Thursday, November 3, 2011

Convey to the Public the Nature and Degree of the Impact!

This painting by Ivan Kliun, "Ozone Fan", dates from 1914.  Ozone, an invisible, unstable gas, was once considered a cleanser and purifier.  At current (and rising) ambient levels in the tropospheric atmosphere, we now know it is toxic to all forms of life.
Often it grieves me to contemplate the ecocide we are fast precipitating.  I suppose like most people, I like to think that humans are exceptional, just because every now and then we produce a Shakespeare or a Mozart - conveniently forgetting that most of our species are ignoble slobs and thieves...or too often far, far worse.  Flaubert was quite close to the truth when he said that "the three finest things God ever made" were Hamlet, Don Giovanni, and the sea.

When I was in California to visit youngest daughter, she took me to the Monterey Aquarium, where I saw Sea Dragons for the first time.  I was crushed that my camera ran out of battery charge just before we came upon their tank, because they were the most incredible creatures I can imagine, a miracle of evolutionary specialization.  I wished I could have filmed their silent and sedate flutterings as they made their tiny majestic promenade through the leaves they mimic so exactly, to watch it over and over.
Think how many generations it took for this intricate level of unique complexity to develop, and the intensely harmonious relationship that exists between this remarkable creature and others in its habitat.  That delicate balance is why, after a mass extinction event such as that upon which we are embarking, it takes at least tens of millions of years for Earth to recover and regain the present rich biodiversity we have enjoyed since we first set about destroying it.

Terribly sad...and yet, for our purposes, the universe is infinite, and so is time.  And so should we be sad, that this particular epoch is drawing to a close, as species plummet through habitat destruction and pollution...or merely because we are eating them out of existence, or hunting them for stupid reasons like grinding their horns into mythical sex-enhancing powders?  Or is it just as much part of the cycle, replayed perhaps countless times, in other galaxies and eras, the cycle of birth and loss, decay and regeneration.

So once I get around to the nitty gritty of this blog's purpose - tropospheric ozone killing trees - I will be sprinkling photos of the splendid Sea Dragon into the latest scientific evidence.  The tragic death of coral reefs where the endangered Sea Dragons live, from acidification and warming, is almost a perfect parallel to the trees dying from ozone, imperiling all the other forms of life that depend upon them, including us.  For stalwarts who slog through to the end, I've embedded a wondrous video of the exquisite Leafy Sea Dragon, which is found only in Australia.

But first!  It's important to have fun, so here is the invitation I made for first daughter's annual Halloween Hayride:
Mobs of people descended for food, as they do every year - but before they did, I took pictures of the tranquil feast:
Best new recipe was a roasted bruschetta, which consisted of caramelized onions, shallots and garlic, with tomatoes, red pepper, zucchini, handfuls of thyme and rosemary.  After it cooled, we added minced fresh basil, and served it on toasted rounds of bread brushed with garlicky olive oil.
Of course there was the usual filet with horseradish sauce, grilled scallops, and shrimp stuffed with goat cheese, wrapped in prosciutto...and figs filled with gorgonzola dolce topped with candied pecans. 
The house was filled with ghoulish floral arrangements in a lime green and lurid purply mix.
Hoards of trick-or-treaters arrived, despite the adverse road conditions, due to the insane weather.  As usual the newscorpse blamed power outages on extreme precipitation weighing down the leaves...without mentioning this is predicted by climate change science, as shown by this NOAA chart:

However, even climate change can't explain why this culprit tree in question toppled across the power lines, smashing into the roof of this historic home, even though it had no leaves remaining!
Splat!  Despite the storm, it's freakishly warm - a delphinium blooms under a snowy blanket, and Canadian geese no longer fly from north to south in strict V formations, instead they swirl in anxious confusion, disorganized clusters of them going back and forth, honking raucously.
The many leafless branches and trees that fell, as well as pine trees that should be able to stand up to snow all winter, are not explained by an October blizzard.  People appear to be outraged that they still do not have power, and roads are still blocked.  It's too much for public works to keep up with...and it's going to get worse until the last tree has been removed.
Dr. James Clark of Duke University has published a new study that apparently reveals that trees are not cooperating with models by adapting to climate change as predicted - in shifting their range northward and up elevation.

"More than half of tree species in eastern U.S. forests aren't adapting to climate change as quickly or consistently as predicted, researchers said.

