Killer Fungus”, a representative from the Woodland Trust says: “I don’t think the government has done enough in the face of a whole series of threats to our ancient woodlands and our native trees. Ash disease is just one of a long line of problems that we’re facing.”
Yet another article, in the Telegraph, begins with the statement: “Ash dieback came after tree disease already at record high…Outbreaks of tree disease in England were at a record high this year – even before ash dieback was discovered in the country, according to the Forestry Commission.” It continues:
“Ash dieback is now in 184 sites around Britain, mostly in East Anglia. But even before the deadly disease was found for the first time, plant health experts were struggling with at least 25 tree diseases spreading around the country.”
“One of the most destructive tree diseases is phytophthora ramorum or sudden oak death.
Despite its name, the disease mostly affects larch, but will also kill off garden shrubs like viburnum. Since 2010 around four million larch trees have been felled.”
“The Forestry Commission have issued 137 Statutory Plant Health Notices to landowners warning of the disease so far this year, meaning they have had to fell even more infected trees. This more than any other previous year in total. At the same time around 100 plant health notices have been issued for other diseases this year including bleeding canker, that attacks conker trees, and red band needle blight, that threatens pines.”
“This year Asian Long-horn beetle was found breeding in maple and poplar trees in Kent for the first time and chestnut blight, that could wipe out our sweet chestnuts, was found in nurseries in East Sussex and Warwickshire. The Forestry Commission England said the total was likely to be the most disease outbreaks the agency have ever had to deal with.”
In reaction to this onslaught of bad news, an opinion piece titled “Bungled Fungals” was published in the Financial Times. The author, Robin Lane Fox, wrote that the government is engaged in “too little too late”. He seems to think everything could be controlled if only they sprayed more – “There are fungicides waiting only for a licence which can attack this sort of epidemic. It is a fungus, after all, not a baffling insect” he claims indignantly. However, he provides a handy summary of tree problems which are clearly not limited to ash. You would think people in the UK, so frantic about one species after another, would wonder if there isn’t something systemic going on, but no. Easier to blame immigrants, and the government:
“Thanks to Kew and the IDS I am now up to date on infections recently recorded on widely grown woodland trees in Britain. They are far worse than I believed when being gloomy here in September before any crisis was being politically discussed. Native alder trees, our Alnus glutinosa, have a deadly pathogen which has already wiped out millions of them in Germany. Corsican pines have a needle blight, new since the late 1990s, which leaves them looking like dead poles. Horse chestnuts, of course, are at risk to a deadly bleeding canker, while the fast-breeding leaf miner has been sapping their energy since 2002. Japanese larch trees are increasingly infected with spores of the killer Phytophthora ramorum and are being felled by the thousand. Fast-growing nothofagus has another deadly pathogen from the same family. Since 2010, yet another pathogen in this broad group is killing Lawsons cypress. Since 2011 native junipers in ancient clusters in Scotland are turning brown and dying off. In 2011 sweet chestnut blight at last showed its lethal head in Britain after 60 years of anxiety among tree watchers that it might cross over from southern France. As in the US, our hemlocks are being killed by fast breeding insects. Rhododendrons on the west side of Britain are plagued with the killer phytophthora too, and it has now transferred on to wild blueberries on heathland. In the face of these other crises, ministers have sat and watched.”
There are now many articles to be found like this one As Forests Disappear, Examining the Mechanisms of their Death published December 24 in the New York Times which begins:
Everywhere, trees are dying.
Exactly!!! Trees are dying everywhere – not just where there is drought or significant temperature change!
“The boreal forests of Canada and Russia are being devoured by beetles. Drought-tolerant pines are disappearing in Greece. In North Africa, Atlas cedars are shriveling. Wet and dry tropical forests in Asia are collapsing. Australian eucalyptus forests are burning. The Amazon basin has just been hit by two severe droughts. And it’s predicted that trees in the American Southwest may be gone by the end of this century.”
“A November article in the UK Guardian proclaims: Scots pine could be the next casualty of a “tidal wave” of tree diseases; threat to British trees “terrifying” say experts, as fears grow over continental pathogens.
“Scientists have pinpointed the Scots pine as the next well-loved British treespecies that could fall victim to foreign pathogens. They believe that the expected devastation triggered as ash dieback disease sweeps Britain – which could see most of the country’s 90 million ash trees killed off – could soon be followed by a second invasion.”
“Pinus sylvestris is considered to be particularly vulnerable because two major pests that attack it have already established themselves in western Europe: the pine wood nematode, a worm that infects pine trees and causes pine wilt, and the fungus Fusarium circinatum, which causes the disease pitch canker.”
“Both pathogens are poised to spread to Britain, say tree experts, and a simultaneous double attack would be devastating. The Scots pine is the national tree of Scotland and is distinctive for its blue-green needles and rich orange-red bark. It is also an important source of timber in the UK.”
“’I am extremely worried about the Scots pine’” said Dr Steve Woodward, reader in tree pathology at Aberdeen University. ‘It is an iconic tree to these islands and it is particularly vulnerable to these two tree pathogens, both of which have established themselves in France, Spain and Portugal and are causing tremendous damage there.’”
“Ash dieback is just one of ‘a tidal wave of pathogens’ that are arriving in Europe, added Dr Martin Ward, Defra’s chief plant officer, who described the situation as terrifying. ‘Unless we have better biosecurity in the EU it will be very difficult to stop them coming in,’ he added.
This view was backed by Woodward, who feared the Scots pine was the most vulnerable of all UK trees to future pathogen invasions. ‘We know that pitch canker is now established in northern Spain where it affects native pines, and we know that the Scots pine is susceptible to it. We also know that thousands of hectares of pines have had to be felled in Portugal to try to contain the pine wood nematode there. Now it has spread to Spain. It could arrive at any time.’”
“Billions of plants and trees are now traded within the EU every year, often with large amounts of soil attached to each plant, and experts like Woodward and Boyd fear such quantities of material make it impossible to control pathogens. “Some plants have 1,000 litres of soil with them,” said Joan Webber, principal pathologist of Forest Research, the research agency of the Forestry Commission. ‘That soil is a black box full of billions of bacteria. It is very difficult to inspect and intercept.’”
“Most experts blame the rising trade in exotic plants from Asia as a key cause of the rise in outbreaks of tree diseases in the UK. Webber said that during the whole of the 20th century, Britain had five major pest and pathogen outbreaks, including two outbreaks of Dutch elm disease. So far this century, there have been more than double the total figure for the previous 100 years.”
On this side of the pond, foresters are fond of blaming the bugs as well. This study about Whitebark Pine claims bark beetles are killing them because of warmer temperatures:
“’Warming temperatures have allowed tree-killing beetles to thrive in areas that were historically too cold for them most years,’ explains Ken Raffa, a UW-Madison professor of entomology and a senior author of the new report. ‘Tree species at these high elevations never evolved strong defences.’”
“A warming world has not only made it easier for the mountain pine beetle to invade new and defenceless ecosystems, but also to better withstand winter weather that is milder and erupt in large outbreaks capable of killing entire stands of trees, no matter their composition.”
“Lodgepole pines (unlike whitebark pines) co-evolved with bark beetles at lower elevations. Over time, they devised countermeasures such as volatile toxic compounds and agents that disrupt the beetle’s chemical communication system. Despite its strong defences, the lodgepole pine is still the preferred menu item for the mountain pine beetle, suggesting that the beetle has not yet adjusted its host preference to whitebark pines. ‘Nevertheless, at elevations consisting of pure whitebark pine, the mountain pine beetle readily attacks it,’ says Townsend.”
“The study, conducted in the Greater Yellowstone Ecosystem, one of the last nearly intact ecosystems in the Earth’s northern temperate regions, also revealed that the insects that prey on or compete with the mountain pine beetle are staying in their preferred lodgepole pine habitat. That, says Townsend, is a concern because the tree-killing bark beetles ‘will encounter fewer of these enemies in fragile, high-elevation stands.’”
If it’s temperature, why aren’t all the bugs moving northward? Why only the tree-attacking bugs??
US foresters also blame imported, alien pathogens, for instance at the Cary Institute. From their website:
“For forests in the Northeast, small invasive species like beetles or fungus pose a more immediate danger than do air pollution and climate change. These pests are assisted by a variety of short-sighted human actions.”
