Year: 2008

PNAS | March 4, 2008 | vol. 105 | no. 9 | 3410-3415
OPEN ACCESS ARTICLE

BIOLOGICAL SCIENCES / ECOLOGY

Impact of an extreme climatic event on community assembly
Katherine M. Thibault, and James H. Brown

Department of Biology, University of New Mexico,
Albuquerque, NM 87131; and Department of Biology,
Furman University, Greenville, SC 29613

Abstract:
Extreme climatic events are predicted to increase
in frequency and magnitude, but their ecological
impacts are poorly understood. Such events are
large, infrequent, stochastic perturbations that
can change the outcome of entrained ecological
processes. Here we show how an extreme flood
event affected a desert rodent community that has
been monitored for 30 years. The flood (i) caused
catastrophic, species-specific mortality; (ii)
eliminated the incumbency advantage of previously
dominant species; (iii) reset long-term
population and community trends; (iv) interacted
with competitive and metapopulation dynamics; and
(v) resulted in rapid, wholesale reorganization
of the community. This and a previous extreme
rainfall event were punctuational
perturbations-they caused large, rapid
population- and community-level changes that were
superimposed on a background of more gradual
trends driven by climate and vegetation change.
Captured by chance through long-term monitoring,
the impacts of such large, infrequent events
provide unique insights into the processes that
structure ecological communities.

desert rodents | incumbency advantage | punctuational dynamics

Freely available online through the PNAS open access option: Go to
http://www.pnas.org/cgi/content/full/105/9/3410

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” … the freeze killed … in an area encompassing Nebraska, Maryland,
South Carolina, and Texas. Subsequent drought limited regrowth.”
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  Public release date: 3-Mar-2008
American Institute of Biological Sciences

Contact: Holly Menninger
hmenninger@aibs.org
202-628-1500

Will global warming increase plant frost damage?

Widespread damage from 2007 Eastern US spring
freeze attributed to earlier warming

Widespread damage to plants from a sudden freeze
that occurred across the Eastern United States
from 5 April to 9 April 2007 was made worse
because it had been preceded by two weeks of
unusual warmth, according to an analysis
published in the March 2008 issue of BioScience.
The authors of the report, Lianhong Gu and his
colleagues at the Oak Ridge National Laboratory
and collaborators at NASA, the University of
Missouri, and the National Oceanic and
Atmospheric Administration, found that the freeze
killed new leaves, shoots, flowers, and fruit of
natural vegetation, caused crown dieback of
trees, and led to severe damage to crops in an
area encompassing Nebraska, Maryland, South
Carolina, and Texas. Subsequent drought limited
regrowth.

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“Now that all the records have been shown to
coincide, “it suggests that the whole world
hydrologic cycle varies in unison, on a pretty
rapid time scale,” said Gisela Winckler …”
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Public release date: 28-Feb-2008
The Earth Institute at Columbia University

Each year, long-distance winds drop up to 900
million tons of dust from deserts and other parts
of the land into the oceans. Scientists suspect
this phenomenon connects to global climate-but
exactly how, remains a question. Now a big piece
of the puzzle has fallen into place, with a study
showing that the amount of dust entering the
equatorial Pacific peaks sharply during repeated
ice ages, then declines when climate warms. The
researchers say it cements the theory that
atmospheric moisture, and thus dust, move in
close step with temperature on a global scale;
the finding may in turn help inform current ideas
to seed oceans with iron-rich dust in order to
mitigate global warming. The study appears in the
Feb. 28 edition of Science Express, the advance
online edition of the leading journal Science.

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