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Abies sachalinensis and Picea glehnii are co-dominant tree species and major components of the forests of Hokkaido, Japan. Recent work suggests that a reversal in potential competitive superiority at different developmental stages could be important to explain their coexistence. Such shifts in competitive advantage can be mechanistically understood by studying the corresponding physiological differences between distinct life stages. Accordingly, our objective was to investigate in the field the photosynthesis of shade-growing juveniles of these species from two different size-classes, seedlings and saplings. Our results show that seedlings of both species had higher concentrations of photoprotective xanthophylls than saplings, especially in spring, and suggest that seedlings have a lower threshold of stress tolerance than saplings. Photosynthetic capacity per needle area and lateral shoot extension rate decreased from the seedling to the sapling stage in A. sachalinensis, while in P. glehnii, both increased from the seedling to the sapling stage. Abies sachalinensis had higher photosynthetic rates at the seedling stage but lower rates at the sapling stage than P. glehnii. Nevertheless, A. sachalinensis had a higher lateral shoot extension rate than P. glehnii at both stages. Our physiological results support previous ecological observations that A. sachalinensis is a superior competitor to P. glehnii in the understory, and show that its competitive advantage is higher at the seedling stage than at the sapling stage. [ABSTRACT FROM AUTHOR]

Windthrow is recognized as an extremely significant disturbance in many forests. Its effects are increased by stand fragmentation, which exposes the stand to strong winds. In this study, we investigated the change in tree mortality in fragmented stands with the distance from the stand edge, in a conifer-broadleaved mixed forest in northern Japan. We set out experimental plots having three stand sizes (400, 1,600, 6,400 m) and examined the stand dynamics over 10 years. Tree mortality tended to be higher in smaller stands, although an effect of stand size was found only in the first 5 years of the study. Distance-dependent individual mortality was obvious in Abies sachalinensis, the most vulnerable major tree species, again in the first 5 years, suggesting that wind-risk management should emphasize the area within ca. 20 m from the stand edge. No distant-dependent effect was found, however, in the latter 5 years, in which there was a strong typhoon; tree deaths occurred throughout the stand (irrespective of distance within) as a result of this event. We conclude that the severity of wind can cause the features of wind-induced damage to differ; stand edge effects peculiar to a small forest are unlikely to occur with particularly strong winds, and the effect of fragmentation might therefore be clear only in weaker disturbances. [ABSTRACT FROM AUTHOR]

We analysed the effects of Quercus crispula acorn abundance on the density dependence of the large Japanese wood mouse Apodemus speciosus using time series data (1992–2007). The data were obtained in a forest in northern Hokkaido, Japan, by live-trapping rodents and directly counting acorns on the ground. Acorn abundance in one year clearly influenced the abundance of wood mice in the following year in all models examined based on the Gompertz and Ricker model; in addition, the abundance of wood mice had effects on the population. Acorn abundance influenced the strength of density dependence (intraspecific competition) of the wood mouse population. When the abundance of acorns was high, density dependence was relaxed, and as a result the equilibrium density at which the population growth rate decreased to zero became higher. Those effects of acorn abundance were regarded as a nonlinear perturbation effect (sensu Royama ). The nonlinearity of density dependence was also detected; higher densities had stronger effects on population growth rates. [ABSTRACT FROM AUTHOR]

We analyzed effects of seed-hoarding by rodents on the variation in seed mass and seed success for a perennial forest undergrowth plant — Symplocarpus renifolius Schott ex Miquel — in Hokkaido, northern Japan. Although density of rodents differed greatly between seasons, more rodents were always captured in mesic Sasa sp. patches with dense foliage than in wet Lysichiton sp. patches. In the season with fewer rodents, they cached seeds close to the original places irrespective of vegetation, while in the season with abundant rodents, they transported seeds further and cached seeds disproportionately in Lysichiton patches. Seeds missed by rodents were larger than seeds that were eaten or that survived. Sasa patches are more suitable for seedlings to establish and a size advantage was observed there, but even small seeds could establish in Lysichiton patches, although seedling success was lower. We concluded that maternal plants of Symplocarpus renifolius increase their reproductive success by having small to middle-sized seeds transported to suitable sites while offering larger seeds as rewards to the transporters. Since the variation in seed mass was not correlated with the biomass per seed of the maternal plant, the large variation in seed mass is considered to have evolved through the density-dependent hoarding by rodents. [ABSTRACT FROM AUTHOR]

