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61.
Salt distribution in response to optical stratification porosity and relative windspeed in a coastal forest in Niigata, Japan 总被引:3,自引:0,他引:3
Wind velocity, vertical stand structure and seasalt distribution were measured at various heights inside a plantation of coastal pine forest, with thinning and unthinning, to assess whether any relationships exist between the wind profile, stand structure and seasalt distribution in the coastal pine forest. The vertical stand structure, i.e., optical stratification porosity (OSP), which is defined as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, was determined for each height by computer analysis of digital images taken with a hemispherical lens. The distribution of OSP in the coastal forest follows the Lambert-Beer's law with absorbency coefficient (). The relative windspeed within canopy can be described using the exponential form with the attenuation coefficient (). The sea-salt was collected using salt gauze (a surgical dressing of loosely woven cotton) both inside and outside the coastal forest, and the distribution of sea-salt within canopy was also in accordance with an exponential function. The relationships among windspeed, OSP and sea-salt indicate that the distributions of both sea-salt and windspeed within canopy were very closely correlated with the distribution of OSP. A linear relationship between OSP and sea-salt has been found. Additionally, linear regression between coefficients and has been obtained as well. Based on these relationships between OSP, wind and sea-salt in the coastal forest, the sea-salt distribution and wind profile within the canopy of the coastal forest can be predicted according to OSP. These results may therefore be useful in analyzing the effects of sea-salt on vegetation and evaluating the filter functions of coastal forests.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
62.
Makoto Kiguchi Yutaka Kataoka Hiroshi Matsunaga Koichi Yamamoto Philip D. Evans 《Journal of Wood Science》2007,53(3):234-238
The market for wood-fiber plastic composites (WPCs) is expanding rapidly in many countries including Japan, where WPCs are
mainly used for exterior products. In such applications, WPCs undergo undesirable color change, chalking, and shrinkage and
swelling, and accordingly there is a need to better understand the mechanisms responsible for the weathering of WPC and develop
methods of improving their weathering resistance. In this study, weatherability of WPC was assessed by natural and accelerated
weathering trials. Discoloration (whitening) of WPC during exposure was caused by degradation of both wood and plastic. Darker
color pigments as additives improved the color stability of WPC; however, chalking on the surfaces still occurred. The color
stability of WPC was improved by application of exterior coatings. Preweathering of WPC (before coatings were applied) increased
the absorption of coatings by the WPC and had a positive effect on the color stability and prevented chalking of the composites.
Parts of this study were presented at the IUFRO XXII World Congress Meeting, Brisbane, August 2005 and the IAWPS 2005, Yokohama,
November 2005 相似文献
63.
Takahisa Nakai Hiroyuki Yamamoto Tetsuya Nakao Masatoshi Hamatake 《Wood Science and Technology》2006,40(8):683-695
This study investigated the relationship between the cellulose crystal lattice strain (crystalline region) and the macroscopic surface strain in specimens of Chamaecyparis
obtusa wood under repeated uniaxial tension stress in the fiber direction. Changes in the strain of the crystal lattice were measured from the peak of (004) reflection using the transit X-ray method. The macroscopic surface strain of each specimen was measured with a strain gauge. In both loading and unloading, the surface strain changed linearly with changes in stress. However, crystal lattice strain was not linear but exhibited changes along a curve with changing stress. Under stressed conditions, the crystal lattice strain was always less than the surface strain, regardless of the frequency of repetition in the loading and unloading cycle. The ratio of the crystal lattice strain to the surface strain showed a negative correlation for stress in both loading and unloading. That is, the ratio decreased with increasing stress, and finally tend to converge to a specific value. The ratio (I/I
0) between the diffracted intensity (I
0) in the (004) plane in the unloaded condition and the diffracted intensity (I) in the (004) plane in the loaded condition tend to converge on a specific value with increasing frequency of repetition. When the substantial tension Young’s modulus of the wood in the longitudinal direction decreased, the ratio of the strain of the crystal lattice to the surface strain also decreased. Moreover, the ratio decreased with increasing microfibril angle of the specimen. 相似文献
64.
Tomoaki Takahashi Kazukiyo Yamamoto Yoshimichi Senda Masashi Tsuzuku 《Journal of Forest Research》2005,10(4):305-312
This study investigated which predictor variables with respect to crown properties, derived from small-footprint airborne light detection and ranging (LiDAR) data, together with LiDAR-derived tree height, could be useful in regression models to predict individual stem volumes. Comparisons were also made of the sum of predicted stem volumes for LiDAR-detected trees using the best regression model with field-measured total stem volumes for all trees within stands. The study area was a 48-year-old sugi (Cryptomeria japonica D. Don) plantation in mountainous forest. The topographies of the three stands with different stand characteristics analyzed in this study were steep slope (mean slope ± SD; 37.6° ± 5.8°), gentle slope (15.6° ± 3.7°), and gentle yet rough terrain (16.8° ± 7.8°). In the regression analysis, field-measured stem volumes were regressed against each of the six LiDAR-derived predictor variables with respect to crown properties, such as crown area, volume, and form, together with LiDAR-derived tree height. The model with sunny crown mantle volume (SCV) had the smallest standard error of the estimate obtained from the regression model in each stand. The standard errors (m3) were 0.144, 0.171, and 0.181, corresponding to 23.9%, 21.0%, and 20.6% of the average field-measured stem volume for detected trees in each of these stands, respectively. Furthermore, the sum of the individual stem volumes, predicted by regression models with SCV for the detected trees, occupied 83%–91% of field-measured total stem volumes within each stand, although 69%–86% of the total number of trees were correctly detected by a segmentation procedure using LiDAR data. 相似文献
65.
