Papers - TANIKAWA Toko

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

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

The Science of the total environment     page： 158809   2022.9

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scitotenv.2022.158809

PubMed

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

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.scitotenv.2018.07.038

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

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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

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

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

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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

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

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Language：English  

DOI： 10.1111/1440-1703.12507

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

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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

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

DOI： 10.1016/j.rhisph.2023.100807

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Scopus

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

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

Plant and Soil     2023.10

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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

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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

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

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Language：Japanese  

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

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11104-022-05675-z

Scopus

Fine root litter traits of Chamaecyparis obtusa Reviewed International journal

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

Ecological Indicators   Vol. 142   2022.9

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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

Scopus

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

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

FORESTS   Vol. 13 ( 9 )   2022.9

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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

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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

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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

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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

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

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japanese Society of Forest Environment  

DOI： 10.18922/jjfe.64.1_39

CiNii Research

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

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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

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Scopus

Sulfur accumulation in soil in a forested watershed historically exposed to air pollution in central Japan Reviewed

Toko Tanikawa, Hiroyuki Sase, Sei Fukushima, Yoshiaki Ito, Michiru Yamashita, Naoyuki Yamashita, Masato Kamisako, Akifumi Sugiyama, Akihiro Imaya, Takuya Ishida, Chisato Takenaka, Masamichi Takahashi

Geoderma   Vol. 407   page： 115544 - 115544   2022.2

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.geoderma.2021.115544

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Scopus

スギ根系が抱きかかえている土壌の量はどれくらい？－台風21号が地上に残した根鉢の解体－

谷川東子, 池野英利, 藤堂千景, 山瀬敬太郎, 大橋瑞江, 岡本透, 溝口岳男, 中尾勝洋, 金子真司, 鳥居厚志, 稲垣善之, 中西麻美, 平野恭弘

水利科学   Vol. 383   page： 1 - 35   2022.2

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Authorship：Lead author,　Corresponding author   Language：Japanese  

Can ground-penetrating radar detect adjacent roots and rock fragments in forest soil? Reviewed

Toko Tanikawa, Hidetoshi Ikeno, Keitaro Yamase, Masako Dannoura, Kenji Aono, Yasuhiro Hirano

PLANT AND SOIL   Vol. 468 ( 1-2 ) page： 239 - 257   2021.11

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Aim Ground-penetrating radar (GPR) has been used for estimating root biomass, estimating pull-out resistance force of roots, and reconstructing root system architecture. Although GPR can estimate the diameter of a single root, it has not yet been verified whether it can successfully estimate the diameters of adjacent roots or whether rock fragments occurring in the soil matrix can be misidentified as roots. This study aimed to (1) evaluate the visual properties of GPR images of root bundles and rock fragments, and (2) clarify whether they have the potential to create non-negligible errors in GPR surveys. Methods Root bundle samples buried in a sandy soil bed were scanned using 900 MHz and 1500 MHz antennas. Sole roots of Cryptomeria japonica and rock fragments in the bed were also scanned. Results A bundle of root formed one hyperbola with an apex in the radar profile, like a sole root. However, the contrast of the hyperbolas was weak and GPR indices relating to diameter were reduced compared to those of the comparably sized sole root. Stones did not form clear images, but boulders were faintly visible with non-negligible GPR indices. Conclusions For evaluation of root biomass, adjacent roots had the potential to lead to significant errors. Similarly, in reconstructions of root system architecture, adjacent roots might lead to incorrect modelling of root point connections, because of incorrect diameters. For pull-out resistance force, adjacent roots could lead to only underestimation, i.e., safe-side error. Misidentification of rock fragments as roots depends on their sizes.

DOI： 10.1007/s11104-021-05116-3

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Scopus

Colonization status and community structure of arbuscular mycorrhizal fungi in the coniferous tree, Cryptomeria japonica, with special reference to root orders Reviewed

Yosuke Matsuda, Kohei Kita, Yudai Kitagami, Toko Tanikawa

PLANT AND SOIL   Vol. 468 ( 1-2 ) page： 423 - 438   2021.11

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Aims Arbuscular mycorrhizal (AM) fungi are intimately associated with fine roots and are involved in nutrient acquisition. However, little information is available on the links between roots of individual orders and fungus colonization and community structure. Our aim was to elucidate AM fungal communities in the fine root systems of the temperate coniferous tree species, Cryptomeria japonica (Cupressaceae). Methods We characterized the morphological traits of AM fungi microscopically and determined the community structure of AM fungi using metabarcoding with an Ion Torrent Personal Genome Machine (PGM) focusing on lower-order roots from first to third order roots. Results Paris-type and Arum-type AM morphologies were both generally more prevalent on first-order roots than on second- or third-order roots, but the colonization rates by the Paris type were higher than those by the Arum type. We found a total of 48 fungal operational taxonomic units dominated by Glomeraceae, and all the AM taxa detected on third order roots were also found on first and/or second order roots. In the case of the second and third orders, AM fungal communities were affected by soil conditions: electrical conductivity, pH, and N concentration. Conclusion These results suggest that the abundance and species richness of AM fungi vary among lower root order systems, and that the AM community is sensitive to soil conditions and turns over as roots age.

DOI： 10.1007/s11104-021-05147-w

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秋田県の海岸砂丘に生育するクロマツおよび植栽広葉樹数種の根系分布 Reviewed

新田響平，野口宏典，太田敬之，小野賢二，萩野裕章，野口享太郎，大谷達也，宇川裕一，小森谷あかね，谷川東子，平野恭弘，鈴木覚.

森林総合研究所研究報告   Vol. 20   page： 169 - 184   2021.10

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Language：Japanese   Publishing type：Research paper (scientific journal)  

海岸防災林造成を目的として植栽された広葉樹とクロマツの土壌特性に基づく成長と根系発達. Reviewed

太田敬之, 新田響平, 宇川裕一, 小野賢二, 萩野裕章, 谷川東子, 大谷達也, 平野恭弘, 小森谷あかね, 野口宏典.

