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Media type:
E-Article
Title:
15N Abundance of Soils and Plants along an Experimentally Induced Forest Nitrogen Supply Gradient
Contributor:
Högberg, Peter
imprint:
Springer-Verlag, 1994
Published in:Oecologia
Language:
English
ISSN:
0029-8549;
1432-1939
Origination:
Footnote:
Description:
<p>
<sup>15</sup>N abundances of soils and a grass species (Deschampsia flexuosa (L.) Trin.) were analysed in a forest fertilization experiment 10 years after the last fertilization. Nitrogen had been given as urea, at seven doses, ranging from 0 to 2400 kg N ha<sup>-1</sup>. Previously, we have shown that plants in systems experiencing large losses of N become enriched with<sup>15</sup>N. This was explained by the fact that processes leading to loss of N, e.g. ammonia volatilization, nitrification followed by leaching or denitrification and denitrification itself, tend to fractionate against<sup>15</sup>N. In this experiment,<sup>15</sup>N abundance increased with dose of N applied in both grass and soil total-N, but more so in the grass. This was interpreted to be due to the grass sampling small but active pools of N subject to losses. In contrast, soil total-N largely consists of inactive N that does not immediately exchange with pools of N from which fractionating losses occur. Hence, soil total-N shows a large pretreatment<sup>15</sup>N memory effect, and is, therefore, an integrator of the long-term N balance. When short-term changes (years, decades) in N balances are monitored using variations in<sup>15</sup>N abundance, plants are more suitable indicators of such change than is soil total-N.</p>