Estimation of symbiotic dinitrogen fixation in alder forest by the method based on natural15N abundance |
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Authors: | A M Domenach F Kurdali R Bardin |
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Institution: | (1) Ecologie microbienne UA CNRS 697, Université Claude Bernard Lyon 1, Bâtiment 741, 43, Bd du 11 novembre 1918, F-69622 Villeurbanne Cedex, France |
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Abstract: | Annual N2-fixation in virgin forest ecosystems has been measured using a15N natural abundance ( 15N) procedure. This method was compared to a15N labelled fertilizer isotopic dilution method. For young alders (5–6 years old), 15N of leaves gave results in good agreement with the isotopic dilution of fertilizer method. Since 15N variability was expected according to plant physiology, for alder trees, leaves were collected at various heights after the end of the growing season, and, to take account of isotopic variations coming from derived inputs, 15N of leaves of a large number of other plants in the same are were measured to give control values. Following this procedure, the 15N method gave reliable evaluation of the nitrogen supply, by through N2-fixation, to alders, which were found to maintain high nitrogen fixing capacity in a sequence ranging from first stage of establishment of climactic formation. Moreover, the same method is reported to discriminate various origins ofAlnus glutinosa grown in natural conditions, possibly in relation to the genetic diversity of this species. |
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Keywords: | N2-fixation 15N fertilizer 15N" target="_blank">gif" alt="delta" align="BASELINE" BORDER="0">15N tree |
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