森林総合研究所研究報告   Vol. 20   page： 195 - 204   2021.10

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Root system of the giant <i>Cryptomeria japonica</i> tree collapsed at Shinmei shrine in Okute town, Gifu, in July 2020. Reviewed

HIRANO Yasuhiro, NANKO Kazuki, DOI Ryuusei, NISHIMURA Rei, IRIYAMA Tetsuya, TANIKAWA Toko

Root Research   Vol. 30 ( 3 ) page： 65 - 75   2021.9

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society for Root Research  

<p>On the night of July 11, 2020, the giant <i>Cryptomeria japonica</i> tree collapsed during the heavy rainfall event in Okute Town, Gifu. The purpose of this study is to clarify the characteristics of the root system of the fallen tree together with the weather conditions such as heavy rainfall at the time. In July 2020, there were few sunshine hours which could induce higher water contents of the tree and soils. A large area of decay was observed in the root system close to the center of the stem and roots remaining in the soil showed signs of stripping. Using a laser scanner, the three-dimensional structure of the tree was digitally reproduced, and the volume of root system was estimated to be 43.2 m³. The diameter of the root-soil plate and the volume ratio to the aboveground part suggested that the root system of the tree was relatively small compared with those of other <i>C. japonica</i> trees. Based on the evaluation of the root system and weather conditions, the soil reinforcement by roots could be reduced due to decay during the long-term growth periods, and the balance between the above- and below-ground parts of the tree might be disrupted by the increase in the water contents of the tree and soils caused by prolonged rainfall and lack of sunlight.</p>

DOI： 10.3117/rootres.30.65

CiNii Research

Reconstruction of Conifer Root Systems Mapped with Point Cloud Data Obtained by 3D Laser Scanning Compared with Manual Measurement Reviewed

Chikage Todo, Hidetoshi Ikeno, Keitaro Yamase, Toko Tanikawa, Mizue Ohashi, Masako Dannoura, Toshifumi Kimura, Yasuhiro Hirano

FORESTS   Vol. 12 ( 8 )   2021.8

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

Three-dimensional (3D) root system architecture (RSA) is a predominant factor in anchorage failure in trees. Only a few studies have used 3D laser scanners to evaluate RSA, but they do not check the accuracy of measurements. 3D laser scanners can quickly obtain RSA data, but the data are collected as a point cloud with a large number of points representing surfaces. The point cloud data must be converted into a set of interconnected axes and segments to compute the root system traits. The purposes of this study were: (i) to propose a new method for easily obtaining root point data as 3D coordinates and root diameters from point cloud data acquired by 3D laser scanner measurement; and (ii) to compare the accuracy of the data from main roots with intensive manual measurement. We scanned the excavated root systems of two Pinus thunbergii Parl. trees using a 3D laser scanner and neuTube software, which was developed for reconstructing the neuronal structure, to convert the point cloud data into root point data for reconstructing RSA. The reconstruction and traits of the RSA calculated from point cloud data were similar in accuracy to intensive manual measurements. Roots larger than 7 mm in diameter were accurately measured by the 3D laser scanner measurement. In the proposed method, the root point data were connected as a frustum of cones, so the reconstructed RSAs were simpler than the 3D root surfaces. However, the frustum of cones still showed the main coarse root segments correctly. We concluded that the proposed method could be applied to reconstruct the RSA and calculate traits using point cloud data of the root system, on the condition that it was possible to model both the stump and ovality of root sections.

DOI： 10.3390/f12081117

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Dynamics of soil reinforcement by roots in a regenerating coppice stand of Quercus serrata and effects on slope stability Reviewed

Keitaro Yamase, Chikage Todo, Nobuyuki Torii, Toko Tanikawa, Tomonori Yamamoto, Hidetoshi Ikeno, Mizue Ohashi, Masako Dannoura, Yasuhiro Hirano

ECOLOGICAL ENGINEERING   Vol. 162   2021.4

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

Regeneration by sprouting in secondary forests is a necessary technique not only for the utilization of forest resources, but also for maintaining forest health by regrowth and avoiding slope instability caused by over-sized aboveground biomass. The strength of soil reinforcement by roots generally decreases during the tree death process in deforestation, such as clear-cutting, whereas root system strength temporarily decreases in trees that regenerate sprouting after cutting. However, quantitative evaluation of decreasing soil reinforcement by roots and slope stability has not been conducted during regeneration. In this study, we evaluated changes in the number of roots and root distribution up to 3 years after cutting in the regeneration process of Quercus serrata, a major dominant species of secondary forests in warm and cool temperate zones in Japan. We also estimated soil reinforcement by roots: additional cohesion from roots using the root bundle model, and slope stability based on a factor of safety by dividing the effect of the tree root system into vertical and horizontal cohesion with soil physical properties. After cutting at the height of approximately 0.2 m, the aboveground sprouting branches immediately regenerated, whereas the belowground root system gradually decayed. The additional cohesion from roots in trees before cutting was calculated as 34.6 kPa, whereas it decreased significantly to 21.7 kPa in living stumps 3 years after cutting. The value for the factor of safety with a saturated soil thickness of 0.7 m was calculated as 1.20 in soil under trees before cutting, whereas it decreased significantly to 1.11 in soil under living stumps in the 3 years after cutting. The safety factor?s value to 0.99 in soil under dead stumps, which did not regenerate sprouts within 3 years after cutting. We concluded that the probability of slope failure was significantly greater in the dead stumps than in the living stumps and could vary depending on the dynamics of above and below-ground parts, including fine roots.

DOI： 10.1016/j.ecoleng.2021.106169

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A quantitative evaluation of soil mass held by tree roots Reviewed

Toko Tanikawa, Hidetoshi Ikeno, Chikage Todo, Keitaro Yamase, Mizue Ohashi, Toru Okamoto, Takeo Mizoguchi, Katsuhiro Nakao, Shinji Kaneko, Atsushi Torii, Yoshiyuki Inagaki, Asami Nakanishi, Yasuhiro Hirano

TREES-STRUCTURE AND FUNCTION   Vol. 35 ( 2 ) page： 527 - 541   2021.4

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

Key message Tree roots hold soil that is dramatically heavier than the tree biomass, wet or dried. This soil might compensate for the imbalance between above- and belowground mass. Root-soil plates are recognized to play an important role in root anchorage of plate-like root system, however, actual measurements of their mass have rarely been reported. Even though the root-soil plate mass is often estimated using aboveground allometric indices, no research confirms the validity. Seven root-soil plates of Cryptomeria japonica fallen by Typhoon Jebi were divided into roots and soil, and their weights were directly measured. Mass of the seven plates ranged from 251 to 3070 kg on a dry basis. Roots accounted for 8% of total plate mass and soil for 92%. The mass of the soil held in the plates was 2.8 times greater than tree biomass. The root-to-shoot biomass ratio was 0.26, whereas the ratio of root-soil plate mass to shoot biomass was 3.9, meaning that the root-soil plate mass was much greater than aboveground biomass. These results suggest that the soil mass held in the plate is the main component of whole-tree mass including the plate. The root system holds soil weighing as much as 13 times the root system's mass. The soil might balance the aboveground weight of the tree by adding mass. Aboveground allometric indices are good indicators of root-soil plate mass and allow the belowground mass to be estimated to understand tree anchorage without soil disturbance.

