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--></style><title>PDF: A reality check on the CO2 "fertilization
effect"</title></head><body>
<div><font face="Lucida Grande">Study finds that plant growth
responses to high carbon dioxide depend on symbiotic
fungi</font><font face="Arial"><br>
</font><font face="Lucida Grande">INDIANA UNIVERSITY PUBLIC
RELEASE: 30-JUN-2016</font></div>
<div><font face="Arial"><br></font></div>
<div><font face="Arial">I have the pdf of the Science article. Feel
free to ask</font></div>
<div><font face="Arial"><br></font></div>
<div><font face="Arial">In the meantime, you can see the abstract
here:</font></div>
<div><font
face="Arial">http://science.sciencemag.org/content/353/6294/72</font></div
>
<div><font face="Lucida Grande"><br></font></div>
<div><font
face="Lucida Grande">============= <b>
Excerpt</b> from press release
=================</font></div>
<div><font face="Lucida Grande">"In some ways, our research
represents encouraging news in that many of our forests may continue
to slow climate change by soaking up carbon dioxide," he added.
"On the other hand, it is sobering in that the CO2 fertilization
effect may occur on a relatively small fraction of the Earth's
surface. And if climate change also increases the frequency and
intensity of disturbances such as droughts and floods, the magnitude
of the plant growth response to high carbon dioxide will be
diminished."</font><font face="Arial"><br>
</font><font
face="Lucida Grande">================================</font><font
face="Arial"><br>
</font><font face="Lucida Grande"><br>
Research by an international team of environmental scientists from the
United Kingdom, Belgium and United States, including Indiana
University, has found that plants that associate with one type of
symbiotic fungi grow bigger in response to high levels of carbon
dioxide, or CO2, in the atmosphere, but plants that associate with the
other major type of symbiotic fungi do not.</font><font
face="Arial"><br>
</font><font face="Lucida Grande"><br>
The study, which appears online today in the journal Science, calls
into question whether the 'greening of the Earth' that results from
carbon dioxide stimulation of plant growth -- often called the
"CO2 fertilization effect" -- will persist as fossil fuel
emissions continue to rise globally.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
"Pumping extra carbon dioxide into a greenhouse is a common
tactic to stimulate plant growth, but nature is much more complex than
a greenhouse," said Richard Phillips, associate professor in the
IU College of Arts and Sciences' Department of Biology, who is a
co-author on the study. "So, there is great debate about whether
pumping carbon dioxide into the atmosphere through fossil fuel
combustion stimulates plant growth in nature, where soil nutrient
levels are typically much lower than in a
greenhouse."</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
Fungi that form symbiotic relationships with plants are called
mycorrhizal fungi. Over 90 percent of all plant life on Earth
associates with mycorrhizal fungi, which provide plants with soil
nutrients in exchange for plant carbohydrates.</font><font
face="Arial"><br>
</font><font face="Lucida Grande"><br>
"While researchers have long known that mycorrhizal fungi play an
essential role in the growth and health of plants, their role in
helping ecosystems store carbon has never been investigated on such a
broad scale -- until now," said second-year PhD student Cesar
Terrer of Imperial College London, who is first author on the paper.
"Our analysis is the first to demonstrate that only plants that
associate with a certain type of fungal partner - one that helps them
acquire nitrogen from soil - are likely to grow bigger as carbon
dioxide levels rise."</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
Other authors are on the study are Colin Prentice of Imperial College
London; Sara Vicca of the University of Antwerp, Belgium; and Bruce A.
Hungate of the Northern Arizona University.</font><font
face="Arial"><br>
</font><font face="Lucida Grande"><br>
The research team examined 83 experimental studies of plant responses
to CO2 levels equivalent to those expected by the year 2050, assuming
an increase of about 2 percent each year globally.</font><font
face="Arial"><br>
</font><font face="Lucida Grande"><br>
They found a marked difference in the ability of certain plants to
take advantage of increased CO2 levels. Plants that grew in
nitrogen-rich soils were able to grow bigger and sustain high levels
of growth throughout the experiment, following expectations. In
nitrogen-poor soils, however, only plants that associate with a
certain type of symbiotic fungi were able to keep growing
larger.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
The group of fungi that enabled plants to grow bigger under high CO2
levels is ectomycorrhizal fungi - a type of fungi that helps plants
access soil nutrients by decomposing organic matter, such as the
remains of dead plants and microbes.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
Plants that associate with the other major type of mycorrhizal fungi -
arbuscular mycorrhizal fungi - were unable to maintain high levels of
growth under elevated CO2. While these fungi also increase plant
access to nutrients, they cannot access nutrients locked up in soil
organic matter.</font><font face="Arial"></font></div>
<div><font face="Lucida Grande"><br>
"Nearly all plants associate with only a single type of
mycorrhizal fungi," said Phillips. "And since the type of
fungal associates are known for most plant species, we can begin to
predict which ecosystems may respond favorably to high levels of CO2
and which ones will not."</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
Ectomycorrhizal fungi associate only with woody plants, such as trees
and shrubs, and tend to dominate in forests at high latitudes.
Arbuscular mycorrhizal fungi associate with all forms of plant life
and dominate in nearly all ecosystems, aside from the boreal forest.
In temperate forests, about the half the tree species associate with
each type of fungi.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
About 30 percent of human CO2 emissions are currently absorbed by
land-based ecosystems, without which climate change would be happening
even faster than it is now.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
The results of this study should enable climate scientists make more
accurate predictions of the effects of CO2 in the future, Phillips
said.</font><font face="Arial"><br>
</font><font face="Lucida Grande"><br>
"In some ways, our research represents encouraging news in that
many of our forests may continue to slow climate change by soaking up
carbon dioxide," he added. "On the other hand, it is
sobering in that the CO2 fertilization effect may occur on a
relatively small fraction of the Earth's surface. And if climate
change also increases the frequency and intensity of disturbances such
as droughts and floods, the magnitude of the plant growth response to
high carbon dioxide will be diminished."</font></div>
<div><font face="Lucida Grande">###</font></div>
<div><br></div>
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color="#000000"
> **************************************************************<span
></span>*****************************<br>
"Our results suggest that climate policy need not reduce happiness
in the long run, even when it reduces income and carbon-intensive
consumption. Climate policy may even raise life well-being, if
accompanied by compensatory measures that decrease formal working
hours and reference consumption standards, while maintaining
employment security."<br>
<br>
Filka Sekulova, Jeroen C.J.M. van den Bergh. Climate change, income
and happiness: An empirical study for Barcelona,<i> Global
Environmental Change</i> 23 (2013) 1467-1475</font></div>
<div><font face="Geneva"
color="#000000">-------------------------------------------------<br>
<font size="-1">"He who knows he has enough is rich."<br>
Lao-Tzu<br>
</font><br>
</font><font face="Lucida Grande" size="-1"
color="#000000"></font></div>
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