Intake of Radionuclides in the Trees of Fukushima Forests 5. Earthquake Could Have Caused an Increase in Xyloglucan in Trees

A megathrust earthquake caused the Fukushima–Daiichi nuclear power plant accident, which dispersed abundant radioiodines, causing them to be bound to xyloglucan into forest trees. Nevertheless, targeted xyloglucan was found in increased quantities in the annual rings of forest trees affected by the earthquake. We propose that trees could acclimate rapidly to shaking stress through an increase in xyloglucan deposition as a plant response under natural phenomena

ジュモク ネンリン ネンダイガク テキ シュホウ ヲ モチイタ ニホンジカ ニ ヨル ツノコスリ ショウガイ ハッセイネン ノ トクテイ ―オクタマ エンシュウリン ニ セイイク スル カラマツ ニ ツイテ―

東京都西多摩郡奥多摩町に位置する東京農業大学奥多摩演習林内のカラマツ（Larix kaempferi）人工林において樹幹にニホンジカ（Cervus nippon）の角こすりによる傷痕が確認される個体が多数確認された。近年，木材としての需要が増えているカラマツ材内部への被害状況を把握することは木材生産をする上で重要である。そこで本研究では，演習林内のカラマツ人工林（2林分）の全木を調査対象として，その傷痕の有無を確認した。さらに，材内部に残された傷害組織をもとに樹木年輪年代学的手法を用いて傷害発生年を特定した。調査を行なった650個体の内190個体に角こすりによる傷痕が確認された。98個体の傷痕から成長錐を用いてコア試料を採取した。採取した試料の中には木部が脆くなっており傷害発生年を特定することが困難なものがあったが，74個体104カ所の傷痕について傷害発生年が特定できた。傷害を受けた個体は1970年代から確認できたが，1980年代に入ると増加し，1990年代で最も多かった。それは2000年以降減少するが，現在まで一定個体数で確認され続けていることがわかった。そして，その推移は奥多摩地域の森林被害に関する報告と関連していることが示唆された。Planted stands of Japanese larch (Larix kaempferi) in the Tokyo University of Agriculture Okutama Practice Forest, located in Okutama, Tokyo, contain numerous trees with fraying scars on their trunks caused by sika deer (Cervus nippon). Given the recent increase in demand for larch as lumber, it is necessary to assess the impact of fraying damage on larch wood and the frequency and change over time in occurrence of such damage. In this study, we investigated the presence or absence of fraying scars caused by sika deer on all trees in two planted larch stands in the Okutama Practice Forest. In addition, we attempted to elucidate the trend over time in fraying damage incidence in the study area by assessing the year of annual tree rings containing scares by dendrochronological method. The results showed that fraying scars were observed in 190 of the 650 trees examined (29% examined trees). Core samples were collected from 98 of these scarred trees. Although scars could not be distinguished or were difficult to distinguish in the xylem of some samples due to rot, we were able to perform measurements for 74 trees (104 scars). Larch trees with scars were found dating back to the 1970s. The number of trees with scars increased in the 1980s and reached a peak in the 1990s. Although the number has since declined, at present, new scarring continues to appear at an essentially constant rate. The observed trend was consistent with trends reported in other studies on forest damage caused by sika deer in the Okutama area