DOI： 10.1007/s00468-020-02054-y

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人工林で営まれる植物-土壌-微生物間相互作用がもたらすもの Invited

谷川 東子

生物資源   Vol. 15 ( 1 ) page： 12 - 24   2021

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：農学生命科学研究支援機構  

CiNii Books

Washing methods for Moso bamboo (Phyllostachys pubescens) leaf litter and effects on elemental components. Reviewed

Umemura, M, Tanikawa, T

Bamboo Journal   Vol. 32   page： 37 - 47   2021

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Effects of microhabitats and soil conditions on structuring patterns of nematode communities in Japanese cedar (Cryptomeria japonica) plantation forests under temperate climate conditions Reviewed

Yudai Kitagami, Toko Tanikawa, Yosuke Matsuda

SOIL BIOLOGY & BIOCHEMISTRY   Vol. 151   page： 108044   2020.12

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

The effect of biotic factors impacted by abiotic conditions on nematode communities is not fully understood in forest ecosystems. Monoculture forests with low understory diversity would provide an ideal model system to investigate the relationship between nematode community structure and environmental factors in forest ecosystems. The aim of this study was to clarify the determinant environmental factors shaping community structures of soil nematodes in Japanese cedar (Cryptomeria japonica) forests. Nematodes collected from litter and soil samples were morphologically identified at the family or genus level and divided into trophic groups. Nematodes were discriminated into a total of 40 (including 2 unique taxa) and 52 (including 14 unique taxa) taxa in litter and soil samples, respectively. Variation in microhabitat substrates created contrasting nematode assemblages between litter and soil samples. Moreover, nematodes identified from litter habitats were a subset of those from soil samples. Bacterivorous and fungivorous nematodes were present in high proportions in both sample types. Herbivorous nematodes were the third most abundant trophic group in soil samples, but were rare in litter samples. The nematode community structure in soils was significantly ordinated by water, C, N, hyphae, and soil pH. The pH is most likely to affect ecological function of soil nematodes indirectly by altering microbial biomass. Our results showed that microhabitat substrates, that is, soil and litter, have a crucial effect on nematode assemblage patterns in temperate coniferous forests. Moreover, soil nematode assemblages were diversified due to the high spatial heterogeneity of proximate soil environments.

DOI： 10.1016/j.soilbio.2020.108044

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Morphological traits of Chamaecyparis obtusa fine roots are sensitive to soil acid buffering capacity Reviewed

Ryuusei Doi, Toko Tanikawa, Ryusei Wada, Yasuhiro Hirano

PLANT AND SOIL   Vol. 452 ( 1-2 ) page： 73 - 85   2020.7

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

Aims The purpose of this study was to clarify how the morphological traits of Chamaecyparis obtusa (Sieb. & Zucc.) Endl. roots vary with soil acid buffering capacity (ABC), i.e., along a gradient in soil acidification. We used an order-based root classification system instead of a diameter-based root classification system, as the former relates better to root function. Methods We sampled 210 intact fine root systems up to the fourth order and measured the morphological traits of a total of 16,657 individual branch-order roots in three C. obtusa stands with high soil ABC and four stands with low soil ABC. Results We found significant differences in the morphological traits of the first- to fourth-order roots between the soil ABCs. In the low-ABC soils, the fine root systems consisted of more and thinner roots than in the high-ABC soils. The diameter of the second-order roots was positively correlated with the soil pH and the concentration of base cations, but negatively with soil aluminum. Conclusion Morphological traits of fine roots are sensitive indicators of soil acidification in C. obtusa forests.

DOI： 10.1007/s11104-020-04561-w

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Detection of Tree Roots Using Ground Penetrating Radar for Disaster Mitigation

  Vol. 64 ( 3 ) page： 87 - 112   2020

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CiNii Books

Estimating slope stability by lateral root reinforcement in thinned and unthinned stands of Cryptomeria japonica using ground-penetrating radar Reviewed

Yamase K, Tanikawa T, Dannoura M, Todo C, Yamamoto T, Ikeno H, Ohashi M Aono K, Doi R, Hirano Y

Catena   Vol. 183 ( 183 ) page： 104227   2019.12

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

Tree root diameter and root distribution are crucial factors for root reinforcement in forest soils and can be estimated using nondestructive ground-penetrating radar (GPR). However, no studies on estimating root reinforcement have been performed using GPR. The aim of this study was to evaluate root reinforcement using GPR in thinned and unthinned stands of Cryptomeria Japonica in Andisols. Roots in each stand were detected using a 900 MHz GPR and the diameter and horizontal distribution of roots were estimated. Roots were also excavated to compare their GPR estimates. The relationships between root diameter and tensile force were established through field pullout tests. Finally, root reinforcements in each stand were estimated using the recently proposed root bundle model (RBM). There were no significant differences in the diameter frequency distribution of roots estimated between thinned and unthinned stands, determined using either the GPR or excavation methods. The detection frequency of the number of roots > 5 mm in diameter using GPR was 27.2%, but it increased to 58.7% for roots > 10 mm. The waveform indexes, determined using the sum of time intervals between zero crossings (ET) of all reflection waveforms of GPR, had a significant linear relationship with the diameters of excavated roots, indicating that waveform index could be used to estimate root diameter using the GPR index in these stands. Furthermore, the relationship between the root tensile force (F) and- root diameter (d) was estimated as F = 15.69 d(1.75) (R-2 = 0.87). The root reinforcements at the center of gaps between individual trees were estimated to be 23.4-32.9 kPa in the thinned stand and 8.8-23.9 kPa in the unthinned stand using GPR. These values ranged from 31.9% to 170.7% of those obtained by using the excavation method. There were no significant differences in root reinforcement between thinned and unthinned stands, regardless of the method used. This study revealed that GPR, together with diameter-tensile force relationships, can nondestructively estimate root reinforcement in managed forests. This protocol can be applied to manage forests to evaluate the effects of management on belowground roots.