Nearly 59 percent of the species examined in a study by Duke University researchers showed signs that their geographic ranges are contracting from both the north and south, a Duke release said Monday.

'Many models have suggested that trees will migrate rapidly to higher latitudes and elevations in response to warming temperatures, but evidence for a consistent, climate-driven northward migration is essentially absent in this large analysis,' James S. Clark, a professor of environment, said.

Fewer species -- only about 21 percent -- appeared to be shifting northward than predicted, the researchers said.

'Warm zones have shifted northward by up to 100 kilometers (62 miles) in some parts of the eastern United States, but our results do not inspire confidence that tree populations are tracking those changes,' Clark said.

The concept of climate-driven migration assumes that as temperatures warm, the southern edge of some tree species' ranges would recede as adult trees die and seeds they leave can no longer sprout.

At the same time, the species could spread to higher latitudes as seedlings dispersed on their northern boundaries are able to take root in newly favorable climates.

The Duke study's findings show 'a lack of evidence for climate-mediated migration, and should increase concern for the risks posed by climate change,' Clark said."
Another version adds this: 

"About 16 percent seemed to be advancing southward, and around 4 percent appeared to be expanding in both directions. 

The scientists analysed data on 92 species in more than 43,000 forest plots in 31 states. 

The study found no consistent evidence that population spread is greatest in areas where climate has changed the most; nor do the species’ response patterns appear to be related to seed size or dispersal characteristics."

You might think that this arboreal refutation would inspire Dr. Clark to reconsider the role of ozone in forest decline, since apparently, climate change isn't explaining what is actually happening with the trees!  I wrote him last April about an earlier study, and this was his reply, as I reported in the spring:

"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).  [This is wishful thinking, it is only true for low levels of ozone.] 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 speciesOzone 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.


So basically, it is what it is.  They study what is happening to trees with the level of ozone in the background as a given, because they can't make it go away.  It's not unimportant, but it's not important enough to design a study to see if air pollution is the reason tree range is "contracting from both the north and south" - in other words, they are in total dieback!!  Even our own Forest Service has more than that to say about ozone affecting trees, on their webpage:

Physiological Effects

Ozone enters a leaf cell through openings, called stomates, that allow for gas exchange.  Once inside the leaf the ozone can result in damage to the mesophyll cells in the center of the leaf.  The mesophyll cells contain the chloroplasts where photosynthesis occurs.  Available research does not clearly show what happens once the ozone contacts the mesophyll.  The phytotoxic effects could be a result of:
  • Direct contact of the ozone with the mesophyll.
  • The chemical product of ozone's reaction with other gases within the leaf's air space.
  • The chemical product of ozone's reaction with the cell membrane.
  • Most likely, it is a combination of all three listed previously.

Effect on Forest Trees

Ozone effects on forest vegetation  are most pronounced when soil moisture and nutrients are adequate, and ozone concentrations are high. Under good soil moisture and nutrient conditions the stomates are likely to be open and  the ozone will enter  into the leaf and can damage the cells that produce the food for the plants through photosynthesis.  Reductions in the photosynthesis will decrease the amount of carbohydrates produced and stored in the roots.  Continual reduction in the annual production of carbohydrates has the potential to decrease the amount of root growth, tree height, and crown width.  Individual trees with reductions in these three areas could be less competitive then neighboring trees for sunlight and nutrients, or the chronic stress could weaken the trees and make them more susceptible to insect attacks.

Effective Dose 

Scientists have determined the ozone parameters that explain most of the vegetation response are:
  • Where a greater weight is placed on the higher ozone concentrations,
  • Are cumulative throughout the growing season, and
  • Take into account when the ozone enters the leaf through the stomata.
The amount of ozone measured with an ozone monitor is the concentration in the atmosphere.  However, the amount of ozone that enters the leaf, called dose, depends on whether the stomates are open and other atmospheric conditions.  The effective dose is the amount of ozone that enters the leaf  during the growing season and has an impact to physiological process or causes cell death.  The stomates are most likely to be open when there is adequate soil moisture and nutrients, and during sunny conditions.  However, the stomates can be open during the nighttime hours, but the amount of ozone dose could be less than during the day.  The impact of ozone entering the leaf will depend upon if the plant is able to neutralize the ozone before causing injury.  It is possible the detoxification mechanism are most effective during the daytime when the greatest uptake (dose) occurs, however ozone entering the leaf at night could cause impacts because the defense mechanisms are not operating or are less efficient.
Research has developed means to estimate the dose of ozone entering the leaf, but the meteorological conditions across the area of concern along with the ozone concentrations need to be known to calculate the dose.  Typically, the USDA Forest Service does not have adequate meteorological data to combine with the ozone monitoring data.  Estimating the dose of ozone is not practical for National Forests or wildernesses at this time.  Furthermore, it will be necessary for further research to be conducted in order to estimate the effective dose to account for the defense mechanisms to ozone for forest vegetation.  Once adequate research has been conducted on effective dose then it will be necessary to translate the results to present what ozone concentrations or exposures caused injury or damage.  This is likely to be necessary since the regulatory agencies show attainment of air pollution standards using data collected from ozone monitors.

