The Root of the Matter

I was planning to avoid mention of the staggering destruction to trees from the Santa Ana winds in Southern California...never mind suggest it could be even partially due to damage from air pollution - because in fact, they did have extraordinarily vicious, no doubt climate-change aggravated gusts.

But then, some news reports that made it obvious that the extent of the damage, even considering the ferocious wind speed, was perplexing the locals - who were themselves wondering why so many trees blew over.  And then, they were making up ridiculous excuses.  So although this post will range over a variety of sources, the pictures will be from that arboreal mass execution.

My personal favorites are the one where trees are crushing cars, which seems only fair, considering.  So let's first look at what Californians had to say in the LA Times, and then we'll dig into the latest research on ozone, which, as we all know, derives from emissions of reactive nitrogen.

"Why did the powerful Santa Ana winds that hit Southern California this week fell so many trees?"

"Experts said one reason was that the winds were remarkably choppy and unpredictable."

"In some places, winds suddenly shifted from 10 mph or 20 mph to more than 80 mph. The shift made trees as well as roofs and power lines vulnerable.

"Everything lined up perfectly," said Bill Patzert, a climatologist for Jet Propulsion Laboratory in La Cañada-Flintridge."

"Trees were no match for the winds, especially those with heavy canopies [note the many that came down that DIDN'T have any canopies at all!].  Patzert noted that trees in urban Southern California neighborhoods don't have the strong root systems found in more natural environments."

"'L.A. trees don't have deep roots. The urban forest is artificial and is primarily watered by lawn sprinklers,' Patzert said. 'So what keeps our urban forest alive is people watering their lawns, which are not natural, so you don't have deep root systems. So our trees are very vulnerable to Santa Ana events.'"

"Walter Warriner, a Santa Monica arborist and community forester, agreed, adding that the large canopies of many local trees lack strong foundations."

"'When you look at a tree above ground there's a ratio of 20 to 1 compared to below ground, so there's not that many roots holding our big trees in place,' he said."

But...but... in this story, it was reported that hundreds of trees in parks fell down, too!  So clearly, that is not explained by shallow root systems under concrete.  Here's a picture of all the pavement in Griffith Park:

High winds blew down 400 trees in Griffith Park

"Los Angeles city crews on Friday were working to clean up debris and some 400 downed trees in shuttered Griffith Park, many of which had fallen on Roosevelt Municipal Golf Course. They said the park would likely be open by sunrise Saturday."

"Officials said two other parks in Northeast L.A. -- Ernest E. Debs and Elysian Park -- also had damage including hundreds of downed trees but were not closed. Other parks across the city were mostly spared, they said."

In comments, indignant people were complaining that the trees were being cleaned up on the golf course but not on their streets.  One person wrote sarcastically:

"Trees fall practically daily in Elysian Park...why don't they put up some yellow caution tape and leave them for a few months like they do in EP?"

So, it sounds like trees falling over are a regular occurrence, having nothing to do with extraordinary winds.  Hmmmm...In this article, it's reported that 80-year old trees were knocked down:

"High winds toppled trees on Christmas Tree Lane in Altadena, where for more than 80 years the deodars on Santa Rosa Avenue have been strung with 10,000 lights over the holiday season.

The trees had been strung with lights Sunday in preparation for the big lighting ceremony Dec. 10, said Maureen Ward, president of the Christmas Tree Lane Assn."

"Photo: Maureen Ward, president of the Christmas Tree Lane Assn. in Altadena, examines a deodar felled by Wednesday night's Santa Ana winds. The tree, damaged by a root fungus, had been slated for removal after this year's festivities."

A root fungus!  Fancy that.  This would appear to be a perfect segue into the recent article about Sudden Aspen Death, SAD.  After years of mystery, when dying aspens couldn't be blamed on the bark beetle that attacks pines out west, the scientists have discovered that they are dying due to *a drought!*, which they determined by examining their shriveled, wizened roots.  I guess they never heard that plants exposed to ozone have reduced allocation of carbohydrates to their root systems, even before they display visible damage?  Considering that ALL trees now display visible damage, I would say their roots are probably in pretty bad shape and have been for some time now.  This study joins an earlier report, also blaming tree death on drought, which also ignores the fact that trees exposed to ozone are more vulnerable to drought - but for this post, we're going to concentrate on roots.