DOI： 10.1016/j.catena.2019.104227

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Variation in the morphology of fine roots in Cryptomeria japonica determined by branch order-based classification Reviewed

Wada R, Tanikawa T, Doi R, Hirano Y

Plant and Soil   Vol. 444 ( 1-2 ) page： 139 - 151   2019.11

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Aims This study assessed intraspecific variation in morphological traits of the fine root branch orders of Cryptomeria japonica, and identified variation in the diameter of the first three-order roots among species types with mycorrhiza, and the diameter of first-order roots at the family level. Methods Diameter, length, and specific root length of branch order roots (up to the fourth-order) were measured in intact fine root systems collected in four C. japonica stands. Relationships between soil chemical properties and morphological traits of the first- to fourth-order roots were investigated. The diameter of roots of 52 tree species reported in previous studies was compared at species types with mycorrhiza and at family level. Results The diameter of first-order roots in C. japonica varied by 1.2 times among stands. Negative correlations between soil NH4+ content and specific root length of the second- and third-order roots were observed in C. japonica. The diameter of first- and second-order roots forming arbuscular mycorrhiza in coniferous trees were significantly higher than those of roots forming ectomycorrhiza in coniferous and broadleaf trees. The diameter of first-order roots in Cupressaceae were significantly larger than those of Pinaceae, Sapindaceae, Betulaceae, and Fagaceae. Conclusions Clarifying intraspecific variation in morphological traits of C. japonica lower-order roots may contribute to understanding their responses to different site conditions such as soil inorganic nitrogen contents.

DOI： 10.1007/s11104-019-04264-x

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Free-living nematodes associated with pine cones of Pinus thunbergii and P. taeda at Japanese coastal and inland forest sites. Reviewed

Kitagami,Y., Kanzaki, N., Tanikawa, T., Matsuda, Y.

Nematology   Vol. 21 ( 4 ) page： 389 - 400   2019.4

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DOI： https://doi.org/10.1163/15685411-00003221

Reconstruction of root systems in Cryptomeria japonica using root point coordinates and diameters. Reviewed

Ohashi, M, Ikeno, H, Sekihara, K, Tanikawa, T, Dannoura, M, Yamase, K, Todo, C, Tomita, T, Hirano, Y

Planta   Vol. 249 ( 2 ) page： 445 - 455   2019.2

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Main conclusionWe developed simple algorithms for reconstructing tree root system architecture using only the root point coordinate and diameter, which can be systematically obtained without digging up the root systems.Root system architecture (RSA) is strongly related to various root functions of the tree. The aim of this study was to develop a three-dimensional (3D) RSA model using systematically obtained information on root locations and root diameters at the locations. We excavated root systems of Cryptomeria japonica and systematically obtained XYZ coordinates and root diameters using a 10-cm grid. We clarified the patterns of the root point connections and developed a reconstructed root system model. We found that the root diameters farther from the stump centre are smaller. Additionally, we found that the root lengths of the segments running between the base and the connected root point were smaller than those of other root segments, and the inner angle between the base and the stump and between the base and the connected root point was narrower than for the other pairs. The new RSA model developed according to these results had average accuracies of 0.64 and 0.80 for estimates of total volume and length, respectively. The developed model can estimate 3D RSA using only root point data, which can be obtained without digging up root systems. This suggests a wide applicability of this model in root function evaluation.

DOI： 10.1007/s00425-018-3011-x

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Response of river water chemistry to changing atmospheric environment and sulfur dynamics in a forested catchment in central Japan Reviewed

Hiroyuki Sase, M. Takahashi, K. Matsuda, K. Sato, T. Tanikawa, N. Yamashita, T. Ohizumi, T. Ishida, M. Kamisako, R. Kobayashi, S. Uchiyama, T. Saito, M. Morohashi, H. Fukuhara, S. Kaneko, T. Inoue, T. Yamada, C. Takenaka, I. Tayasu, T. Nakano, T. Hakamata, S. Ohta

Biogeochemistry   Vol. 142 ( 3 ) page： 357 - 374   2019.2

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

DOI： 10.1007/s10533-019-00540-1

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Other Link： http://link.springer.com/content/pdf/10.1007/s10533-019-00540-1.pdf

Stability of Pinus thunbergii between two contrasting stands at differing distances from the coastline Reviewed

Chikage Todo, Chie Tokoro, Keitaro Yamase, Toko Tanikawa, Mizue Ohashi, Hidetoshi Ikeno, Masako Dannoura, Kouhei Miyatani, Ryuusei Doi, Yasuhiro Hirano

FOREST ECOLOGY AND MANAGEMENT   Vol. 431   page： 44 - 53   2019.1

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The extent of damage to Pinus thunbergii trees in coastal forests resulting from the tsunami caused by the Great East Japan Earthquake in 2011 differed depending on the local environment. The height (H) of P. thunbergii was generally limited in stands closer to the coastline and these trees could fail due to the force of the tsunami. The resistance forces of coastal forests to tsunamis are expressed as critical turning moments and measured by tree pulling experiments. However, few studies have focused on the differences in the critical turning moment between stands with locally different environmental conditions among P. thunbergii coastal forests. We determined the differences in the critical turning moments of P. thunbergii in two contrasting sites having different distances from the coastline. We also estimated the tolerance of P. thunbergii in the two sites against loading from tsunami. Two experimental plots, sea-side and land-side, in a coastal P. thunbergii forest were established with different depths of the water table belowground and wind forces. In both plots, the aboveground traits, including the diameter at breast height (DBH), and H x DBH2 of P. thunbergii, were positively correlated with the critical turning moments. In particular, when P. thunbergil had the same H x DBH2 between the plots, there were no differences in the critical turning moments. This result suggested that P. thunbergii at the sea-side had acclimated for 50 years to their environment by changing shallow tap roots for shallower belowground water and developing horizontal roots for strong winds. The depth of the center point of rotation was significantly deeper and was positively correlated with moments in the land-side plot, suggesting changes from a tap root system to a plate root system in the sea-side plot with a shallower water table. The estimated loading from the tsunami with a 2 m wave height was over the critical turning moments for both plots. P. thunbergii trees at the sea-side plot could be more susceptible to overturning by lower-height waves than at the land-side plot because of differences in aboveground traits of H x DBH. We propose that the practical management of coastal forests is to create an embankment by raising the ground level to develop tree growth with capable of enhanced resilience to tsunamis.