“Cary Institute forest ecologist Gary Lovett, who studies the ecosystem effects of introduced insects and pathogens such as gypsy moth, hemlock woolly adelgid, and beech bark disease, is sounding the alarm for citizens and politicians. ‘This problem is not new—most people are familiar with how chestnut blight and Dutch elm disease eliminated these species from our landscapes—but the pace at which new pests are being introduced is new,’ Lovett notes. ‘People don’t realize the grave threat these invaders present to whole species and ecosystems. It’s biological pollution.’”
“Unlike global warming, which creeps up slowly over decades, biological pollution is a surprise attack, and time is not on the side of invaded forests. The emerald ash borer, for example, was introduced in Detroit in 2002, probably through untreated wood packing material in cargo containers from Asia. The larvae of this exotic beetle feed on the inner bark of ash trees, disrupting the flow of nutrients and killing the tree. The pest has spread east and west, and outbreaks have already occurred in Saugerties and West Point. “It’s only a matter of time before it reaches the east side of the Hudson. I predict large stands of ash trees will not exist in this area in ten years,” says Lovett.”
“Sudden Oak Death disease is a good example of how biological pollution needlessly occurs when people choose exotic plants,” remarks Lovett. “This pathogen probably arrived on imported rhododendrons and, in a little over a decade, has devastated some species of oak in Oregon and northern California. Yet native rhododendrons are widely available from nurseries.”
Another recent arrival that might have been avoided is the Asian longhorned beetle, which affects North American hardwoods, especially maples. Outbreaks have been recorded from Chicago to central Massachusetts, where over 25,000 affected trees have been removed at a cost of hundreds of thousands of dollars to taxpayers.”
The alien fervor is absurd anyway, because plants and other trees have been traded around the globe for centuries with fungus, insects and diseases attached, and even their own research is trying to discover why imported pathogens can exist for decades before they impact their host on an ecosystem-wide scale:
“Hemlock is a ‘foundation’ tree species in eastern forests and its presence defines the properties of a unique ecosystem that is presently declining due to the introduction and spread of an invasive insect, the hemlock woolly adelgid (HWA), which currently covers 25% of hemlock’s geographic range. However, the impacts of HWA are highly variable, causing rapid, stand-wide hemlock removal in some regions and little visible impact in others.”
“…The relationship among winter temperatures, HWA populations, and hemlock impact is generally assumed to be temperature-driven. However, in many parts of the HWA range, sites with similar climates experience diverse HWA-related impacts, ranging from apparent coexistence of HWA with hemlock for over a decade to complete collapse of the hemlock ecosystem in under five years.”
“This research integrates experimental and field data with Bayesian data-model assimilation techniques and GIS to evaluate how multiple interacting forces, including climate, air pollution and other insect pests, generate spatio-temporal heterogeneity in hemlock forest decline.”
4. Ozone Is Toxic
Oddly enough, in 2008, Lovett was the lead author when the Cary Institute together with The Nature Conservancy produced a report about a century of air pollution’s impacts on the Eastern US ecosystems, having convened 32 experts to evaluate hundreds of studies. A press release said:
“If you are living in the eastern United States, the environment around you is being harmed by air pollution. From Adirondack forests and Shenandoah streams to Appalachian wetlands and the Chesapeake Bay, a new report by the Cary Institute and The Nature Conservancy has found air pollution is degrading every major ecosystem type in the northeastern and mid-Atlantic United States.”
“The report, Threats From Above: Air Pollution Impacts on Ecosystems and Biological Diversity in the Eastern United States, is the first to analyze the large-scale effects four air pollutants are having across a broad range of habitat types. The majority of recent studies focus on an individual pollutant. More than 32 experts contributed to the effort; the prognosis is not good.”
“’Everywhere we looked, we found evidence of air pollution harming natural resources,’ said Gary M. Lovett, Ph.D., an ecologist at the Cary Institute and the report’s lead author. ‘Decisive action is needed if we plan on preserving functioning ecosystems for future generations.’”
“Co-author Timothy H. Tear, Ph.D., of The Nature Conservancy, notes, ‘Deposited pollutants have tangible human impacts. Mercury contamination results in fish that are unsafe to eat. Acidification kills fish and strips nutrients from soils. Excess nitrogen pollutes estuaries, to the detriment of coastal fisheries. And ground-level ozone reduces plant growth, a threat to forestry and agriculture.’”
“The report urges U.S. policymakers to establish air quality standards based on critical loads. This is defined as the maximum level of deposited pollution ecosystems can tolerate before harmful effects occur. By establishing thresholds, pollutants can be regulated in a way that preserves functioning ecosystems. In some areas, such as Rocky Mountain National Park, federal agencies have already adopted this approach to evaluate air pollution threats. It is also being used to regulate air pollution throughout Europe.”
“Establishing critical loads will require renewed investment in monitoring programs for air pollution and the ecosystems it affects. ‘We can’t assess if ecosystems are harmed by air pollution if we don’t monitor them. While some good pollution monitoring programs exist, our current system is fragmented, underfunded and has serious gaps,’ Lovett said.”
“While there may be initial costs to ramping up monitoring efforts, consider the alternative. The fishless lakes of the Adirondacks are a harsh reminder air pollution does not recognize property lines. Tear concludes, ‘In the absence of critical loads, there is a false security in conventional land conservation. We can manage natural areas with the best possible protocols, but we can’t really ‘protect’ the land if it is continually exposed to air pollution.’”
Here’s a link to the actual report, Threats From Above, one part of which states:
“The fog and mist that are so prevalent in alpine and subalpine ecosystems carry high loads of acid pollution. There have been few studies on acid deposition’s impact on alpine ecosystems in the eastern or western U.S. However, the effects of acid deposition in the subalpine zone of the eastern U.S. have been studied in great detail. There, acid deposition leaches calcium from the needles of red spruce trees, rendering the tree less frost hardy and causing winter damage and in many cases, tree death. This impact is thought to be responsible for the widespread spruce decline observed in northeastern mountains during the 1980s, a problem that continues to this day.”
“Ozone gas (O3) is formed in the atmosphere when nitrogen oxides react in the presence of sunlight with other gases known as volatile organic compounds. Research on the effects of ozone has shown clear impacts on plant growth and other vital functions. Once ozone enters a plant through small pores known as stomata, it reduces the plant’s ability to harness sunlight for growth. While ozone at the levels found in the eastern U.S. usually does not kill plants outright, it does slow their growth and may make them more susceptible to other fatal stresses such as insect attack or disease.”
“Ozone exposure also can reduce the flowering of some plants, compromising the establishment of new plants. In addition, ozone can slow the rate of decomposition of leaves shed from plants. Because plant species vary in their sensitivity, ozone can shift the competitive balance among plant species in a forest to the detriment of sensitive species such as white ash, black cherry, and American sycamore. Further, ozone exposure can cause changes in the genetic structure of plant populations by reducing or eliminating sensitive individuals. Studies show that ambient levels of ozone can decrease forest productivity in the Northeast from 2 percent to 16 percent, with potential economic consequences.”
Caption: “Ozone can damage the leaves of native trees and other plants, as illustrated by the brown spots on the needles of this white pine. © Andrew Boone from ForestryImages.org”
“Invasions of non-native species also interact with air pollution. Deposition of nitrogen may make some habitats more suitable for weedy invasive plants and may make trees more susceptible to exotic pests.”
The report ends with A Call to Action:
“Air pollution harms every major ecosystem type in the northeastern and Mid-Atlantic States, producing economic losses, reducing scenic beauty, decreasing the value of conservation investments, and damaging forests, lakes, rivers, wetlands, and coastal waters. Despite these widespread impacts, there are no standards in place to actually limit the amount of pollution deposited to the landscape.”
“Conventional land protection tools and current air pollution regulations are necessary but insufficient to protect the nation’s life support systems from high levels of atmospheric pollutants such as sulfur, nitrogen, mercury and ozone. The science shows that we must act to address this dangerous gap.”
It’s actually a pretty good report, I recommend reading the whole thing and checking the extensive references to scientific studies. And of course, although it’s about the eastern US that doesn’t mean the same stresses aren’t occurring everywhere else on earth:
Caption: “Nitrogen deposition has serious impacts on Rocky Mountain National Park in Colorado. Critical loads have been established for this park to help evaluate the threat. © Melannie Hartman”
But how the scientists could go from writing that and similar passages in 2008, to declaring that insects are more of a problem than pollution today, I can only imagine…particularly because the real problem is fungus transmitted by insects.
