Research Themes

• イボタケ類菌糸マットを構成し土壌酸性化作用を担う微生物群の解明とその活性評価　　　　　　　　　　　　　　　
  科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
  07 Oct. 2022 - 31 Mar. 2027
  宮本 敏澄, 原口 昭, 礒田 玲華
  日本学術振興会, 国際共同研究加速基金(国際共同研究強化(B)), 北海道大学, 22KK0086
• 腐朽菌を用いた低コストかつ近自然プロセスによる流木の断片化促進技術の開発　　　　　　　　　　　　　　　
  河川基金助成
  Apr. 2022 - Mar. 2024
  一般財団法人河川財団, Principal investigator
• ダムの存在による河川洪水の撹乱頻度と強度の変化が河畔林の立木腐朽に与える影響　　　　　　　　　　　　　　　
  WEC応用生態研究助成
  2020 - 2021
  Water Resources Environment Center (WEC), Principal investigator
• Is biodegradation of leaf-litter strongly regulated by the occurrence of lignin?
  Grants-in-Aid for Scientific Research
  01 Apr. 2015 - 31 Mar. 2019
  Koda Keiichi, Miyamoto Toshizumi
  A novel method applicable to determination of lignin content of tree leaves was developed and proposed. The validity and reliability of this method was confirmed by the comparison with the conventional methods such as Klason and acetyl bromide methods, using wood and leaf samples. It was shown that this method was applicable to leaf samples from conifer and broad-leaved trees, and that lignin contents of leaf samples were found much lower than those obtained by the conventional methods. This method was further applied to field experiments, using leaf litter. Lignin itself was not necessarily the most important rate-limiting factor affecting biodegradation of oak leaf litter, because it was found that oak leaf litter was decomposed in accordance with its lignin at a similar rate. Our results also showed that other environmental factors such as nitrogen influx could affect the degradation of leaf litter.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 15K07468
• イボタケ類菌糸マットによる北方林のポドゾル形成の検証とその微生物群集の機能性解析　　　　　　　　　　　　　　　
  科学研究費補助金（基盤研究(B)）
  2016 - 2019
  宮本敏澄
  Principal investigator, Competitive research funding
• Searching for nitrogen cycling factors at N2O emitting hotspots in different latitude zones and biological agents for rehabilitation of N2O emitting hotspots
  Grants-in-Aid for Scientific Research
  01 Apr. 2014 - 31 Mar. 2018
  Hashidoko Yasuyuki
  Hyper-N2O emitting microorganisms were screened from Sphagnum riparium, which is tolerant to conditions polluted with minerals and ammonia. According to our N2O emission assay, Rhizobium sp. of class Alphaproteobacteria was isolated as a hyper-active N2O emitting eubacteria. This bacterium formed almost equivalent mixture with a Serratia sp. of class Gammaproteobacteria and administered an ability to produce N2O to the Serratia. In addition, we have isolated non-denitrifying N2O quenchers from both Andisol in Hokkaido and degrading palsa mire in Finland, and the potent N2O quenchers were identified as Rhodococcus sp. and Chitinophaga sp. respectively. Both of the N2O quenchers were missing both nosZ gene for denitrifiers and atypical nosZ genes for dissimilatory nitrite reduction to ammonia (DNRA) bacteria. Hence their N2O quenching mechanisms were not simple reduction of N2O to N2 gas, but more drastic and active catabolic reaction of N2O as their nitrogen source was predicted.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 26304042
• Srudy on hot monent inducing the abrupt change of ecosystem nitrogen cycle under climate change
  Grants-in-Aid for Scientific Research
  01 Apr. 2013 - 31 Mar. 2016
  SHIBATA Hideaki, TODA Hiroto, MIYAMOTO Toshizumi, INAGAKI Yoshiyuki, FUKUZAWA Karibu, UGAWA Shin, ISOBE Kazuo, HISHI Takuo, TATENO Ryunosuke, SASAI Takahiro, SUWA Yuichi, ENOKI Tsutomu, SAIGUSA Nobuko, OHTE Nobuhito, FUKUSHIMA Keitaro
  This research project aimed to clarify the pattern of abrupt changes of soil environment, vegetation process and dynamics on ecosystem nitrogen cycles during the period between dormant and growing periods, and analyze their impacts on the ecosystem processes and functions including primary productivity, nutrient retention and the environmental conservation functions of the ecosystem during the growing season. Our results indicated that soil freeze-thaw cycle was amplified due to the snowpack decrease in winter, causing the alteration of sol microbe biomass and soil nitrogen mineralization and nitrification. It was suggested that those environment changes in winter impacted to nitrogen cycles of the ecosystem during the growing season.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 25252026
• 積雪下でのリグニン分解活性を備えたリター分解菌類の分子系統および生態生理　　　　　　　　　　　　　　　
  科学研究費補助金 (基盤研究(C))
  2013 - 2015
  宮本敏澄
  Principal investigator, Competitive research funding