DOI： 10.1016/j.foreco.2018.05.040

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Free-living nematodes associated with pine cones of Pinus thunbergii and P. taeda at Japanese coastal and inland forest sites Reviewed

Yudai Kitagami, Natsumi Kanzaki, Toko Tanikawa, Yosuke Matsuda

Nematology   Vol. 21 ( 4 ) page： 389 - 400   2019

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<title>Summary</title>
We surveyed the distribution of nematodes in 56 cones of <italic>Pinus thunbergii</italic> collected from both live branches and on the forest floor in three coastal and inland habitats and in 11 cones of <italic>P. taeda</italic> collected at different heights. We identified 47 nematodes to family or genera by analysis of an 18S small subunit rRNA gene sequence. The frequencies of occurrence of free-living cone nematodes were 97% in coastal <italic>P. thunbergii</italic>, 92% in inland <italic>P. thunbergii</italic>, and 82% in <italic>P. taeda</italic>. Phylogenetic analysis assigned the nematodes to four clades with high bootstrap values. Nine sequences that were found only in cones on live branches were clustered with <italic>Panagrobelus stammeri</italic> and an unknown <italic>Panagrobelus</italic> sp. Our results imply that nematodes are commonly associated with cones in pine forest ecosystems and that a capacity for anhydrobiosis may be a key to surviving above-ground.

DOI： 10.1163/15685411-00003221

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Other Link： https://brill.com/downloadpdf/journals/nemy/21/4/article-p389_4.xml

Ground-penetrating radar estimates of tree root diameter and distribution under field conditions Reviewed

Keitaro Yamase, Toko Tanikawa, Masako Dannoura, Mizue Ohashi, Chikage Todo, Hidetoshi Ikeno, Kenji Aono, Yasuhiro Hirano

TREES-STRUCTURE AND FUNCTION   Vol. 32 ( 6 ) page： 1657 - 1668   2018.12

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Key messageUse of ground-penetrating radar (GPR) can non-destructively estimate diameter and distribution of coarse roots in Cryptomeria japonica in weathered granite soils under field conditions.AbstractGround-penetrating radar (GPR) has been used as an assessment tool for non-destructive detection of tree root biomass, but few studies have estimated root diameter under forest field conditions. The aim of this study was to clarify whether coarse root diameter of C. japonica in weathered granite soils can be estimated using GPR in a forest. Roots of mature C. japonica were scanned using a 900MHz GPR antenna before being excavated. The diameter and distribution of excavated roots were compared with those identified by GPR, and the relationships between the diameter and waveform indices in radar profiles were also examined. The detection frequency of the number of roots larger than 5mm in diameter was 47.7%. Limiting factors affecting root detection using GPR in forest field conditions were small root diameter, increasing root depth, and number of adjacent roots. Only one waveform index, using the sum of time intervals between zero crossings (sigma T, ns) of all reflection waveforms of GPR within the range from the first break time at the root top to the delay point time at the root bottom, had a significant relationship with excavated root diameters. A linear regression model was constructed to estimate root diameter using sigma T, and a significant positive relationship in diameter between GPR-estimated and excavated roots was confirmed. The results in this study indicate that the diameter and distribution of C. japonica coarse roots under forest field conditions could be estimated using GPR and this technique could contribute to future evaluation of slope stability by evaluating tree roots under vulnerable soils, such as weathered granite.

DOI： 10.1007/s00468-018-1741-9

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Nematode communities in pine forests are shaped by environmental filtering of habitat conditions Reviewed

Kitagami Yudai, Tanikawa Toko, Mizoguchi Takeo, Matsuda Yosuke

JOURNAL OF FOREST RESEARCH   Vol. 23 ( 6 ) page： 346 - 353   2018.11

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Soil nematodes are involved in nutrient cycles through feeding on microorganisms, and the extent of their functioning is affected by subtle environmental changes and by biological interactions. Considering these features, soil nematodes can serve as bio-indicators reflecting environmental changes in a given ecosystem. However, the mechanism of shaping community structures of nematodes is not well understood due to the complex biological interactions in forest ecosystems. The aim of this study was to clarify the nematode communities and their determinant factors in both coastal and inland Pinus thunbergii forests of central Japan under contrasting environmental conditions. For this purpose, nematodes retrieved from soil samples were morphologically identified at generic levels and discriminated into trophic groups. We also determined whether nematode community structures varied with coastal or inland locations based on non-metric multidimensional scaling. Our results showed that generic richness of nematode at inland habitats (16.2 +/- 0.7, mean +/- SE) was significantly greater than that at coastal habitats (12.4 +/- 0.4). Moreover, the non-metric multidimensional scaling scatter-plot showed nematode communities clustered significantly within their respective coastal and inland habitats. These clusterings were further significantly influenced by surrounding environmental factors; soil water content, soil temperature, litter layer thickness, pH, total both N and C concentrations and C:N ratio. For characteristic trophic groups, microbial-feeding nematodes were represented in coastal forests while predaceous ones were dominated in inland forests. Our study provided fundamental knowledge on the formation of nematode community structures that were shaped by environmental filtering.

DOI： 10.1080/13416979.2018.1516920

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Quantification of the contrasting root systems of Pinus thunbergii in soils with different groundwater levels in a coastal forest in Japan Reviewed

Yasuhiro Hirano, Chikage Todo, Keitaro Yamase, Toko Tanikawa, Masako Dannoura, Mizue Ohashi, Ryuusei Doi, Ryusei Wada, Hidetoshi Ikeno

Plant and Soil   Vol. 426 ( 1-2 ) page： 327 - 337   2018.5

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

© 2018, Springer International Publishing AG, part of Springer Nature. Aims: The different root systems of Pinus thunbergii observed after the tsunami in 2011 were possibly influenced by different groundwater levels before the tsunami. The aims of this study were to quantify the tap and horizontal root structure and evaluate their relationship with the above-ground parts under different groundwater levels in a coastal P. thunbergii forest. Methods: Two plots, sea- and land-side, with different groundwater levels, in a P. thunbergii stand, were established, and the entire root-systems of three select trees each were harvested to evaluate the biomass, lengths, and cross-sectional areas of the tap and horizontal roots. Results: In the sea-side plot, which had a shallower groundwater level, plate root systems with thicker and longer horizontal roots, but fewer tap roots were observed, whereas tap root systems were well developed in the land-side plots, where the groundwater level was deeper. The root-to- shoot ratio was significantly higher in the sea-side plot than in the land-side plot. Conclusion: We confirmed that quantitative contrasting root systems of P. thunbergii develop under different groundwater levels and higher biomass allocation to horizontal roots occur under shallower groundwater depths, emphasizing the need for management practices that promote the development of tap root systems to enhance resistance to tsunamis.