The kauri tree in New Zealand, which is dying from an oomycete, even has its own website, where we learn that, although the presence of the water mold was known for at least 40 years, it wasn’t until 2008 that widespread dieback was perceived as a threat, even on very young saplings. The hemlock has several websites, like one in North Carolina.
One well known symptom of pollution is premature senescence – early leaf color and drop in the fall. Well before Sandy this autumn, the trees on were losing leaves early, many skipping bright colors altogether and just turning brown, a trend that has been notably accelerating the past few years.. Many photos and comparisons to prior years can be seen here, here and here…if you like that sort of thing!
One comprehensive meta-analysis of forest losses due to ozone was Victoria Wittig’s dissertation. An article in PhysOrg about her research, from December, 2008, states:
“Modern day concentrations of ground level ozone pollution are decreasing the growth of trees in the northern and temperate mid-latitudes, as shown in a paper publishing today in Global Change Biology. Tree growth, measured in biomass, is already 7% less than the late 1800s, and this is set to increase to a 17% reduction by the end of the century.”
“The study is the first statistical summary of individual experimental measurements of how ozone will damage the productivity of trees, including data from 263 peer-reviewed scientific publications…But more importantly, it has the potential to leave more carbon dioxide, ranked as the first strongest greenhouse gas, in the atmosphere by decreasing carbon assimilation in trees…’”
“‘This research quantifies the mean response of trees to ozone pollution measured in terms of total tree biomass, and all component parts such as leaf, root and shoot, lost due to ozone pollution,’ said Dr. Victoria Wittig, lead author of the study. ‘Looking at how ozone pollution affects trees is important because of the indirect impact on carbon dioxide concentrations in the atmosphere which will further enhance global warming, in addition to ozone’s already potent direct impact.’”
“‘Beyond the consequences for global warming, the study also infers that in mixed forests conifers will be favored over broad-leaved trees, and that the decrease in root size will increase the vulnerability to storms,’ said Wittig.”
Last sentence of the abstract: “This implies that a key carbon sink currently offsetting a signi?cant portion of global fossil fuel CO2 emissions could be diminished or lost in the future.”
“Diminished or LOST.”
In 1986, a fumigation study – Regional tree growth reductions due to ambient ozone: evidence from field experiments – demonstrated reductions in growth of sycamore saplings even when they were exposed to levels below the levels of exposure were below air quality standards:
“Observations from extensive regions in Europe and North America suggest that many forests may be in early stages of ecosystem decline. The authors present experimental evidence from open-top chamber field studies indicating that ambient ozone at levels below the ambient air quality standard (235 ..mu..g m/sup –3/) causes significant reductions (19%) in the growth of sapling poplars (hybrid Populus). While ozone-induced reductions in growth have been observed under laboratory and greenhouse conditions, demonstration of this effect under field conditions is critical to the establishment of ozone standards. Growth reductions for Populus deltoides and Robinia pseudoacacia were not significant. Reductions in productivity and height growth occurred without visible symptoms of foliar injury and at ozone concentrations below current standards. If this invisible injury is typical in other tree species, the extent of ozone-induced forest damage may presently be greatly underestimated. Additional field studies on a regional basis are needed.”
Excerpts from an article designed for the general public by Dr. Mary Topa are also reproduced here. The title reads:
Smog may be contributing to the decline of sugar maples, one of Northeast Ohio’s iconic trees — and our high-mileage lifestyle is a big cause.
“On average, tropospheric ozone is increasing at 0.5–1 percent per year. However, tropospheric ozone is considered a regional pollutant, and urban areas are major sources of ozone precursors that can travel hundreds or thousands of kilometers.”
“The overall effects of ozone in plants are that it damages tissues and accelerates cellular aging in leaves, not unlike what happens when ozone enters our lungs. Ozone enters the leaf through open stomata. Once in the leaf, ozone reacts with water to form highly reactive, oxygen free radicals, damaging membranes and directly inhibiting photosynthesis.”
“Plants may close their stomata so that ozone cannot enter the leaf; however, this avoidance mechanism also prevents atmospheric CO2 from entering the leaf and carbon fixation rates decline. Plants that are more tolerant to ozone synthesize antioxidant compounds that scavenge these oxygen free radicals before damage occurs, and often repair tissue if damaged.”
“In some tree species that are more tolerant to ozone, there will be no visible sign of foliar injury; however, a reduction in growth often occurs because newly-fixed carbon is reallocated to antioxidant production and injury repair mechanisms.”
“Although Acer saccharum (sugar maple) has been considered moderately ozone tolerant, some of my research has shown that ozone not only accelerates visible signs of leaf senescence in sugar maple, but that leaf physiological processes such as photosynthesis start shutting down in August under ozone levels typical of what we find at Holden.”
“This significant decline in photosynthesis in mid-to late August reduced the seasonal carbon fixation for some maple trees by as much as 25–30 percent and reduced growth in some plants by as much as 50 percent by the end of a three-year exposure regime.”
“Trees are long-lived perennial organisms that have a carbon storage system (similar to a savings account) that they can tap into during times of stress. Ozone is a background stress for many urban-influenced trees, and it is one that negatively impacts a tree’s ability to fix and store carbon. Any reduction in stored carbon can not only reduce growth, but increase a tree’s susceptibility to other stresses such as pest or pathogen invasion.”
“Smog is an air pollutant stress that is often overlooked as one of the multiple, interacting causes of sugar maple decline, most likely because, until the last decade, sugar maple was thought to be fairly tolerant to ozone. ”
The US EPA has produced a report in support of stricter ozone regulation. The “Welfare Risk and Exposure Assessment for Ozone – First External Review Draft” refers to effects on the ecosystem (as opposed to human health). The draft was circulated last summer and comments from the Science Advisory Board were posted last November. You can go to the originals at those links but the draft is hundreds of pages long with all sorts of excellent appendices and references – for more fun you could go to my post about it at Wit’s End, which has the juiciest parts and graphs.
Briefly, the report models “relative biomass loss” from ozone exposure for different tree species and reaches various conclusions, among them:
“Across species, the estimated potential O3-related biomass loss associated with recent O3 concentrations ranged from 0.1 percent for Douglas fir to almost 100 percent for Eastern Cottonwood. The estimated median potential O3-related biomass loss for individual species ranged from 0 percent for Douglas fir to 56 percent for Eastern Cottonwood.”
“The C-R function for some species (e.g. sugar maple) demonstrates a very rapid change in biomass loss over a small range of O3 concentrations, 30 to 35 ppm for sugar maple, that behaves similar to a threshold.”
“After simulating just meeting the current secondary O3 standard, the estimated potential O3-related biomass loss for individual tree species was on average 70 percent of the estimated potential biomass loss at recent O3 levels, with a range between 8 and 89 percent.”
The report explains the complicated “non-linear” chemistry of ozone formation. Section 2.3 says:
“In rural areas and downwind of urban areas, O3 production is generally NOx-limited. This is particularly true in rural areas such as national parks, national forests, and state parks where VOC emissions from vegetation are high and anthropogenic NOx emissions are relatively low. Due to lower chemical scavenging in non-urban areas, O3 tends to persist longer in rural than in urban areas and tends to lead to higher cumulative exposures in rural areas than in urban areas.”
Section 6.4, Discussion, states:
“O3 damage to vegetation and ecosystems causes widespread impacts on an array of ecosystem services. Biomass loss impacts numerous services including supporting and regulating services such as net primary productivity, community composition, habitat, and climate regulation. Provisioning services are also affected by biomass loss including timber production, agriculture, and non-timber forest products. Cultural services such as non-use values, aesthetic services, and recreation are all affected by the damage to scenic beauty caused by foliar injury due to O3 exposure. It is possible for several aspects of O3 effects to interact to contribute to an impact on ecosystem services. For example biomass loss directly impacts timber provision but other contributing effects include increased susceptibility to drought and insect attack. ”
“The regulating services identified as potentially affected by O3 exposure include climate, water, pollination, and fire regulation.”
