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滋賀県立大学 環境科学部 生物資源管理学科 講師 2019年04月 ～ 現在
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滋賀県立大学 環境科学部 生物資源管理学科 助教 2013年11月 ～ 2019年03月
所属学会・委員会 【 表示 ／ 非表示 】
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日本土壌肥料学会
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日本腐植物質学会
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日本地球惑星科学連合
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International Humic Substances Society
論文 【 表示 ／ 非表示 】
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伊吹山のヨモギと黒色火薬の生産／琵琶湖集水域の環境メタロミクス 連載第12回
飯村康夫・水野隆文・原田英美子
金属 2022年10月
共著 共同（主担当）
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Organic carbon stock and composition in 3.5-m core mangrove soils (Trat, Thailand)
Kida M., Watanabe I., Kinjo K., Kondo M., Yoshitake S., Tomotsune M., Iimura Y., Umnouysin S., Suchewaboripont V., Poungparn S., Ohtsuka T., Fujitake N.
Science of the Total Environment Science of the Total Environment 801 2021年12月
10.1016/j.scitotenv.2021.149682 共著
[概要]
Mangroves are increasingly recognized as an important component of regional and global carbon cycles especially for their high carbon storage capacity. Global estimation of mangrove soil organic carbon (SOC) storage requires detailed regional studies, but estimates of SOC data in deep soils are currently missing in many countries. Furthermore, little is explored on the molecular composition of mangrove SOC. Here, we assessed the SOC stock in a Trat mangrove forest (Thailand) by collecting deep soils (3.5 m) and analyzed the SOC composition for better understanding its potential sources and influencing factors. The Trat mangrove forest had four times higher SOC stock than has been considered for Thai mangrove forests, with the per-area SOC stock of nearly 1000 Mg C ha–1 which rivals that of Indo-Pacific mangrove forests. The SOC composition analyzed by C/N ratios and spectroscopic techniques differed by tree species and depth. Compositional data principal component analysis revealed that a biological factor (root abundance) had stronger influences than the soil texture (sand versus clay) on the abundance and composition of mangrove SOC. Although surface soil (~1 m) C density was largely controlled by the recent vegetation, deep soil C density reflected other historical processes. This study contributed to a refined estimate of Thailand mangrove SOC stock and revealed that factors influencing SOC abundance and composition differ by tree species and depth.
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Ohtsuka T., Onishi T., Yoshitake S., Tomotsune M., Kida M., Iimura Y., Kondo M., Suchewaboripont V., Cao R., Kinjo K., Fujitake N.
Forests Forests 11 (10) 1 ～ 15 2020年10月
[概要]
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The significance of aquatic lateral carbon (C) export in mangrove ecosystems highlights the extensive contribution of aquatic pathways to the net ecosystem carbon budget. However, few studies have investigated lateral fluxes of dissolved organic carbon (DOC) and inorganic carbon (DIC), partly due to methodological difficulty. Therefore, we evaluated area-based lateral C fluxes in a small mangrove estuary that only had one exit for water exchange to the coast. We sampled water from the mouth of the creek and integrated discharge and consecutive concentration of mangrove-derived C (∆C). Then, we estimated the area-normalized C fluxes based on the inundated mangrove area. DIC and DOC concentrations at the river mouth increased during ebb tide during both summer and winter. We quantified the ∆C in the estuary using a two-component conservative mixing model of freshwater and seawater. DIC and DOC proportions of ∆C concentrations at the river mouth during ebb tide was between 34% and 56% in the winter and 26% and 42% in the summer, respectively. DIC and DOC fluxes from the estuary were estimated to be 1.36 g C m−2 d−1 and 0.20 g C m−2 d−1 in the winter and 3.35 g C m−2 d−1 and 0.86 g C m−2 d−1 in the summer, respectively. Based on our method, daily fluxes are mangrove area-based DIC and DOC lateral exports that can be directly incorporated into the mangrove carbon budget.
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Integrative assessment of the effects of shrub coverage on soil respiration in a tundra ecosystem
Masumoto S., Kitagawa R., Nishizawa K., Osono T., Hasegawa M., Iimura Y., Matsuoka S., Kaneko R., Uchida M., Mori A.S.
