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<front>
<journal-meta>
<journal-id journal-id-type="publisher">BG</journal-id>
<journal-title-group>
<journal-title>Biogeosciences</journal-title>
<abbrev-journal-title abbrev-type="publisher">BG</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Biogeosciences</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1726-4189</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/bg-8-3077-2011</article-id>
<title-group>
<article-title>Distinct patterns in the diurnal and seasonal variability in four components of soil respiration in a temperate forest under free-air CO&lt;sub&gt;2&lt;/sub&gt; enrichment</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Taneva</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Gonzalez-Meler</surname>
<given-names>M. A.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Ecology and Evolution Group, Department of Biological Sciences, University of Illinois at Chicago, 845 W. Taylor Street M/C 066, Chicago IL 60607, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>31</day>
<month>10</month>
<year>2011</year>
</pub-date>
<volume>8</volume>
<issue>10</issue>
<fpage>3077</fpage>
<lpage>3092</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2011 L. Taneva</copyright-statement>
<copyright-year>2011</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://bg.copernicus.org/articles/8/3077/2011/bg-8-3077-2011.html">This article is available from https://bg.copernicus.org/articles/8/3077/2011/bg-8-3077-2011.html</self-uri>
<self-uri xlink:href="https://bg.copernicus.org/articles/8/3077/2011/bg-8-3077-2011.pdf">The full text article is available as a PDF file from https://bg.copernicus.org/articles/8/3077/2011/bg-8-3077-2011.pdf</self-uri>
<abstract>
<p>Soil respiration (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt;) is a major flux in the global carbon (C) cycle.
Responses of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; to changing environmental conditions may exert a strong
control on the residence time of C in terrestrial ecosystems and in turn
influence the atmospheric concentration of greenhouse gases. Soil
respiration consists of several components oxidizing soil C from different
pools, age and chemistry. The mechanisms underlying the temporal variability
of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; components are poorly understood. In this study, we used the
long-term whole-ecosystem &lt;sup&gt;13&lt;/sup&gt;C tracer at the Duke Forest Free Air
CO&lt;sub&gt;2&lt;/sub&gt; Enrichment site to separate forest &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; into its autotrophic
(&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt;) and heterotrophic components (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;H&lt;/sub&gt;). The contribution of
&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;H&lt;/sub&gt; to &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; was further partitioned into litter decomposition
(&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt;), and decomposition of soil organic matter (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;SOM&lt;/sub&gt;) of two age
classes – up to 8 yr old and SOM older than 8 yr. Soil respiration was
generally dominated by &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;SOM&lt;/sub&gt; during the growing season (44% of
daytime &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt;), especially at night. The contribution of heterotrophic
respiration (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;SOM&lt;/sub&gt; and &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt;) to &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; was not constant, indicating
that the seasonal variability in &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt; alone cannot explain seasonal
variation in &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt;. Although there was no diurnal variability in &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt;,
there were significant compensatory differences in the contribution of
individual &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; components to daytime and nighttime rates. The average
contribution of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;SOM&lt;/sub&gt; to &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; was greater at night (54%) than
during the day (44%). The average contribution of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt; to total
&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; was ~30% during the day and ~34% during the night.
In contrast, &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt; constituted 26% of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; during the day and only
12% at night. About 95% of the decomposition of soil C older than 8 yr
(&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;pre-tr&lt;/sub&gt;) originated from &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;SOM&lt;/sub&gt; and showed more pronounced
and consistent diurnal variability than any other &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; component;
nighttime rates were on average 29% higher than daytime rates. In
contrast, the decomposition of more recent, post-treatment C (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;pre-tr&lt;/sub&gt;)
did not vary diurnally. None of the diurnal variations in components of
&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;H&lt;/sub&gt; could be explained by only temperature and moisture variations. Our
results indicate that the variation observed in the components of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; is
the result of complex interaction between dominant biotic controls (e.g. plant
activity, mineralization kinetics, competition for substrates) over abiotic
controls (temperature, moisture). The interactions and controls among roots
and other soil organisms that utilize C of different chemistry,
accessibility and ages, results in the overall soil CO&lt;sub&gt;2&lt;/sub&gt; efflux.
Therefore understanding the controls on the components of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;S&lt;/sub&gt; is
necessary to elucidate the influence of ecosystem respiration on atmospheric
C-pools at different time scales.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
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