Faculty Profiles - TANIKAWA Toko

Papers - TANIKAWA Toko

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Downward growth dynamics of Pinus thunbergii taproots and their relation to site environment in a coastal forest Reviewed International journal

Toko Tanikawa, Koh Yasue, Yosuke Matsuda, Hidetoshi Ikeno, Chikage Todo, Keitaro Yamase, Mizue Ohashi, Masako Dannoura, Toru Okamoto, Yasuhiro Hirano

Plant and Soil 2025.8

Contrasting patterns of nitrogen release from fine roots and leaves driven by microbial communities during decomposition. Reviewed International coauthorship International journal Open Access

Tanikawa T, Maie N, Fujii S, Sun L, Hirano Y, Mizoguchi T, Matsuda Y

The Science of the total environment page： 158809 2022.9

Leachate from fine root litter is more acidic than leaf litter leachate: A 2.5-year laboratory incubation. Reviewed

Tanikawa, T., Fujii, S., Sun L., Hirano, Y., Matsuda, Y., Miyatani, K., Doi, R., Mizoguchi, T., Maie, N.

Science of the Total Environment Vol. 645 page： 179 - 191 2018

Acidification processes in soils with different acid buffering capacity in Cryptomeria japonica and Chamaecyparis obtusa forests over two decades. Reviewed

Tanikawa, T., Sobue, A., & Hirano, Y.

Forest Ecology and Management Vol. 334 page： 284 - 292 2014.12

Tree root mat development as a response to highly acidic soil shapes distinct soil microarthropod community Reviewed International journal

Ryota Hayashi, Saori Fujii, Tomohiro Yoshida, Yasuhiro Hirano, Tetsuya Iriyama, Toko Tanikawa

Plant and Soil Vol. 518 ( 2 ) page： 1525 - 1543 2026.1

Microbial mechanisms underlying the reduction of soil mineral nitrogen availability by ectomycorrhizal tree introduction in cedar plantations Reviewed International journal

Kozue Sawada, Chikae Tatsumi, Han Lyu, Yoshiyuki Inagaki, Keiko Mori, Takashi Kunito, Soh Sugihara, Koki Toyota, Jun Murase, Toko Tanikawa, Shinya Funakawa

Plant and Soil 2025.12

Air pollution recovery still falls short of pre-industrial conditions: sulfur stable isotope analysis of tree rings from two giant trees Reviewed International journal Open Access

Ayumi Shiode, Takeshi Nakatsuka, Yoshikazu Kato, Hiroyuki Sase, Masayuki Morohashi, Takuya Ishida, Yasuhiro Hirano, Toko Tanikawa

Biogeochemistry Vol. 168 ( 6 ) 2025.11

Intraspecific variation in root system structure in a Pinus thunbergii stand grown in a gravelly spit coast. Reviewed

Hirano, Y., Todo, C., Tanikawa, T., Yamase, K., Ohashi, M., Dannoura M., Okamoto, Y., Doi, R., Yoshida, G., Ikeno, H.

Journal of Forest Research 2024.11

Effects of fungicide treatments on mycorrhizal communities and carbon acquisition in the mixotrophic <i>Pyrola japonica</i> (Ericaceae) Reviewed International coauthorship International journal

Sakae, K; Kawai, S; Kitagami, Y; Matsuo, N; Selosse, MA; Tanikawa, T; Matsuda, Y

MYCORRHIZA 2024.6

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

Pyrola japonica, a member of the family Ericaceae, is a mixotroph that grows on forest floors and obtains carbon (C) from both its photosynthesis and its mycorrhizal fungi. Its mycorrhizal community is dominated by Russulaceae. However, the mechanism of its C acquisition and its flexibility are not well understood. Our aim was to assess the impact of disturbance of the mycorrhizal fungal communities on C acquisition by P. japonica. We repeatedly applied a fungicide (Benomyl) to soils around P. japonica plants in a broad-leaved forest of central Japan, in order to disturb fungal associates near roots. After fungicide treatment, P. japonica roots were collected and subjected to barcoding by next-generation sequencing, focusing on the ITS2 region. The rate of mycorrhizal formation and α-diversity did not significantly change upon fungicide treatments. Irrespective of the treatments, Russulaceae represented more than 80% of the taxa. Leaves and seeds of the plants were analysed for 13C stable isotope ratios that reflect fungal C gain. Leaf and seed δ13C values with the fungicide treatment were significantly lower than those with the other treatments. Thus the fungicide did not affect mycorrhizal communities in the roots, but disturbed mycorrhizal fungal pathways via extraradical hyphae, and resulted in a more photosynthetic behaviour of P. japonica for leaves and seeds.