Did you catch how they snuck in “fire regulation?” That’s because, I assume, we can expect many more and much more intense wildfires since vegetation is turning into tinder…oh, wait…
Figure 2- 2 “Conceptual diagram of the major pathway through which O3 enters plants and the major endpoints that O3 may affect in plants and ecosystems. Figure numbers in this figure refer to Chapter 9 of the ISA. (Ozone Integrated Science Assessment, US EPA 2012)”
Caption: “Overall causal determinations are made based on the full range of evidence including controlled exposure studies and ecological studies. Figure 2- 3 shows the O3 welfare effects which have been categorized by strength of evidence for causality in the O3 ISA (US EPA, 2012a, chapter 2). These determinations support causal or likely causal relationships between exposure to O3 and ecological and ecosystem level effects.”
Figure 4–1 Individual monitor 8-h daily max O3 design values displayed for the 2008–2010 period (U.S. EPA, 2012, Figure 3–52A)
Figure 5- 12 Summed Relative Biomass Loss (scaled) for 7 species, excluding eastern cottonwood, under ambient O3 conditions…
No wonder they left out Cottonwood:
And keep in mind that this is reduction in growth from ambient ozone and doesn’t include the far, far more serious knock-off effects of biotic attacks and increased susceptibility to drought and wind.
The fact is, that there have been an absolutely staggering number of papers written and research done indicating that ozone is poisonous to plants. With the miracles of the interwebs, you can do a search that yields more articles and papers and books than you could read in a lifetime, which sort of begs the question…if it’s not such a bad problem, why have people spent their entire careers studying it?
5. Proof that Ozone Predisposes Pathogen Attacks
It is of paramount importance to understand that plants compromised by pollution become more susceptible to attacks from pathogens. Most foresters are downright hostile to the notion even though it has been demonstrated many times, including in controlled fumigation experiments, and the mechanisms through which trees are weakened and lose immunity are well accounted for. These secondary, opportunistic attacks are what magnify the effects of pollution and finish off the trees.
Here is the first paragraph of a 2004 research paper, Influence of Ozone and nitrogen deposition on bark beetle activity under drought conditions:
“In a healthy forest, the distribution of bark beetles and pathogenic fungi is typically limited to a few stressed trees. Bark beetle activity on weakened trees results in scattered tree death which can increase habitat complexity for wildlife, reduce tree crowding, create canopy openings and promote plant diversity. However, stresses such as drought and air pollution can contribute to reduced tree resistance to beetle attack, and many trees in a stand could be affected. Consequently, many trees may become susceptible to beetle colonization and large-scale tree mortality could be an outcome.”
Following is the abstract, and notice, this happened in southern California where is never freezes, quite independently to a lack of cold temperatures, which is typically blamed for bark beetle attacks further north:
“Four years of severe drought from 1999 through 2003 led to unprecedented bark beetle activity in ponderosa and Jeffrey pine in the San Bernardino and San Jacinto Mountains of southern California. Pines in the San Bernardino Mountains also were heavily impacted by ozone and nitrogenous pollutants originating from urban and agricultural areas in the Los Angeles basin. We studied bark beetle activity and bark beetle associated tree mortality in pines at two drought-impacted sites in the San Bernardino Mountains, one receiving high levels of atmospheric pollutants, and one with more moderate atmospheric input.We also investigated the effects of nitrogen addition treatments of 0, 50 and 150 kg N ha–1 year–1 at each site.”
“Tree mortality and beetle activity were significantly higher at the high pollution site. Differences in beetle activity between sites were significantly associated with ozone injury to pines, while differences in tree mortality between sites were significantly associated with both ozone injury and fertilization level. Tree mortality was 9% higher and beetle activity 50% higher for unfertilized trees at the high pollution site compared to the low pollution site. Tree mortality increased 8% and beetle activity increased 20% under the highest rates of nitrogen additions at the low pollution site.”
From Michigan Tech:
Ozone: Bad for Trees, Good for What Eats Them
“The trees of the future may be much more vulnerable to a variety of pests, say scientists studying greenhouse gases in northern Wisconsin forests. Their work is published in the Nov. 28 edition of the journal Nature.”
“Researchers in the Aspen FACE (Free-Air Carbon Dioxide Enrichment) Experiment, based in Rhinelander, Wis., have been measuring the effects of elevated levels two greenhouse gases, carbon dioxide and ozone, on aspen forest ecosystems. While the trees, Populous tremuloides (trembling aspen), seem to do relatively well in a carbon dioxide-rich atmosphere, ozone is another story.”
“Trees growing in an ozone-enriched atmosphere have been hit much harder by their traditional enemies: forest tent caterpillars, aphids and the rust fungus Melampsora.”
“’This has been a surprise,’ said Professor David Karnosky of Michigan Technological University’s School of Forest Resources and Environmental Science, a principal investigator on the Aspen FACE project. ‘Our experiment was never meant to look at pest occurrence. But it became obvious that the greenhouse gases were affecting the abundance of pests.’
The number of aphids increased about five-fold in plots with elevated ozone, while the number of aphid predators was cut in half. In plots with elevated levels of both carbon dioxide and ozone, the aphid population tripled, while the number of natural enemies increased slightly, mitigating the aphids’ effect on the aspen.”
“Melampsora infection in the control and CO2-enriched plots was about the same, but increased about 400 percent in the O3 plots and doubled in the plots with extra CO2 and O3. The number of forest tent caterpillars increased by about one-third in the O3 plots and actually decreased slightly in the CO2 plots and the plots with extra CO2 and ozone.”
There is a video of the experimental station, embedded here, with interviews of the researchers.
Dr. Karnosky: “We’re seeing increased levels of mortality…we’re seeing increased levels of insect and disease attack. We see injury both on lower leaf surface and the upper leaf surface.”
Dr. Kubiske: “The first effect is the air pollution… it’s all the biotic stuff that moves in after that…the sharks that smell blood in the water so to speak, that causes real problems.”
In 1999, a book was published, titled Environmental Pollution and Plant Responses. Excerpts posted here, from Chapter 9, Effects of Tropospheric Ozone on Woody Plants, follow:
“Many studies show that ambient O3 concentrations are potentially high enough to cause significant reductions in growth and yields of agricultural crops and trees. In this chapter, the overall responses and reactions of woody plants to tropospheric O3 levels are discussed at different hierarchical levels of organization based on an extensive, recent literature review. Furthermore, the variation in response to O3 among different genera and the interactions with other biotic and abiotic factors are documented.”
“…Oscillations in gas exchange have also been measured in response to O3, and this is attributed to loss of stomatal control and an uncoupling of the relationship between photosynthesis and stomatal conductance. This results in a disturbed water balance, reduced ability to control water loss, and higher sensitivity to drought. Accordingly, reduce water use efficiency has been reported in response to O3.”
“…A loss in canopy carbon gain will not only result from loss of photosynthetic capacity by individual leaves, but to a greater or lesser extent by a decrease of photosynthesizing leaf area caused by accelerated leaf shedding.”
“…The appearance of characteristic lesions on the leaves, chlorosis, bleaching, and accelerated abscission of leaves have long been known to be associated with elevated O3 levels. These signs of damage by O3 are observed especially on older and mature leaves.”
“Ozone-induced visible injury frequently is used to assess forest damage, although the extent of foliage injury does not necessarily correlate with physiological damage or reductions in growth….Biochemical and physiological injury may occur before the appearance of any visible symptoms. Acute ozone stress will generally result in visible symptoms, but low concentrations over long periods may lead to hidden damage without the appearance of visible foliar injury.”
“… In many tree species O3 stimulates senescence processes. Natural senescence is characterized by a controlled degradation of cellular and leaf functions during which cellular constituents are remobilized before abscission. Lippert et al demonstrated high nitrogen (N) losses for beech after O3 exposure due to inhibited N-translocation before leaf drop, which differs from natural autumnal senescence where N is withdrawn from the leaves. Similar results were reported for birch. Ozone-induced degradation of leaves should therefore not be confounded with natural senescence, as it seems more like an unregulated degradation than an accelerated natural senescence.”
“…Chlorosis is not a primary result of O3 exposure, but a secondary effect due to impaired photosynthetic capacity. When chlorophyll molecules are arranged structurally in thylakoids, they are very resistant to direct oxidation, and chlorosis more likely is associated with accelerated senescence than with direct effects of O3, or its oxidative products.”