DOI： 10.1007/s11104-018-3630-9

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Sulfur accumulation rates in volcanic soils of eastern Japan over the last millennium based on tephrochronology Reviewed

Toko Tanikawa, Yohey Hashimoto, Noriko Yamaguchi, Masamichi Takahashi, Shuichiro Yoshinaga

Geoderma   Vol. 315   page： 111 - 119   2018.4

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

Soils have an important role as a reservoir of essential elements for forest ecosystems. Although previous chronosequence studies have determined accumulation rates of several elements in soils, they have not focused on sulfur (S), a secondary macronutrient. We investigated S accumulation rates in five volcanic soils, dated by the use of tephras from the following volcanoes: Mt. Komagatake (tephra Ko-a, 1929 CE), Mt. Tarumae (tephra Ta-a, 1739 CE), Mt. Fuji (tephra F-Ho, 1707 CE), Towada caldera (tephra To-a, 915 CE), and Mt. Haruna (tephra Hr-FP520, 520 CE). The soils were sampled from A horizons formed above the tephra layer, and total S and pedogenic minerals (Ald, Fed, Alo, and Feo) were analyzed to determine the relationships between their estimated pools and soil age. The fractionation of S by oxidation state was determined by S K-edge XANES analysis in constituents of soils from Mt. Komagatake and Mt. Haruna. Our results showed that the S accumulation rate was almost constant over the last millennium. To extend our analysis to longer soil formation times, we extrapolated the S accumulation–age relationship to 10 cal. ka and compared the resulting values with previously reported S data from horizons that likely developed during that time period in soils from Mt. Nantai dated by tephra Nt-S (14–15 cal. ka). The similarity of the extrapolated values to the Nantai soil values suggests that the S accumulation rate may have been constant since 10 cal. ka. In addition, the growth of the S pool with soil age was linearly proportional to the growth of pedogenic mineral pools. Sulfur isotope composition of soil total S depended not on soil age, but rather on the soil origin as indicated by location. The predominant oxidation state of the S fraction changed from reduced to oxidized with soil age during the Holocene. These results suggest that the constant S accumulation rate may reflect the variable influence of exogenous S sources as well as the association of S compounds with pedogenic minerals. Sulfur compounds may accumulate at a constant rate in Japanese volcanic soils as the result of biological transformation followed by retention of S in association with the pedogenic minerals.

DOI： 10.1016/j.geoderma.2017.11.023

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Relationships between specific root length and respiration rate of fine roots across stands and seasons in Chamaecyparis obtusa Reviewed

Kouhei Miyatani, Toko Tanikawa, Naoki Makita, Yasuhiro Hirano

PLANT AND SOIL   Vol. 423 ( 1-2 ) page： 215 - 227   2018.2

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Fine root respiration (R (r) ) is closely linked with fine root morphology, especially with specific root length (SRL), in short-term measurements in some tree species. However, whether these relationships are also valid across different stands and seasons is not yet known. This study aimed to investigate these relationships in the fine roots of Chamaecyparis obtusa.The R (r) , mean root diameter, and SRL of fine root segments of two C. obtusa stands were determined every three months over two years.We detected significant positive correlations between R (r) and SRL of fine root segments across the stands over two years. The relationship of R (r) with SRL was stronger than that with the mean diameter of fine roots. The slopes and intercepts for the R (r) and SRL relationships did not differ among stands and measurement times. Further, we proposed a simple approach for estimating CO2 flux from fine roots at the stand level based on SRL and confirmed that the ranges of estimated CO2 values were comparable with those of values reported using the conventional approach.The fine root morphology typified by SRL is a key variable in R (r) of fine roots and CO2 flux at the stand level.

DOI： 10.1007/s11104-017-3499-z

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Calcium is cycled tightly in Cryptomeria japonica stands on soils with low acid buffering capacity Reviewed

Toko Tanikawa, Yoshiaki Ito, Sei Fukushima, Michiru Yamashita, Akifumi Sugiyama, Takeo Mizoguchi, Toru Okamoto, Yasuhiro Hirano

FOREST ECOLOGY AND MANAGEMENT   Vol. 399   page： 64 - 73   2017.9

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Calcium (Ca) is a key cation in the soil acidification process and in the fertility of forest soils. We investigated total concentrations of Ca, magnesium (Mg), and potassium (K) in both soil and fresh leaf litter in eight plantation stands of Cryptomeria japonica divided into two groups of highly contrasting soil acid buffering capacity (ABC). In addition to conventional methods, we used a double-crystal high resolution X-ray fluorescence (HRXRF) spectrometer to determine Ca fractions in soils with low and high ABC. Total Ca had accumulated in the 0-10 cm depth horizons of the high-ABC soils, but not in the low-ABC soils. The exchangeable Ca concentration was correlated with total Ca concentration in the 0-10 cm depth of the low-ABC soils. Calcium-K alpha(1,2) emission spectra of the 0-10 cm soils obtained by HRXRF spectrometry separated the total Ca into two fractions, suggesting that the predominant Ca constituents had either passed through biological processes or were derived from weathering hydration in both the high- and low-ABC soils. Calcium concentration in the fresh leaf litter was significantly lower in the stands with low-ABC soil than in those with high-ABC soil and was positively correlated with soil exchangeable Ca concentration in the low-ABC stands; no such correlation was observed in the high-ABC stands. Exchangeable Ca pools in the 0-10 cm depth range were equal to or less than the annual input of Ca via leaf litterfall in the low-ABC stands, but were seven times the annual input in the high-ABC soils. These results suggested that the accumulation of Ca in the upper soil occurs via the process of Ca circulation within C. japonica ecosystems, and that sufficient supply of Ca for tree needs was accompanied by the large accumulation of available Ca by C. japonica in the high-ABC soils. Nevertheless, it is likely that only small amounts of Ca were circulated in the stands on low-ABC soil. The lack of Ca accumulation in the surface soil and the accompanying tight circulation of Ca in the plant-soil system may explain the observed positive feedback in which ABC is gradually reduced in low-ABC soils. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.foreco.2017.04.022