I have read in numerous places that root systems become depleted from ozone damage, so I looked around on Wit's End and found an excerpt from the NE-1030, a USDA/Forest Service investigation into the effects of ozone on vegetation:

"In addition to its effect on shoots, O₃ is known to adversely affect carbon flow to the root and consequently its biology and biomass (Sane et al. 1996). This has significant consequences for water transport to support gas exchange (Grantz et al. 1999)."

But hey, I gave up looking on my blog, which isn't very well organized, for citations from published scientific research and tried a fresh google search for "ozone root carbohydrate allocation reduced". That yielded a monumental 123,000 results, so it's obviously no secret!  On the very first page is this gem of a paper, "Source–sink balance and carbon allocation below ground in plants exposed to ozone" funded by our very own EPA and published in New Phytologist, which begins with a delicious, antique quote:

"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."

"Professor M. Carey Lea was perhaps the first to study the effects of a highly oxidized atmosphere on plant growth. A member of the chemistry faculty at the University of Pennsylvania, Professor Lea used 3-l bell jars as exposure vessels in studies of wheat and corn, and generated O3 by ‘the action of sulphuric acid upon chameleon mineral’ (potassium permanganate). The exposure was regenerated every 2–3 d as ‘the presence of vegetation would tend to destroy the O3 rapidly.’ Ozone reduced ‘moulding’ and caused roots to grow upward, away from the bathing nutrient and water solution."

The summary begins:

"It is clear that O3 alters source–sink balance in plants, resulting initially in carbon retention in shoots and decreased carbon allocation below ground. Decreased carbon allocation to roots occurs relatively quickly, and in some cases root responses develop before shoot effects are observed. Decreased

allocation below ground alters carbon flux to soil, and it is probable that soil processes are altered as a result."

"There has been increased understanding of the effects of O3 on plants since 1864, particularly during the last half of the 20th century. Recognition that O3 was a problem in agricultural crops dates at least to 1944 when certain vegetables were observed to have leaf injury (Middleton et al., 1950; Richards

et al., 1958). Although originally attributed to sulfur dioxide, it was later recognized that other components of smog were causing the damage. Soon oxidant damage was recognized as a potential stress in sensitive species throughout the US and in Europe (Heggestad & Middleton, 1959; Daines  et al., 1960; Bell & Cox, 1975; Posthumus, 1976; Ro-Paulsen et al., 1981). Since that time, emphasis has often been on readily observable effects of O3, such as leaf injury, growth and yield, including factors leading to variation in response. This has led to a substantial database on the effects of O3 on plant growth and development."

"Ozone is only one of many stresses present in natural systems that can lead to shifts in ecosystem structure. An example to illustrate this point is found in southern California, where unique topographical and climatic conditions have combined with air pollutants in the Los Angeles basin to result in elevated O3 exposure to forests in the San Bernardino mountains during the last half-century (Miller et al., 1982;

Miller et al., 1989). Ponderosa pine (Pinus ponderosa) and Jeffery pine (Pinus jeffreyi) were most sensitive to O3 , and therefore were weakened by chronic exposure. Weakened trees were more susceptible to bark beetle (Dendroctonus brevicomis) and root rot (Fomes annosus), and O3-tolerant species such as shrubs and oak were favored as pine mortality increased (Miller et al., 1982). It is important to note that O3 was a predisposing factor for stresses that were already present in this

ecosystem. The interaction of stresses affecting San Bernardino forests is still under investigation, particularly the role of N deposition in conjunction with O3 (Fenn et al., 1996; Takemoto et al., 2001)."

"The relative inaccessibility of plant roots has hampered efforts to understand effects of O3 below ground. Current levels of O3 are capable of altering the timing and quantity of carbon flux to soils, and therefore are affecting interactions in the rhizosphere. We still have very limited understanding of how O3 affects interactions of roots with soil organisms, and no idea how these changes alter soil physical and biological properties in ecosystems. Ozone may cause greater disruption of processes below ground than above, and these changes may occur before changes are observed above ground (Hofstra et al., 1981). Past emphasis on shoot responses, for example, photosynthesis, foliar injury, and reduced yield, has diverted our attention from a discussion of below-ground effects, which may in fact be more critical than above-ground effects in determining the long-term consequences of O3 exposure to ecosystems."