“…For several poplar hybrids exposed to O3, visible effects on stems have been reported. Where leaves were shed, lesions or intumescences appeared on the stems, resulting in bark cracking and the exposure of soft cortical tissue. It has been hypothesized that ethylene is possibly responsible for the induction of these stem lesions.”
“…Ozone causes reduction in carbon uptake by reduction of photosynthesis and of photosynthetic leaf area. The subsequent translocation of carbon to different plant organs and to different pools can also be altered by O3. In many tree species carbon retention is increased in the leaves and consequently carbon allocation to the roots is reduced. Very often, the shoot/root ratio increases following O3 exposure, due to higher reductions in root growth than in shoot growth.”
“This higher retention of C in the leaves may be explained by higher carbon demands for repair of damaged foliage, by reduced assimilate transport in the phloem, or by decreased phloem loading. In loblolly pine needles a decreased partitioning of assimilated carbon into starch and protein, and an increased partitioning into organic acides, lignin, plus structural carbohydrates, and lipids plus pigments has been reported after O3 exposure.”
“It is the ability to produce phloem that protects the tree from insect infestations.
This shift in partitioning from storage compounds to soluble carbohydrates and carbon compounds involved in repair might be a compensatory response to maintain photosynthetic rates. Effects on the amounts of foliar starch are sometimes contrasting, since both increases and decreases have been reported. Further research is needed to elucidate the mechanisms underlying the effects of O3 on carbohydrate metabolism.”
“…Reduced root growth can alter the functioning of rhizosphere organisms and could make trees more susceptible to drought or nutrient deficiency. Andersen et al. reported lower carbohydrate levels in new roots of ponderosa pine seedlings after O3 exposure, which may result in reduced plant growth over time. In addition, O3 exposure during one year resulted in less new root growth in the year following exposure (carryover effect).”
“…Ozone can alter the response of trees to biotic stresses. Damage due to O3 may change their tolerance or resistance to insect herbivores and plant pathogens. In general, O3 exposure has shown to increase palatability, increase herbivorous consumption, and enhance insect performance. In addition to increased susceptibility to invasion by plant pathogens, inhibitory effects of O3 against microorganisms and fungi have been reported as well. Mycorrhizae have been shown to offer beneficial effects in ameliorating O3 stress, while O3 can have negative effects on mycorrhizal development. A decrease in photosynthesis and carbon allocation to the roots would imply less carbohydrates available for the mycorrhizae.”
“…Tropospheric O3 has profound negative impacts on the growth, development, and productivity of many plants and vegetations, including trees and forests. Significant effects of O3 have been observed on a wide range of characteristics such as early leaf senescence, decreased photosynthetic assimilation, altered stomatal behavior, decreased growth and productivity, and reduced carbon allocation to roots. Although related species or genera may show very different responses to O3, and there may be large differences in sensitivity between different cultivars or clones of the same species, the initial mechanism of O3 induced stress on plants is uniform.”
“…A better understanding of the effects of O3 and O3-derived oxidants is necessary for a more-detailed insight into the impact of O3 on plant growth and development. As rising tropospheric O3 levels are likely to be a continuing problem, overall growth and yield of trees and forests may be increasingly affected. In particular, the responses of trees to increased tropospheric O3 levels in combination with other environmental changes will play a very important role in determining growth, development, survival, and abundance of individual plants as well as plant communities in the future.”
6. Ozone Pollution is Inexorably Worsening
There is a common misperception in developed nations that the Clean Air Act in the US and regulations in other countries fixed air pollution long ago. This conceit has been abetted by three facts:
- The reduction in SO2 – the dirty, smelly part of smog – has not been matched by a reduction in NOx, which is an invisible, but a highly toxic precursor to ozone.
- Tall smokestacks have disbursed precursors; and, perhaps most important
- We exported our manufacturing to Asia, which, combined with the transport of goods
and the overall, global surge in population, has been increasing pollution and bringing it right back to us.
There is so much readily available information available about all of those issues that I hardly see any point in going into it extensively. It should suffice to share two links.
First: a Princeton team, Lin et al, has been using satellites to track the travel of emissions from Asia where:
“…we quantify the contribution of Asian pollution to surface O3 levels on highly polluted days in both densely populated regions such as the Los Angeles (LA) Basin and in rural areas such as national parks.”
Second: Watch this brief BBC video, Great Smog 60 Years On, which illuminates the difference between the “old” pollution from sulpher dioxide which caused acid rain, and the ever-increasing problem of tropospheric ozone.
The compartmentalization and separation of pollutants (never mind the synergy between them) by regulators, academics, and the big green activist organizations and think tanks serves very effectively as a strategy to dilute public understanding, which is discussed in more detail here. One absurd tactic is to separate nitrogen pollution from ozone, when they are inextricably intertwined. The famous study delineating Nine Planetary Boundaries, for example, lists the nitrogen cycle as one threshold that has been violated. The report from the integrated Nitrogen Committee is discussed in this post. Also referred to as the “Nitrogen Cascade” – as in, an out-of-control gush…or then again as, “the biggest environmental disaster you’ve never heard of” according to Professor Townsend of University of Colorado.
From the article linked to above, where he is quoted:
“By 2005, human activity was producing about 400 billion pounds of reactive nitrogen each year.”
A not inconsiderable portion of this derives from the insane production of corn for biofuels.
“‘A single atom of reactive nitrogen can contribute to air pollution, climate change, ecosystem degradation and several human health concerns,’ Townsend said. He is an ecology and evolutionary biology professor at the University of Colorado at Boulder. Damage to the ecosystem — a biological community interacting with its nonliving environment — includes water pollution and reduced biological diversity, including the loss of certain plant species.”
“Though the full extent is currently unknown, nitrogen pollution can impact human health. Reactive nitrogen is a key contributor to air pollution, including the formation of ground-level ozone, which is a well-known health risk. Recent estimates suggest that nitrogen-related air pollution costs the U.S. well over $10 billion per year in both health costs and reduced crop growth.”
Thus these sources of reactive nitrogen are inextricably connected to ozone but not monitored, measured, or regulated as described in great detail at this post about the report of the EPA Science Advisory Board on Reactive Nitrogen mentioned above above:
Passages from the cover letter to the administrator summarize the report:
“The introduction of human created Nr into the environment degrades air and water quality, which can cause harmful algae blooms, hypoxia, fish kills, loss of drinking water potability, loss of biodiversity, forest declines, and human health problems resulting in losses of billions of dollars per year.”
“The greater the inputs of Nr to the landscape, the greater the potential for negative effects caused by greenhouse gas (GhG) production, ground level ozone, acid deposition, and Nr overload that can contribute to climate change, degradation of soils and vegetation, acidification of streams, lakes and rivers, estuarine and coastal eutrophication, hypoxia, and habitat loss. (p. ES3)”
“…Reactive nitrogen (Nr) includes inorganic chemically reduced forms of N (NHx) [e.g., ammonia (NH3) and ammonium ion (NH4+)], inorganic chemically oxidized forms of N [e.g., nitrogen oxides (NOx), nitric acid (HNO3), nitrous oxide (N2O), N2O5, HONO, peroxyacetyl compounds such as peroxyacytyl nitrate (PAN), and nitrate ion (NO3-)], as well as organic compounds (e.g., urea, amines, amino acids, and proteins).”
“…The negative consequences of Nr flux in the U.S. environment include increases in photochemical smog and atmospheric particulate matter (pM2.5), decreases in atmospheric visibility, both increases and decrease in productivity of grasslands and forests, acidification of soils and freshwaters, accelerating estuarine and coastal eutrophication, increases in the emission of greenhouse gases (GhG) to the atmosphere, and decreases in stratospheric ozone concentrations.”
“….3.3. Impacts of Nr on Terrestrial Ecosystems…
As previously discussed, in many terrestrial ecosystems the supply of biologically available Nr is a key factor controlling the nature and diversity of plant life, and vital ecological processes such as plant productivity and the cycling of carbon and soil minerals. Human activities have not only increased the supply but enhanced the global movement of various forms of nitrogen through air and water…”
>“Ozone-induced predisposition of forest trees to damage by fungal diseases and insect pests, most clearly established in the case of root disease and bark beetles in the pine forests of southern California.”
“…It is clear that a causal relationship exists between current levels of N and S deposition and numerous biologically adverse effects on ecosystems across the U.S.”