• Development of snow control techniques that facilitate natural tree regeneration
  Grants-in-Aid for Scientific Research
  2011 - 2013
  OWARI Toshiaki, MIYAMOTO Toshizumi, SHIBANO Hirofumi, SAKAUE Daisuke
  As a novel technique for natural forest management in snowy regions, we aimed at developing snow control treatments that contribute to prevent snow blight diseases at the seed germination stage and to facilitate natural tree regeneration. Results from our field trials indicated that the artificial formation of uneven ground surface may be an effective treatment particularly on a lower elevation. It enhances soil frost during winter, which likely has a positive effect inhibiting seed infection and damage caused by the pathogenic fungus and increasing the rate of germination in a natural forest.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), The University of Tokyo, 23580198
• The impact of snowpack change by climate change on biogeochemical cycles in forest soil
  Grants-in-Aid for Scientific Research
  2010 - 2012
  SHIBATA Hideaki, INAGAKI Yoshiyuki, MIYAMOTO Toshizumi, TATENO Ryunosuke, HISHI Takuo, TODA Hiroto, FUKUZAWA Karibu, SUWA Yuichi, NAKATA Makoto, KOBA Keisuke, NAKANISHI Asami, HIRAI Keizo
  We conducted the field experiments using natural environmental gradient in Japanese archipelago to clarify the impact of snowpack changes in winter on soil nitrogen dynamics in forest ecosystem. We found that nitrogen mineralization by soil microbe increased by the amplification of soil freeze-thaw cycles induced by the decrease of snowpack and its heat insulation ability. It was suggested that winter processes in biologically dormant season were not negligible for biogeochemical cycles and water quality formation in the growing season.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 22248016
• Composition of litter-decomposing fungal community under snow cover in a cool-temperate forest and their extracellular enzyme activity
  Grants-in-Aid for Scientific Research
  2009 - 2011
  MIYAMOTO Toshizumi, KOUDA Keiichi
  We investigated the decomposition of leaf litter and the composition of litter-decomposing fungal community under snow cover in some forest stands in Hokkaido, and their extracellular enzyme productivity at low temperature. It was observed that while the oak and fir foliage litter lost their original weight under snow during the winter season, some fungi appeared or increased the frequency. Some fungi isolated from oak litter were found to extend the mycelia on the media and indicated ligninolytic activity at 0℃. These results suggest that some litter-decomposing fungi, which have potential ability to degrade lignin at 0℃, significantly contribute the litter decomposition under snow cover.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Principal investigator, Competitive research funding, 21570013
• Complete understanding of the nitrogen missing link in boreal forest ecosystems and evaluation of nitrogen provision and loss
  Grants-in-Aid for Scientific Research
  2008 - 2011
  HASHIDOKO Yasuyuki, HARAGUCHI Akira, KOIKE Takayoshi, HATANO Ryusuke, TAMAI Yutaka, HORIUCHI Junichi, MIYAMOTO Toshizumi
  Nitrogen imbalance of the boreal forest ecosystem has long been a mystery, called missing link of nitrogen in boreal forest. We challenged to this mystery, to practically understand the effects of climate change on forest biomass productivity in several types of boreal forests. Precise investigation of optimal culture conditions including compositions of the medium were obviously close to the reported conditions of the forest bed soil in summer seasons. The 16S rRNA gene-targeting DGGE analysis combined with gellan gum medium revealed the presence of Dugnella (class y-Proteobacteria) and Clostridiumin (phylum Firmicutes) in the A-horizon of the subarctic tundra soil, and also showed the aboveground vegetation affect on bacterial activity in soil. Thus, it was strongly suggested that scale of the elemental circulation in the boreal forests near the forest limit highly regulates acetylene reducing activity of free-living nitrogen-fixing bacteria. Also it was speculated that the low acetylene reduction in the forest bed soil would be highly regulated as corroborative events together with ericoid mycorrhizal and/or ectomycorrhizal fungi, leading to effective nitrogen supply to the forest ecosystem.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 20255002
• Ecological functions of large herbivore for bio diversity under forest ecosystem : A large scale field experiment.
