I came across an article about a long-term tree study and promptly contacted the author, Dr. Jim Clark of Duke University, to enquire whether he had considered the role of ozone in his research, and this was his reply:
"Gail, thanks for the note, a few thoughts.
Ozone is a problem for plants, hard to study for large trees. For crops, it's increasingly evident that rising CO2 can mitigate effects of rising ozone (or if you prefer, ozone offsets the stimulation that would have occurred with rising CO2). For large trees, it's difficult to obtain more than leaf to branch level responses. For juvenile trees the evidence for a CO2 stimulation of growth is mixed--when experimentally increased as in FACE experiments, the initial stimulation of growth is not maintained, but it's hard to manipulate ozone at that scale (whole trees competing for light in closed forests). Nonetheless, all evidence is that ozone is bad for all plants and certainly contributes to the health of trees in our study.
In any study of mortality, there are risk factors that cannot be experimentally manipulated, so they become the background factors. Ozone levels have been high in our region throughout the duration of this study, and mortality rates could be higher throughout for that reason alone. What we studied are the factors that varied against this background, and they show the differing impacts of temperature, drought, and competition for light on different species. Ozone is not included in the study, because we could not experimentally manipulate it or design the experiment to benefit from a broad range of ozone levels. That does not mean it is unimportant.
best,
Jim"
This was kind of discouraging. It reminds me of the sea-level rise discrepancy. Scientists don't know how to model ice sheet melting, because the contemporary rapid warming is unprecedented, so they won't predict how quickly melting will occur. They base sea level rise projections solely on thermal expansion of the ocean, and just leave out the contribution from ice sheets (which far surpasses thermal expansion). So I guess since we can't build greenhouses big enough to do controlled experiments on trees in pristine air to compare to ambient and future concentrations of ozone, we just won't know what it is doing to trees until they're all dead.
But, in a followup message Dr. Clark kindly referred me to another scientist at the University of Georgia who has also been researching trees, including ozone. Of course that meant I should write him too, but I have been procrastinating all week - hence, not writing anything at all! Honestly, I am so weary of experts telling me I'm wrong or discounting the existential nature of the threat. Finally this morning I forced myself to draft yet another missive, to ask him about ozone and also whether he thought it at all possible that peroxyacetyl nitrate from ethanol emissions might play a significant role in the abrupt decline of trees. In the process I googled PANs just to be sure I spelled it correctly (I always feel like I've got it wrong - chemical names do not come naturally tripping off my keyboard) and almost fell off my chair when the search led to this new wiki entry that is short but so, so sweet! I'm going to post the whole thing, with pictures I've been collecting in lieu of writing. The first set are from a nearby horse farm, which has a magnificent barn.
Shrubs are dying too.
The rubble of broken branches is piled along the road.
Quince is blooming, while a cardinal looks at a tangle of dead wood.
AmericanForests.org produced a ridiculously overoptimistic survey, "Changing Climate, Shifting Forest" that doesn't even mention ozone among the threats it lists, such as temperature shifts, droughts, wildfires, insects and rising sea levels. Instead of anticipating the end of forests, which is where we are headed, it concentrates on changes in composition, and altered boundaries. Although, they did get it right towards the conclusion (quoted excerpts in lavender):
This used to be a deep dark grove of white pine.
Quite of few of them have gone over.
Those still standing have hardly any needles left.
Their trunks are splintered.
Not long ago it was an impenetrable, dense wall of green.
Lets see what a gardening forum says about white pine.
"This plant is fairly tolerant to adverse environmental conditions, however it is susceptible to ice storm damage, sulfur dioxide, ozone, and salt sea spray."
It also says..."The foliage may be susceptible to damage from severe winters and air pollution. "
Well, I think after a certain number of years of damage to foliage, the impacts spread and include peeling bark.
Bronzed like this Mayapple perhaps?
"Gail, thanks for the note, a few thoughts.
Ozone is a problem for plants, hard to study for large trees. For crops, it's increasingly evident that rising CO2 can mitigate effects of rising ozone (or if you prefer, ozone offsets the stimulation that would have occurred with rising CO2). For large trees, it's difficult to obtain more than leaf to branch level responses. For juvenile trees the evidence for a CO2 stimulation of growth is mixed--when experimentally increased as in FACE experiments, the initial stimulation of growth is not maintained, but it's hard to manipulate ozone at that scale (whole trees competing for light in closed forests). Nonetheless, all evidence is that ozone is bad for all plants and certainly contributes to the health of trees in our study.
