bluuebunny/crossref_metadata_2025_split huggingface dataset:
Holocene sedimentary history of some coastal plains in Hokkaido, Japan IV. Diatom assemblages in the sediments from Kushiro moor (2)
Authors: Kumano Shigeru , Ihira Masashi , Maeda Yasuo , Yamauchi Misako , Matsumoto Eiji , Matsuda Isao 
Published: March 2006

AbstractDiatom assemblages of sediments obtained from three sites on Kushiro Moor were analyzed to investigate the Holocene sedimentary history. The results showed that: 1) The Takkobu site was originally at the bottom of the paleo‐Kushiro Bay, and after‐wards the paleo‐Takkobu Lagoon developed, became sealed off, and changed to a freshwater lake. The succession to peat moor probably began about 2000 yr B.P. at the Takkobu site. 2) The Tsurui site was originally at the bottom of the paleo‐Kushiro Bay, then changed to the paleo‐Kushiro Lagoon and became peat moor as a result of the first Holocene regression, which finished about 3600 yr B.P. The site then returned to a brackish lake again, probably due to the second Holocene transgression between 3600 and 3000 yr B.P., thereafter passing through brackish lake and freshwater lake stages, and eventually becaming peat moor at about 2000 yr B.P., 3) At the Chuo site, the second paleo‐Kushiro Bay developed again as a result of the second Holocene transgression, which finished about 3000 yr B.P. Thereafter, brackish or freshwater lakes, rivers, and then peat moor developed in the central area of Kushiro Moor. 4) The second marine diatom zone (MD2Zone), which indicates the second Holocene transgression, complete by about 3000 yr B.P., is detected only at the Chuo site in the central area of Kushiro Moor.
Effects of water level fluctuation on the growth of Nelumbo nucifera Gaertn. in Lake Kasumigaura, Japan
Authors: Nohara Seiichi , Tsuchiya Takayoshi 
Published: March 2006

AbstractInvestigations were made of the growth of Nelumbo nucifera, an aquatic higher plant, in a natural stand in Lake Kasumigaura. A rise of 1.0 m in the water level after a typhoon in August 1986 caused a subsequent decrease in biomass of N. nucifera from the maximum of 291 g d.w. m−2 in July to a minimum of 75 g d.w. m−2. The biomass recovered thereafter in shallower regions. The underground biomass in October tended to increase toward the shore. The total leaf area index (LAI) is the sum of LAI of floating leaves and emergent leaves. The maximum total LAI was 1.3 and 2.8 m2 m−2 in 1986 and 1987, respectively. LAI of floating leaves did not exceed 1 m2 m−2. The elongation rates of the petiole of floating and emergent leaves just after unrolling were 2.6 and 3.4 cm day−1, respectively. The sudden rise in water level (25 cm day−1) after the typhoon in August 1986 caused drowning and subsequent decomposition of the mature leaves. Only the young leaves were able to elongate, allowing their laminae to reach the water surface. The fluctuation in water level, characterized by the amplitude and duration of flooding and the time of flooding in the life cycle, is an important factor determining the growth and survival of N. nucifera in Lake Kasumigaura.
Photosynthesis and respiration of Pinus pumila needles in relation to needle age and season
Authors: Kajimoto Takuya 
Published: March 2006

AbstractRates of net photosynthesis and dark respiration were measured for detached needles of Pinus pumila trees growing on the Kiso mountain range in central Japan in 1987. Dependency of photosynthesis on light and temperature was examined in relation to needle age and season. The light saturation point of net photosynthesis was lower in 3‐ and 4‐yr‐old needles than that in current (flushed in 1987), 1‐ and 2‐yr‐old needles. Pnmax, net photosynthetic rates at 1000 μmol m−2 s−1 and 15°C, of needles from 1‐ to 4‐yr‐old generally decreased with needle age. Pnmax of 1‐ to 4‐yr‐old needles became higher in August than in other months, and Pnmax of current needles did so in September. Current needles showed high respiration rates (at 15°C) only in August. Optimum air temperatures for net photosynthesis at 1000 μmol m−2 s−1 were between 10 and 15°C for current and 1‐yr‐old needles. The temperature coefficient of dark respiration rates was 2.3–3.3 for current needles from August to October, and 2.2 for 1‐yr‐old needles in mid‐July.
Evolution of airborne infectious diseases according to changes in characteristics of the host population
Authors: Kakehashi Masayuki , Yoshinaga Fumitaka 
Published: March 2006