Polar Science Polar Science 2020年01月
10.1016/j.polar.2020.100562 共著
[概要]
© 2020 Elsevier B.V. and NIPR Shrub encroachment and soil respiration (SR) are predicted to increase in the tundra ecosystem under climate warming, but little is known regarding potential causal relationships between shrubs and SR at a local scale. Multiple and complex belowground processes exist between the two phenomena, and consolidation is logistically difficult. Our study aimed to identify and integrate multiple belowground processes to elucidate the impact of shrub coverage on SR, using structural equation modeling (SEM). Results indicated that shrub coverage enhanced SR through root biomass, fungal community composition and soil temperature. SEM also revealed a potential indirect effect via interactions among those soil factors. Soil factors relating heterotrophic respiration affected on SR through more complex interaction among the factors. However, total effect sizes on SR were similar between factors relating autotrophic respiration and that relating heterotrophic respiration, suggesting that SR increases with shrub coverage would be unlikely to result from decreases in soil organic matter.
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Iimura Y., Tanaka D., Nagao S., Fujitake N., Ohtsuka T.
Soil Science and Plant Nutrition Soil Science and Plant Nutrition 2020年01月
10.1080/00380768.2020.1753481 共著
[概要]
© 2020, © 2020 Japanese Society of Soil Science and Plant Nutrition. The stability of black soil carbon in the deep layers of Japanese volcanic ash soil (i.e., buried A horizons) is often explained by its unique chemical (molecular structure) and physical (associated with short-range-order minerals) recalcitrance. However, the stability of black soil C in buried A horizons may be changed by labile C supply for soil microbes. Here, we hypothesized that the mineralization of black soil C in buried A horizons of Japanese volcanic ash soil could be easily accelerated by a supply of labile C (i.e., a priming effect; PE). To test our hypothesis, we investigated the direction and magnitude of the PE with a buried A horizon in Japan using 13C-labeled glucose (2.188 atom %) in a short-term (21 days) incubation study. We also investigated the effect of mineral nitrogen (N), which could contribute to microbial activity in this incubation study. We found that a positive PE occurred by glucose supply with (182%) or without (181%) mineral N input over the 21-day incubation, and its values were very similar to the PE ratios previously reported in other deep soils. The estimated mean residence time (MRT) of black soil C considering PE was clearly accelerated by glucose supply, regardless of mineral N input, compared with the initial soil MRT. These results strongly support our hypothesis that the mineralization rate of black soil C in buried A horizons is easily accelerated by a labile C supply, and it also demonstrates important implications for the effects of global warming on buried A horizons (e.g., increased root exudation, fine root biomass supply, and N deposition) in Japanese volcanic ash soils.
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大白川ブナ・ミズナラ成熟林（old-growth forest）における土壌窒素無機化速度の空間変動解析
飯村 康夫, Vilanee Suchewaboripont, 廣田 充, 吉竹 晋平, 大塚 俊之
日本土壌肥料学雑誌 2019年08月
共著
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冷温帯落葉広葉樹林における林床ササ群落（Sasa senanensis）の有無が火山灰土壌の窒素無機化速度に及ぼす影響
飯村 康夫, 森田 悠介, 大塚 俊之
日本土壌肥料学雑誌 2019年07月
単著
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Ohtsuka T., Tomotsune M., Suchewaboripont V., Iimura Y., Kida M., Yoshitake S., Kondo M., Kinjo K.
Regional Studies in Marine Science Regional Studies in Marine Science 27 2019年03月
[概要]
© 2019 Elsevier B.V. There are insufficient data regarding forest productivity of mature mangroves near the northern limit of mangrove distribution in subtropical East Asia. We conducted the present study to determine the stand dynamics and net primary production (NPP) of a mature mangrove forest on Ishigaki Island in south-western Japan over three successive years, using a large permanent plot. The two mangrove species present were Bruguiera gymnorrhiza and Rhizophora stylosa. The aboveground biomass in the plot was high, despite the high latitude (24 ∘ 29 ′ N) of the site, gradually increasing from 158.4 Mg ha −1 to 164.6 Mg ha −1 over the three-year study period. This increase was attributable to an increase in the biomass of B. gymnorrhiza. The biomass of R. stylosa, however, decreased during the same period because of a threefold-higher mortality rate and a lower relative growth rate of this species compared with B. gymnorrhiza. The mangrove forest was in the late successional stage, following a pioneer R. stylosa forest that was widely distributed throughout the study plot as standing dead trees and logs. The aboveground NPP of the mangrove forest was 10.66 ± 1.46 Mg ha −1 y −1 , partitioned into 3.10 ± 0.51 Mg ha −1 y −1 as woody NPP (net increase in aboveground woody parts, SI), and 7.56 ± 0.99 Mg ha −1 y −1 as foliage NPP (litter production, including foliage and reproductive organs, L n ). The mature mangrove forest had a relatively low SI/L n ratio (0.41 ± 0.03), although litter fall production was within the range previously recorded for mangroves. The lower woody NPP in the mature mangroves was due to the exclusion of R. stylosa once the stand was in a late successional stage dominated by B. gymnorrhiza.