Ozone Symptoms

Certain plant species have been used as "bioindicators" that ozone is causing phytotoxic impacts. One symptom used is the presence of a stippling (reddening or black) confined to the upper leaf surface between the veins.  The presence of ozone symptoms indicates the plant had a physiological response to the ozone exposure.  Symptoms are not an accurate indicator of how much growth loss has occurred to a sensitive plant from an ozone exposure.  An adequate amount of soil moisture and nutrients at a specific site (microsite) appears to be one factor in determining if ozone will cause visible symptoms.  Vegetation's sensitivity to ozone varies  -- not only between species, but also within a species.  For example, there may be two black cherry trees growing next to one another, and one will have severe ozone symptoms while the adjacent black cherry has no visible symptoms.   Also, there is no relationship between the amount of ozone a plant is exposed to and the amount and severity of ozone symptoms.

How We Use Exposure Indices 

Some air resource specialists rely upon measurements taken with ozone monitoring equipment at a site of interest, along with soil moisture estimates, to predict if a biomass (roots, shoots, and/or stem) reduction has occurred.  Ozone monitors can provide over 4000 ozone readings from April through October.  Researchers and technical specialists have examined ways to summarize and use this extensive information.  The Ozone Calculator is one tool that has been developed to estimate if ozone exposures recorded at a monitoring site could cause a biomass reduction to the vegetation where fumigation studies have been conducted.  The USDA Forest Service has compiled hourly average data which is compatible with the Ozone Calculator.  Furthermore, a web-based spatial database has been developed which shows the location of the ozone monitoring sites where ozone data are available.
Everyone is all worked up because there are reports that important supplies of peanuts, coffee, wine and chocolate, cherries, maple syrup, almonds, apples and pistachios are threatened with reduced yield and quality because of climate change.  See their chart of zone shifts:
Note, they haven't shifted so much yet that the northern range of plants should already be impacted!  So, why don't these articles ever mention the threat from ozone, which is well established - as we shall see.  Always, more research must be done to determine the dose and results of ozone exposure to trees...Fine!  Let's look at annual agricultural crops, instead.  Here is an abstract from research published in 2009:

"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. Extrapolation of these findings supports previous studies that estimate the global economic loss to the farming community of more than $10 billion annually."
The first paragraphs (minus citations) read:

"The impact of elevated ozone (O3) concentrations on vegetation has been well documented in both chamber studies and at field sites where concentrations can be experimentally controlled. The onset of injury in a number of O3-sensitive plants has been observed with seasonal daytime average concentrations as low as 40 ppbv (parts per billion, by volume), and concentrations above this level are commonplace during the growing season in many food-producing regions of the world. Nationally, the seasonal 8-h average O3 concentration ranges from 50 to 55 ppbv during the summer, although diurnal and day-to-day concentrations vary widely.

Ozone monitoring stations, however, are predominately located in urban areas and are sparse in most rural locations worldwide, making estimates of potential O3 impacts on crop production less certain. Furthermore, recent analyses of O3 measurements entering the U.S. from East Asia source regions show an increase of 0.46 ppbv yr since 1984, implying that background O3 concentrations may continue to rise despite the enactment of pollution control measures in the U.S. The Cooper et al. (2010) findings likewise support the Intergovernmental Panel on Climate Change (IPCC) projection that O3 concentrations will increase by 25% over the next 30-50 years,
exacerbating the negative impacts of O3 on yield and biomass production.

