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too</title></head><body>
<div><font face="Arial"><i>Forest Ecology and Management</i> Volume
358, 15 December 2015, Pages 130-138<br>
<br>
<b>Stand dieback and collapse in a temperate forest and its impact on
forest structure and biodiversity</b><br>
Philip A. Martin, Adrian C. Newton, Elena Cantarello, Paul Evans<br>
<br>
Highlights<br>
*There is global concern about forest dieback which may result in
forest loss.<br>
<br>
*We examine a forest undergoing dieback using a dataset collected over
50 years.<br>
<br>
*Basal area declined, with a transition to a grass-dominated system in
some areas.<br>
<br>
*The decline may have been driven by interactions between drought and
overgrazing.<br>
<br>
*Resilience of the forest is low and management is needed to improve
the situation.<br>
<br>
Abstract<br>
<u>http://www.sciencedirect.com/science/article/pii/S037811271500465X</u
></font><br>
<font face="Arial"></font></div>
<div><font face="Arial">Concern is increasing about large-scale
dieback that is occurring in many forest ecosystems. However,
understanding of the processes of dieback and its potential impacts is
limited, partly owing to the lack of long-term monitoring data for
forest stands in which dieback has occurred. Here we present
monitoring data collected over 50 years along two transects in a
temperate forest ecosystem, in which the canopy dominant beech
(<i>Fagus sylvatica</i> L.) has demonstrated significant dieback. Our
results show that basal area in the forest has declined by 33%, and
juvenile tree densities have also been reduced by approximately 70%.
Growing season temperatures have steadily increased and there have
been a number of droughts causing climatic water deficits in recent
decades, particularly in 1995. We hypothesise that these droughts may
have interacted with novel pathogenic fungi to cause mortality of
large trees. Curvilinear responses to BA loss were observed in tree
community change, ground flora species richness, and percentage cover
of grass, providing evidence of thresholds associated with stand
dieback. Evidence also suggested that BA failed to recover once it
declined. Critical values of basal area for a change in ground flora
species richness and grass cover were around 40% decline from initial
values. While these changes are dramatic, they cannot be considered a
regime shift as the pressures that may have contributed to the
ecosystem transition, drought, pathogenic fungi and overgrazing, are
on-going. While managers might consider accepting forest dieback as
part of an adaptive response of the system to novel environmental
conditions, this would likely be associated with significant change in
biodiversity and ecosystem service provision.<font size="-1"
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<div><font face="Cambria" size="-1"
color="#000000"><b
>====================================================================<span
></span>===============<br>
</b></font><font face="Bookman Old Style" size="-1"
color="#000000">"The growth in CO2 emissions closely follows the
growth in Gross Domestic Product (GDP) corrected for improvements in
energy efficiency."<br>
<br>
P. Friedlingstein, et al. "Update on CO2 emissions."</font></div>
<div><font face="Bookman Old Style" size="-1"
color="#000000"><i>Nature Geoscience.</i> Published online: 21
November 2010</font></div>
<div><font face="Geneva" size="-1"
color="#000000"
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></span>===</font></div>
<div><font face="Geneva" size="-1" color="#000000">"An impressive
study across all of northern Russia from 1953-2002 showed a shift in
tree allometries. In areas where summer temperatures and precipitation
have both increased, a general increase in biomass (up 9%) is
primarily a result of increased greenery (33% more carbon in leaves
and needles), rather than woody parts (roots and stem). In areas that
have experienced warming and drying trends, greenery has decreased,
and both roots and stems have increased (Lapenis et al.
2005)."</font></div>
<div><font face="Geneva" size="-1" color="#000000"><br></font></div>
<div><font face="Geneva" size="-1" color="#000000">" ...
there is little theoretical or experimental support to suggest that
climate warming will cause absolute climatic tolerances of a species
to evolve sufficiently to allow it to conserve its geographic
distribution."</font></div>
<div><font face="Bookman Old Style" color="#000000"><br></font></div>
<div><font face="Bookman Old Style" color="#000000">Camille Parmesan.
"Ecological and Evolutionary Responses to Recent Climate
Change."<i> Annual Review of Ecol. Evol. & Systematics </i>
2006. 37:637-69</font><font face="Geneva" size="-1"
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