"...Biomass and ratios of biomass such as root-shoot ratio do not necessarily reveal physiological changes in response to O3 stress. Decreased carbon allocation leads to reduced carbohydrate levels and storage pools in O3-exposed plants (Tingey et al., 1976; Ito et al., 1985; Cooley & Manning, 1987; Rebbeck et al., 1988; Andersen  et al., 1991; Gorissen  et al., 1994; Andersen et al., 1997). Although difficult to quantify changes in the field, Grulke  et al. (1998) found decreased coarse, medium and fine root biomass with increased pollutant load across a gradient in southern California. Coarse and fine root starch concentrations also were lowest in mature trees at the most polluted site (Grulke et al., 2001). The effects of O3 could not be completely separated from other known stresses across the pollutant gradient, but it appeared that O3 was an important factor in the patterns observed."

"Decreased storage pools can lead to carry-over effects on root growth over time. Decreased carbohydrate storage pools were associated with decreased root growth during the spring following exposure to ozone, even in the absence of additional O3 exposure (Andersen et al., 1991, 1997). Decreased spring root growth was attributed to decreased stored reserves as well as premature loss of older foliage age classes the previous fall.  Aside from the loss of photosynthetic surface area associated with premature senescence, early loss of foliage in the fall occurs when allocation to roots is at a maximum in many species (Kozlowski & Pallardy, 1997). Older needle age classes preferentially allocate photosynthate  roots (Rangnekar et al., 1969; Gordon & Larson, 1970), and their absence in the fall during allocation to root growth and storage, and in the spring during periods of root growth, preferentially impacts roots and root processes."

[oh wasn't I just saying something about leaves falling off early in autumn??]

"There is still little understanding of the effects of O3 on root metabolism, although in the source–sink model decreased allocation will lead to down regulation of metabolic processes. As a measure of root metabolic activity, Edwards (1991) found decreased root and soil CO2 efflux during a 2-yr exposure to loblolly pine. Fine root respiration increased in mature red oak exposed to O3, while total soil CO2

efflux increased in the spring and decreased in the summer and fall (Kelting et al., 1995). The authors attributed increased root respiration to increased nutrient uptake in support of increased demands in the shoot. Ozone decreased root system respiration in aspen after 12 wk of exposure, but the decrease

was closely associated with decreased root biomass (Coleman et al., 1996). Whether or not other metabolic shifts occur in roots of plants exposed to O3 needs to be examined.  Since the site of action of O3 is in the leaf, physiological changes in the root are considered (Fig. 2)."

[did somebody mention aspen??]

"Applying the shared-control model (Farrar & Jones, 2000), O3 stress affects source control of allocation and not sink control since O3 does not penetrate the soil to affect roots directly. However, measurable effects on roots may occur before effects on shoots are observed since shoots have immediate access to carbon for repair and compensation. Mortensen (1998) found decreased root but not shoot growth in Betula pubescens at exposures of 42 nMol mol-1 (applied 12 h d−1), whereas both root and shoot growth were reduced at higher exposures. Chromosomal aberrations were found in root tips of Norway spruce exposed to O3, even in the absence of biochemical changes in needles (Wonisch, 1999). Using relatively high concentrations of O3 (0.15 ppm O36 h d−1), Hofstra et al. (1981) found metabolic changes in P. vulgaris root tips before the development of leaf injury. Morphological changes in root tips occurred within 2–3 d, and metabolism declined within 4 –5 d of initiation of exposure."

