Updated on 2024/04/13

写真a

 
KOIZUMI, Hiroshi
 
Affiliation
Faculty of Education and Integrated Arts and Sciences
Job title
Professor Emeritus
 

Research Projects

  • バイオチャーを用いた森林における炭素隔離効果と生態系応答機構の解明

    Project Year :

    2015.04
    -
    2019.03
     

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    バイオチャーに対する森林生態系の応答解析においては、バイオチャー散布区で引き続き生態系純生産、純一次生産、従属栄養生物呼吸の測定を行った。特に従属栄養生物呼吸については新たにトレンチ法を用いることで、バイオチャー散布が従属栄養生物呼吸の土壌呼吸に対する寄与を変化させ、生態系純生産に影響を与えていることが明らかになった。また、新たに幼齢林にバイオチャーを散布し、室内実験とともに植物の光合成に対する影響を評価した。その結果、バイオチャーの一部の成分が間接的に肥料として働き、光合成活性を高め、それと同時に植物バイオマスの増加を引き起こしていることが示された。バイオチャーの特性と動態解明においては、散布直前から継続してサンプルを採取し、バイオチャー層、有機物層、鉱質土層の物理化学、微生物特性を測定した。その結果、有機物堆積層においては昨年度に認められた差は小さくなりつつあるが、新たに硬質土層の微生

  • A contribution of root exudation to carbon cycle and its responsibility to environmental conditions in forest ecosystems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2015.04
    -
    2018.03
     

    Koizumi Hiroshi, TOMOTSUNE Mitsutoshi, HONDA Asahi, TANAZAWA Yumina, MARIKO Shigeru, MURAOKA Hiroyuki

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    To clarify seasonal variation in carbon flux from live root to pedosphere (root exudation) and contribution of it net primary production (NPP), root exudation rate was measured from 2016 to 2017 in two types of forests; dominated by Quercus serrata (deciduous broad-leaved tree; Q forest) and Pinus densiflora (evergreen conifer tree; P forest). Using a new method developed by us, averaged exudation was measured at 0.49 and 1.09 mg C g fine root-1 day-1 in the Q and P forest, respectively. It in Q forest showed significant seasonal variation with high value in summer season, although that in P forest showed no clear seasonal variation. Annual exudation was estimated at 30 and 61 gC m-2 year-1, which contributed to NPP at 2.6 and 9.6%, in Q and P forest, respectively. These results suggest that the root exudation rate vary based on tree functional type, and is important factor to evaluate the carbon balance of forest ecosystem.

  • Long-term durability of carbon sequestration in terrestrial ecosystems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2007
    -
    2010
     

    MARIKO Shigeru, KOIZUMI Hiroshi, YOKOZAWA Masayuki, OHTSUKA Toshiyuki, TAMURA Kenji, KAMIJO Takashi, HIROTA Mitsuru

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    This study consists of the following three sub-themes : 1) quantitative evaluation of temporal variability of carbon cycle parameters along with secondary succession ; 2) examination of sustainable carbon sequestration within developing ecosystems in terms of a succession/carbon dynamics model ; 3) temporal variation of soil organic carbon with primary succession. Our chronosequence study of secondary succession in Sugadaira, Nagano prefecture, used for the following ecosystem sequence : Artemisia-dominant grassland, Miscanthus-dominant grassland, Populus-dominant forest, Pinus-dominant forest, Quercus-dominant forest and Fagus-dominant forest. Carbon sequestration within the plants increased with succession. However, litter carbon showed no increase or decrease with succession. Soil carbon increased in herbaceous sere, and decreased in early forest stages. Thus, our results demonstrated that secondary succession influenced the size of carbon pools within the ecosystems. The measured results were confirmed by a simulation in terms of a succession/carbon dynamics model. In primary succession study (Miyakejima study site), soil organic carbon increased from a naked land to a climax s

  • Evaluation of soil carbon sequestration in a small basin ecosystem

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2003
    -
    2006
     

    KOIZUMI Hiroshi, AKIYAMA Tsuyoshi, MARIKO Shigeru, OHTSUKA Toshiyuki, BEKKU Yukiko, YOKUZAWA Masayuki