DOI： 10.1007/s00572-024-01157-5

Web of Science

Scopus

PubMed

Volcanic ash in soil is a source of strontium in stream water in chert-bedrock forests in Mount Amamaki, Japan. Reviewed Open Access

Koshikawa, M.K., Watanabe, M., Sase, H., Morohashi, M., Takahashi, M., Tanikawa, T., Takahashi, M., Takahashi, A., Murata, T., Takamatsu, T., Miura, S., Shin, KC, Nakano, T.

Ecological Research 2024.5

Effect of sprouting and corresponding root distribution of the shrub species Eurya japonica on slope stability Reviewed International journal

Yamase K., Ikeno H., Hotta N., Imawaka M., Ohashi M., Tanikawa T., Todo C., Dannoura M., Hirano Y.

CATENA Vol. 238 2024.2

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

After disturbance sprouts emerge from the ground, generating multi-stemmed plants as they grow, which represents a means of rapidly recovering above ground biomass. We hypothesised that the above- and below ground characteristics would differ depending on the number of stems in individual shrubs, which is likely to compensate for the slope stability of soil reinforcement by plant roots in forests. We focused on the dominant shrub species of abandoned secondary forests, Eurya japonica, and conducted an excavation of the entire root system. The aims of this study were to (i) determine the root system architecture of single- and multi-stemmed E. japonica, (ii) determine whether there were differences in the slope stability by soil reinforcement of roots between the single- and the multi-stemmed plants, and (iii) provide recommendations based on the study finding on how single- and multi-stemmed plants generated during the disturbance should be managed to improve the slope stability. Our results showed that an increase in the total basal stem area at 0.1 m above ground level (BA0.1) increased the above- (MA) and the below ground biomass (MB) with high fitting linear regression, regardless of whether the plants were single- or multi-stemmed. In contrast, the spread of roots, as indicated by the maximum lateral root spread (Rdis) and maximum rooting depth (Rdep), was related to the maximum stem diameter at 0.1 m above ground level (D0.1) with high fitting linear regression among the shoots in the plant. If the above ground shoots and below ground roots are considered as a continuous pipe and the multi-stemmed plants as an assemblage of single-stemmed plants, we can effectively explain the relationship between the total basal stem area or maximum diameter of each stem, and the below ground biomass, or the spread of the roots. There is less space available below ground than above ground for multi-stemmed trees. This is especially the case around the root stump, where the roots of each stem compete and inhibit growth. This can result in significant lower root–shoot ratios of 0.23 ± 0.04 for multi-stemmed plants compared to 0.33 ± 0.01 for single-stemmed plants. This imbalance suggests that multi-stemmed plants growing on forest slopes are more unstable and are more likely to fall. Soil reinforcement by roots did not significantly differ between single- and multi-stemmed plants. However, the displacement at the maximum soil reinforcement by roots was significantly greater in 83.3 ± 21.7 cm for the multi-stemmed plants than in 40.0 ± 18.2 cm for single-stemmed plants because multi-stemmed plants with competing roots resulted in fewer roots of less than 15 mm in diameter. This allowed the formation of a slip surface on the forest slopes because of the substantial displacement (bundle elongation) of roots during the pullout. Therefore, the resistance of multi-stemmed plants to shallow landslides on forest slopes was lower than that of single-stemmed plants. Traditional forest management, that is, reducing the number of stems of multi-stemmed plants, is effective in increasing sprouting growth and biomass production. It may also be effective in increasing forest slope stability at landscape levels over longer timescales.

