Inorganic nitrogen source utilization byFagus crenata on different soil types |
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Authors: | Ryunosuke Tateno Noriyuki Osada Masakazu Terai Naoko Tokuchi Hiroshi Takeda |
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Affiliation: | (1) Laboratory of Forest Ecology, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan;(2) Research Institute for Humanity and Nature, 335 Takashima-cho, Marutamachi-dori Kawaramachi nishi-iru, Kamigyo-ku Kyoto, 602-0878, Japan;(3) Nikko Botanical Garden, Graduate School of Science, University of Tokyo, Nikko Tochigi, 321-1435, Japan;(4) Field Science Education and Research Center, Kyoto University, Kyoto, 606-8502, Japan |
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Abstract: | The nitrogen source utilization by Fagus crenata distributed on soils with different forms of inorganic nitrogen in a cool-temperate deciduous forest in central Japan was determined by measuring foliar 15N. Two soil habitat types along a slope were delineated based on nitrogen transformation patterns, i.e., soils with high net nitrification rates and with no or low net nitrification, respectively. Despite differences in soil types, the study species, F. crenata, was distributed along the entire slope. The foliar 15N value of F. crenata from the lower slope area was significantly lower than that from the upper slope. Given the finding of a previous study that the 15N of NO3– was lower than that of NH4+, our results indicate that reliance on NO3– as a nitrogen source was greater in the lower slope area than in the upper slope area. Differences in the values of foliar 15N were about 1 , which is far less than the 10 15N value of soil inorganic N reported in the previous study. This discrepancy might suggest that the study species utilized NO3– even in the upper site where net nitrification had not been detected. Measurements of nitrate reductase activity, an index of NO3– uptake, also supported this interpretation. Nitrate reduction occurred in leaves and roots at both the lower and the upper sites. Thus, the study species may be able to use NO3– even in soils with no net nitrification, a factor that could allow the distribution of F. crenata along the entire length of the slope. |
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Keywords: | Beech forest Nitrogen isotope Nitrogen use Nitrification Nitrate reductase activity |
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