Faculty Profiles - IIMURA Yasuo

Papers - IIMURA Yasuo

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Effects of soil temperature and tidal condition on variation in CO2 flux from soil sediment in a subtropical mangrove forest Reviewed

Tomotsune M, Yoshitake S, Iimura Y, Kida M, Fujitake N, Koizumi H, Ohtsuka T

Journal of Tropical Ecology 34 ( 268 ) 275 2018

Dissolved organic carbon (DOC) input to the soil: DOC fluxes and their partitions during the growing season in a cool-temperate broad-leaved deciduous forest, central Japan Reviewed

Siyu Chen, Shinpei Yoshitake, Yasuo Iimura, Chiyuki Asai, Toshiyuki Ohtsuka

ECOLOGICAL RESEARCH 32 ( 5 ) 713 - 724 2017.9

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

Dissolved organic carbon (DOC) plays an important role in C cycling in forest ecosystems. Here we measured the concentrations and fluxes of DOC in a cool-temperate broad-leaved deciduous forest (Takayama Forest) to quantify the contribution of DOC from different forest water flux conditions. Mean DOC concentration during the growing season increased in the sequence from bulk precipitation (2.98 +/- 0.45 mg L-1), throughfall above dwarf bamboo (6.84 +/- 0.45 mg L-1), throughfall below dwarf bamboo (7.08 +/- 0.42 mg L-1), stemflow (15.05 +/- 0.98 mg L-1), and litter leachate (21.33 +/- 1.01 mg L-1). Litter leachate DOC concentration, being high in spring and autumn, which was fairly correlated with the amount of litterfall of bamboo and trees. In stemflow, the DOC concentration was high during early summer and gradually decreased, in addition, it also showed dramatic variation among different plant species. Litter leachate (72.5%) accounted for most of the DOC input to the soil during the growing season (311.5 kg C ha(-1) 7 months(-1)), while stemflow (1.6%) contributed the least. A great quantity of precipitation at the study site was associated with a subsequent high atmospheric contribution of DOC flux (8.6%), which was more than half of throughfall (16.5%). The high input of DOC to the soil and andisol soil characteristics at the Takayama Forest suggest that the DOC fluxes are vital to the soil carbon sequestration. Therefore, DOC fluxes should be taken into account when the carbon balance is assessed at forest ecosystems.

DOI： 10.1007/s11284-017-1488-6

Web of Science

Scopus

High salinity leads to accumulation of soil organic carbon in mangrove soil Reviewed

Morimaru Kida, Mitsutoshi Tomotsune, Yasuo Iimura, Kazutoshi Kinjo, Toshiyuki Ohtsuka, Nobuhide Fujitake

CHEMOSPHERE 177 51 - 55 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Although mangrove forests are one of the most well-known soil organic carbon (SOC) sinks, the mechanism underlying SOC accumulation is relatively unknown. High net primary production (NPP) along with the typical bottom-heavy biomass allocation and low soil respiration (SR) have been considered to be responsible for SOC accumulation. However, an emerging paradigm postulates that SR is severely underestimated because of the leakage of dissolved inorganic carbon (DIC) in groundwater. Here we propose a simple yet unique mechanism for SOC accumulation in mangrove soils. We conducted sequential extraction of water extractable organic matter (WEOM) from mangrove soils using ultrapure water and artificial seawater, respectively. A sharp increase in humic substances (HS) concentration was observed only in the case of ultrapure water, along with a decline in salinity. Extracted WEOM was colloidal, and <= 70% of it re-precipitated by the addition of artificial seawater. These results strongly suggest that HS is selectively flocculated and maintained in the mangrove soils because of high salinity. Because sea salts are a characteristic of any mangrove forest, high salinity may be one of mechanisms underlying SOC accumulation in mangrove soils. (C), 2017 Published by Elsevier Ltd.