DOI： 10.1016/j.catena.2024.107869

Scopus

Fungi and bacteria in the rhizosphere of Cryptomeria japonica exhibited different community assembly patterns at regional scales in East Asia Reviewed

Keisuke Obase, Yudai Kitagami, Toko Tanikawa, Chien-Fan Chen, Yosuke Matsuda

Rhizosphere Vol. 28 page： 100807 - 100807 2023.12

Soil acidity accelerates soil organic matter decomposition in Cryptomeria japonica stands and Chamaecyparis obtusa stands Reviewed International journal Open Access

Ryota Hayashi, Nagamitsu Maie, Rota Wagai, Yasuhiro Hirano, Yosuke Matsuda, Toru Okamoto, Ryusei Wada, Toko Tanikawa

Plant and Soil 2023.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

DOI： 10.1007/s11104-023-06308-9

Open Access

Web of Science

Scopus

Other Link： https://link.springer.com/article/10.1007/s11104-023-06308-9/fulltext.html

里山林伐採後の樹木根による土壌補強強度の変化 Invited Open Access

山瀬敬太郎・藤堂千景・鳥居宣之・谷川東子・山本智究・池野英利・大橋瑞江・檀浦正子・平野恭弘

水利科学 Vol. 387 page： 1 - 17 2022.10

Fine root litter traits of Chamaecyparis obtusa Reviewed International journal Open Access

Yoshida G., Doi R., Wada R., Tanikawa T., Hirano Y.

Ecological Indicators Vol. 142 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Ecological Indicators

The purpose of this study was to clarify the process of Chamaecyparis obtusa (Sieb. & Zucc.) Endl. fine root shedding and the morphological traits of the resulting root litter. We developed a method for direct monthly sampling of root litter from the fine root system in the field. We proposed a field incubation method using centrifuge tubes with glass beads as the medium and throughfall as the nutrient solution, in which an undamaged sample of the fine root system still connected to the tree is inserted. Using this method, we collected root litter from C. obtusa for 12 months after the installation. The monthly amounts of the root litter of from the incubated fine root systems differed significantly among the sampling months. On the other hand, the morphological traits such as the root litter length and diameter of each branch order did not differ significantly among months. The first-order root litter was shorter than the incubated living first-order roots. The first-order roots were shed both at the branching positions and in the middle of first-order roots. We concluded that fine root litter with similar morphology is shed every month. Assessment of the fine root litter traits by using the new direct sampling method and the new soil ecological indicator “initial tissue C inputs” from fine roots into forest soil will improve our understanding of forest belowground carbon cycling and its indexation.

DOI： 10.1016/j.ecolind.2022.109276

Open Access

Scopus

An increase of fine-root biomass in nutrient-poor soils increases soil organic matter but not soil cation exchange capacity Reviewed International journal

Hayashi, R, Maie, N, Wagai, R, Hirano, Y, Matsuda, Y, Makita, N, Mizoguchi, T, Wada, R, Tanikawa, T

Plant and Soil 2022.9

Maximum Rooting Depth of Pinus thunbergii Parl. Estimated with Depth at the Center Point of Rotation in a Tree-Pulling Experiment in a Coastal Forest in Japan Reviewed Open Access

Todo Chikage, Yamase Keitaro, Ikeno Hidetoshi, Tanikawa Toko, Ohashi Mizue, Hirano Yasuhiro

FORESTS Vol. 13 ( 9 ) 2022.9

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

Tree resistance to uprooting can be estimated as the critical turning moment in tree-pulling experiments. The depth at the center point of rotation (Dcp) in tree-pulling experiments is measured as an indicator of below-ground traits and is related to this critical turning moment. However, few researchers have investigated the relationship between the Dcp and maximum root depth. Our objective in this study was to clarify whether the Dcp in tree-pulling experiments can be estimated as the maximum root depth of Pinus thunbergii Parl. in sandy soils. We also estimated which position of displacement of the center of rotation (Cp) can be applied as the Dcp. We conducted tree-pulling experiments, and compared the Dcp obtained from images with the measured maximum root depth. We found significant positive correlations between the Dcp and maximum root depth. The Cp displacement concentrated immediately below the stem when the maximum critical turning moment was reached. This position should be measured as the Dcp, which is related to the maximum root depth. We found that the Dcp can serve as a parameter, preventing the need for uprooting, when tree-pulling experiments are performed to obtain an important below-ground trait for understanding the critical turning moment.