So why is it that all those scientists studying SAD didn't mention ozone?  Oh wait...there isn't any ozone!  This reminds me of a comment I found at Scientific American and reposted ages ago, by someone named DownRiverDiva, who so expressed my sentiments as divinely as only a Diva could, when she wrote:

"Why is it that there is all this reporting of things happening to the Earth and problems that are potentially devastating to the people and the environment by scientists but when they are asked why or what is going on they don't know? How are they reporting these things but don't understand them? Are the scientist just stupid and pretending to be working? Or are they in over their heads and need to be out painting billboards instead of in a science
 lab? Or don't they read their own studies? An example: "It's clear that humans are adding nitrogen to Earth's surface. Researchers do not know yet where it all goes, 'but we do know that increasing concentrations of nitrogen in unexpected places will cause significant environmental damage that we will all learn to regret,' Schlesinger wrote in a 2009 report in Proceedings of the National Academy of Sciences."  But then who can question scientists who have all kinds of degrees? Of course when this happens in medical science, they always say, "we don't know what the appendix does, but it's ok to remove it. It must not do anything if we can't figure out what purpose it serves."  Never fails. They do it all the time, for decades, till somebody says, "Hey, it does do something and we better leave it alone!" Bunch of educated fools, all of them. And don't question me, I have a couple of degrees too!"

How Hawt is THAT ??

Along these lines, I wanted to revisit the nitrogen cascade, because some new information has lately been published.  First though, let's recall that Dr. Alan Townsend, who is quoted in the following article, never answered my letter to him, probably because he is quite certain we are going to find some chemical fix for the problem, even as he describes it in very alarming terms:

"'It's been said that nitrogen pollution is the biggest environmental disaster that nobody has heard of,' Alan Townsend, Ph.D., observed at the 242nd National Meeting & Exposition of the American Chemical Society (ACS), being held here this week. Townsend, an authority on how human activity has changed the natural cycling of nitrogen to create a friend-turned-foe dilemma, called for greater public awareness of nitrogen pollution and concerted global action to control it. He spoke at a symposium on the topic, which included almost a dozen reports (abstracts of each presentation appear below) by other experts."

"'Awareness has grown, but nitrogen pollution remains such a little-recognized environmental problem because it lacks the visibility of other kinds of pollution,' Townsend explained. 'People can see an oil slick on the ocean, but hundreds of tons of nitrogen spill invisibly into the soil, water and air every day from farms, smokestacks and automobile tailpipes. But the impact is there - unhealthy air, unsafe drinking water, dead zones in the ocean, degraded ecosystems and implications for climate change. But people don't see the nitrogen spilling out, so it is difficult to connect the problems to their source.'"

"Townsend described the scope and the intensification of the nitrogen pollution problem as 'startling'.  He noted that nitrogen inputs to the terrestrial environment have doubled worldwide during the past century. This increase is due largely to the invention and widespread use of synthetic fertilizer, which has revolutionized agriculture and boosted the food supply."

"The concern focuses on so-called 'reactive' nitrogen. Air contains about 78 percent nitrogen. But this nitrogen is unreactive or 'inert', and plants can't use the gas as a nutrient. In 1909, chemist Fritz Haber developed a way to transform this unreactive gas into ammonia, the active ingredient of synthetic fertilizer. By 2005, human activity was producing about 400 billion pounds of reactive nitrogen each year."

"'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. And though less well studied, high nitrogen levels in water can cause a variety of health concerns, ranging from the effects of drinking water nitrate to the potential to alter the risks of several human diseases."

"Increased nitrogen levels also have implications for climate change, Townsend noted. Excess nitrogen can affect the rate of climate change in multiple and opposing ways. One the one hand, it leads to more warming via the greenhouse gas nitrous oxide, but on the other hand, it can reduce warming by fueling extra plant growth and by forming substances called reflective aerosols in the atmosphere, the scientists noted."

"'The net effect of these processes remains uncertain, but appears to result in minor cooling presently,' Townsend said. However, he noted that excess nitrogen also has large and clear consequences for some worrisome impacts of a changing climate, notably air and water pollution."

"'Climate change is expected to worsen each of these problems worldwide, but reduction of nitrogen pollution could go a long way toward lessening such climate-driven risks,' he added."

"'We're just now starting to recognize the scope of the problem,' said Townsend. 'But the good news is that there are many opportunities for us to lessen the problems. These include ways in which chemists can help, ranging from the development of new technologies to reduce nitrogen's impact to new measurement technologies and techniques that can better diagnose the problems we face with nitrogen.'"

