研究者詳細 - 谷川　東子

論文 - 谷川　東子

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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査読有り

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 20 巻頁： 169 - 184 2021年10月

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. 査読有り

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 20 巻頁： 195 - 204 2021年10月

2020年7月に倒木化した岐阜県大湫町神明大杉の根系状況査読有り

平野恭弘, 南光一樹, 土居龍成, 西村澪, 杁山哲矢, 谷川東子

根の研究 30 巻 ( 3 ) 頁： 65 - 75 2021年9月

担当区分：最終著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：根研究学会

令和2年7月豪雨中の7月11日夜，岐阜県瑞浪市大湫町の神明神社に生育し，町のシンボルである大杉が倒木化した．本研究は，大杉倒木化の要因解明に向けた基礎的な知見を得るため，倒木時の豪雨など気象状況とともに大杉倒木の根系状況を明らかにすることを目的とした．2020年7月11日の日降水量は137 mm day－1，時間最大雨量43 mm h－1の豪雨を記録したが，これは過去40年間に大杉が経験した雨量であった．2020年7月は特に日照時間が短く，樹体や土壌が乾きにくい状態であることが推察された．倒木化した大杉は，横方向に最大9.1 m, 縦方向に最大 6.6 mの直径, 最大厚さ2.3 mをもつ巨大な根鉢を地表面に露わにした．根鉢中心部には腐朽が広がり，倒木時に土壌に残存した根には剥ぎ取られたような形跡が認められた．レーザースキャナを用いて，倒木化した大杉の三次元構造をデジタル化して再現した結果，根系体積は43.2 m3と推定された．倒木化した大杉の地下部の広がりや地上部との体積比からも，スギとして大杉の根系は小さいことが示唆された．根系および気象の状況から倒木化の要因として，長年の生育中に根系に進んだ腐朽，および長期間の雨と日照不足に伴う土壌水分量増加による根の土壌支持力の低下，さらにこの気象下における樹体地上部の水分量増加によって，地下部・地上部バランスが崩れたことが推察された．

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 査読有り

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

FORESTS 12 巻 ( 8 ) 2021年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Forests

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

Web of Science

Scopus

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

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

ECOLOGICAL ENGINEERING 162 巻 2021年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Ecological Engineering

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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Scopus

A quantitative evaluation of soil mass held by tree roots 査読有り

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

TREES-STRUCTURE AND FUNCTION 35 巻 ( 2 ) 頁： 527 - 541 2021年4月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Trees - Structure and Function

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. Abstract: 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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Scopus

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招待有り

谷川東子

生物資源 15 巻 ( 1 ) 頁： 12 - 24 2021年

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

Umemura, M, Tanikawa, T

Bamboo Journal 32 巻頁： 37 - 47 2021年

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

Kitagami Yudai, Tanikawa Toko, Matsuda Yosuke

SOIL BIOLOGY & BIOCHEMISTRY 151 巻頁： 108044 2020年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Soil Biology and Biochemistry

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 査読有り

Doi Ryuusei, Tanikawa Toko, Wada Ryusei, Hirano Yasuhiro

PLANT AND SOIL 452 巻 ( 1-2 ) 頁： 73 - 85 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plant and Soil

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

Web of Science

Scopus

地中レーダがもつ樹木の根系可視力を減災に生かす試み

谷川東子, 山瀬敬太郎, 藤堂千景, 池野英利, 大橋瑞江, 檀浦正子, 金澤洋一, 平野恭弘

水利科学 = Water science 64 巻 ( 3 ) 頁： 87 - 112 2020年

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

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

CATENA 183 巻 ( 183 ) 頁： 104227 2019年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Catena

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 (ΣT) 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 d1.75 (R2 = 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 査読有り

Wada Ryusei, Tanikawa Toko, Doi Ryuusei, Hirano Yasuhiro

PLANT AND SOIL 444 巻 ( 1-2 ) 頁： 139 - 151 2019年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plant and Soil

