Japan Geoscience Union Meeting 2016

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS06] Biogeochemistry

Sun. May 22, 2016 10:45 AM - 12:15 PM A03 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Muneoki Yoh(Tokyo University of Agriculture and Technology), Hideaki Shibata(Field Science Center fot Northern Biosphere, Hokkaido University), Naohiko Ohkouchi(Japan Agency for Marine-Earth Science and Technology), Youhei Yamashita(Faculty of Environmental Earth Science, Hokkaido University), Chair:Tomoya Iwata(Faculty of Life and Environmental Sciences, University of Yamanashi), Urumu Tsunogai(Graduate School of Environmental Studies, Nagoya University), Yoshiyuki Inagaki(Forestry and Forest Products Research Institute), Kazumichi Fujii(Forestry and Forest Products Research Institute)

11:30 AM - 11:45 AM

[MIS06-10] Long-term nitrogen dynamics in pine forest using 15N tracer

*Karibu Fukuzawa1, Hideaki Shibata1, Takashi Wakamatsu2, Yoshiyuki Inagaki3 (1.Field Science Center for Northern Biosphere, Hokkaido Univ., 2.Central Research Institute of Erectric Power Industry, 3.Forestry and Forest Products Research Institute)

Keywords:15N tracer, pine forest, nitrogen deposition

We investigated the retention of applied nitrogen(N) to vegetation and soil after application of 15N tracer to determine the effects of atmospheric N deposition on the N dynamics in forest ecosystem. Most of previous studies using 15N focused on relatively short duration effect, and it has been reported that microbes in organic layer is the major sink of the 15N. However, it is not clear the long-term effects on N dynamics. This study clarified the 15N retention to vegetation and soil ten years after the 15N application.
We conducted survey in pine (Pinus densiflora) forest in Akagi field of Central Research Institute of Erectric Power Industry (CRIEPI) in Gunma prefecture, Japan. We established the six plots (4×5m) surrounding each mature pine tree, and applied NH4Cl solution (50mgN m-2) in added plots (three plots) in 2002. Other three plots were control plots to compare with added plots. We collected boles, branches, leaves, roots O layer and soils (0-10, 10-20, 20-40 cm depth) in January 2013. Disks of boles were sampled at a height of 7-15 m and three radical replications were set. Furthermore, we sampled latest 15 years part and divided every five years. We determined delta-15N by using mass spectrometer.
Delta-15N of the bole were from -2.0 to -3.3‰ and from -4.7 to -5.3‰ in added and control plots, respectively. Delta-15N values of the branches, leaves, and roots were also high in added plots. Especially, in roots, delta-15N value was high (from 9.7 to 10.0‰) compared with from -5.7 to -5.1‰ in control. In the soil, the difference was large in organic layer and surface 10 cm layer. These results suggest applied N was retained in forest ecosystem even ten years after application. We will also discuss the changes of 15N distribution and 15N recovery during ten years.