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Intraspecific variation in morphological traits of root branch orders in Chamaecyparis obtusa Reviewed

Ryuusei Doi, Toko Tanikawa, Kouhei Miyatani, Yasuhiro Hirano

PLANT AND SOIL   Vol. 416 ( 1-2 ) page： 503 - 513   2017.7

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We aimed to clarify the intraspecific variation in the morphological traits of branch orders under different soil conditions in Chamaecyparis obtusa (Siebold & Zucc.) Endl.
We investigated the morphological traits of branch orders, based on 16,351 individual roots that were dissected from 12 intact fine root systems, up to a diameter of 2 mm at three C. obtusa stands. We also measured the concentrations of soil carbon, nitrogen, and inorganic nitrogen.
The intact fine root systems up to the diameter of 2 mm had branched into between five and seven orders. The diameter of first- to fourth-order roots and the lengths of second- and third-order roots were significantly different among the three stands. The morphological traits of lower order (first to third) roots correlated with soil inorganic nitrogen concentrations, but higher order (fourth to sixth) roots correlated with soil carbon concentrations.
We clarified the possible ranges of intraspecific variation in the morphological traits of root branch orders within C. obtusa. Both the lower and higher orders of the intact fine root systems were tightly related to the surrounding soil conditions.

DOI： 10.1007/s11104-017-3230-0

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Calculation procedures to estimate fine root production rates in forests using two-dimensional fine root data obtained by the net sheet method Reviewed

Kyotaro Noguchi, Toko Tanikawa, Yoshiyuki Inagaki, Shigehiro Ishizuka

TREE PHYSIOLOGY   Vol. 37 ( 6 ) page： 697 - 705   2017.6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Several recent studies have used the net sheet method to estimate fine root production rates in forest ecosystems, wherein net sheets are inserted into the soil and fine roots growing through them are observed. Although this method has advantages in terms of its easy handling and low cost, there are uncertainties in the estimates per unit soil volume or unit stand area, because the net sheet is a two-dimensional material. Therefore, this study aimed to establish calculation procedures for estimating fine root production rates from two-dimensional fine root data on net sheets. This study was conducted in a hinoki cypress (Chamaecyparis obtusa (Sieb. & Zucc.) Endl.) stand in western Japan. We estimated fine root production rates in length and volume from the number (RN) and cross-sectional area (RCSA) densities, respectively, for fine roots crossing the net sheets, which were then converted to dry mass values. For these calculations, we used empirical regression equations or theoretical equations between the RN or RCSA densities on the vertical walls of soil pits and fine root densities in length or volume, respectively, in the soil, wherein the theoretical equations assumed random orientation of the growing fine roots. The estimates of mean fine root (diameter &lt;1 mm) production rates were similar to 80-100 gm(-2) year(-1) using the empirically obtained regression equations, whereas those from the theoretical equations were similar to 40-50 gm(-2) year(-1). The difference in the estimates was attributed to larger slope values of the empirical regression equations than those of the theoretical equations, suggesting that fine root orientation was not random in our study site. In light of these results, we concluded that fine root production rates were successfully estimated from two-dimensional fine root data on the net sheets using these calculation procedures, with the empirical regression equations reflecting fine root orientation in the study site.

DOI： 10.1093/treephys/tpx044

Web of Science

PubMed

Biomass and morphology of fine roots in eight Cryptomeria japonica stands in soils with different acid-buffering capacities Reviewed

Yasuhiro Hirano, Toko Tanikawa, Naoki Makita

FOREST ECOLOGY AND MANAGEMENT   Vol. 384   page： 122 - 131   2017.1

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Cryptomeria japonica, which is one of the main silvicultural species in Japan, accumulates calcium (Ca) in soils with high acid buffering capacity (ABC) but has depleted Ca in soils with low-ABC over the past two decades. However, the contribution of fine roots in C japonica to the accumulation or depletion of Ca in soils with different ABCs has not been evaluated. The aim of this study was to clarify the responses of C. japonica fine roots in terms of biomass and morphology in eight plantation stands to soils with two contrasting ABCs, which have different trends of soil acidification. We evaluated the biomass and specific root length (SRL) of fine roots divided into three diameter classes (&lt;0.5, 0.5-1.0, and 1.0-2.0 mm), obtained from the organic layer and two mineral soil layers from 0 to 10 and 10 to 20 cm depths, in soils with high- and low-ABCs. We also investigated root traits of seedlings grown in soil monoliths in-situ in a greenhouse condition to compare the response of mature trees in stands. The biomass of fine roots (&lt;2.0 mm) in mature C japonica was significantly higher and the SRL was significantly lower in low ABC soils than in high-ABC soils. In the organic layer, the biomass of very fine roots (&lt;0.5 mm) at the organic soil layer in low ABC soils was higher than that in high ABC soils. However, the SRL and the dry weight of the seedlings in the greenhouse condition showed no differences between the soils with two contrasting ABCs. We concluded that fine roots of C japonica stands could have changed and contributed differently to soils with contrasting ABCs. The conflicting root responses of mature trees in stand and seedlings under controlled conditions suggest that careful caution should be taken to extrapolate in situ mature trees from the results of seedlings, particularly when evaluating the effects of soil degradation such as soil acidifications on sustainable C. japonica plantation forests. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.foreco.2016.10.043

Web of Science

Scopus

Ungulates decelerate litter decomposition by altering litter quality above and below ground. Reviewed

Kasahara, M., Fujii, S., Tanikawa, T., & Mori, A. S.

European Journal of Forest Research   Vol. 135 ( 5 ) page： 849 - 856   2016.7

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Leaf litter thickness, but not plant species, can affect root detection by ground penetrating radar. Reviewed

Tanikawa, T., Ikeno, H., Dannoura, M., Yamase, K., Aono, K., & Hirano, Y.