Takuyuki Yoshioka Kazuhiro Aruga Toshio Nitami Hiroshi Kobayashi Hideo Sakai 《Journal of Forest Research》2005,10(2):125-134
Using the method of a life cycle inventory (LCI) analysis, the energy balance and the carbon dioxide (CO2) emission of logging residues from Japanese conventional forestry as alternative energy resources were analyzed over the entire life cycle of the residues. The fuel consumption for forestry machines was measured in field experiments for harvesting and transporting logging residues at forestry operating sites in Japan. In addition, a total audit of energy consumption was undertaken. It involved an assessment of materials, construction, and the repair and maintenance of forestry machines as well as the costs associated with an energy-conversion plant. As a result, the ratio of energy output to input was calculated to be 5.69, indicating that the system examined in this study could be feasible as an energy production system. The CO2 emission per MWhe (e: electricity) of the biomass-fired power generation plant was calculated to be 61.8kgCO2/MWhe, while that of coal-fired power generation plants in Japan is 960kgCO2/MWhe. Therefore, the reduction in the amount of CO2 emission that would result from replacing coal with biomass for power generation by as much as 3.0 million dry-t/year of logging residues in Japan was estimated to be 1.66 million tCO2/year, corresponding to 0.142% of the national CO2 emission. This study provides evidence that Japan could reduce its domestic CO2 emission by using logging residues as alternative energy resources. 相似文献
66.
Based on paper of “Theoretical derivation of risk-ratios for assessing wind damage in coastal forest“,wind damage in the pine coasteal forest,which was thinned at four levels in December of 1997,was investigated for four successive growing seasons.Besides wind damage,the wind profiles outside and inside the coastal forest stand and the distributions of optical stratification porosity (OSP) were also observed.Based on these data,risk-ratios of wind damage for both individual trees and stands were estimated according to the methods developed in “Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest“.The results showed that risk-ratios of wind damage,which were calculated from the meen height and diameter only and from the combination of wind and stand sructure profiles,accurately predicted wind damage in the plantation.Relationships between different thinning ratios and incidence of wind damage showed that stand stability decreased soon after the thinning.This was due to the immediate effects of thinning on increasing the canopy roughness and wind load,and on decreasing the sheltering effects from surrounding trees.However,thinning strategies could improve the stability by long-term effects on growthand development of trees against extreme wind.Only canopy damage was recorded during the experimental period,no stem damage was found,even though the maximum 10-min wind speed outside the coastal forest attained 30.2m s^-1.The results obtained in this study indicate that thinning is the most effective silvicultural strategy available for managing coastal forest despite the increased probability of wind damage soon after thinning. 相似文献
67.
68.
Sujan KC Yamamoto Hiroyuki Matsuo Miyuki Yoshida Masato Naito Kazuhiro Shirai Tatsuya 《Wood Science and Technology》2015,49(6):1157-1169
Wood Science and Technology - Tension wood, when kiln-dried, is likely to deform hugely, which is probably caused by a gelatinous layer of the gelatinous fiber. To elucidate the mechanism behind... 相似文献
69.
Kazuyuki SUZUKI Toshio SHIMAMORI Ayano SATO Kenji TSUKANO Masakazu TSUCHIYA Jeffrey LAKRITZ 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(8):977-979
The aim of the present study was to compare the ability of the commercially available portable test system (PTSTM) to detect endotoxin activity in bovine serum, with that of the traditional LAL-kinetic turbidimetric (KT) and chromogenic (KC) assays. Prior to testing, serum samples, which were obtained from endotoxin-challenged cattle, were diluted 1:20 in endotoxin-free water and heated to 80°C for 10 min. The performance of the PTSTM was not significantly different from that of the traditional LAL-based assays. The results using PTSTM correlated with those using KT (r2=0.963, P<0.001) or KC assays (r2=0.982, P<0.001). Based on these findings, the PTSTM could be applied as a simplified system to assess endotoxin activity in bovine serum. 相似文献
70.
Viskam WIJEWARDANA Kikuya SUGIURA Daluthgamage Patsy H. WIJESEKERA Shingo HATOYA Toshiya NISHIMURA Ryoji KANEGI Takahiro USHIGUSA Toshio INABA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(7):771-775
Previously, we reported that ovarian hormones affect the immune response against
E. coli isolated from the dogs affected with pyometra. In order to
investigate mechanisms underlying the immune modulation, we examined the effects of
ovarian hormones on the generation of dendritic cells (DCs), the most potent antigen
presenting cell. DCs were differentiated from peripheral blood monocytes (PBMOs) using a
cytokine cocktail. Both estrogen receptor and progesterone receptors were expressed by the
PBMOs and immature DCs. When various ovarian hormones were added to the culture for the DC
differentiation, progesterone significantly decreased the expression of DC maturation
markers, such as CD1a, CD80 and CD86, on mature DCs. Conversely, the addition of estrogen
to the cultures increased the expression of CD86, but not other maturation makers.
Furthermore, DCs differentiated in the presence of progesterone did not stimulate
allogeneic mononuclear cells in PB. Taken together, these results indicate that
progesterone diminishes the maturation of DCs, leading to decreased immune responses
against invading pathogens. 相似文献