タンバンチュウ ノ ウラワレ ノ ハッセイ ヲ ソウテイ シタ モクザイチュウ ノ キレツデンパ ノ サイボウレベル デノ カンサツ

単板切削において単板に生ずる裏割れは単板の品質に,また単板をエレメントとする合板の品質に大きく影響を及ぼす。裏割れの発生は切削に伴って工具刃先近傍に発生する諸切削応力のうち,主として引張応力に起因することが明らかになっている。単板内での裏割れの発生および成長過程を細胞レベルにおいて検証するべく,小さい試験片(厚さ2.5mm)の曲げ試験を実施した。試験片の引張側に亀裂を事前に施し,負荷に伴う亀裂の伝播を細胞の変形および破壊挙動を観察した。また,二次元切削を実施し,得られた切屑の横断面(木口面)で確認できる裏割れの微視的観察を行い,曲げ試験による亀裂の伝播状況と比較した。In veneer production, lathe checks created during the cutting process affect the veneer qualities. Previous studies have clarified that lathe checks are generated due to tensile stress in bending at the rake face of the knife. To compare lathe checks propagated inside veneers in orthogonal cutting, small thin wood specimens with minute cracks inserted beforehand on the tension side were bended. Deformation and fracture of the wood structures due to propagation of the cracks were observed continuously through a digital microscope at the cellular level. The modes of crack propagation on early wood and late wood of Japanese cedar, sugi, (Cryptomeria japonica D. Don) were differed due to the difference in hardness between early wood and late wood, and classified into three patterns in early wood and twos in late wood according to the anatomy of the wood. The results obtained in this study were as follows ; 1) Crack propagation in early wood showed any one or a combination of the following characteristics in both the radial and tangential directions : (1) Propagation by separation between cells ; (2) propagation by partial splitting of cell walls ; and (3) propagation by rupture of cell walls. 2) Crack propagation in the radial direction in late wood almost always proceeded by separation between cells. This was also true in the tangential direction, but in rare cases, cracks propagate by the rupture of cell walls. 3) The mode of crack propagation differed with propagation direction. 4) The development of lathe checks in orthogonal cutting of wood perpendicular to grain, lathe checks developed chips inside from the loose side of the chips almost same modes as crack propagation observed in fundamental bending tests

Tsunami in a Canal of Varying Width

本報告において,筆者は桃井の方法を巾の変る水路に適用し,次の結論を導いた.巾の広い方から津波が押し寄せてくる場合,巾の広い方への反射波および巾の狭い方への進行波の第零次モードはそれぞれ,(I.12)の前式および後式によつて与えられる.この零次モードはkd(但し,kは進入波の波数,dは水路の巾とす)の第一次近似の範囲で出された式であり,水路の高次のモード(零次モードを除いた)の計算をkdの一次の範囲に限れば,巾の広い水路へ反射する高次モードの波は(I.21)で与えられる.更に進んで巾の狭い水路への高次モード波の位数評価をおこなうと,それはkdの二次の位数であることがわかる.上に述べた高次のモードに対する考察は,長波近似で,kdが1より十分に小さいという曖昧な仮定に基いているために,単にorderを評価し,定性的な議論をおこなうにとどまつている

27. A Long Wave in the Vicinity of an Estuary [4]

The RD (reflected and diffracted) wave around the estuary is elucidated for kd (k: the wave number of the incident wave, d: the half width of the canal) in the range 0.01 to 1.2, and the comparison of our and other authors'theories is also made.|本報告においては河口近傍でのRD(反射回折)波について,kd(k:入射波の波数,d:水路の巾の半分の長さ)が0.01より1.2までの範囲について論じられている.又筆者の理論と他の理論との比較がなされている

31. A Long Wave in the Vicinity of an Estuary[II] : An Analysis by the Method of the Buffer Domain

Succeeding the previous study on long waves in the vicinity of an estuary, the theory is developed, in this paper, under the second approximation to inquire numerically into the behaviors of the waves around an estuary. When the approximation proceeds from the first to the second one, the minute behaviors of the waves come to light, which do not appear in the first approximation. The newly exposed facts are as follows:- High waves appear in the interior of the canal, which is due to the diffraction of the waves in the estuary. The way in which the incident waves invade the canal is such that the waves first advance towards the center of the mouth of the canal from the open sea(of which the crest line is a triangular form) and then, as they progress, they are diverted to the direction of the axis of the canal. The damping reflected waves in the open sea are not so much affected, when the approximation is generalized from the first to the second one, expecting that the directivity of the damping reflected waves is smoothed. In developing the theory, a basic principle is based on themethod of the buffer domain which has been introduced by the author.筆者はすでに河口近傍における長波に関する研究をベッセル函数の線型近似の範囲でおこなつた.そしてその近似を第2次近似まで上げて解析をおこなつた結果をまとめたのが今回の報告である.その結果,第1近似ではわからなかつた河口近傍の波の細かい変化が判明してきた.新しくわかつたことは次のようなことである