Plant and Soil   Vol. 408 ( 1-2 ) page： 271 - 283   2016.5

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DOI： https://doi.org/10.1007/s11104-016-2931-0

Fine root traits in Chamaecyparis obtusa forest soils with different acid buffering capacities. Reviewed

Miyatani, K., Mizusawa, Y., Okada, K., Tanikawa, T., Makita, N., & Hirano, Y.

Trees   Vol. 30 ( 2 ) page： 415 - 429   2015.10

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Intraspecific variation in fine root respiration and morphology in response to in situ soil nitrogen fertility in a 100-year-old Chamaecyparis obtusa forest. Reviewed

Makita, N., Hirano, Y., Sugimoto, T., Tanikawa, T., & Ishii, H.

Oecologia   Vol. 179 ( 4 ) page： 959 - 967   2015.8

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Calibrating the impact of root orientation on root quantification using ground-penetrating radar. Reviewed International coauthorship

Guo, L., Wu, Y., Chen, J., Hirano, Y., Tanikawa, T., Li, W., & Cui, X.

Plant and Soil   Vol. 395 ( 1-2 ) page： 289 - 305   2015.6

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同心円状レーダ探索による海岸に生育するクロマツ個体の水平根の広がりの検出 Reviewed

大橋瑞江， 柿添哲也， 池野英利， 山瀬敬太郎， 谷川東子， 檀浦正子， 青野健治， 藤堂千景， 平野恭弘

日本緑化工学会誌   Vol. 41   page： 385 - 390   2015

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Language：Japanese   Publishing type：Research paper (scientific journal)  

間伐がスギの最大引き倒し抵抗モーメントにもたらす影響 Reviewed

日本緑化工学会誌   Vol. 41   page： 308 - 314   2015

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Language：Japanese   Publishing type：Research paper (scientific journal)  

異なる土壌環境下における根系構造と引き抜き抵抗力との関係 Reviewed

山瀬敬太郎， 谷川東子， 池野英利， 藤堂千景， 大橋瑞江， 檀浦正子， 平野恭弘

日本緑化工学会誌   Vol. 41   page： 301 - 307   2015

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減災の観点から樹木根系を非破壊的に推定する地中レーダ法の現状と課題 Reviewed

平野恭弘， 山瀬敬太郎， 谷川東子， 檀浦正子， 大橋瑞江， 藤堂千景， 池野英利

日本緑化工学会誌   Vol. 41   page： 319 - 325   2015

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Sulfur accumulation in Melanudands during development by upbuilding pedogenesis since 14–15cal. ka. Reviewed

Tanikawa T, Hashimoto Y, Yamaguchi N, Ito Y, Fukushima S, Kanda K, Uemura M, Hasegawa T, Takahashi M, Yoshinaga S

Geoderma   Vol. 232   page： 609 - 618   2014.11

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Sequential transformation rates of soil organic sulfur fractions in two-step mineralization process. Reviewed

Tanikawa T, Noguchi K, Nakanishi K, Shigenaga H, Nagakura J, Sakai H, Akama A, Takahashi M

Biology and fertility of soils   Vol. 50 ( 2 ) page： 225 - 237   2014

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Reply to:“Comment on root orientation can affect detection accuracy of ground-penetrating radar” Reviewed

Tanikawa, T., Dannoura, M., Yamase, K., Ikeno, H., & Hirano, Y.

Plant and soil   Vol. 380 ( 1-2 ) page： 445 - 450   2014

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Root orientation can affect detection accuracy of ground-penetrating radar. Reviewed

Tanikawa T., Hirano Y., Dannoura M., Yamase K., Aono K., Ishii M., Igarashi T., Ikeno H., & Kanazawa Y.

Plant and soil   Vol. 373 ( 1-2 ) page： 317 - 327   2013.6

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Soil sulfur content and its spatial distribution in a small catchment covered by volcanic soil in the montane zone of central Japan. Reviewed

Tanikawa T., Yamashita N., Aizawa S., Ohnuki Y., Yoshinaga S., & Takahashi M.

Geoderma   Vol. 197   page： 1 - 8   2013.4

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Highly accumulated sulfur constituents and their mineralogical relationships in Andisols from central Japan. Reviewed

Tanikawa T., Takahashi M., Imaya A., Ishizuka K.

Geoderma   Vol. 151 ( 1 ) page： 42 - 49   2009.6

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奥日光の森林衰退地域の樹木生葉と土壌の養分特性－他の亜高山地域との比較から－ Reviewed

谷川東子・高橋正通・野口享太郎・重永英年・長倉淳子・酒井寿夫・石塚和裕・赤間亮夫

環境科学会誌   Vol. 22   page： 401 - 414   2009

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森林土壌における硫黄化合物の蓄積実態 Invited Reviewed

谷川東子・高橋正通・今矢明宏

環境科学会誌   Vol. 17   page： 211 - 215   2004

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森林生態系における硫黄の循環と土壌の硫黄集積機構の意義 ―土壌の硫黄蓄積とその理化学性との関係― Invited Reviewed

谷川東子・高橋正通・今矢明宏

地球環境   Vol. 9   page： 19 - 28   2004

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アンディソルとインセプティソルにおける硫酸イオンの土壌断面分布と現存量 ―吸着態および溶存態硫酸イオンについて― Reviewed

谷川東子・高橋正通・今矢明宏・稲垣善之・石塚和裕

日本土壌肥料学雑誌   Vol. 74   page： 149 - 155   2003

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落葉広葉樹林におけるN2O生成とその空間的異質性. Reviewed

石塚成宏・阪田匡司・谷川東子・石塚和裕

日本林学会誌   Vol. 82   page： 62 - 71   2000

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Extractable sulfate content in Japanese forest soils Reviewed

Tanikawa, T., Ishizuka, K., & Imaya, A.

Journal of Forest Research   Vol. 4   page： 191 - 194   1999

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Relating sulfate adsorption to soil properties in Japanese forest soils. Reviewed

Journal of Forest Research   Vol. 4   page： 217 - 222   1999

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異なる森林土壌中における硫酸イオンの吸着 ―有機物による吸着阻害― Invited Reviewed

谷川東子・竹中千里

日本林学会論文集   Vol. 105   page： 415 - 416   1994

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土壌中における硫酸イオンの吸着 Reviewed

谷川東子・竹中千里

日本林学会中部支部論   Vol. 42   page： 125 - 126   1994

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Language：Japanese