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competition f</title></head><body>
<div>Andrew J. Larson, James A. Lutz, Daniel C. Donato, James A.
Freund, Mark E. Swanson, Janneke HilleRisLambers, Douglas G. Sprugel,
and Jerry F. Franklin 2015.<b> Spatial aspects of tree mortality
strongly differ between young and old-growth forests</b>.<i>
Ecology</i> 96:2855-2861.<u>
http://dx.doi.org/10.1890/15-0628.1</u></div>
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<div>Abstract<b> bold added</b></div>
<div>http://www.esajournals.org/doi/abs/10.1890/15-0628.1</div>
<div><br>
Rates and spatial patterns of tree mortality are predicted to change
during forest structural development.<b> In young forests, mortality
should be primarily density dependent due to competition for
light,</b> leading to an increasingly spatially uniform pattern of
surviving trees. In contrast, mortality in old-growth forests should
be primarily caused by contagious and spatially autocorrelated agents
(e.g., insects, wind), causing spatial aggregation of surviving trees
to increase through time.<b> We tested these predictions by
contrasting a three-decade record of tree mortality</b> from
replicated mapped permanent plots located in young (<60-year-old)
and old-growth (>300-year-old)<i> Abies amabilis</i> forests.<b>
Trees in young forests died at a rate of 4.42% per year, whereas trees
in old-growth forests died at 0.60% per year.</b> Tree mortality in
young forests was significantly aggregated, strongly density
dependent, and caused live tree patterns to become more uniform
through time. Mortality in old-growth forests was spatially
aggregated, but was density independent and did not change the spatial
pattern of surviving trees. These results extend current theory by
demonstrating that<b> density-dependent competitive mortality leading
to increasingly uniform tree spacing in young forests</b> ultimately
transitions late in succession to a more diverse tree mortality regime
that maintains spatial heterogeneity through time.</div>
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<div><font face="Lucida Grande" size="-1" color="#141413">"Climate
change will alter ecosystem services, perceptions of value, and
decisions regarding land uses. Outcomes for people will be determined
by the interaction between changes in biophysical environments (e.g.,
climate, disturbance, and invasive species) and human responses to
those changes (management and policy)."<br>
<br>
</font><font face="Arial" size="-1" color="#141413">United States
Department of Agriculture<br>
Forest Service<br>
Pacific Northwest Research Station<br>
General Technical Report PNW-GTR-870<br>
December 2012</font></div>
<div><font face="Cambria" size="-2"
color="#FFFF00"><u
>http://www.fs.fed.us/pnw/pubs/pnw_gtr870/pnw_gtr870.pdf</u></font></div
>
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