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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Scopus

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

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

Nematology 21 巻 ( 4 ) 頁： 389 - 400 2019年4月

Reconstruction of root systems in Cryptomeria japonica using root point coordinates and diameters 査読有り

Ohashi Mizue, Ikeno Hidetoshi, Sekihara Kotaro, Tanikawa Toko, Dannoura Masako, Yamase Keitaro, Todo Chikage, Tomita Takahiro, Hirano Yasuhiro

PLANTA 249 巻 ( 2 ) 頁： 445 - 455 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Planta

Main conclusion: We 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

Web of Science

Scopus

PubMed

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

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

BIOGEOCHEMISTRY 142 巻 ( 3 ) 頁： 357 - 374 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Biogeochemistry

Reduction of atmospheric sulfur (S) deposition and recovery of terrestrial ecosystems from acidification are matters of concerns in Asia. The Lake Ijira catchment (IJR) is located in the downwind region of the Chukyo Industrial Area in central Japan and has historically experienced large-scale deposition of S and nitrogen (N) from the atmosphere. Long-term monitoring data on the river water (RW) chemistry since 1988 were assessed with intensive-survey datasets on the input–output material budgets and S isotopic analysis (δ 34 S). Previous studies have suggested that IJR was acidified and N-saturated, which was triggered by climatic anomalies (cold summer and drought summer) in the mid-1990s. Analysis shows that with a decline in NO3- concentrations, RW pH recovered to its original level in the early 2000s. Reductions in atmospheric deposition, diminished effects of climatic anomalies, and forest management practices, have all contributed to RW chemistry recovery. Although the SO42- concentration in the RW has declined continuously after the peak in 1994, the mean SO42- output significantly exceeded the input; the 5-year means from 2010 to 2014 are 2.5 kmol c ha −1 year −1 and 0.86 kmol c ha −1 year −1 , respectively. The mean δ 34 S values of SO42- in rainwater and soil solution at 20 cm depth were 4.3 ‰ and 3.5 ‰, respectively, and that in the RW was −13.2‰. The contributions of groundwater S to the RW S were estimated to range from 75 to 91%. Geological S with significantly low δ 34 S values largely contributed to the discrepancy of the input–output budget, while atmospheric S appeared to accumulate in soil as organic S. The tree-ring δ 34 S profile recorded historical changes in the atmospheric inputs in the region. With recovery of the RW, the relative contribution of atmospheric S became smaller. However, most of the atmospheric S is still retained in soil. Over the last few decades, RW chemistry has sensitively responded to changes in the atmospheric environment, including the atmospheric deposition of S and N and climatic anomalies, and as future changes are likely, long-term monitoring is essential.

DOI： 10.1007/s10533-019-00540-1

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その他リンク： 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 査読有り

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

FOREST ECOLOGY AND MANAGEMENT 431 巻頁： 44 - 53 2019年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Forest Ecology and Management

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 × DBH2 of P. thunbergii, were positively correlated with the critical turning moments. In particular, when P. thunbergii had the same H × 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 × 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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J-GLOBAL

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

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

Nematology 21 巻 ( 4 ) 頁： 389 - 400 2019年

Ground-penetrating radar estimates of tree root diameter and distribution under field conditions 査読有り

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

TREES-STRUCTURE AND FUNCTION 32 巻 ( 6 ) 頁： 1657 - 1668 2018年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Trees - Structure and Function

Key message: Use 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. Abstract: Ground-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 900 MHz 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 5 mm 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 (ΣT, 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 ΣT, 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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Scopus

Nematode communities in pine forests are shaped by environmental filtering of habitat conditions 査読有り

Kitagami Yudai, Tanikawa Toko, Mizoguchi Takeo, Matsuda Yosuke

JOURNAL OF FOREST RESEARCH 23 巻 ( 6 ) 頁： 346 - 353 2018年11月

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