  Grants-in-Aid for Scientific Research
  2006 - 2008
  AGETSUMA Naoki, HIURA Tsutomu, MIYAMOTO Toshizumi, HIURA Tsutomu, MIYAMOTO Toshizumi, MURAKAMI Masashi, HINO Takafumi, TOYOTA Ayu, ARAKI Natsuko, HIRONAGA Takuo, YAMAZAKI Akinobu, AGETSUMA Yanagihara, AGETSUMA Yoshimi
  森林環境においてシカ密度と林床植物の生産性(光条件・土壌栄養)を操作し、大型植食者の採食圧と林床植生、土壌動物の反応を調べた。3年間の実験で、シカ密度が林床植物の種数・種多様性・ミミズ密度に対し有意な影響を与えていないことが示された。また、シカが土壌微生物の多様性や活性に促進的な機能を持っていることが示唆された。なお、光条件向上のため択伐を行ったが、この択伐が林床植生・土壌動物ひいてはシカの採食行動に大きな影響を与えることが解った。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 18380086
• 心材腐朽を考慮した緑化木の暴風に対する幹折れ抵抗性の評価
  科学研究費助成事業
  2005 - 2006
  小泉 章夫, 宮本 敏澄, 矢島 崇, 平井 卓郎
  心材腐朽を有する不整な樹幹断面をもつ樹木の暴風による幹折れ挙動を定量的に評価する方法の確立を目的として研究を行った。平成18年度の研究実績は以下の通りである。
  1.緑化木樹種の強度データの集積
  台風0418による北海道大学構内の風倒木などを供試木として,28樹種の木材の成長・密度分布・強度特性を測定して基礎的データを収集した。
  2.不整断面の断面係数の数値計算手法の検討
  16本の内部腐朽を持つ広葉樹および針葉樹大径木の伐根を試験対象として,測定を行なった。
  対象樹幹の外部形状の計測は以下のようにして行なった。(1)かたどりゲージを用いて外周の形状を30cm区間ずつに分けて順次かたどり,それぞれの測定区間についてかたどった形状をデジタルカメラで撮影する。(2)外周上の測定区間(30cm)ごとに設定した標点間の距離を大型コンパスとスケールで測定する。(3)標点間の距離から各標点の座標を決定し,隣接する標点間に,対応するデジタルカメラの撮影画像を貼り付けて,外周形状を決定する。
  内部の木部形状(心材腐朽によって強度のなくなった部分を除く)は以下のようにして推定した。(1)樹幹のいくつかの方向からレジストグラフを用いて強度を有する木部の厚さを測定する。(2)測定した厚さの平均値を一律の木部厚と仮定して,推定した外周形状とあわせて木部断面を決定する。
  このようにして決定した木部断面について,前年度に開発した画像解析と数値計算法による断面係数評価法にしたがって,断面係数を算出し,別途撮影した伐根の断面形状の写真と比較してその精度を検討した。検討の結果,断面係数の推定値に対する実測値の比は平均で1.06であり,この方法によって比較的精度よく推定できることがわかった。
  以上の結果を総合して,樹木の幹折れ破壊に関する限界風速の評価方法を示すことができた。
  日本学術振興会, 萌芽研究, 北海道大学, 17658067
• The effects of above- and below-ground interaction on the productivity in a deciduous broad-leaved forest.
  Grants-in-Aid for Scientific Research
  2003 - 2005
  HIURA Tsutomu, TODA Masanori, KANEKO Nobuhiro, TAWARAYA Keitarou, MIYAMOTO Toshizumi
  1.In this project, we clarified some links among the species diversities of producer, consumer, and decomposer with special reference to the response to environmental gradient for Quercus crispula.
  2.We carried out the cutting and fertilization experiment in secondary forests to reveal the community-level and ecosystem-level responses to light-nutrient resource gradient. In results, the fertilization accelerated herbivory in Quercus crispula.
  3.We set up the experimental plots that manipulate the density of earthworm, and examined the density effects on ecosystem function. The fact that high accumulation of litter in the low density plots suggests that the lower density of earthworm would result the lower decomposition rate although nitrogen mineralization rates were not different among manipulations at least during the two years.
