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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-6-1849-2009</article-id>
<title-group>
<article-title>Forest floor carbon exchange of a boreal black spruce forest in eastern North America</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Bergeron</surname>
<given-names>O.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Margolis</surname>
<given-names>H. A.</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>Coursolle</surname>
<given-names>C.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Centre d&apos;étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Université Laval, Québec, Québec, Canada</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>now at: Department of Natural Resource Sciences, McGill University, Montréal, Québec, Canada</addr-line>
</aff>
<pub-date pub-type="epub">
<day>02</day>
<month>09</month>
<year>2009</year>
</pub-date>
<volume>6</volume>
<issue>9</issue>
<fpage>1849</fpage>
<lpage>1864</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2009 O. Bergeron et al.</copyright-statement>
<copyright-year>2009</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/6/1849/2009/bg-6-1849-2009.html">This article is available from https://bg.copernicus.org/articles/6/1849/2009/bg-6-1849-2009.html</self-uri>
<self-uri xlink:href="https://bg.copernicus.org/articles/6/1849/2009/bg-6-1849-2009.pdf">The full text article is available as a PDF file from https://bg.copernicus.org/articles/6/1849/2009/bg-6-1849-2009.pdf</self-uri>
<abstract>
<p>This study reports continuous automated measurements of forest floor carbon
(C) exchange over feathermoss, lichen, and sphagnum micro-sites in a black
spruce forest in eastern North America during snow-free periods over three
years. The response of soil respiration (&lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;auto&lt;/sub&gt;) and forest floor
photosynthesis (&lt;i&gt;P&lt;sub&gt;ff&lt;/sub&gt;&lt;/i&gt;) to environmental factors was determined. The
seasonal contributions of scaled up &lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;auto&lt;/sub&gt; adjusted for spatial
representativeness (&lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;adj&lt;/sub&gt;) and &lt;i&gt;P&lt;sub&gt;ff&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-eco&lt;/sub&gt;) relative to that
of total ecosystem respiration (&lt;i&gt;R&lt;sub&gt;e&lt;/sub&gt;&lt;/i&gt;) and photosynthesis (&lt;i&gt;P&lt;/i&gt;&lt;sub&gt;eco&lt;/sub&gt;),
respectively, were also quantified.
&lt;br&gt;&lt;br&gt;
Shallow (5 cm) soil temperature explained 67–86% of the variation in
&lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;auto&lt;/sub&gt; for all ground cover types, while deeper (50 and 100 cm) soil
temperatures were related to &lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;auto&lt;/sub&gt; only for the feathermoss
micro-sites. Base respiration was consistently lower under feathermoss,
intermediate under sphagnum, and higher under lichen during all three years.
The &lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;adj&lt;/sub&gt;/&lt;i&gt;R&lt;sub&gt;e&lt;/sub&gt;&lt;/i&gt; ratio increased from spring through autumn and ranged
from 0.85 to 0.87 annually for the snow-free period. The &lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;adj&lt;/sub&gt;/&lt;i&gt;R&lt;sub&gt;e&lt;/sub&gt;&lt;/i&gt;
ratio was negatively correlated with the difference between air and shallow
soil temperature and this correlation was more pronounced in autumn than
summer and spring.
&lt;br&gt;&lt;br&gt;
Maximum photosynthetic capacity of the forest floor (&lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-max&lt;/sub&gt;) saturated
at low irradiance levels (~200 μmol m&lt;sup&gt;&amp;minus;2&lt;/sup&gt; s&lt;sup&gt;&amp;minus;1&lt;/sup&gt;) and
decreased with increasing air temperature and vapor pressure deficit for all
three ground cover types, suggesting that &lt;i&gt;P&lt;sub&gt;ff&lt;/sub&gt;&lt;/i&gt; was more limited by
desiccation than by light availability. &lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-max&lt;/sub&gt; was lowest for sphagnum,
intermediate for feathermoss, and highest for lichen for two of the three
years. &lt;i&gt;P&lt;sub&gt;ff&lt;/sub&gt;&lt;/i&gt; normalized for light peaked at air temperatures of 5–8&amp;deg;C,
suggesting that this is the optimal temperature range for &lt;i&gt;P&lt;sub&gt;ff&lt;/sub&gt;&lt;/i&gt;. The
&lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-eco&lt;/sub&gt;/&lt;i&gt;P&lt;/i&gt;&lt;sub&gt;eco&lt;/sub&gt; ratio varied from 13 to 24% over the snow-free
period and reached a minimum in mid-summer when both air temperature and
&lt;i&gt;P&lt;/i&gt;&lt;sub&gt;eco&lt;/sub&gt; were at their maximum. On an annual basis, &lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-eco&lt;/sub&gt; accounted
for 17–18% of &lt;i&gt;P&lt;/i&gt;&lt;sub&gt;eco&lt;/sub&gt; depending on the year and the snow-free season
totals of &lt;i&gt;P&lt;sub&gt;ff&lt;/i&gt;-eco&lt;/sub&gt; were 23–24% that of &lt;i&gt;R&lt;sub&gt;s-&lt;/i&gt;adj&lt;/sub&gt;.</p>
</abstract>
<counts><page-count count="16"/></counts>
</article-meta>
</front>
<body/>
<back>
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