“…Ozone and PM, the two most recalcitrant of the criteria pollutants, cover large spatial scales. All of the ozone and much of PM are secondary pollutants in that they are not released at the tailpipe but form in the atmosphere. Ample evidence shows that much or most of the PM in American cities is secondary. Violations are declared on urban scales, responsibility for their control was assigned to states, but the physics and chemistry of smog and haze are regional. In the eastern U.S., ozone episodes often cover several states and involve pollutants emitted in upwind states that do not themselves experience violations.”
As if all these sources weren’t enough, it happens that methane is also a precursor – a long-lived, well mixed source of background ozone…and methane is being released via numerous pathways.
Fugitive releases of methane, from fracking and at all points of production and distribution, are going up – and then there is also outgassing in the Arctic and tundra from melting permafrost and the seabed.
The European Environmental Bureau issued a call to include methane within the National Emission Ceilings Directive in order to curb ozone. I added emphasis to the most important points.
“Methane is both a powerful greenhouse gas and an ozone precursor. Reducing methane emissions therefore has simultaneous benefits for both climate change mitigation and human health. “
“However, there is currently no direct regulation of methane emissions in the EU. Methane is specifically excluded from the National Emissions Ceilings Directive and the Industrial Emissions Directive. It is only indirectly addressed through directives on waste, landfill, biofuels and nitrates and through the Common Agricultural Policy.”
“The forthcoming revision of the NECD is an opportunity to fill this regulatory gap. This note therefore makes the case for the inclusion of national ceilings for methane in the 2013 revision of the NECD.”
“Methane is a major source of background tropospheric ozone.”
“Together with particulate matter, ozone is the air pollutant with the highest estimated impact on human health. Ozone is a powerful and aggressive oxidising agent, elevated levels of which cause respiratory health problems and lead to premature mortality. High levels of ozone can also damage plants, leading to reduced agricultural crop yields and decreased forest growth.”
“Current measures on ozone precursors have focused primarily on decreasing the peaks of ozone, especially in urban areas, and therefore on precursors such as NOx and non-methane VOCs. However, over the past decades background levels of tropospheric ozone have been steadily rising. While many of the cheapest and easiest measures to decrease these other ozone precursors have already been taken, specific controls for methane are still lacking.”
“Methane is a relatively short-lived gas, with an atmospheric lifespan of 12 years.
Cutting emissions of methane can therefore have an impact on global climate in the near term, thus complementing the benefits from necessary CO2 mitigation.”
“Because of the well-mixed nature of methane, measures taken anywhere can impact the availability of methane for ozone formation, and there is a strong continued role for action under the UNFCCC, for development assistance and innovative financial mechanisms that can aid in methane reductions in developing countries, and for methane’s inclusion in international agreements such as the Gothenburg Protocol due to transport of ozone from for example North America to Europe. It is nevertheless important that the EU lead in addressing methane also through its early regulation.”
“There is a scientific consensus around the need to reduce emissions of both short-lived climate pollutants, including methane and tropospheric ozone, as well as CO2, if dangerous global climate change is to be avoided.”
7. Annual Agricultural Crops
We have known from many studies that ozone shrinks the roots of trees. In one growing season the impact on potatoes is dramatic. The photo below is from a European website, Ozoneinjury.org. On the left are potatoes grown in filtered (clean) air, the middle group in non-filtered (ambient, 2002 polluted background levels) – and on the right, additional ozone added (30 ppb/8hours/day). This is from the research abstract: “In comparison with the ?ltered treatment, the ozone treatments signi?cantly reduced commercial tuber production, by 53% (NF) and 65% (NF+)”.
That is an excellent site in general, which has information both about ozone’s impacts on forests and crops, with an extensive library of photographs of visible symptoms on foliage and microscopic studies of tissue, quite a bit of which is reproduced at Wit’s End as well.
In 2011, a group of scientists at Princeton University published two studies, one examining the current reduction in crop yield due to ozone and a second companion study modeling what future scenarios might hold. The following is taken from the second paper, Global crop yield reductions due to surface ozone exposure: 2. Year 2030 potential crop production losses and economic damage under two scenarios of O3 pollution:
“Our results suggest that O3 pollution poses a growing threat to global food security even under an optimistic scenario of future ozone precursor emissions.”
Fig. 5. Total crop production loss (CPL, left panels) and economic loss (EL, right panels) under the 2030 A2 scenario for all three crops derived from (a) M12 and (b) AOT40 estimates of O3 exposure.
Following is the abstract of a 2010 study by NASA titled: An investigation of widespread ozone damage to the soybean crop in the upper Midwest determined from ground-based and satellite measurements.
“Abstract: Elevated concentrations of ground-level ozone (O3) are frequently measured over farmland regions in many parts of the world. While numerous experimental studies show that O3 can significantly decrease crop productivity, independent verifications of yield losses at current ambient O3 concentrations in rural locations are sparse. In this study, soybean crop yield data during a 5-year period over the Midwest of the United States were combined with ground and satellite O3 measurements to provide evidence that yield losses on the order of 10% could be estimated through the use of a multiple linear regression model. Yield loss trends based on both conventional ground-based instrumentation and satellite-derived tropospheric O3 measurements were statistically significant and were consistent with results obtained from open-top chamber experiments and an open-air experimental facility (SoyFACE, Soybean Free Air Concentration Enrichment) in central Illinois. Our analysis suggests that such losses are a relatively new phenomenon due to the increase in background tropospheric O3 levels over recent decades. [emphasis added] Extrapolation of these findings supports previous studies that estimate the global economic loss to the farming community of more than $10 billion annually.”
A series of excited headlines blared above an article in the UK Daily Mail, January 2012:
Pollution from America causes Europe to lose a million tonnes of wheat a year Man-made ozone can travel thousands of miles
Pollution on one continent can affect others
Loss in Europe is biggest worldwide
Separate from damage to ozone layer – caused by chemicals from combustion and power plants
“Man-made air pollution from north America causes Europe to lose 1.2 million tonnes of wheat a year, a new study has found. Ozone pollution – produced by coal fired power stations and cars – travels between continents much more easily than thought, traveling thousands of miles on the wind.”
“Crops on every continent are damaged by pollution from others. The wheat loss in Europe is the biggest worldwide. The chemical – a powerful air pollutant – is produced when pollutants near the ground react with sunlight.”
The researchers say that the pollution could even endanger the security of the food supply in future. Ozone pollution in all of the northern hemisphere’s major industrialised regions – Europe, America and southeast Asia – harms major crops such as wheat, maize, soy, cotton, potato and rice on other continents. The scale of the impact has previously been unknown.
“Dr Steve Arnold, a senior lecturer in atmospheric composition at the University of Leeds, who led the study, said: ‘Our findings demonstrate that air pollution plays a significant role in reducing global crop productivity.’”
“’It shows that the negative impacts of air pollution on crops may have to be addressed at an international level rather than through local air quality policies alone.’”
“…Dr Lisa Emberson a senior lecturer from the University of York: ‘This study highlights the need for air pollution impacts on crops to be taken more seriously as a threat to food security.
Air quality is often overlooked as a determinant of future crop supply. Given the sizeable yield losses of staple crops caused by surface ozone, coupled with the challenges facing our ability to be food secure in the coming decades further coordinated international efforts should be targeted at reducing emissions of ozone forming gases across the globe.’”
In a blogpost I discuss the transcript of a radio interview on Public Radio with Dr. John Reilly, from back in 2008, about his research at MIT:
Question: Ozone is not only bad for the lungs, but it’s also damaging to plants. Ground level ozone turns their leaves brown and spotty, and stunts their growth. It’s particularly noxious to crops. Ozone has already cut cereal production in the U.S. by about five percent, and at the current levels could slash world crop yields nearly 40 percent by the end of the century. Those figures come from John Reilly – he’s associate director of the MIT Joint Program on the Science and Policy of Global Change. He led a recent study on ozone and crops, and joins me now in the studio. Hello, Dr. Reilly.
Question: I gather looking at your study that you see ozone pollution as not only a city problem, but a rural problem, and a global one at that.
REILLY: Many years ago when some of the first clean air legislation was passed. I think people thought it was very much as just an urban problem. When measurements have extended, people have realized that the ozone actually lives in the atmosphere for a few months, and so over that time it spreads out across the landscape and in fact, over the course of three months you can have a lot of transport around the entire globe. And so that means that ozone can appear at high levels in different places. The actual ozone levels, then, get higher because the background level is higher.