DOI： 10.3390/f13091506

Open Access

Web of Science

Scopus

Archaeal community structures associated with fine root systems of Cryptomeria japonica (Cupressaceae) in central Japan Reviewed International journal

Mine Taichiro, Kitagami Yudai, Tanikawa Toko, Matsuda Yosuke

JOURNAL OF FOREST RESEARCH 2022.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Forest Research

Archaea live in extreme environments and have been found in non-extreme environments in recent years. Although most studies have focused on the nitrification function of archaea in forest soils, few studies have focused on how archaea in rhizospheres are involved in nutrient absorption. To elucidate the archaeal community pattern inhabiting the fine roots of trees, we examined the taxonomic identity and community structure of archaea in Japanese cedars (Cryptomeria japonica). Root samples were collected from six C. japonica plantations in central Japan. DNA was separately extracted from the first- and third-order roots, and archaeal taxa were determined by the cloning method focusing on 16S rDNA. As a result, 90% of the sequences were classified as in the phylum Thaumarchaeota, with 1.1b and 1.1c groups in the phylum accounting for 65% and 25%, respectively. Archaeal community structures were significantly correlated with soil pH, but neither the root orders nor the plantation sites showed significant clustering. These results suggest that Thaumarchaeota is the dominant archaeal group in the fine roots of C. japonica, and community structures are affected by a proximate chemical factor of soil acidity.

DOI： 10.1080/13416979.2022.2108657

Web of Science

Scopus

Report on the symposium “Ten years after the earthquake: the ‘past’ and ‘future’ of afforestation/reforestation of coastal forests with high tsunami resilience” Invited Open Access

Ono Kenji, Noguchi Hironori, Yoshida Toshimichi, Fujita Saki, Watanabe Natsuki, Nitta Kyohei, Otani Tatsuya, Ota Takayuki, Tanikawa Toko, Hirano Yasuhiro, Watanabe Hitoshi, Yamashita Naoyuki

Japanese Journal of Forest Environment Vol. 64 ( 1 ) page： 39 - 44 2022.6

3D reconstruction using Structure-from-Motion: a new technique for morphological measurement of tree root systems

Okamoto Yuki, Ikeno Hidetoshi, Hirano Yasuhiro, Tanikawa Toko, Yamase Keitaro, Todo Chikage, Dannoura Masako, Ohashi Mizue

PLANT AND SOIL 2022.5

Language：Japanese Publisher：Plant and Soil

Purpose: Clarification of root architecture is important for understanding tree root functions. 3D laser scanning reconstructs the 3D structure of root system with high accuracy, but the devices are large and expensive. The Structure-from-Motion with multi-view stereo-photogrammetry (SfM-MVS) method reconstructs the 3D structure of an object from multiple images. This method is suitable for field research because it acquires the 3D data with a commercially available digital camera. Our aim in this study was to test the applicability of the SfM-MVS method for morphological measurement of tree root systems. Methods: The 3D root system model was created using a dummy and three black pine (Pinus thunbergii) root systems. Image data were collected from the root systems using a camera and reconstructed using the free software, VisualSfM and MeshLab. We evaluated the accuracy of morphological data estimated from the 3D models by comparing them with real data obtained from manual measurements of the root systems. Results: The 3D reconstructions of the dummy and black pine root systems were successful. The root mean squared error values for the morphological features in the pine root systems ranged from 4 to 24%, which was sufficiently accurate for a successful 3D model. However, the RMSE values were larger than that of dummy root, ranging from 2 to 9%. Conclusion: The SfM-MVS method is a new tool, based on non-specialised equipment and free software, to obtain the 3D structure of tree root systems. The morphological features of it can be successfully measured from the reconstructed models.

DOI： 10.1007/s11104-022-05448-8

Web of Science

Scopus

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Papers - TANIKAWA Toko