In any study of mortality, there are risk factors that cannot be experimentally manipulated, so they become the background factors. Ozone levels have been high in our region throughout the duration of this study, and mortality rates could be higher throughout for that reason alone. What we studied are the factors that varied against this background, and they show the differing impacts of temperature, drought, and competition for light on different species. Ozone is not included in the study, because we could not experimentally manipulate it or design the experiment to benefit from a broad range of ozone levels. That does not mean it is unimportant.
best,
Jim"
This was kind of discouraging. It reminds me of the sea-level rise discrepancy. Scientists don't know how to model ice sheet melting, because the contemporary rapid warming is unprecedented, so they won't predict how quickly melting will occur. They base sea level rise projections solely on thermal expansion of the ocean, and just leave out the contribution from ice sheets (which far surpasses thermal expansion). So I guess since we can't build greenhouses big enough to do controlled experiments on trees in pristine air to compare to ambient and future concentrations of ozone, we just won't know what it is doing to trees until they're all dead.
But, in a followup message Dr. Clark kindly referred me to another scientist at the University of Georgia who has also been researching trees, including ozone. Of course that meant I should write him too, but I have been procrastinating all week - hence, not writing anything at all! Honestly, I am so weary of experts telling me I'm wrong or discounting the existential nature of the threat. Finally this morning I forced myself to draft yet another missive, to ask him about ozone and also whether he thought it at all possible that peroxyacetyl nitrate from ethanol emissions might play a significant role in the abrupt decline of trees. In the process I googled PANs just to be sure I spelled it correctly (I always feel like I've got it wrong - chemical names do not come naturally tripping off my keyboard) and almost fell off my chair when the search led to this new wiki entry that is short but so, so sweet! I'm going to post the whole thing, with pictures I've been collecting in lieu of writing. The first set are from a nearby horse farm, which has a magnificent barn.
I had a friend who has long since moved, who once rented a cottage on this property, and my children had many lessons at the outdoor riding ring. Now the gorgeous pines are dying. This is indicative of how our sensibilities have become degraded. Not so long ago, any owner would have recognized those bare evergreens as an extreme hazard and removed them. Now most people are so inured to dying trees, they don't take obvious precautions. Here's what wiki says about PAN which is of staggering important, because it basically corroborates my suspicions: Ozone from ethanol is not only different, but WORSE than ozone from gasoline! The following is a verbatim quote, and, according to a chemist reader, does not use the term "oxidant" correctly, it should be "oxidizer":
"It is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radical and nitrogen dioxide gas. It is a lachrymatory substance.
Peroxyacetyl nitrate, or PAN, is an oxidant more stable than ozone. Hence it has capabilities of long-range transport greater than that of ozone. It serves as a carrier for oxides of nitrogen (NOx) into rural regions and causes ozone formation in the global troposphere.
The formation of PAN on a secondary scale becomes an issue when ethanol is used as an automotive fuel. Acetaldehyde emissions increase, which subsequently react in the atmosphere to form smog. Whereas ethanol policies solve domestic oil supply problems, they drastically exacerbate air quality conditions."
Hmmm...drastically exacerbate air quality conditions? A lachrymatory substance? Maybe that's why so many trees are weeping. Of course this is disputable: "Whereas ethanol policies solve domestic oil supply problems..." in fact I would say, ludicrously wrong. But never mind.
Something is causing trees to die off at a rapidly accelerating rate - it's not just old trees.
These trunks are perfectly typical of the rotted condition to be found.
More patches of ground are bare.
Limbs are snapped, bark is stripping off - it's a mess.
But, it being spring, valiant efforts are made by the flowering shrubs at Wit's End. I took a walk around, and following are photos from the garden, along with the latest in the accumulating news about our collapsing ecosystem.
This harrowing report from the BBC, "Air Pollution damage Europe's Wildlife Havens" describes two studies about the effects of excess nitrogen on plants. I haven't had time to read the originals referred to in the story, but here's the synopsis from the news:
"Air pollution is damaging 60% of Europe's prime wildlife sites in meadows, forests and heaths, according to a new report."
"A team of EU scientists said nitrogen emissions from cars, factories and farming was threatening biodiversity."
"The Nitrogen Deposition and Natura 2000 report was published at a key scientific conference in Edinburgh."
"Earlier this week, the European Nitrogen Assessment - the first of its kind - estimated nitrogen damage to health and the environment at between £55bn and £280bn a year in Europe, even though nitrogen pollution from vehicles and industry had dropped 30% over recent decades."
"Nitrogen in the atmosphere is harmless in its inert state, but the report says reactive forms of nitrogen, largely produced by human activity, can be a menace to the natural world."
"Emissions mostly come from vehicle exhausts, factories, artificial fertilisers and manure from intensive farming."
"The report said 60% of wildlife sites were now receiving a critical load of reactive nitrogen."
Did I mention that certain lichens thrive in high levels of nitrogen pollution and branches are being smothered by them?
One bright spot is that a yellow magnolia that I planted 5 years ago - before I realized trees are dying and quit gardening - has bloomed this year for the first time! It smells heavenly, too.
Meanwhile, London was warned of a smog alert.