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    Ecosystem carbon pools and fluxes were measured with chronosequece in cool-temperate zone, central Japan. Five study sites for secondary succession, ranging from clear-felled site to 100-years mature deciduous forest, were selected in the Takayama and Sugadaira research sites. Four study sites were set on the lower mountain zone of Mt. Fuji for primary succession, young pine forest, mature pine forest, conifer forest and climax deciduous forest, which had different age after vegetation establishment (12-2850 y). SOC pool was the highest (376 tC ha^<-1>) at the herbaceous stage on secondary succession. The SOC pool greatly decreased at pioneer pine forest stage (259 tC ha^<-1>), in turn, gradually recovered at mature deciduous forest. Drastic change of SOC pools was resulted from the differences of NPP allocation between herbaceous stage and pioneer tree stages : the former allocated NPP to short-lived herbaceous parts which recruited to SOC pool, and the latter allocated NPP to long-lived woody component. In contrast, SOC pools increased along the primary succession, 16 to 173 tC ha^<-1>, in Mt. Fuji. The proportion of the biomass pool to the total ecosystem C pool gradually decrea

  • Ecological study of the factors controlling spatial and temporal variations of carbon cycle in a High Arctic terrestrial ecosystem

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2003
    -
    2006
     

    NAKATSUBO Takayuki, KANDA Hiroshi, KOIZUMI Hiroshi, OHTSUKA Toshiyuki, MURAOKA Hiroyuki, UCHIDA Masaki

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    This research aims to clarify the factors controlling spatial and temporal variations of carbon cycle in a High Arctic terrestrial ecosystem and to construct a model for estimating the impact of climate change on the cycle. For these purposes, we conducted following studies on a glacier foreland in Svalbard.(1) The relationships between vegetation and soil factors were investigated along three 2.6km lines which extended from newly deglaciated area to later succesional stages with well-developed vegetation cover.(2) Factors controlling net ecosystem production in the latter successinal stage were examined.(3) Photosynthetic characteristics of the lichen Cetrariella delisei were examined to estimate its contribution to the primary production of the ecosystem.(4) Photosynthetic characteristics of three dominant vascular plants were determined to study the spatial variation of productivity.(5) Factors controlling methane emission rate was examined along topographical gradients.(6) The relation of soil phospholipid fatty acid content (an index of microbial community structure) to vegetation was examined for soil samples collected from Svalbard and Canadian High Arctic.(7) CO2 emission r

  • Testing a common allometric equation for predicting the above-ground weight of trees and estimation of net ecosystem production

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2003
    -
    2005
     

    KOMIYAMA Akira, KOIZUMI Hiroshi, KATO Shogo

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    In the previous study (Komiyama et al. 2005 ; J.Trop.Ecol. 21:471-477), a common allometric equation for predicting the above-ground weight was developed for mangrove tree species based on a biological theory of statical model of plant form. In the present study, I examine whether this equation is applicable to a wide variety of tree species growing in East-Asia, including mangroves. The 387 tree data consisted of over 71 species were collected from tropical to temperate forests located in Indonesia, Thailand, and Japan. A common allometric equation between the above-ground tree weight and trunk diameter held significantly for these trees adding the wood density of trunk as a variable. The relative error between actual and estimated above-ground weight was 19.5% for this equation.In 110-year-old secondary forest, Net primary production (NPP) of aboveground=9.96 ton/ha/year. NPP of underground=0.97 ton/ha/year. Thus, in 110-year-old secondary forest, NPP=10.93 ton/ha/year. On the other hand, net ecosystem production (NEP) is calculated by subtraction of heterotrophic respiration (HR) from NPP. HR assumes half of soil respiration and carbon content also assumes half of tree and/or li

  • Integrated assessment of global warming influence of ecosystems based on ecosystem global warming potential