The effects of the abundance of acorns of the oak, Quercus crispula, on the population dynamics of three rodent species ( Apodemus speciosus, A. argenteus, and Clethrionomys rufocanus) were analyzed using time series data (1992–2006). The data were obtained in a forest in northern Hokkaido, Japan, by live trapping rodents and directly counting acorns on the ground. Apodemus speciosus generally increased in abundance following acorn masting. However, the clear effect of acorn abundance was not detected for the other two rodent species. Acorns of Q. crispula contain tannins, which potentially have detrimental effects on herbivores. Apodemus speciosus may reduce the damage caused by acorn tannins with tannin-binding salivary proteins and tannase-producing bacteria, whereas such physiological tolerance to tannins is not known in the other two rodent species. The differences in the effects of acorns between the three species may be due to differences in their physiological tolerance to tannins. [ABSTRACT FROM AUTHOR]

We investigated the changes in soil microbial biomass C (MBC), microbial biomass N (MBN) and N mineralization in Sasa kurilensis-present (SP) and S. kurilensis-removed (SR) stands in a Betula ermanii forest. The mean levels of MBC and MBN were significantly higher in the SR stand than in the SP, which may have positively influenced the N-mineralization rate as depicted by a significant positive correlation between these variables and the N-mineralization rate. N immobilization and subsequent N release along with decreased use of available soil N due to S. kurilensis removal may have ensured greater N availability in the SR stand. [ABSTRACT FROM AUTHOR]

• Background and Aims Serpentine soils are characterized by the presence of heavy metals (Ni and Cr) and excess Mg; these elements often suppress plant growth. Picea glehnii is nevertheless distributed widely on serpentine soils in northern Japan. Growth characteristics were compared among P. glehnii, Picea jezoensis (distributed in the same region) and Picea abies (planted for timber production), and concentrations of elements in various tissues over time and the amount of ectomycorrhizal infection in short roots were evaluated.• Methods Seedlings of three spruce species were planted in two types of experimental plots, comprising serpentine soil and brown forest (non-serpentine) soil, and these seedlings were grown for 3 years. Growth, ectomycorrhizal infection of short roots, and elemental composition of tissues were examined.• Key Results The total dry mass of P. glehnii planted on serpentine soil was almost the same as on brown forest soil, and a large number of needles survived to reach later age classes. By contrast, growth of P. jezoensis and P. abies in serpentine soil was significantly less than in brown forest soil, and needle shedding was accelerated. Moreover, roots of seedlings of P. glehnii on serpentine soil were highly infected with ectomycorrhiza, and the concentration of Ni in needles and roots of P. glehnii was the lowest of the three species.• ConclusionsPicea glehnii has a high ability to maintain a low concentration of Ni, and the ectomycorrhizal infection may have the positive effect of excluding Ni. As a result, P. glehnii is more tolerant than the other spruce species to serpentine soil conditions. [ABSTRACT FROM AUTHOR]

Unlabelled: Despite intravenous immunoglobulin therapy, a certain percentage of patients with Kawasaki disease (KD) still develop coronary arterial lesions (CAL). In an effort to find new combined therapies to reduce the incidence of CAL, we focused on the oedema which can be an important sign of the increased vascular permeability in KD. A total of 127 patients with KD were included in the retrospective study. Serial weekly changes in serum sodium and albumin levels from the 1st to the 4th week of illness were examined. In addition, the maximum rate of increase in body weight from admission to the 14th day of illness was evaluated. Serum sodium levels (mEq/l) in only the 2nd week of illness were significantly lower in patients with CAL than in those without CAL (mean +/- SD, 135.5+/-4.5 versus 138.0+/-2.4, P<0.05). Serum albumin levels in all 4 weeks were significantly lower in patients with CAL than in those without CAL ( P<0.001). The maximum rate (%) of increase in body weight from admission to the 14th day of illness was significantly higher in patients with CAL than in those without CAL (ranges and median values, 0-12.3 (7.0) versus 0-10.3 (3.2), P<0.001).Conclusion: these results suggest that water retention in the acute phase of Kawasaki disease may be a risk factor for CAL, and water intake of both infusion and oral intake should be kept to a minimum in order to avoid progressive oedema. [ABSTRACT FROM AUTHOR]