  4.The reconstruction process of species diversity of consumer on the canopy of Quercus crispula was compared between the disturbed canopy by using canopy fogging method and non-disturbed canopy. This experiment suggest that the community of herbivorous insects is converge to single stable equilibrium depend on the quality of a leaf, while the community of detritivorous insects varies depend on the assemblage process of the species (multiple stable equilibria). We also examined the diversity of decomposer community in stands that having different tree species diversity, however, the results suggest that oribatid mite community structure was minimally affected by tree species diversity and associated changes in litter diversity.
  5.We manipulated fungal diversity by some sterilizations to examine the function of fungal groups by estimating mineralization, decomposition rate and growth rate of some plants. The results suggested that Basidiomycota had higher decomposition ability than Ascomycota, and mycorrhiza on Maianthemum dilatatum contributed to uptake for phosphorous and its growth.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), HOKKAIDO UNIVERSITY, 15208014
• Study on the vegetation-enbironment interaction in the rooting zone of disturbed area.
  Grants-in-Aid for Scientific Research
  2000 - 2003
  YAJIMA Takashi, MIYAMOTO Toshizumi, KIKUCHI Shun-ichi, TAMAI Yutaka
  This study was carried out to elucidate the vegetation-environment interaction in the rooting zone of plants growing on heavily disturbed area for the purpose of applying the relationships to revegetation works. To explain the vegetation-environment interaction, we selected the disturbed areas such as Mt.Usu for volcanic disturbed site which erupted in 2000, river side of Satsunai-gawa for riparian disturbed area, and mountain slopes of Hidaka district for large scale erosion disturbance area. The survey were conducted in each site for the disturbance resume, revegetation process, growth analysis of invaded trees, mycorrhiza infection to the plant roots and physical and chemical site conditions.
  On the volcanic disturbed site around the new craters of Mt.Usu, early stage of vegetation recovery process was recorded and ectomycorrhiza (ECM) or arbuscular mycorrihza (AM) types which infected to the plant roots were investigated. On the disturbed area of river sides, we investigated the stand dynamics and growth characteristics of Chosenia arbutifolia in addition to the nutrient condition of riparian zone. Further, the infection ratio, the types of ECM and seasonal dynamics of ECM infection on the roots of Salix sachalinensis seedlings were surveyed.
  And also, we investigated the culture medium of tree seedlings which expected to use for vegetation works. We succeeded in artificial infection of ECM in semi-open condition. These are the certain progress for the application to the advanced works of the vegetation-enbironment interaction systems in the rooting zone.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 12460062
• 大規模野外実験による森林生態系のC/Nバランスと生産性の関係解明
  科学研究費助成事業
  2002 - 2002
  日浦 勉, 宮本 敏澄, 金子 信博, 戸田 正憲
  1.5月下旬に被食排除区を作るために、ミズナラとシラカバの展葉前の枝先に袋かけを行った。10月下旬の落葉期に、ミズナラとシラカバの調査木の下に設置したリタートラップから落ち葉を回収し、葉の食害の程度を5段階にわけ、各段階の葉の枚数を数えたうえで、食害度別に風乾し、リターバッグを設置した。
  2.土壌マイクロコズムを林内に設置し、落葉の多様性(ミズナラ、混合の2処理)、大型土壌動物の多様性(大型なし、ミミズのみ、ヒメフナムシのみ、ミミズとヒメフナムシの4処理)を操作して、落葉の分解速度、土壌化学性の変化、および土壌小型節足動物と細菌群集への影響を解析した。落葉の質が分解系に与える影響を評価するための標準的な方法を確立することができた。フトミミズのバイオマスは日本の森林のなかでも大きい方であり、フトミミズがこの森林でのキーストン種であることが予測された。一方、ヒメフナムシとの相互作用は明確ではなかった。
  3.フェノロジーの異なるユリ科草本4種の資源分配と結実率が伐採・施肥によりどのように変化するかを調べた。その結果、開花・開葉の早いミヤマエンレイソウとユキザサのバイオマスと結実率は土壌養分が制限になっており、開花・開葉の遅いチゴユリとオオアマドコロのバイオマスと結実率は光資源が制限になっていることが明らかとなった。
  4.春植物(ミヤマエンレイソウとユキザサ)とミズナラリター、夏植物(ヌスビトハギとハエドクソウ)とミズナラリターの混合と伐採・施肥が窒素無機化に与える効果を調べた。その結果、春植物とミズナラリターを混ぜた場合に負の混合効果が検出されたが、夏植物と混ぜた場合は混合効果は検出されなかった。またこの混合効果には伐採・施肥は影響を与えていなかった。
  日本学術振興会, 萌芽研究, 北海道大学, 14656059