...The future use of a satellite that is designed to study tropospheric composition explicitly should provide exciting possibilities for both the air quality and agricultural communities in the forthcoming decades when the impact of air pollution on crop productivity is likely to result in significantly greater detrimental consequences as background concentrations continue to increase."
An earlier paper from 2007 by the same author, Booker, "Ambient Ozone Impacts on Specialty Crops" has these observations:

"While peak ozone concentrations in the U.S. may be lower on average recently, chronic exposure in the range that can affect plants interspersed with episodes of higher concentrations continue to occur.

In fact, intermediate concentrations of ambient ozone may have the largest impact on crop yields. 

Ozone uptake is highest during mid-day and early afternoon when high rates of leaf gas-exchange coincide with rising ozone concentrations.  There appears to be a tipping point around seasonal average ozone concentrations of 50 ppb or greater that results in yield suppression in ozone-sensitive crops.

Most ozone studies, however, have been single factor or two-way interaction experiments.  The effects of ambient ozone in combination with two or more other environmental factors have been little explored.  But, it has been shown in rice that the magnitude of the ozone and elevated carbon dioxide responses and interactions can be influenced by high temperature episodes, nutritional status and intra-plant competition (Reid and Fiscus, 2008).  Such experiments are complicated and expensive to conduct.  However, plant responses to ozone are highly influenced by site conditions, and comprehensive assessment of their relative influences needs attention."
"One way to obtain insight about the effects of ambient ozone on plants is to compare the growth and productivity of plant cultivars and clones that are known to differ from each other in response to ozone as detected by ozone injury symptom expression and/or changes in biomass and yield.  This has been done with clonal clover and selected bean lines.

In experiments utilizing ambient air exposures in New York, North Carolina, and California, ambient ozone concentrations were sufficient to cause respectively a 25%, 39% and >50% biomass reduction in sensitive versus tolerant clones of white clover.

While ozone is a normal component of the troposphere, background levels of ozone have been increasing for more than 100 years.  They have doubled since pre-industrial times, and are continuing to increase, with average annual concentrations ranging from 20 to 45 ppb.  Despite national air quality regulations aimed at controlling ground level ozone pollution, it continues to be a major concern for crop production and forest health.

Moreover, every region of the U.S. except for the Pacific Northwest and much of the Great Plains experiences phytotoxic ambient ozone concentrations periodically during the growing season.  East Asian countries, India, Pakistan, many countries around the Mediterranean, parts of Mexico and Brazil are currently experiencing reductions in crop production due to ambient ozone.

Climate model projections forecast that the largest rice and peanut producing regions in the world, located mainly in China, Japan, India, central Africa, the southern U.S., and Indonesia, may experience significantly higher levels of tropospheric ozone in the coming 50 years."
"There are at least 12 major crop species within the U.S. that are considered ozone-sensitive, many of which are classified as specialty crops.

These include alfalfa, barley, bean, clover and other forages, grape, oat, peanut, potato, rice, tomato and watermelon....

In addition, a commercial sugarcane clone in California may be ozone-sensitive (D. Grantz, personal communication).  Ornamental plants such as petunia and buddleia, fruit bushes (blueberry), and landscape shrubs can also be damaged by ambient ozone ...

Ozone-sensitive plants frequently exhibit visible foliar injury, and chronic ozone exposures can reduce yields and biomass.  Nutritional quality also declines in some crops and forages.  Agronomic crop yield loss due to ambient ozone in the U.S. is estimated to range from 5 to 15%...

An international cooperative programme indicates the widespread occurrence of ozone injury on crops.

A full assessment of ambient ozone impacts on crop performance is likely to be complex.  In addition, growers may not perceive the yield losses due to ozone because there is no clean-air reference for comparison.  Also, environmental conditions influence ambient ozone effects and inter-annual variability in weather conditions complicates the picture.  It is impossible to assess yield loss in the field or to positively diagnose ozone symptoms without comparisons at a range of ozone concentrations.  This can be accomplished through studies using a variety of approaches.

These include outdoor controlled-environment chambers, open-top field chambers, free-air exposure systems, open air experiments with sensitive/tolerant cultivars, ozone-protectants, and multivariate modeling of plant responses to ambient ozone using multiple study locations and similar experimental protocols.  These protocols can be used in various combinations, augmented by modern molecular biology techniques such as quantitative trait loci (QTL) analyses with available recombinant inbred lines (e.g., rice, peanut and tomato), to screen crops for ozone sensitivity.