AbstractThe authors predicted evolutionary changes in airborne infectious diseases according to changes in the characteristics of the host population. The predictions were based upon a mathematical model of infectious diseases and the validity of the predictions was verified against the history of man and pathogens. The feature of this model is that it involves a density of pathogens in the environment as an additional variable which can be regarded as more suitable to airborne infectious diseases. In spite of this modification, this study reached a similar conclusion to the threshold density theory: that is, susceptible host density in the absence of the pathogen must be larger than that in the presence of the pathogen, for the pathogen to be persistent. Moreover the authors concluded that one type of pathogen cannot be replaced by another type of pathogen as long as the susceptible host density of the former type is the mininum one. The predictions were considered to be valid for a wide range of infectous diseases. Making use of these principles, the authors predicted that the variety of infectious diseases should increase as host density increases and that pathogens should evolve to be less virulent as the host life‐span increases. The finalidea discussed is whether or nor the history of man and pathogen can be verified by the predictions.
Survivorship of a monocarpic bamboo grass, Sasa kurilensis, during the early regeneration process after mass flowering
Authors: Makita Akifumi 
Published: March 2006

AbstractThe survivorship of a monocarpic bamboo grass, Sasa kurilensis, during the early regeneration process was documented by a 10 year observation of the seedling population after mass flowering in the Hakkoda Mountains, northern Japan. Three phases were recognized: the establishment, density‐stable and thinning phases. The mortality of the densely germinated seedlings (932.9m−2 in a Betula ermanii forest and 1222.3 m−2 in a Sasa grassland) was high, up to 0.5 year−1, in the establishment phase (0–1 year after germination) and low in the density‐stable phase (1–3 years after germination). After reaching full density state, the seedling population showed a nearly constant mortality of 0.18 year−1 due to self‐thinning (the thinning phase). The high C/F ratio presumably caused suppressed seedlings to die. Recovery of the S. kurilensis population was estimated to require ca 20 years in the study plots, judging from the height growth and the decrease in culm density of the seedling population. The illuminance on the ground was higher in the flowered population than in the unflowered one for 5 years after mass death. The duration of high ground illuminance is an important factor affecting the dynamics of forests with Sasa undergrowth, because tree seedlings need to establish under high ground illuminance for the successful regeneration of the forests.
Enclosure experiment on the control mechanism of planktonic bacterial standing stock
Authors: Kato Kenji , Oh Su‐wan , Yamamoto Hiroyuki , Hanazato Takayuki , Yasuda Ikuko , Otuki Akira , Takahashi Masayuki 
Published: March 2006

AbstractIn order to understand the control mechanisms of a large, stable bacterial standing stock, enclosure experiments were conducted in a eutrophic lake, where both bacterial productivity and grazing pressure were very high. Total bacterial number in the different enclosures ranged from 1.2 to 2.7×107 cells mL−1 throughout the experiment. The average bacterial cell production rate estimated from a grazer eliminating experiment was 6.3×105 cells mL−1 h−1. Difference in the bacterial cell production rate between shaded and unshaded enclosures was not apparent. Bacteria showed a reduction in standing stock of only about 25–30% even after the supply of light was cut to 1%. Bacteria in the shaded enclosures then recovered their production rate in the first 12 days of perturbation. Grazing pressure in the shaded enclosures was not less than that for the control. Thus, it was considered a control mechanism of bacterial stable standing stock that the bacteria shifted their organic substrate from extracellular dissolved organic carbon freshly released from phytoplankton to that already stocked in the water column, though it is not known whether the dominant bacteria were the same.
Female mate preference and offspring fitness in the melon fly
Authors: Kasuya Eiiti 
Published: March 2006