DOI： 10.1016/j.chemosphere.2017.02.074

Web of Science

Scopus

Spatial Upscaling of Soil Respiration under a Complex Canopy Structure in an Old-Growth Deciduous Forest, Central Japan Reviewed

Vilanee Suchewaboripont, Masaki Ando, Shinpei Yoshitake, Yasuo Iimura, Mitsuru Hirota, Toshiyuki Ohtsuka

FORESTS 8 ( 2 ) 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

The structural complexity, especially canopy and gap structure, of old-growth forests affects the spatial variation of soil respiration (Rs). Without considering this variation, the upscaling of Rs from field measurements to the forest site will be biased. The present study examined responses of Rs to soil temperature (Ts) and water content (W) in canopy and gap areas, developed the best fit model of Rs and used the unique spatial patterns of Rs and crown closure to upscale chamber measurements to the site scale in an old-growth beech-oak forest. Rs increased with an increase in Ts in both gap and canopy areas, but the effect of W on Rs was different between the two areas. The generalized linear model (GLM) analysis identified that an empirical model of Rs with the coupling of Ts and W was better than an exponential model of Rs with only Ts. Moreover, because of different responses of Rs to W between canopy and gap areas, it was necessary to estimate Rs in these areas separately. Consequently, combining the spatial patterns of Rs and the crown closure could allow upscaling of Rs from chamber-based measurements to the whole site in the present study.

DOI： 10.3390/f8020036

Web of Science

Scopus

Change in biomass of an old-growth beech-oak forest on the eastern slope of Mt. Hakusan over a 17-year period. Reviewed

Suchewaboripont V, Iimura Y, Yoshitake S, Kato S, Komiyama A, Ohtsuka T

Journal of Forest Environment 2015

The effect of canopy structure on soil respiration in an old-growth beech forest in central Japan. Reviewed

Suchewaboripont V, Ando M, Iimura Y, Yoshitake S, Ohtsuka T

Ecological Research 2015

Role of coarse woody debris in the carbon cycle of Takayama forest, central Japan. Reviewed

Ohtsuka T, Shizu Y, Hirota M, Yashiro Y, Jia S, Iimura Y, Koizumi H

Ecological Research 2014

Investigations of environmental changes based on chemical analyses of humic substances. Reviewed

Kawahigashi M, Ono K, Iimura Y, Fujitake N

Humic Substances Research 2013

Black humic acid dynamics during natural reforestation of Japanese pampas grass (Miscanthus sinensis). Reviewed

Iimura Y, Fujimoto M, Tamura K, Higashi T, Kondo M, Uchida M, Yonebayashi K, Fujitake N

Soil Biology and Biochemistry 2013

Carbon cycling and sequestration in a Japanese red pine (Pinus densiflora) forest on lava flow of Mt Fuji. Reviewed

Ohtsuka T, Negishi M, Sugita K, Iimura Y, Hirota M

Ecological Research 2013

Comparison of quantity and quality of soil organic carbon between matured and gap areas in an old-growth beech forest. Reviewed

Iimura Y, Hirota M, Ida H, Ohtsuka T

Journal of Geography 2013

Investigation of the composition and origin of particle organic matter in a forested river. Reviewed

Li W, Numata T, Kobayashi S, Yamada T, Li F, Ohtsuka T, Iimura Y

Journal of Water and Environment Technology 2013

Characterization of DAX-8 adsorbed soil fulvic acid fractions by various types of analyses. Reviewed

Iimura Y, Ohtani T, Chersich S, Tani M, Fujitake N

Soil Science and Plant Nutrition 2012

The effect of dense dwarf bamboo (Sasa senanensis) understory on soil respiration before and after clearcutting of cool temperate deciduous broad-leaved forest. Reviewed

Yashiro Y, Shizu Y, Adachi T, Ohtsuka T, Lee N, Iimura Y, Koizumi H

Ecological Research 2012

Molecular size fractionation of soil humic acids using preparative high performance size-exclusion chromatography. Reviewed

Asakawa D, Iimura Y, Kiyota T, Yanagi Y, Fujitake N

Journal of Chromatography A 2011

Effects of ecological succession on surface mineral horizons in Japanese volcanic ash soil. Reviewed

Iimura Y, Fujimoto M, Hirota M, Tamura K, Higashi T, Yonebayashi K, Fujitake N

Geoderma 2010

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