Question: How surprised were you by the results of your study?
REILLY: Well I was, you know, dramatically surprised that the results were so negative, and we checked them several times. There is a threshold, 40 parts per billion of ozone in the atmosphere, above which damage starts occurring. What really happened here is that the actual ozone levels only increased 50 percent, but when measured above this threshold, the amount of ozone increased by six-fold. So that was a dramatic increase and led to this high damage.
Discuss Policy Relevant Background level with links to research at this post:
This is a critically important concept. For most of the history of the study of ozone, the emphasis has been on damage done by episodic high peaks. However, cumulative damage from persistent background ozone, which is inexorably increasing, is emerging as a far more serious threat.
As Reilly describes, because the background level is getting higher, when there are peaks even more damage is done. This is the problem the EPA has with regulation – the “Policy Relevant Background” level is so high that even though evidence is mounting that ozone is dangerously high for people and for vegetation, the EPA cannot tighten regulations because the PRB is almost at the level of regulations already in many places. So for numerous rural areas downwind of precursor emissions, they will be penalized for non-compliance, but because the background level is so high, there’s nothing they can do to prevent exceedences. That is what Reilly was referring to in his last sentences referring to the threshold, and that is why the Obama administration notoriously refused to let (soon to be former) EPA Administrator Jackson tighten the regulations over which rumor had in the New York Times it she contemplated resignation over a year ago. And now she has. I discuss the PRB controversy extensively here.
I cannot resist the temptation to digress to a case history, that of lung cancer and smoking.
Following is an observation from a book, Air Quality, written by the late Professor Thad Godish. First published in 1997, the 4th edition dates from 2005, p. 188
“…It is probable that tobacco smoking has caused a high percentage of diagnosed cases of such diseases as COPD because smokers have a higher incidence of these diseases than nonsmokers.
“Tobacco smoking is a major cause of human cancer. Strong epidemiological evidence exists to implicate smoking as the causal factor in lung cancer and cancers of the larynx, oral cavity, esophagus, urinary, bladder, kidney, and pancreas. Overall, lung cancer risk for smokers is about 10 to 12 times greater than that for nonsmokers.”
“In the public mind, lung cancer is the most important health consequence of smoking. It is not generally realized that smoking-related mortality from cardiovascular disease is approximately twice that for all forms of smoking-related cancer. Smoking is a major independent risk factor for heart attacks in adults. It also appears to contribute to more severe and extensive atherosclerosis of the aorta and coronary arteries.”
What parallel does the health effects from smoking have to do with tree mortality? Several. First of all, we have been in effect forcing the trees to indulge in a very bad smoking habit and so it would be surprising if they weren’t showing signs of the arboreal equivalent of lung or heart disease. This is particularly so because vegetation ingests carbon not only to “breathe” but to absorb energy. Proportionately to animals that breathe air for oxygen, but eat food, plants take in far more of whatever is in the air, including ozone. But what is interesting is that none of the diseases listed above have been PROVEN to result from smoking, or even which part of smoking – tar? nicotine? chemicals? – which is what enabled the tobacco industry to get away with, literally, murder for so long.
What finally led to consensus and acceptance of causality from tobacco was the overwhelming epidemiological connection, which was so emphatic more than just correlation was implied. I maintain the same can be said for forest decline and air pollution.
I suppose a skeptic could say that unlike with tobacco use, there is no control population to compare with, since trees everywhere are sharing the same atmosphere. However, that’s not quite true because there did exist a control group, which would be all those millions of trees over thousands of years that did just fine before the industrial revolution started creating pollution, as evidenced by the ancient trees that greeted the Europeans before they began slashing the forests in every continenet from North and South America, to New Zealand, Africa, Asia and Australia, having already denuded their own.
But let’s see what Dr. Godish had to say. In the preface to the newest edition he wrote:
“In the 1970s and 1980s, acidic deposition was identified as a major environmental concern in North America, and we responded by enacting and then implementing major acidic deposition control measures. In conducting research studies on acidic deposition, it became increasingly apparent that it was only a part of a much larger environmental concern, atmospheric deposition, which includes mercury, nitrate nitrogen and organochlorine compounds such as pesticides, polychlorinated biphenyls (PCBs), dioxins and furans.”
“The health protection issues that dominate air quality management in the U.S. continue to evolve as more powerful statistical procedures increasingly demonstrate that pollutant exposures at levels previously considered safe cause adverse health effects, with a resultant need for more stringent regulatory requirements. This has been particularly the case for ozone and PM2.5.”
There is available online a powerpoint presentation for a lecture given in a 2008 Spring semester course at the University of Florida, by Dr. Chang-Yu. It’s based on Chapter 6 of the aforementioned book, titled “Welfare Effects” – which refers to the damage done by pollution to agricultural crops, ornamental plants, and trees, as opposed to human or animal or insect health (a neglected area of study). The slides end with the words “Air is pervasive; Effects are felt throughout the world.” Some of those slides are interspersed with sections from Chapter 6.
“Plants have long served as sentinels of the biological injury that air pollutants are capable of producing as a result of acute and chronic exposures. Phytotoxic responses to pollutants such as SO2, hydrogen chloride (HCl), and hydrogen fluoride (HF) have been reported in Europe since the middle of the 19th century.”
“…Until the 1940s and 1950s, damage to agricultural crops, ornamental plants, and forests was, for the most part, a problem associated with point sources. As a result of intensive scientific investigation, the widespread injury to agricultural crops observed (as early as the mid–1940s) in the Los Angeles Basin was determined to be due to phytotoxic air pollutants such as O3 and peroxyacyl nitrate (PAN), produced in the atmosphere as a result of photochemical reactions.”
“…Ozone injury on sensitive vegetation has since been observed throughout the U.S. and many parts of the world. Ozone levels sufficient to cause injury on very sensitive vegetation are reported in most areas east of the Mississippi River. Because of its ubiquitous distribution and high phytotoxicity, O3 is the most important phytotoxic air contaminant.”
“Control efforts and changes in operating practices have resulted in a significant reduction in the localized plant damage that had been associated with many point sources. Paradoxically, one of these changes, the use of tall stacks for more effective dilution of emissions from coal-fired power plants, has, as expected, resulted in decreased injury to vegetation in the vicinity of these sources, but inadvertently contributed to the problem of long-range transport and atmospheric deposition of strong acids and other pollutants.”
“Injury to plants can be manifested as visible or subtle effects. The former are identifiable changes in leaf structure, which may include chlorophyll destruction (chlorosis), tissue death (necrosis), and pigment formation. Visible symptoms may result from acute or chronic exposures.”
“…Chronic injury results from intermittent or long-term exposures to relatively low pollutant concentrations, with chlorophyll destruction and chlorosis the major symptoms.”
“…Scientists generally agree that O3 causes 90% or more of the air pollution injury to crops in the U.S. This recognition has led to the establishment of a National Crop Loss Assessment Network (NCLAN). From summaries of O3 monitoring data; determination of the O3 sensitivity of major crop plant such as corn, soy beans, wheat, coating, grain, sorghum, and barrel; and economic data, NCLAN-participating scientists have modeled the economic impact of O3 on U.S. agriculture. They have estimated that a 25% reduction in ambient tropospheric O3 would result in a $1.71 billion annual increase in agricultural production; a 40% reduction would result in a $2.52 billion annual increase.”
NOTE: no such decrease in ambient ozone has occurred. Those dollar amounts reflect value from decades ago, the equivalent in today’s dollars would be much greater. Funding for the NCLAN was allowed to “expire” in 1987. Since then, instead, researchers turned en mass to climate change from CO2 – or, even more insidiously, the USDA has sought to develop genetically ozone “resistant” strains of annual crops. Of course, this is idiotic because even if they could do so successfully – which they haven’t – it would do nary a thing to help wild plants or trees survive.
This is on the USDA website about ozone:
Caption: Seasonal mean of ambient ozone concentrations between 09:00 and 16:00 h over the continental United States from 1 July to 31 September 2005 (Tong et al. 2007Atmos. Environ. 41:8772). Areas shown in brown, orange and red can experience significant crop yield loss and damage to ecosystem function from ambient ozone.
Above are examples of ozone damage to crops from the USDA.