The effects of understory dwarf bamboo ( Sasa kurilensis) on soil water and the growth of overstory trees were studied in a dense secondary forest of Betula ermanii in northern Japan. Four plots were established in a Betula ermanii forest with Sasa kurilensis in the understory. The Sasa was removed in two of the plots. The annual increment of the trunk diameter for each tree was measured in the first two years from the commencement of the experiment. Soil water potential was similar in the plots following significant rainfall, but was found to be greater in the plot without Sasa between rainfall events. This suggests that the removal of Sasa slows the reduction of soil water after rainfall. The relative growth rate of the trunk diameter of Betula ermanii increased with tree size in all of the plots because taller trees strongly suppressed smaller ones in the dense forest. The growth rates of Betula ermanii were higher in the plots without Sasa. However, the difference in growth rates between all of the plots tended to be smaller in smaller size classes, possibly because smaller trees were strongly suppressed by larger ones, irrespective of the presence/absence of Sasa. Therefore, the removal of Sasa increased soil water and encouraged the growth of larger Betula ermanii in dense forest during the first two years after the Sasa was removed. The present study suggests that Sasa can reduce the growth of larger Betula ermanii in dense forest by limiting available soil water to these trees. [ABSTRACT FROM AUTHOR]

The stand structure and regeneration dynamics of trees >2.0 m in trunk height were studied during 1982–1998 in a 1 ha plot in a sub-boreal conifer–hardwood mixed forest, northern Japan, with a dense dwarf bamboo in the understory. Total density was low in 1982 (651 trees/ha), as compared with other forests in Japan. Quercus crispula was dominant in the upper canopy layer but their saplings were rare, while Acer mono, Acer japonicum and Abies sachalinensis were dominant in the sub-canopy and understory layers with many saplings. Mortality of each species was quite low during the census period (average 0.57% per year), and there was no clear difference among the four species. The age structure of Q. crispula was bell-shaped with a peak at ca. 200 years, while that of the other three species was weakly reverse-J-shaped or a rough plateau. In addition, no recruits growing over a height of 2 m were observed during the census period in Q. crispula, but many recruits of the other species were observed. These suggest that Q. crispula depended on episodic disturbances for the persistence of its population. Recruits of the three species except for Q. crispula did not concentrate in canopy gaps probably because of the dense dwarf bamboo cover there. They showed a negative spatial association with their own canopy trees, but a positive association with canopy trees of Q. crispula. Most of the crowns of the three species (A. sachalinensis and the two Acer spp.) were lower than that of overtopping Q. crispula. These spatial associations between recruits and canopy trees brought about the competitive effect of Q. crispula on the growth rates of other species and that of itself. However, the low mortality of trees taller than 2 m indicates that intra- and interspecific competition was not strong as a structuring force of the tree community. Our long-term study suggests that factors affecting recruitment (disturbances and dwarf bamboo in the forest floor) are more important for species coexistence than intra- and interspecific competition between trees taller than 2 m. [Copyright &y& Elsevier]

Summary 1 The gradient relations proposed by Wheeler & Proctor for NW European mires were tested for six Carex species common in north Japanese mires. Hydrochemical properties of their preferred habitats were compared with above-ground biomass data. 2 Canonical discriminant analysis showed that soil water pH was the strongest discriminant between habitats of the Carex species, with total dissolved nitrogen (TDN) concentration also contributing, independently of pH. 3 Two major patterns were apparent in the distribution of Carex species: pH determines a bimodal distribution into fens with pH > 5.0 and bogs with pH < 5.5, whilst TDN captures the variation in above-ground biomass within both fen and bog, but does not differ significantly between them. 4 Concentrations of Ca and Mg were low throughout the pH range. The floristic gradients associated with base richness seen in Euramerican mires do not therefore apply in north Japanese mires, where periodic flooding with neutral water removes the acid fractions in fens, and is the major determinant of pH. 5 Thus, pH is the best variable for distinguishing between fen and bog, as the poor fen-rich fen classification is inappropriate for non-calcareous north Japanese mires. [ABSTRACT FROM AUTHOR]

Spatial patterns of the oxidation–reduction potential (Eh) of soil, water level and chemistry were examined in the fen area of the Tohfutsu mire, northern Japan, where horse pasturage has been carried out throughout the growing season every year. The fen vegetation consisted mosaically of communities mono- or codominated by Eleocharis kamtschatica, Iris setosa and Carex lyngbyei . The highest concentration of total dissolved nitrogen of soil water was observed in the dwarf community dominated by E. kamtschatica with smaller biomass, whereas the nutrient level was lower in the community monodominated by C. lyngbyei with larger biomass. Principal component analysis denoted well that Eh, N, K, and pH contributed to the differentiation of these communities significantly. During the growing season that was investigated, the highest nitrogen concentration was observed in midsummer, when plants are expected to absorb nutrients intensely, indicating that the supply of dissolved nitrogen far exceeded the nutrient uptake of plants. Multiple habitats with reduced soil were formed by submergence and by an excess of nitrogen due to pasturage, and the soil reduction indirectly inhibited the incursion of species with large biomass at such sites. It was demonstrated that soil Eh contributed to the anomalous pattern of vegetation where the supply of available nitrogen exceeds the uptake by plants. [ABSTRACT FROM AUTHOR]