"He outlined several possible solutions to the problem. They include continued and greater support for technologies that remove or reduce reactive nitrogen formation during fossil fuel burning and incentives that can encourage farmers to be more efficient with their fertilizer use. The latter could include subsidies that reward the application of environmental practices that reduce nitrogen levels,' he said.

Several other solutions exist for improving the efficiency of agricultural nitrogen use, Townsend added. 'In many ways, we already know how to do it - the problems are largely about finding the political and cultural means to implement these new practices,' he said.'"

Dr. Townsend is a member of a five-year project to study nitrogen that began last March, funded by the National Science Foundation, but since he seems to think wonderful living through new chemistry is in our future, I don't have much hope for realistic information emerging from it:

"The National Science Foundation (NSF) has funded a 5-year project, beginning March 2011, to create a network of researchers who specialize in a wide range of disciplines pertaining to excess nitrogen in the environment, including aquatic and terrestrial ecology, agronomy, atmospheric chemistry, groundwater dynamics, engineering, epidemiology, and economics. We propose to partner with Resource Media, which has created Nitrogen News as part of a project supported by the David and Lucile Packard Foundation. Nitrogen News was created as a resource for journalists and bloggers covering nitrogen science and management policy."

"Demand for nitrogen fertilizers is increasing in response to growing human population, improving diets, and expanding biofuel crop production. Unfortunately, only about half of the applied nitrogen is used by crops, and the rest is unintentionally released to groundwater, rivers, and to the air, where it presents problems for human health and ecosystem health. Burning fossil fuels for industry and transportation also releases nitrogen into the air, which falls on soils and water bodies. The objective of this research coordination network is to engage a community of researchers from many disciplines, including atmospheric chemistry, agronomy, terrestrial and aquatic ecosystems, social science, and human and wildlife health, who individually study aspects of this issue, but whose collective, inter-disciplinary synthesis is needed to define integrative potential solutions."

"A series of workshops will be convened on topics such as impacts of excess nitrogen on climate, air pollution, water pollution, and agricultural production. Framing the scientific issues of excess nitrogen in the environment in a context relevant to human and ecosystem health will increase understanding for both scientific and non-scientific audiences of the extent of the health and pollution problems associated with excess nitrogen, as well as options and trade-offs for finding solutions."

The most recent publication of Issues in Ecology, "Setting Limits: Using Air Pollution Thresholds to Protect and Restore U.S. Ecosystems", is devoted to a comprehensive look at the nitrogen cascade and ways to use the concept of critical thresholds to conduct research and establish public policy.  It's also got a lot of really scary warnings about acidifying fresh water (every wonder why there are so many reports about fish kills?) and mercury deposition and accumulation up the food chain...but since we are at Wit's End already, we'll stick to nitrogen and vegetation:

It starts right out, in the Introduction with this:

"Natural ecosystems have been altered in various ways by nitrogen, sulfur, and mercury deposited in rain, snow, or as gases and particles in the atmosphere. Through decades of scientific research, scientists have documented how local, regional, and global sources of air pollution can produce profound changes in ecosystems. These changes include acidification of soils and surface waters, harmful algal blooms and low oxygen conditions in estuaries, reduced diversity of native plants, high levels of mercury in fish and decreased tolerance to other stresses, such as pests, disease, and climate change."

So, pollution underlies decreased tolerance to other stresses, such as pests, disease and climate change - meaning warmer temperatures and altered patterns of precipitation and wind.  Why do scientists refuse to acknowledge what they themselves say?

"Pollutants can accumulate with little noticeable impact on plants or animals until major changes occur as a tipping point is reached (Box 1). These changes are measured by scientifically determined chemical or biological indicators (Box2). Such environmental changes might eliminate a single sensitive species, or a broad shift may occur in biodiversity throughout an ecosystem. Once a species or ecosystem has passed a tipping point, a return to the previous state may not be possible."