Back to our textbook:
6.1.3 Forest Declines
“In many real-world cases, particularly forest ecosystems, the relationship between observed injury and exposures to atmospheric pollutants has not been clearly established. This has been particularly true of many ‘forest declines.’”
“The term decline is used to describe the process by which large numbers of trees die. In a decline, tree death occurs progressively; i.e., trees are weakened, become less vigorous, and eventually die. “
“Declines may occur as a result of a variety of natural or anthropogenic stress factors. Natural phenomena initiating forest declines are drought, insects, and freezing temperatures. Weakened trees may succumb to other factors, including root rot, insects, and disease. In many cases, no single factor can explain the observed death of trees.”
“A number of forest declines have occurred in North America and central Europe in the past five decades. In some cases, forest declines have been definitively linked to atmospheric pollutants. In others one or more atmospheric pollutants are suspected, at least in part, of contributing to the death of forest species.”
He goes on to cite examples of central European dieback – and in the US lists: California Ponderosa and Jeffery pines; Eastern White Pine; Red Spruce and Fraser Fir from New England to North Carolina, Tennessee and Virginia; Loblolly and slash pines in Virginia, North and South Carolina, Georgia and Florida; and Hardwoods – sugar maple, yellow birch, American beech, and white birch from Pennsylvania to Vermont and southeastern Canada.
His conclusion of this section reads:
“Research studies indicate that air pollutants, through mechanisms that vary by site, are a significant causal factor in forest declines. A link to air pollution is suggested by the large number of species affected, rapid onset of symptoms, large geographical areas affected, and wide range of associated climates and soil conditions involved. The scientific consensus on these declines is that they are caused by a combination of direct foliar damage and nutrient imbalance, both due to pollutant exposures. Ozone, along with acid fogs, appears to be the principal cause of tree damage and decline of European forests.”
He presents a huge bibliography for further reading.
What is to be Done?
Already in 2001 it was understood that “sudden drastic switches to a contrasting state” can occur in forests. Consider the abstract to a paper, Catastrophic Shifts in Ecosystems, published in the journal Nature:
“All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.”
Also relevant is the thesis written by Michael H. Smith at Australia National University, submitted in 2006 and awarded in 2009, Advancing and Resolving the Great Sustainability Debates and Discourses, which is a spectacular tour de force, if you like that sort of thing – only partially undermined by this delusional assertion in the abstract: “…it is possible to simultaneously pursue environmental sustainability, social justice and economic growth in ways that mutually re-enforce each other…”.
For the purposes of Wit’s End, the relevant parts are these portions of Chapter Three:
Feedbacks: The Problem of Overshoot and Positive Feedbacks
“The fact that nature is a complex system which often has a delayed feedback to environmental pressures is a key factor in why ancient civilisations have collapsed from environmental factors and why insufficient progress has been made on sustainable development over the last 100 years. It is often difficult to immediately see how pollution and development are reducing the resilience of natural ecosystems until it is often too late and the ecological system has been pushed past a particular irreversible threshold. Jared Diamond showed in his publication Collapse that this delayed feedback has been a factor in the collapse of many past civilisations.”
“Richard St Barbe Baker’s quote first outlined in Chapter 2 is even more pertinent here ‘The great Empires of Assyria, Babylon, Carthage and Persia were destroyed by floods and deserts let loose in the wake of forest destruction. Erosion following forest destruction and soil depletion has been one of the most powerfully destructive forces in bringing about the downfall of civilizations and wiping out human existence from large tracts of the earths surface. Erosion does not march with a blast of trumpets or the beating of drums, but its tactics are more subtle, more sinister.’ ~ Richard ST. Barbe Baker- I Planted Trees – 1944”
“In addition, many decision makers, untrained in ecology, have mistakenly believed that humankind can pull back once humanity’s environmental pressure starts to cause serious ecological collapse. However, often by then the ecosystem may have already passed the ecological threshold and the collapse is either irreversible or the environmental pressure (pollution, system change) will need to be reduced by a factor of ten or more to allow the ecosystem to recover. This phenomenon is known as hysteresis.”
“Also in the past some have expected change will be incremental and linear when in fact with ecosystems change is often non-linear and hence ecological collapse can occur suddenly.”
“Natural ecosystems are complex. Therefore it is often hard to determine what safe levels of emissions of pollutants are. It is also difficult understand the causal links between pollutants and negative environmental effects. There is usually significant uncertainty. Faced with uncertainty political and business leaders often call for more research to be done. This is often in areas where there will always be uncertainty because the systems are either so complex or it would take years and many people to collate enough data and analyse it to reduce the uncertainty significantly.”
Another reflection on this is from Barnosky, et al who wrote brilliantly in Approaching a State Shift in Earth’s Biosphere:
“Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence.”
In a world culture that seems obsessed with consuming every drop of fossil fuels, in cannibalizing every untouched habitat, is there much hope? Mismatches from a rapidly destabilizing climate in pollination, nesting, mating, foraging, migration and plant emergence will, if paleohistory is any guide, ultimately lead to mass extinctions. Must we hurry it along by killing the trees, the most essential form of life on land?
I cannot close without mentioning the work of Paul Kingsnorth, who elaborated so eloquently against the neo-environmentalist “blinding obsession with carbon” in an essay a year ago in Orion Magazine – and with even more seering insight in the last issue.
He expounds on the meaningless blather from scientists and activists which is motivated by the underlying desperate attempt to enable the party to continue unabated – by religiously adhering to the proposition that all we need do to secure “sustainable growth” (that oxymoron), is switch to clean energy sources and eliminate emissions of CO2. This entails completely neglecting – even repudiating with vitriol – the havoc from other pollutants, habitat destruction, and human overpopulation that are the crux of our inextricable predicament on a finite planet.
Ironically, as recently as 2005, those same foresters who now proclaim far and wide that drought from climate change is all of merit that underlies forest decline, even in wetter areas, attended a “Bark Beetle Symposium” – Snowbird Utah, 2005 USFS – the summary of which said otherwise:
“Air Pollution: Local and long-distance dispersal of air pollution from heavily populated areas and increasing development on the edges of forests also can have an indirect influence on bark beetle outbreaks. Ozone can damage needles, disrupting the tree’s photosynthetic capacity, thereby weakening the tree and making it more susceptible to bark beetle attack. An increase in atmospheric nitrogen deposition can stimulate growth in trees, leaving energy resources too depleted to produce sufficient resin to defend against bark beetle attack.”
Right next to this “Q&A” sidebox:
“Are the current bark beetle outbreaks unprecedented?” we read:
“Relative to what we know about the scale of historic outbreaks, many of the current bark beetle outbreaks do appear to be larger, more widespread, more severe, and occurring in new and novel habitats. This is, in part, due to the fact that the inputs to the system have changed, allowing bark beetles to thrive.”
“Bark beetles have, for millennia, been a natural part of the forest regeneration process. Bark beetles help to winnow out old and mature trees so that younger, more productive trees can replenish an aging forest. They also accelerate the process of tree decay to help forests capture and recycle nutrients. In recent years, however, a combination of factors, including warm temperatures, drought stressed trees, susceptible landscapes, and historical management practices, may have tipped many systems out of the balance we have observed over the past century. Beyond the troubling sight of vast areas of dead trees scattered over large landscapes in western North American forests, scientists are concerned that the current levels and rates of tree mortality in some forest ecosystems maybe pushing these systems beyond their ability to recover and regenerate.”
p. 18: “Since 1997, bark beetles have collectively killed billions of trees across billions of acres of forest in western North America. The fact that so many regionwide bark beetle events are happening concurrently at such intensity across so many ecosystems is truly remarkable and suggests common factors.”
Maybe…the common factor is ozone.
Is this a distinction without a difference, when ice sheets are melting and we face catastrophic climate change? It could matter. The melting is now unstoppable, thanks to the albedo effect and the length of time that CO2 will continue to warm the planet. But ozone doesn’t persist nearly as long as CO2 in the atmosphere…and all the trees aren’t dead yet. If we stopped emitting precursors, the forests could recover. If we don’t, a major CO2 sink will be gone and it will become so hot our planet will become uninhabitable far sooner than otherwise. And in the end, what matters more than time?
As I was finishing this post, friends from New Hampshire who went cross-country skiing sent me a photo of this sign.