Studies are needed to: a) define crop responses to ozone under a range of controlled environmental conditions; b) identify molecular markers for ozone sensitivity; c) assess plant responses to ambient ozone in natural settings; and, d) construct predictive models of crop performance in a changing climate.  These are costly studies to conduct and have not been performed for currently relevant cultivars.  In general, it is important to remember that elevated ozone is toxic to all living things.  Our current understanding of crop responses to ozone indicates that measurable yield losses due to ozone toxicity are likely occurring in many regions of the U.S. and elsewhere in the world.  However, to refine the range of likely losses will require updating and expanding previous studies using modern cultivars grown under current production conditions of fertility and water management.  Potential gains achieved by screening modern cultivars for ozone sensitivity utilizing marker-assisted selection is an unexplored arena although preliminary studies are underway."

[The paper ends with future projects - my favorite is the last one (which I have highlighted in red), which nobody seems to have gotten around to yet.]

"Research issues

Assess the impact of ambient ozone pollution on specialty crop production and nutritional quality, both nationally and internationally.

Determine the influence of other growth-regulating environmental factors on plant responses to ozone.

Determine the influence of ambient ozone in plant pest and pathogen relationships.

Quantify the contributions of ambient ozone from those of the other factors to crop productivity and chemistry.

Determine the potential of modern genetic screening techniques, e.g., QTL analysis and marker-assisted selection, for assessing ozone-sensitivity of new crop cultivars.

Convey to the public the nature and degree of the impact."

Has ANYBODY tried to convey to the public the nature and degree of the impact of ozone on our food supply???
I have found more books about ozone's impact on vegetation.  They are quite expensive textbooks, so I'll have to try to get them from a university library.  I can read some pages on line, although I can't cut and paste, so I have to retype the text.  The first is from pages 204 and 205 from a book, copyright 1999, called "Environmental Pollution and Plant Responses".  I strongly recommend following the link and reading 204 through 207, to get a sense of the myriad ways that plants are affected by O3.

"Air pollution is not a new problem in agriculture.  For decades, farmers in congested or industrialized areas have experienced air pollution damage to their crops, often without realizing it.  Ozone primarily injures the leaf mesophyll tissues causing leaf chlorosis and/or a characteristic flecking of the upper leaf surface.  Important physiological processes such as photosynthesis (Pn), respiration, carbon allocation, and stomatal function are often adversely affected by O3.  Estimates of yield losses in major crop plants, resulting from ambient O3 stress...translates into economic losses in the U.S. at about $4 - $5 billion, or about 5.6% of the gross values of farm commodities...

In general, C3 species such as soybean, cotton, peanuts, spinach, radish, bean, potato and tomato are more sensitive to O3 stress..."

And here are yet two other books, the first, "Forest Decline and Ozone", has, imagine this, an illustration of a bark beetle on the cover!  Do you suppose the authors think that the bark beetle infestation just might have something to do with trees being more vulnerable because they are damaged by ozone??
The other, with the exotic title:  "Molecular Ecotoxicology of Plants", also by Sandermann, has an excellent introduction about what, exactly, ecotoxicology is, and has much to say about ozone, starting with this:

"...more recently ozone, a ubiquitous air pollutant that regularly exceeds limit values, has also been recognized to act as a powerful abiotic elicitor.  As summarized in Fig. 1.3, ozone can induce five major known defense responses of plants against pathogens.  Ozone therefore acts as an inducer that is able to activate plant genetic and biochemical programs originally developed for another environmental stress (in this case fungal attack).

It's quite amazing how many ways that ozone changes the internal functions of a tree...and ludicrous that scientists don't follow their own observations through to the rather obvious conclusion that we have reached a tipping point where trees of all species have succumbed to the invisible, toxic gases being absorbed by their leaves and needles, transmitting poison and wreaking havoc throughout their systems.  In hindsight, I think this most recent mess of downed trees will be seen as the beginning of the utter collapse of the very foundation of our terrestrial ecosystem, just as corals have had their fate sealed in the oceans.

Sea dragon photo credits here here and here

1 comment:

  1. "Has ANYBODY tried to convey to the public the nature and degree of the impact of ozone on our food supply???"

    YOU have, Gail. Thanks, and keep up the good research. Somewhere, somehow, someone MUST listen!


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