Regional variation in size and shape of Sphagnum hummocks of eight lowland mires throughout Hokkaido Island, northern Japan, was examined in relation to climatic factors. The size and shape of hummocks significantly differed among the regions: low and flat hummocks occurred in the northern region and next to the Sea of Japan; moderately raised and conical hummocks occurred in the western part of the Pacific coast; and extremely raised and cylindrical hummocks occurred in the eastern region. Multiple regression analysis revealed that the mean and maximum heights and height/basal area of hummocks were negatively correlated with evapotranspiration rate (E[sub 0] ) in summer, duration of sunshine, and air temperature. Of these, evapotranspiration rate in summer positively correlated with radiation and thermal factors. Mean height of hummocks within a mire was increased with precipitation during the growing season. Because the regional difference of the hummock form was not related to the difference in nutrient conditions, the effects of evapotranspiration and precipitation prevailed over edaphic conditions. Higher E[sub 0] in summer was considered to cause water stress for hummock species in the northern region and next to the Sea of Japan, whereas heavy rainfall relieved it in the western region of the Pacific coast. Consequently, lower and flat hummocks were a result of the higher E[sub 0] in summer, moderately raised and conical hummocks of the medium E[sub 0] and high precipitation, and extremely raised and cylindrical hummocks of a lower E[sub 0] due to prolonged foggy days.Key words: evapotranspiration, duration of sunshine, minerotrophy, ombrotrophy, precipitation.Les auteurs ont examiné l'effet du climat sur la variation régionale de la dimension et de la forme des hummocks à Sphagnum, sur huit sites de tourbières basses, dans l'ensemble de l'île d'Hokkaido, au nord du Japon. La dimension et la forme des hummocks diffèrent significativement selon les régions : on retrouve des hummocks bas et plats dans les régions nordiques et près de la mer du Japon; des hummocks modérément élevés ou coniques dans la partie ouest de la côte du Pacifique; et des hummocks très élevés et cylindriques vers l'est. L'analyse par régressions multiples révèle que les hauteurs moyennes et maximum, ainsi que les hauteurs/les surfaces basales des hummocks sont négativement corrélées avec le taux d'évapotranspiration (E[sub 0] ) estival, la durée d'ensoleillement, et la température de l'air. Parmi ceux-ci, le taux d'évaporation estival montre une corrélation positive avec la radiation et les facteurs thermiques. La hauteur moyenne des hummocks, dans une tourbière donnée, augmente avec les précipitations au cours de la saison de croissance. Parce que la différence régionale des formes des hummocks n'est pas reliée à la différence dans les conditions trophique, les effets de l'évapotranspiration et de la précipitation prévalent sur les conditions édaphiques. On considère qu'une E[sub 0] plus élevée augmente le stress hydrique sur les espèces des régions nordiques et près de la mer du Japon, alors que la précipitation élevée le diminue dans la région occidentale de la côte du Pacifique. Conséquemment, les hummocks bas et plats résultent d'une E[sub 0] estivale plus élevée, les hummocks modérément élevés et coniques d'une E[sub 0] moyenne et de fortes précipitations, et les hummocks extrêmement élevés et cylindriques d'une E[sub 0] plus faible due à une prévalence de jours brumeux.Mots clés : évapotranspiration, durée d'ensoleillement, minérotrophie, ombrotrophie, précipitation.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The relationship between water chemistry and vegetation was studied in a coastal ombrotrophic mire in northern Hokkaido, Japan. The distributions of Sphagnum and Phragmites communities were separated clearly by the pH and ion concentration of the peat surface-pore water. The drainage ditches along the road across the center of the mire had a high pH and ion concentration, as did the peat water in the western part of the mire. It was found that fields used for livestock farming on a hill to the west of the mire leached materials into the mire through drainage ditches, surface runoff, and probably also through ground water, and thus influenced the water chemistry of the mire. Management of the water, including that in the catchment of the mire, should be introduced before biological buffering capacity against excess nutrient loading caused by human activity is exceeded and the mire loses its ombrotrophic status. [ABSTRACT FROM AUTHOR]

Describes several Japanese patients who developed neoplasms after the onset of Kawasaki disease. Details of the medical history of the patients; Development of lymphoid malignancies in several cases; Summary of patients with neoplasms after the onset of Kawasaki disease.