The Polarization of Waves in an Anisotropic Nonlinear-Elastic Medium

In an anisotropic linear-elastic medium, polarization of waves due to anisotropy of the medium is known to occur. In a way similar to phenomena in an anisotropic linear-elastic medium, polarization of waves takes place even in an anisotropic nonlinear-elastic medium. Polarized waves in a nonlinear-elastic medium are also soliton-like or step-shaped waves named simple waves. In an isotropic nonlinear-elastic medium, the simple waves are separated into two categories, non-coupled and coupled simple waves. The former are dilatational waves, while the latter are coupled waves with dilatational (u-component) and distorsional (v- and w-components) properties, where u and {v, w} are longitudinal and transverse components, respectively. In the case of anisotropic nonlinear-elastic medium, two kinds of simple waves mentioned above also appear with some modification due to the presence of anisotropy. The secondary waves produced by anisotropy are exact simple waves instead of only disturbance-type waves. Equations are numerically evaluated by use of an extended finite difference method expanded in a Taylor series. The wave source then has the form of a mountain ridge with a width -4<hx<4, where hx is a distance x normalized by wave number h of P waves in the linear theory.線形の異方性媒質におけると同様に非線形異方性媒質においてもまた波の偏光がみられる.非線形等方性媒質において単純波(Simple waves)は二つの部類に分けられる,すなわち非結合単純波(Noncoupled simple waves)および結合単純波(Coupled simple waves)である.前者は伸縮波(u成分)で後者はねじれ波(v,w成分)である

Implication of a Surface Wave Orbit with Stability, Drift and Azimuthal Distribution of Waves in Weakly Anisotropic Media

The anisotropy of elastic media, in general, causes drift and uneven distribution of waves in the azimuthal direction. Surface waves in weakly anisotropic media are discussed, focusing attention on the implication of a wave orbit on a transverse plane with drift of waves and azimuthal distribution of wave amplitude. When waves drift rightward(leftward), the orbit tilts leftward(rightward), where the term rightward(leftward) is used in the advancing direction of waves. Under the assumption that uneven distribution of waves in the azimuthal direction is caused only by the anisotropy of media, we find that a surface wave orbit on a transverse plane at the surface tilts rightward(leftward) when the wave amplitude increases(decreases) rightward. It is noted that the above-mentioned drift and uneven distribution of surface waves in the azimuthal direction in anisotropic media can be fundamentally explained by use of the solution of the characteristic equation obtained from stress-free surface conditions.一般に,異方性媒質において表面波は媒質の異方性のために,漂流現象やその進行彼の横(方位角)方向に振幅の不均質な空間分布を引き起こす.本論文では弱い異方性媒質において,波の進行方向と垂直な平面に投影された表面波の軌道の傾きと波の漂流現象および方位角方向の波の空間分布との間の関係が論じられている.つぎのような結論が得られている

Wave Propagation in Nonlinear-elastic Isotropic Media : Two-Dimensional Case

Wave propagation in the nonlinear-elastic isotropic media was analyzed in a two-dimensional case. In the analysis, governing equations take into account both the physical nonlinearity caused by the stress-strain relation and the geometric nonlinearity resulting from the quadratic strain-displacement relation. The equations obtained are numerically evaluated by use of the extended finite difference method expanded in Taylor series. The wave sources have a form of mountain ridge with a width -2<hx<2, where hx is a distance x normalized by wave number h of P waves in the linear theory. The waves generated are then aperiodic. Only soliton-like or step-shaped simple waves (after gas-dynamics) are found numerically. Existence of these waves are also confirmed analytically by use of the second order theory. Unlike the linear theory, the velocity of the simple waves in the nonlinear theory is not exactly the same as that of P or S waves in the linear theory relying on the elastic media. Advancing speed of the waves depends on the gradient of the front simple wave. In simple waves with large amplitude, the u component (in the direction of the propagation) is more remarkably dispersed than the transverse component. This phenomenon is likely to be observed at a great distance as the P wave dispersion instead of simple wave dispersion.非線形等方性矧生体において,エネルギー関数,非線形歪-応力テンソル,非線形歪テンソルを用い,変位微分の三次項まで含む非線形動的方程式(Nonlinear dynamic equation)が導入された

An Example of Application of the General Method of Treating Water Waves Produced by a Vibrating Bottom with an Arbitrary Form

筆者は前に任意の形をした底によつておこされる水波を取り扱う一般的方法を導入した.本論文では,筆者はこの方法を正方形の底が,一様な振巾をもつて振動する場合に適用して見た.その結果次のような結論を得た.すなわち,(1)発生するWater Waveは,正方形の辺に垂直な方向で一般に波高は大きく,正方形の対角線方向では,波高は小さい.(2)そして,また,正方形の辺に垂直な方向と対角線方向のWaveのphase差は,正方形の対角線の長さが大きくなるにつれて大となつてくる