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2003
    -
    2005
     

    MARIKO Shigeru, KOIZUMI Hiroshi, TODA Hideshige, SEKIKAWA Seikoh, SUGITA Mikio

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    Our aim is to assess the influence of ecosystems on global warming based on the budgets of three greenhouse-effect gases (CO_2,CH_4,N_2O) between the atmosphere and ecosystems. The data of the gas fluxes were obtained from in situ measurements by some chamber methods and survey of previous papers. Here, gas influx to the ecosystem has a positive unit, and gas efflux from the ecosystem a negative unit. Based on global warming potential (GWP,IPCC 1996), the fluxes of CH_4 and N_2O were converted into an equivalent of CO_2. The sum of CO_2 flux and CO_2-equivalent fluxes of CH_4 and N_2O is defined as ecosystem global warming potential (EGWP).1.EGWPs in various types of ecosystemsStudied ecosystems (forest, grassland, wetlands, agroecosystems including croplands, rice paddy fields, orchards) were a sink for CO_2, a sink for CH_4 except wetlands, N2O and a weak source for N_2O. The strongest source of N_2O was croplands which were supplied with chemical fertilizer. The calculated EGWPs were positive in all the ecosystems, and the magnitude differed between ecosystems. Forests showed the highest EGWP, and wetlands the lowest EGWP. In agroecosystems, EGWP assessment revealed that croplan

  • Examination on Processes and Mechanisms Involved in Carbon Dynamics in an Alpine Meadow on the Qinghai-Tibetan Plateau

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2001
    -
    2004
     

    TANG Yanhong, KOIZUMI Hiroshi, MARIKO Shigeru, SEKIGAWA Seiko

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    The Qinghai-Tibetan Plateau is the highest plateau in the world. Covering mainly by alpine grasslands, the plateau plays an important role in the region's carbon budget. The plateau is characterized by high irradiance, low atmospheric pressure, and low temperature. To examine the carbon dynamics of grassland ecosystems on the plateau, we developed a new simulation model, the carbon dynamics model for alpine grasslands (CDMag). CDMag is composed of a gross photosynthesis (Ac) submodel including pbotoinhibition simulation, an ecosystem respiration (ER) submodel that considers both autotrophic and heterotrophic respiration, and an intercellular CO_2 partial pressure and canopy conductance submodel. A photoinhibition simulation is included to describe the gross production of alpine ecosystems in response to the high-irradiance environment A multilayered irradiance transfer scheme is adopted to estimate the irradiance on sunlit and shaded leaves within grassy canopies, and a coupled canopy conductance - net photosynthesis function is integrated into the Ac submodel. CDMag was used to simulate the carbon dynamics of the most extensively distributed alpine grassland, a Kobresia meadow eco

  • Carbon sequestration in different successional stage in deciduous forest ecosystems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2000
    -
    2002
     

    KOIZUMI Hiroshi, KAWASHIMA Hiroyuki, KOMIYAMA Akira, AKIYAMA Tsuyoshi, MARIKO Shigeru

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    Carbon dynamics and budgets were investigated in different successional stage ecosystems in cool temperate deciduous forest. The experiments were carried out in 0 year-old, 50 year-old and 110 year-old deciduous forest and Miscanthus sinensis grassland in central Japan, between April 2000 and March 2003. Carbon budgets were different among the different successional stage ecosystems. The annual carbon balance (NEP) was estimated to be -172 gCm^<-2> for the 0 year-old forest (just after deforestation), +117 gCm^<-2> for the 50 year-old forest and +16 gCm^<-2> for Miscanthus sinensis grassland, respectively. Moreover, the balance was estimated to be -270〜-320 gCm^<-2> for the upland single-cropping field, -160〜-270 gCm^<-2> for the upland double-cropping field, and only -20 gCm^<-2> for the paddy rice single-cropping field. These results suggest that 0 year-old forest ecosystem and the upland agricultural ecosystems may contribute to the increase in the carbon dioxide concentration of the atmosphere as the carbon accumulated in the soil is constantly being released in the atmosphere. On the other hand, the carbon balance for the grassland ecosystem and the paddy ecosystem were in

  • Indices for evaluating sustainable production of cropland, forest land and grassland