AbstractThe influence of female mate preference on the fitness components of offspring was studied in the melon fly, Dacus cucurbitae. Adult flies were allowed to mate under two experimental treatments. In one treatment, 100 females and 100 males were allowed to mate freely in a cage (cage‐mating). In the other treatment, a single female was allowed to mate with a single male in a small chamber (chamber‐mating). Viability in the immature stages was not different between two treatments. The developmental speed of female offspring in the cage‐mating treatment was faster than that in the chamber‐mating treatment. The wing length of offspring of both sex in the cage‐mating treatment was also larger than that in the chamber‐mating treatment. These results were considered to support 3‐trait handicap models of the evolution of female mate preference.
Factors affecting individual variation in resting site fidelity in the patellid limpet, Cellana toreuma (Reeve)
Authors: Iwasaki Keiji 
Published: March 2006

AbstractAn investigation was made of individual variation in resting site fidelity in the limpet, Cellana toreuma, with special attention to the adaptiveness of its homing behaviour. Limpets resting in the higher part of the study site showed strong resting site fidelity while those in the middle part showed weaker fidelity and tended to shift their resting sites to higher parts. Limpets resting in the lower part where there were an abundant supply of food and high predation intensity, had the strongest resting site fidelity and always returned to fixed resting sites with mucous sheets. The resting site fidelity varied continuously among individuals. Four causes for shift of resting site were detected: fleeing from starfish, Coscinasterias acutispina, pushing contests for resting site, non‐returning excursions following and without following other's trail. The frequency of shift of resting sites due to each of these causes varied among individuals. Estimation of energy budget during about half a month showed that the location of resting site and frequency of shift of the site considerably affected the growth of limpets through energy expenditure by respiration and stationary mucus secretion, and energy intake by foraging. These variations were proposed as being a result not of density dependent dispersal nor adaptation to a single factor such as desiccation, heavy wave impacts or predation, but being due to individual difference in a compromise between two conflicting factors, susceptibility to predation and accessibility to food resources.
High SO2 resistance of Clethra barbinervis established in a smoke‐polluted area of Ashio, Tochigi Prefecture, Japan
Authors: Ikeda Hiroaki , Natori Toshiki , Totsuka Tsumugu , Iwaki Hideo 
Published: March 2006

AbstractThe effect of SO2 on the photosynthesis of Clethra barbinervis collected from a smoke‐polluted area near the Ashio copper smelter in Tochigi Prefecture was compared with C. barbinervis collected from a nonpolluted district in Tsukuba, Ibaraki Prefecture and Quercus mongolica var. grosseserrata grown in a nonpolluted field in Nagano Prefecture. The plants were exposed to 0.5–1.5 p.p.m. SO2 for 90 min (short‐term) and to 0.3 p.p.m. SO2 for 31–39 days (long‐term). The Clethra plants from both sites had a lower intrinsic stomatal conductance and photosynthetic rate than Quercus plants. Short‐and long‐term fumigation caused stomatal closure in Quercus plants, but had little effect on the stomatal conductance of Clethra plants. Under short‐term fumigation, nonstomatal photosynthetic inhibition per unit of absorbed SO2 was smallest in Clethra plants from Ashio. Long‐term fumigation caused photosynthetic decline and visible foliar injury to Quercus plants, but had no effect on Clethra plants from Ashio. Consequently, Clethra plants from Ashio had a higher photosynthetic rate than Quercus plants after long‐term fumigation. These results suggest that C. barbinervis populations in the smoke‐polluted area of Ashio had evolved high SO2 resistance connected with SO2 detoxification ability in mesophyll cells.
Vegetation history since the last glacial period in the Mikata lowland, the Sea of Japan area, western Japan
Authors: Takahara Hikaru , Takeoka Masaji 
Published: March 2006

