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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Douglas A. Johnson</dc:contributor>
  <dc:contributor>Nicanor Z. Saliendra</dc:contributor>
  <dc:contributor>Kanat Akshalov</dc:contributor>
  <dc:contributor>Bruce K. Wylie</dc:contributor>
  <dc:creator>Tagir G. Gilmanov</dc:creator>
  <dc:date>2004</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Compared to other characteristics of CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;exchange, gross primary productivity (&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;) is most directly related to photosynthetic activity. Until recently, it was considered difficult to obtain measurement-based&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;. The objective of our study was to evaluate if&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;can be estimated from continuous CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;flux measurements using nonlinear identification of the nonrectangular hyperbolic model of ecosystem-scale, light-response curves. Estimates of&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;and ecosystem respiration (&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;e&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;) were obtained using Bowen ratio&amp;ndash; energy-balance measurements of CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;exchange in a true-steppe ecosystem in northern Kazakhstan during four growing seasons (1998&amp;ndash;2001). The maximum mean weekly apparent quantum yield (&amp;alpha;&lt;/span&gt;&lt;span&gt;max&lt;/span&gt;&lt;span&gt;) was 0.0388 mol CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;mol photons and the maximum mean weekly&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;was 28 g CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;/m&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;/day in July 2000. The highest mean weekly&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;e&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;max&lt;/i&gt;&lt;span&gt;&amp;nbsp;(20 g CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;m&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;/day) was observed in July of both 1999 and 2000. Nighttime respiration calculated from daily respiration corrected for length of the dark period and temperature (using&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;Q&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;10&lt;/span&gt;&lt;span&gt;&amp;nbsp;= 2) was closely associated with measured nighttime respiration (&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;= 0.67 to 0.93). The 4-year average annual gross primary production (GPP) was 1617 g CO&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;/m&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;/ year (range = 1308&amp;ndash;1957). Ten-day normalized difference vegetation index corrected for the start of the season (NDVI&lt;/span&gt;&lt;span&gt;sos&lt;/span&gt;&lt;span&gt;) was closely associated with 10-day average&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;(&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;= 0.66 to 0.83), which was higher than&amp;nbsp;&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;values for regressions of mean 10-day net daytime fluxes on NDVI&lt;/span&gt;&lt;span&gt;sos&lt;/span&gt;&lt;span&gt;&amp;nbsp;(0.55&amp;ndash;0.72). This demonstrates the advantage of using&lt;/span&gt;&lt;i class="EmphasisTypeItalic"&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i class="EmphasisTypeItalic"&gt;g&lt;/i&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;in scaling up flux-tower measurements compared to other characteristics (net daytime flux or net 24-h flux).&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1007/s00267-003-9157-7</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Springer</dc:publisher>
  <dc:title>Gross primary productivity of the true steppe in central Asia in relation to NDVI: scaling up CO&lt;sub&gt;2&lt;/sub&gt; fluxes</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>