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1999
    -
    2002
     

    AKIYAMA Tsuyoshi, ITANO Shiro, SHINODA Seiro, KOIZUMI Hiroshi, SHIYOMI Masae

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    Three methods are applied on croplands, forestlands and grasslands in order to evaluate sustainability of production, and developed comprehensive indices for it.【1!○】 Index using carbon dynamics : Carbon budgets were compared under 3 different cropping systems. As the results of calculation of carbon budgets, paddy field is the most sustainable system, then followed double cropping and fee worst was single cropping of upland field. While, carbon storage in a cool-temperate deciduous forest by a precise field sampling method. As the results, it was clarified that 107tC/ha was stored in plants, 334tC/ha in soils. Soil is a large sink of carbon in forest ecosystem.【2!○】 Index using diversity index : Grassland sustainability may be evaluated by diversity of botanical composition and spatial heterogeneity of plant distribution. Grassland team applied beta-binomial distribution on grassland survey in Inner Mongolia steppe. As the results, the process of recovering after fence protection was manifested by beta-binomial index.【3!○】 Modeling and remote sensing approach : Real time monitoring is the most important which makes possible the sustainable grassland management. N

  • Ecological Basin Management Plan for Kiso Rivers

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1999
    -
    2001
     

    AKIYAMA Tsuyoshi, KOMIYAMA Akira, SHINODA Seiro, KOIZUMI Hiroshi, FUJIHARA Michio, NAKAGAWA Hajime

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    In order to propose an ecological management plan for Kiso rivers, 15 scientists belonging to 8 institutes were enrolled during the term of 1999 to 2001. Several new methods and important technologies had developed in the results of the project.(1) Development of new method to evaluate basin environment(1) New technology was developed to detect movement of land surface using satellite borne microwave SAR data (2) Technology was applied to evaluate environment of tea plantation examining insect fauna as indicator in the field with and without chemicals. (3) Change of landscape structure was analyzed by old maps and aerial photos during these 100 years. (4) Method was proposed to evaluate forest biomass judging from canopy area taken in aerial photos. (5) More precise land use classification became capable applying correction methods of solar angle and DEM on Landsat data, and it permitted to estimate nitrogen absorption in the whole Nagara river basin.(2) Clarification of matter cycling in ecosystems(6) Matter cycling was measured in an artificial needle-leaved forest, and broad-leaved forests cut in different years. (7) Also carbon storage map was created in one ha of a cool-temper

  • Micrometeomlogical and biological analysis on carbon, water and heat fluxes over various types of ecosystems

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    This project included three subprojects locus on carbon cycle of various ecosystems across the Japanese archipelago : (1)Long-term monitoring on carbon dioxide, water vapor and heat fluxes over various types of ecosystems, (2)Understanding the characteristics of matter cycle for various types of ecosystems, and (3)Development of biosphere-atmosphere interaction model The aims of this project were (1) to estimate CO_2, H_2O and heat exchanges between ecosystem and atmosphere, and especially concerning the various forest ecosystems and grassland ecosystems (subproject 1) ; (2) to clarify driven factors on CO_2, H_2O and heat exchanges for the studied ecosystems by the means of plant physiological, ecological and micrometeorological analysis (subproject 2) ; and (3) to integrate results of flux measurements and analysis to mathematic models (subproject 3), and finally to understand interactions within carbon cycle of terrestrial ecosystems and their environmental variables.Use of the limited research fluid to achieve the maximum results, flux measurements were concentrated on the five sites in which the flux tower has been built up in advance, i.e. an evergreen coniferous forest, a de