AbstractLocal and regional vegetation since the last glacial period was reconstructed on the basis of a palynological study of sediment at Iwaya, in the Sea of Japan area, western Japan. During the interstade (before about 30 000 years BP), forests were composed predominantly of Cryptomeria japonica with Tsuga sieboldii and cool‐temperate deciduous broad‐leaved trees. In the pre‐full‐glacial, the full‐glacial and the early late‐glacial (30 000‐12 000 years BP), forests were dominated by temperate (montane) and boreal (subalpine) Pinaceae and Betula. During the early full‐glacial, the pinaceous forests were mixed with cool‐temperate trees such as Fagus crenata. In the late full‐glacial (18 000‐16 000 years BP), the maximum development of pinaceous conifer forests was recognized. Cool‐temperate broad‐leaved forests composed mainly of F. crenata and Quercus (Lepidobalanus) replaced the pinaceous forests at about 12 000 years BP and were maintained to the early postglacial. Cryptomeria japonica was distributed around the Mikata lowland during the last glacial. Cryptomeria japonica, which began to increase at 16 000 years BP, increased abruptly in the early postglacial and spread throughout the postglacial in the lowlands. After 6300 years BP, lucidophyllous forests composed mainly of Quercus (Cyclobalanopsis) and Castanopsis were established in the Mikata district; this was later than in the inland and the Pacific Ocean areas in the Kinki region, western Japan. In historic times (after ca 2000 years BP), secondary forest of Pinus densiflora, which can grow as a pioneer in disturbed habitats, spread.
Distribution pattern and age structure of Abies firma saplings in a mature mixed forest of A. firma and Fagus japonica
Authors: Agetsuma Naoki 
Published: March 2006

AbstractAge and spatial distribution of Abies firma saplings were analyzed in a mature mixed forest of A. firma and Fagus japonica. There were two major peaks in the age structure of Abies saplings at around 10 and 75 years of age. Distribution of these age classes of saplings was contagious, while that of all saplings was approximately random. These facts showed that most of the establishment of A. firma occurs just after a gap is formed, and the frequency at which such establishment occurs is about once every 60 years in a 1600 m2 area.
Responses of photosynthesis, leaf conductance and growth to different salinities in three coastal dune plants
Authors: Ishikawa Shin‐ichi , Oikawa Takehisa , Furukawa Akio 
Published: March 2006

AbstractThe effects of soil‐water salinity on growth and photosynthesis of three coastal dune plants were examined by salt‐treatment in order to clarify the causal relationship between salinity and plant distribution in a dune habitat. Plants were cultivated hydroponically at three salinity levels: 0, 10 and 100 mM NaCl. With the 100 mM salt treatment, Calystegia soldanella (C3 species) had the highest relative growth rate (RGR) (0.085 g g−1 d−1), followed by Carex kobomugi (C3) (0.066), and Ischaemum anthephoroides (C4) (0.060). This order coincides with the distribution pattern of the three species on coastal dunes;Calystegia soldanella is generally distributed in more seaward areas whereas I. anthephoroides occurs further inland. The order of RGR was determined exclusively by leaf area ratio (LAR) among the three species. Due to its C4 pathway, I. anthephoroides had higher net photosynthetic rate (Pn) and net assimilation rate (NAR) than the two C3 plants at all NaCl concentrations, despite its low RGR. This apparent discrepancy is explainable by differences of LAR among the three species; LAR of I. anthephoroides was lowest, and about half that of Calystegia soldanella. These results suggest that LAR is one of the main determinants of salt tolerance based on RGR, whereas Pn or NAR may not be significant.
Land‐use selection by dandelions in the Tokyo metropolitan area, Japan
Authors: Ogawa Kiyoshi , Mototani Isao 
Published: March 2006