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Iimura Y., Tabara I., Izumitsu K., Fujitake N.
Soil Science and Plant Nutrition Soil Science and Plant Nutrition 2019年01月
10.1080/00380768.2019.1665969 共著
[概要]
© 2019, © 2019 Japanese Society of Soil Science and Plant Nutrition. The response of soil organic matter (SOM) to global warming is a crucial subject. However, the temperature sensitivity of SOM turnover remains largely uncertain. Changes in the mineralization of native SOM, i.e., priming effect (PE) may strongly affect the temperature sensitivity of SOM turnover in the presence of global warming. We investigated the direction and magnitude of the PE in a Japanese volcanic ash soil at different temperatures (15°C, 25°C, and 35°C) using a natural 13C tracer (C4-plant, maize leaf) in a short-term (25 days) incubation study. In addition, we evaluated the temperature sensitivity expressed as Q10 value with and without the addition of maize to the soil and their relations to PE. We found that positive PE occurred at each temperature condition and tended to increase with decreased temperature, and these PE results were consistent with the microbial biomass at the end of the incubation period. CO2 emission from control soil (without maize) increased with increasing temperature (Q10 = 2.6), but CO2 emission from the soil with added maize did not significantly change with increasing temperature (Q10 = 1.0). This was caused by the suppression of CO2 emission from the soil with increasing temperature (Q10 = 0.9). On the other hand, soil-originated CO2 emission clearly increased with increasing temperature (Q10 = 3.4) when Q10 values were calculated on the assumption that the temperature and substrate supply increase at the same time (from 25°C). These results suggest that not only the temperature increase but also the labile carbon supply may be important for the temperature sensitivity of Japanese volcanic ash soil.
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Iimura Y., Kinjo K., Kondo M., Ohtsuka T.
Soil Science and Plant Nutrition Soil Science and Plant Nutrition 2019年01月
10.1080/00380768.2019.1660589 共著
[概要]
© 2019, © 2019 Japanese Society of Soil Science and Plant Nutrition. Mangrove ecosystems play an important role in carbon (C) accumulation in tropical and subtropical regions. Below-ground deep anoxic soil is especially important for C accumulation. However, quantitative data on below-ground soil C stocks in mangrove ecosystems are lacking compared with data on above-ground biomass. In addition, soil C accumulation processes in mangrove ecosystems have not been sufficiently clarified. In this study, we quantified soil C stocks and focused on the mass of fallen litter and below-ground roots, which are produced by tree and that may directly influence soil C stocks in a mature subtropical mangrove in the estuary of Fukido River, Ishigaki Island, southwestern Japan. The principal species in this study site were Bruguiera gymnorhiza and Rhizophora stylosa, and total above-ground biomass at the site was 80.7 ± 1.3 (mean ± SD) Mg C ha−1 over the period from 2014 to 2016. Litter was collected in six litter traps from May 2013 to November 2016, it ranged from 7.8 to 11.5 Mg C ha−1, with the major proportion of litter being from foliage (leaves and stipules). The root C density at 90-cm depth was 27.1 ± 11.3 Mg C ha−1. The soil C stock in the mangrove forest at a depth of 90 cm at the study site was 251.0 ± 34.8 Mg C ha−1, and it seems to be lower value in the tropical region but it to be higher in subtropical East Asian mangrove sites. Dead roots, especially dead fine roots, but not fallen litter, were significantly positively correlated with soil C stocks. The δ13C values obtained from soils ranged from −29.3‰ to −27.0‰; these values are consistent with those for below-ground fine roots. These results strongly suggest that dead fine roots could be a main factor controlling soil C stocks at this study site.
著書 【 表示 ／ 非表示 】
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Ecological significance of throughfall and stemflow to he carbon cycle in forest ecosystems
Chen S, Cao R, Yoshitake S, Iimura Y, Ohtsuka T
Springer 2022年
単行本（学術書） 共著
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Biometric-Based Estimations of Net Primary Production (NPP) in Forest Ecosystems.
Ohtsuka T, Muraoka H, Saigusa N, Iimura Y, Koizumi H
Springer, UK. 2015年
単行本（学術書） 共著