  • 新たな土壌呼吸速度モデルの開発を目指した生理生態学的研究

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    平成21年度は土壌呼吸に対するリター呼吸の寄与率を明らかにするために、冷温帯放牧草原において以下の実験を行った。陸域生態系は地球規模の炭素循環の中核を担っている。土壌からの土壌CO2フラックスは68~77×1015gC/yrと推定されており、これは植物の推定NPP量(50~60×1015gC/yr)を上回る。したがって、土壌呼吸の量的評価及び発生機構の解明なしに地球規模の炭素循環系を理解することはできない。その中でも草原生態系は陸域生態系においてその面積と炭素貯蓄量の30-40%を占めている主要な生態系の一つでありながら、その土壌呼吸の量的評価についての研究は少なく、とりわけ地上部リター呼吸の土壌呼吸に対する寄与率についての報告は少ない。しかしながら、リターは分解が遅いため地上に多くが蓄積されており、また、地下部と異なって周囲の環境要因の変動を受けやすく、その動態を知ることは重要である。本研究は岐阜県高山市のシバ型放牧草原にて行なった。2007年4月か

  • 森林・草原生態系の群落構造と相互作用機構およびその時間変動性の解明

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    平成21年度は管理放棄されたカラマツ林において炭素動態に関する研究を行った。1997年の京都議定書において日本の温室効果ガスの削減目標が決定され、2002年にはマケラシュ合意によりその削減目標内において森林の炭素蓄積増加による吸収量が認められることとなった。日本においては人工カラマツ林の炭素固定能が高いことが認められ、今後炭素吸収林としての役割を含めた人工林の増加が予想される。一方で、日本林業の現状として放棄人工林の面積は増大し人工林の約40%は管理放棄されているとの報告もある。しかし管理放棄された森林の炭素循環に関する情報は不足している。そこで本研究では「管理放棄されたカラマツ林」という一つの生態系に着目し、炭素の動態と収支の解明を行うことを目的とした。調査は岐阜県高山市、樹齢平均約50年の管理放棄されたカラマツ林を対象に2007年から2009年の3年間にわたり行われた。植生はカラマツと林床のクマイザサの2種で構成され

  • 小型MRI装置による森林土壌の非破壊計測研究のための技術的基礎の確立

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Internal Special Research Projects

  • 地球温暖化が放牧草地における温室効果ガス収支に与える影響―フィールドにおける昇温操作実験を基礎として―

    2009  

     View Summary

    IPCCの報告書によると、CO2濃度の上昇に伴う地球温暖化により、過去100年で地球の平均気温は0.74℃上昇し、今後100年でさらに1.1~6.4℃の気温上昇が予測されている。温暖化の影響を調査するために、様々な生態系で温暖化操作実験が行われてきた。しかし、温暖化が草原生態系の炭素収支にどのようにして影響を及ぼすのかを研究している例は未だ十分とは言えない状況にある。そこで本研究では、昇温により炭素収支を評価する指標である生態系純生産量(NEP)がどのように変化するのかと、それにどのような要因が関わっているかを調査することを目的とした。岐阜県の乗鞍岳にある冷温帯シバ草原において、赤外線ヒーターを用いて野外温暖化操作実験を実施し、地下2cmの地温を2℃上昇させた。1.2m×0.8mのシバを10区画設置し、その半分について5月から12月にかけて昇温を行った。NEPの測定を密閉法で行い、それに影響を与えうる要因として、生態系呼吸量(Re)、 光合成量(GPP)、シバの地上部現存量(AGB)、栄養塩類としてアンモニア態窒素と硝酸態窒素の2項目、微生物現存量を測定した。その結果、NEPは昇温により増加する事が確認された。Re、GPP、AGB、アンモニア態窒素、硝酸態窒素は実験期間を通じて昇温した区画で増加し、微生物現存量は昇温した区画で減少する傾向が見られた。また、Reと温度、GPPと温度の間には正の相関が見られた。NEPが増加したのは、GPPの増加量がReの増加量よりも大きかったためである。GPPの増加は植物体が増えたことによるものと考えられ、これは豊富な栄養塩類と温度上昇に伴う光合成速度の増加による影響と考えられる。また、栄養塩類が増加したのは、昇温により微生物の代謝が向上し、窒素無機化速度が速まったためと考えられる。以上のことから、冷温帯シバ草原において温暖化が生じると、窒素無機化速度の増加や光合成速度の増加により植物体の成長が促進され、NEPが増加することが示唆された。