Definition of tipping point:  "The point at which an ecosystem shifts to a new state or condition in a rapid, often irreversible, transformation."  Remember, we ARE at Point B1, barreling towards extinction:

"Line 'B' represents a rapid decline in ecosystem condition, with a clearly identified, ecological
threshold at which a tipping point occurs (B1)."

"A. Effects of Excess Nitrogen on Ecosystems"

"The nitrogen gas that makes up most of the Earth's atmosphere is inert, with little impact on ecosystems. Nitrogen converted to its reactive forms such as NH3 and NOx, however, can cause profound biological changes.  Activities such as fertilizer manufacturing, intensive livestock production and the burning of fossil fuels convert nitrogen to these reactive forms which can then enter and potentially over-fertilize ecosystems. This can lead to problems such as algal overgrowth in lakes, reduced water quality, declines in forest health, and decreases in aquatic and terrestrial biodiversity by favoring 'nitrogen loving' species at the expense of other species with low nitrogen preferences."

"Adding nitrogen to forests whose growth is typically limited by its availability may appear desirable, possibly increasing forest growth and timber production, but it can also have adverse effects such as increased soil acidification, biodiversity impacts, predisposition to insect infestations, and effects on beneficial root fungi called mycorrhizae. As atmospheric nitrogen deposition onto forests and other

ecosystems increases, the enhanced availability of nitrogen can lead to chemical and biological changes collectively called “nitrogen saturation.” As nitrogen deposition from air pollution accumulates in an ecosystem, a progression of effects can occur as levels of biologically available nitrogen increase (Figure 5)."

"Because of the multiple potential effects of nitrogen deposition in terrestrial and aquatic ecosystems, the ecosystem services affected vary depending on the sensitive receptors found within a given ecosystem and the level of atmospheric deposition. Prominent examples of affected ecosystem services in forests include timber production, climate regulation, recreational use, and biodiversity loss."

The authors end with a plea to use ecological thresholds to establish science-based policy!  Good luck with that:

"The National Ambient Air Quality Standards (NAAQS) for air pollutants such as NOx and SOx are based on concentrations of these pollutants in ambient air rather than on deposition levels experienced by ecosystems. Scientific progress has improved our ability to relate ambient air concentrations to atmospheric deposition inputs and effects through the estimation of critical loads. The secondary standards provide a framework for addressing these issues and ample evidence exists for applying  and modeling to the case of acidifying deposition impacts on sensitive aquatic ecosystems."

"Similar applications of secondary standards toward protection of terrestrial ecosystems from the effects of nitrogen and sulfur pollution would also be of great benefit. Nitrogen as ammonia and ammonium (NH3 and NH4+), are increasingly important sources of nitrogen air pollution, but are not regulated by EPA as criteria pollutants in the NAAQS."

"Air pollution thresholds based on science provide a mechanism for evaluating the extent to which ecosystem services have been compromised and for restoring impaired ecosystems. Establishing priorities such as the levels at which various ecosystem services should be maintained will require the mutual engagement of public stakeholders, policymakers, and scientists. Use of ecological thresholds for


assessing the impacts of air pollution on essential ecosystem services and for informing public policy is gaining ground. These ecological thresholds provide a strong basis for development of policy thresholds and offer a scientifically sound approach to protecting and restoring U.S. ecosystems."

As usual, and typical, the Advisory Board of this milquetoast publication is tainted by the presence of a polluting industry representative, in this case by Robert A. Goldstein, of the Electric Power Research Institute.  By now, most people understand that the banksters and the lobbyists on K Street go round and round through a revolving door of government appointments.  Fewer people realize the same systems operates between, say, the US Forest Service and Georgia Pacific timber interests, between the Dept. of Ag and Monsanto, between EPA and big polluters.  So, what entity is the benevolently named EPRI, you may ask?  Well, according to their website, this "research" group:  "...is funded by membership participation in its research activities. Members represent more than 90% of the electricity generated and delivered in the U.S. International participation extends to 40 countries".  By way of enhancing the credibility of their "research" about the burdensome costs of meeting EPA proposed regulations, they approvingly quote Senator James "climate criminal" Inhofe.  You can stop laughing now.

I'm pretty sure I found this wonderful tune over at The Downward Spiral: