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forests</title></head><body>
<div>PNAS<font face="Arial"> Early Edition doi:
10.1073/pnas.1525678113</font></div>
<div><font face="Arial"><b><br></b></font></div>
<div><font face="Times"><b>Meta-analysis reveals that hydraulic traits
explain cross-species patterns of drought-induced tree mortality
across the globe</b></font></div>
<div><font face="Arial">William R. L. Anderegg, Tamir Klein, Megan
Bartlett, Lawren Sack, Adam F. A. Pellegrini, Brendan Choat, and
Steven Jansen</font></div>
<div><font face="Arial"><b><br>
</b></font><font face="Times"><b>Abstract</b></font></div>
<div><font
face="Times"
>http://www.pnas.org/content/early/2016/04/13/1525678113.abstract</font
></div>
<div><font face="Times"><br>
</font><font face="Arial">Drought-induced tree mortality has been
observed globally and is expected to increase under climate change
scenarios, with large potential consequences for the terrestrial
carbon sink. Predicting mortality across species is crucial for
assessing the effects of climate extremes on forest community
biodiversity, composition, and carbon sequestration. However, the
physiological traits associated with elevated risk of mortality in
diverse ecosystems remain unknown, although these traits could greatly
improve understanding and prediction of tree mortality in forests. We
performed a meta-analysis on species' mortality rates across 475
species from 33 studies around the globe to assess which traits
determine a species' mortality risk. We found that species-specific
mortality anomalies from community mortality rate in a given drought
were associated with plant hydraulic traits. Across all species,
mortality was best predicted by a low hydraulic safety margin-the
difference between typical minimum xylem water potential and that
causing xylem dysfunction-and xylem vulnerability to embolism.
Angiosperms and gymnosperms experienced roughly equal mortality risks.
Our results provide broad support for the hypothesis that hydraulic
traits capture key mechanisms determining tree death and highlight
that physiological traits can improve vegetation model prediction of
tree mortality during climate extremes.</font></div>
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<div><font face="Bookman Old Style" size="-1"
color="#000000"><b
>============================================================</b></font
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<div><font face="Geneva" size="-1" color="#000000">The global climate
change agreement brokered in Paris in December by 195 nations will
come into effect two years earlier than originally planned, the top
United Nations climate diplomat predicted.</font></div>
<div><font face="Geneva" size="-1" color="#000000"><br></font></div>
<div><font face="Geneva" size="-1" color="#000000">Even so, she said
the deal had come "10 years too late," and that the world is now
at "two minutes to midnight."</font></div>
<div><font color="#000000"><br></font></div>
<div><font size="-2"
color="#000000"
>http://www.bloomberg.com/news/articles/2016-04-11/paris-climate-deal<span
></span>-seen-taking-effect-two-years-ahead-of-plan</font></div>
<div><font face="Geneva" size="-1"
color="#000000"
>---------------------------------------------------------------------<br
>
"What can be said with some assurance is that there is a unique and
nearly ubiquitous compound, with the empirical formula<b>
H</b>(2960)<b>O</b>(1480)<b>C</b>(1480)<b>N</b>(16)<b>P</b>(1.8)<b>S</b
>, called living matter. Its synthesis, on an oxidized and
uncarboxylated earth, is the most intricate feat of chemical
engineering ever performed - and the most delicate operation that
people have ever tampered with."<br>
<br>
Edward S. Deevey, Jr. Mineral Cycles,<br>
<i>Scientific American</i>, September 1970.</font></div>
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