Unable to clean their city, they likely will face expensive fines from the Olympic Committee, whose athletes had been promised the greenest Olympics ever. Ironically, air pollution is even more dangerous for them than couch potatoes, because they breathe harder and more deeply.
More from the UK - a "catastrophic decline" in the number of spring bird arrivals is a mystery. Because they migrate from overwintering in places as far off as Africa, it's difficult to trace the cause. Personally, I think it may have something to do with a lack of food.
Rising levels of CO2 contribute directly to increased ozone and mortality, according to this research from Mark Jacobson at Stanford. A tangled web indeed.
Moving from tropospheric ozone, which we of course don't like, to stratospheric ozone, which we do want, it turns out that hole over Antarctica is wreaking havoc on weather patterns in Australia, and a new study reveals at least 30% of the awful drought there is due to the ozone hole.
But the CO2 obsessed won't care. If you really want to know about the petty scientific rivalries that are serious obstacles to progress, read this and this. I can't decide if it's better or worse than the competition between climate and environmental activist organizations. Maybe I should do a poll.
The trouble with predicting the future — for mangroves, redwoods, or any species — is the vast number of variables that must be considered. Mangroves, for example, will be confronted with a long list of threats that include rising sea level, increasing tempera- tures, more frequent and violent storms, and human habitat alteration. In some areas, natural or human- influenced subsidence and erosion are also important factors, effectively accelerating sea-level rise.
The threats associated with climate change vary from species to species and habitat to habitat, but one thing remains constant: no tree or forest is affected by just one thing.
“It’s not just one factor,” explains Hayhoe. “It’s all the confounding factors, each of which is negative. They just add up on each other.” The cumulative effect is difficult to predict, and often devastating to the species it affects.
Amid these complexities, some things are certain. Temperatures will continue to rise. Sea levels will continue to encroach on the shore. Altered precipita- tion, migrating pests, and more frequent and violent storms will remain with us far into the future. “These trends will just continue,” says Hayhoe. And as long as they continue, our forests will continue to respond. We think of forests as timeless places where life holds still. But this is no more than a comforting fal- lacy, born of the contrast between our short attention spans and trees’ great patience.
Forests do change, albeit slowly. Trees shift their ranges via windblown seeds, buried acorns, and flocks of hungry birds. As our climate continues to change, these natural migrations will be pressed to keep pace with shifting temperature extremes and precipitation patterns. Some trees could expand their ranges mightily, while others could disappear almost entirely from the American landscape. Ultimately, climate change will draw new lines between species and ecosystems.
Some changes may be subtle and hard to notice, such as the gradual decline of coastal redwood forests over the coming centuries. Other changes will be hard to miss, such as the absence of blazing sugar maple trees in much of New England’s autumn landscape.
“If you haven’t seen changes yet, you probably will soon,” says Hayhoe. “If you are a careful observer, you probably already have.”
I decided to leave the garden with its flowers that look so lovely in isolation and take a short walk through the woods for some context.
The path is often impeded by fallen trees. My neighbor has to work hard to keep it clear for horses.
I heard a rustle and found Tishy had snuck under the deer fence and was eager to lead the way.
This wood has changed so much from the thirty years ago I moved here. The understory was so thick it was impossible to walk through it, or see any sky in the distance, even in winter.
Every now and then I get a little glimmer of how wonderful it is for spring to follow winter, when the air is soft and I can hear birds singing.
But for the most part it is barren and sad.
This dead tree snared in the branches of its neighbor is high on the hill behind the treehouse.
The platform is 20'x20', built around a very old, large ash tree.
The kids loved playing there when they were young, and even as teenagers, not least because it was completely private.
Now so much has died that it's easy to see through to the house from the treehouse.
This is the house from the high path above the treehouse. It, too used to be invisible.
Maple trunks are blackened and the bark is falling off.
The slightest tug and it peels away.
Ugh. Let's wind up with a look at some pines not far from Wit's End.
Well, it's certainly not sea salt spray, here in western New Jersey, that is killing off these pines.
The same website has this warning about green beans:
"Leaves Look Scorched Or Bronzed From Ozone Pollution
Bean plants are sensitive to ozone produced by industry and car emissions. Tissues of affected plants appear bronzed or slightly scorched and leaves develop spots that penetrate through the entire leaf. This type of environmental injury can kill a young plant in a matter of days."
Or this variety of holly?
Spots like on this leaf - already, in April?
It's going to be an interesting growing season! If the plants on the patios fail, there are replacements. Somehow I feel this yard could serve as inspiration. The elderly owner was forced to remove all the plastic cages, flotsam and jetsam he had assembled as refuge for hundreds of birds in the Flatbush neighborhood of Brooklyn.
This little feathered friend is building a nest on the porch light at Wit's End, and steals food from the cats' dish. You can be sure if I get a reply to my letter from the professor at the University of Georgia, it will be posted here on the blog.