Diagnostic guidelines for Kawasaki Disease was revised to meet the present situation in 2002. This issue intends to explain new guidelines and their backgrounds. Major alterations are interpretation of cases with 4 or fewer febrile days shortened by early intravenous immunoglobulin treatment, and the clinical importance of atypical (incomplete, or suspected) cases. [ABSTRACT FROM AUTHOR]

Abstract: In a Japanese forest, CH4 uptake rate and methanotrophic community structure in the soil were investigated at four sites of different vegetation. At two of these sites, undergrowth was dominated by Sasa senanensis, and that of another was dominated by Sasa kurilensis. At the rest site, undergrowth had been removed artificially. The tree-layer composition differed between the two sites with S. senanensis, but tree layer of the other two sites were dominated by the same species. At the site lacking undergrowth, observed CH4 uptake rate was twice as high as that at the other sites. Under laboratory conditions, soil sample from the site lacking undergrowth exhibited CH4 consumption rate higher than that of the adjacent site with the same dominating tree species. The community structures of methanotrophs were investigated with denaturing gradient gel electrophoresis (DGGE) of the gene encoding particulate methane monooxygenase (pmoA). The banding patterns observed were different depending on the type of undergrowth vegetation. The sequences of the DGGE bands were closely related to each other and belonged to the “upland soil cluster alpha” (USCα). These results imply possible close relationship between the undergrowth vegetation and methanotrophic communities in forest soils. [Copyright &y& Elsevier]

Knowledge of long-term spatiotemporal effects of disturbances on forest structure, tree regeneration and species composition is key for understanding forest dynamics and predicting future forest responses to climate change. Here, we explore the spatiotemporal impact of disturbances of different severities on tree recruitment and diversity in species-rich oak-fir-maple forest in Hokkaido, a typhoon-prone area in northern Japan, over the past 230 years. The forest disturbance history was reconstructed by growth-release analysis from more than 45,500 tree rings of 385 trees belonging to 15 species. A mixed severity disturbance regime was prevalent over the study period. Altogether, 310 major and 293 moderate growth releases were identified. These were both temporally and spatially localized, with 80% of events detected in only four time periods: 1775–1784, 1815–1839, 1880–1909 and 1950–1979. Disturbances were followed by major recruitment pulses, each lasting around 30 years. Dendrochronological reconstructions alone indicate that severe (i.e. high proportion of releases), infrequent disturbances control tree regeneration and forest development (from oak-dominated forests to mixed-stand with higher proportion of shade-tolerant tree species). However, a combination of temporal and spatial pattern analysis revealed that less severe disturbances, creating small gaps, promote higher density and diversity of recruitment (altogether 19 tree species recorded) compared with severe disturbances. The latter create large forest gaps which became overgrown by dwarf bamboo and suppress tree regeneration. These results provide evidence that severe disturbances interacting with a strong biotic understory filter (as dwarf bamboo), can disrupt forest ecosystem dynamics by significantly reducing the extent and diversity of tree recruitment. Our findings are important as most climate models predict an elevated intensity of typhoons in Northeast Asia. We conclude that a combination of temporal and spatial analyses, as presented here, is necessary to disentangle the complex drivers of long-term forest dynamics. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether reduced levels of plasma platelet-activating factor acetylhydrolase (PAF-AH) as a result of a genetic polymorphism are involved in the pathogenesis of Kawasaki disease (KD)., Study Design: The frequency of a V279F polymorphism (G/T transversion) in the PAF-AH gene was quantified in 76 Japanese children with KD and 112 healthy Japanese adults using the allele-specific polymerase chain reaction (PCR). Associations between genotype, clinical features, and resistance to intravenous immunoglobulin (IVIG) were investigated in the patients with KD. Plasma PAF-AH activity was measured by using [3H]-acetyl-PAF., Results: There were no significant differences in genotype frequency between patients and controls (P = .51). Compared with the GG (normal genotype) group, significantly more patients in the GT (heterozygous) +TT (homozygous deficient) group required additional IVIG (52% vs 14%, P = .001). The duration of fever and maximum serum C-reactive protein (CRP) levels also were significantly increased in the GT+TT group (P = .012 and .036, respectively), whereas plasma PAF-AH activity was significantly lower (P <.0001)., Conclusion: We conclude that the V279F polymorphism in the plasma PAF-AH gene and consequent enzymatic deficiency is one of the factors for IVIG nonresponse in Japanese patients with acute KD.