The mobility of nitrogen across tree‐rings of Norway spruce (Picea abies L.) and the effect of extraction method on tree‐ring δ15N and δ13C values. (20th April 2014)

• Record Type: Journal Article
• Authors: Tomlinson, G.; Siegwolf, R. T. W.; Buchmann, N.; Schleppi, P.; Waldner, P.; Weber, P.
• Is Part Of: Rapid communications in mass spectrometry. Volume 28:Number 11(2014)
• Page Start: 1258
• Page End: 1264
• Publication Date: 2014-04-20
• Subjects: Mass spectrometry -- Periodicals; 543.65
• DOI: 10.1002/rcm.6897
• Languages: English
• ISSNs: 0951-4198

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="rcm6897-sec-0001" sec-type="section"> <title>RATIONALE</title> <p>The use of stable nitrogen (N) isotope ratios (δ<sup>15</sup>N values) in dendroecological studies is often preceded by an extraction procedure using organic solvents to remove mobile N compounds from tree‐rings. Although these mobile N compounds may be capable of distorting potential environmental signals in the tree‐ring δ<sup>15</sup>N values, recent investigations question the necessity of such an extraction.</p> </sec> <sec id="rcm6897-sec-0002" sec-type="section"> <title>METHODS</title> <p>We used an on‐going experiment with simulated elevated N deposition previously labelled with <sup>15</sup>N, in conjunction with control trees, to investigate the necessity of extracting mobile N compounds (using a rapid extraction procedure) for tree‐ring δ<sup>15</sup>N and δ<sup>13</sup>C studies, as well as N and C concentration analyses. In addition, we examined the magnitude of radial redistribution of N across tree‐rings of Norway spruce (<italic>Picea abies</italic>).</p> </sec> <sec id="rcm6897-sec-0003" sec-type="section"> <title>RESULTS</title> <p>The <sup>15</sup>N label, applied in 1995/96, was found in tree‐rings as far back as 1951, although the increased N availability did not cause any significant relative increase in tree growth. The rapid extraction procedure had no significant effect on tree‐ring δ<sup>15</sup>N or δ<sup>13</sup>C values in either labelled or control trees, or on N concentration. The C concentrations, however, were significantly higher after extraction in control samples, with the opposite effect observed in labelled samples.</p> </sec> <sec id="rcm6897-sec-0004" sec-type="section"> <title>CONCLUSIONS</title> <p>Our results indicate that the extraction of mobile N compounds through the rapid extraction procedure is not necessary prior to the determination of Norway spruce δ<sup>15</sup>N or δ<sup>13</sup>C values in dendrochemical studies. δ<sup>15</sup>N values, however, must be interpreted with great care, particularly when used as a proxy for the N status of trees, due to the very high mobility of N within the tree stem sapwood of Norway spruce over several decades. Copyright © 2014 John Wiley & Sons, Ltd.</p> </sec> </abstract>