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--></style><title>Streamflows change when old-growth converted to
doug-fir p</title></head><body>
<div><font face="Lucida Grande" size="-1"><i>Ecohydrology:</i> Early
View, Online Version of Record before inclusion in an
issue</font></div>
<div><font face="Lucida Grande" size="-1"><b>First published:</b> 14
November 2016</font></div>
<div><font face="Lucida Grande" size="-1"><b><br></b></font></div>
<div><font face="Lucida Grande" size="-1">Summer streamflow deficits
from regenerating Douglas-fir forest in the Pacific Northwest,
USA</font></div>
<div><font face="Lucida Grande" size="-1">Timothy D. Perry, Julia A.
Jones</font></div>
<div><font face="Lucida Grande" size="-1"><br></font></div>
<div><font face="Lucida Grande" size="-1">Abstract<b> [bold
added]</b></font></div>
<div><font face="Lucida Grande"
size="-1">http://onlinelibrary.wiley.com/doi/10.1002/eco.1790/full</font
></div>
<div><font face="Lucida Grande" size="-1"><br></font></div>
<div><font face="Lucida Grande" size="-1">Analysis of 60-year records
of daily streamflow from eight paired-basin experiments in the Pacific
Northwest of the United States (Oregon) revealed that the conversion
of old-growth forest to Douglas-fir plantations had a major effect on
summer streamflow. Average daily streamflow in summer (July through
September) in basins with 34- to 43-year-old plantations of
Douglas-fir was 50% lower than streamflow from reference basins with
150- to 500-year-old forests dominated by Douglas-fir, western
hemlock, and other conifers. Study plantations are comparable in terms
of age class, treatments, and growth rates to managed forests in the
region.<b> Young Douglas-fir trees, which have higher sapwood area,
higher sapflow per unit of sapwood area, higher concentration of leaf
area in the upper canopy, and less ability to limit transpiration,
appear to have higher rates of evapotranspiration than old trees of
conifer species, especially during dry summers</b>. Reduced summer
streamflow in headwater basins with forest plantations may limit
aquatic habitat and exacerbate stream warming, and it may also alter
water yield and timing in much larger basins. Legacies of past forest
management or extensive natural disturbances may be confounded with
effects of climate change on streamflow in large river basins.
Continued research is needed using long-term paired-basin studies and
process studies to determine the effects of forest management on
streamflow deficits in a variety of forest types and forest management
systems.</font></div>
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<div><font face="Geneva" size="-1" color="#000000">"The global
average lake summer surface water warming rate found here implies a
20% increase in algal blooms and a 5% increase in toxic blooms over
the next century [<i>Brookes and Carey</i>,<b> 2011</b>;<i> Rigosi et
al.</i>,<b> 2015</b>], as well as a 4% increase in methane emissions
from lakes during the next decade. Increased evaporation associated
with warming can lead to declines in lake water level, with
implications for water security [<i>Vorosmarty</i>,<b> 2000</b>;<i>
Hanrahan et al.</i>,<b> 2010</b>], substantial economic consequences
[<i>Gronewold and Stow</i>,<b> 2014</b>], and in some cases, complete
ecosystem loss (e.g., [<i>Smol and Douglas</i>,<b> 2007</b>]).
Already, changes in thermal structure and mixing have decreased
productivity of some lakes, which threaten human communities that
depend on fisheries as a nutritional and economic resource
[<i>O'Reilly et al.</i>,<b> 2003</b>]. Lakes with high rates of
surface temperature change may appear more likely to experience major
ecosystem changes [<i>Smol et al.</i>,<b> 2005</b>;<i> Smol and
Douglas</i>,<b> 2007</b>], but we caution that even lakes with low
rates of change may be under ecosystem stress if the initial water
temperatures are already near physiological maxima [<i>Tewksbury et
al.</i>,<b> 2008</b>]. The widespread warming reported here suggests
that large changes in Earth's freshwater resources and their processes
are not only imminent but already under way."</font></div>
<div><font face="Geneva" size="-1" color="#000000"><br></font></div>
<div><font face="Geneva" size="-1" color="#000000">Catherine M.
O'Reilly, Sapna Sharma, Derek K. Gray, Stephanie E. Hampton et al.
Rapid and highly variable warming of lake surface waters around the
globe.<i> Geophysical Research Letters</i>, December 28,
2015</font></div>
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color="#FFFF00"><u><br></u></font></div>
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