AbstractLand use by native and introduced dandelion groups in man‐made habitats was studied at 7090 survey points in the Tokyo metropolitan area, Japan, in order to clarify the replacement phenomenon occurring among dandelions. In the center of Tokyo, where the native group was rare, the percentage occurrence of the introduced group was lower than in other regions, whereas in the outskirts of Tokyo, both groups showed much higher occurrence. Roadsides, vacant areas and urban land‐use categories were significantly favorable for growth of the introduced group, whereas preserved or rural land use was more favorable for the native group. Seed fertility in the introduced group was more than 80%, and was independent of population size, whereas in the native group it was not as high, and for a small population was dependent on population size, being stable at about 70% in populations larger than 70 plants. Thus, both large populations and solitary plants in the introduced group appeared to act as seed sources, making it likely that the introduced group will spread increasingly through roadsides and urban land, which are becoming more widespread as a result of urbanization. It is feared that, unless deliberately retained, the amount of preserved or rural land which has fostered large populations of the native group will further decrease with urbanization and other forms of development, thus depleting the seed sources and reducing the population.
Effect of flooding‐drawdown cycle on vegetation in a system of floating peat mat and pond
Authors: Haraguchi Akira 
Published: March 2006

AbstractThe relationship between vegetation and seasonal changes in water level was examined in a system of terrestrializing floating peat mat and pond in a warm temperate zone. The duration of flooding, or drawdown period, is related to vegetation in the mat. The first process of terrestrialization would be the attenuation of floating‐sinking movement of the mat and the consequent stabilization of water level. Water level at the time when the movement of the mat was attenuated determined the subsequent vegetation change at the site. Two series of succession according to terrestrialization were recognized, and started from initial conditions of low and high water levels respectively. Habitats in low initial water levels experienced short flooding and long drawdown periods. Species changes in the successional series were:Menyanthes trifoliata‐Rhynchospora fauriei‐Eriocaulon sikokianum‐Sphagnum cuspidatum. Submerged peat was experimentally emerged, and the crowded community of Rhynchospora fauriei and Eriocaulon sikokianum established within one or two years. Appearance of these species was controlled by the water level of the habitats in winter. Another series of species changes in terrestrialization process was:Menyanthes trifoliata‐Phragmites australis‐Carex thunbergii or Isachne globosa. Habitats of these types of vegetation were in the area with relatively high initial water level (long flooding and short drawdown) when the floating‐sinking movement of the mat attenuated. After the temporal paludification, the water level was lowered by the accumulation of peat in the process of terrestrialization.
Influence of livestock grazing on vegetation in a saline area in Northeast Thailand
Authors: Nemoto Masayuki , Panchaban Santibhab 
Published: March 2006

AbstractThe influence of grazing by water buffalo (Bubalas bufalis) and cattle (Bos taurus) was estimated for vegetation inside and outside cages in a saline area at Khon Kaen, Northeast Thailand.The home range of water buffalo and cattle shifted in response to the period of rice cultivation: during the rice‐growing season these animals grazed on roadsides and abandoned places such as the study area; after rice harvest they grazed mainly rice stubble on the paddy.The vegetation in the study area was divided into three types: 1) dominated by the annual grasses Chloris barbata and Ischaemum rugosum; vegetational cover and plant height in the cage increase due to the increase of these grasses; 2) thorny shrub patch of Maytenus mekongensis; other species in this patch almost died a year after experimental elimination of this shrub; this salt‐tolerant shrub not only protected the co‐existing species from grazing, but also suppressed salt accumulation; 3) almost pure stand of Panicum repens; livestock preferred this perennial grass over others.Electrical conductivity (EC) of surface soil did not increase under the vegetation protected from grazing. Litter and other organic matter in the soil suppressed the upward movement of brine. Grazing led to an increase of bare ground where NaCl accumulated, and modified the heterogeneity of vegetation, which was reflected in the degree of salt accumulation.
Succession of sessile organisms on experimental plates immersed in Nabeta Bay, Izu Peninsula, Japan IV. Temporal changes in metabolism, biomass and maturity of community
Authors: Hirata Tetsu 
Published: March 2006

AbstractCommunity succession in the metabolism, biomass and maturity of sessile organisms on concrete plates immersed at depths of 1.0, 2.5, 4.0 and 5.5 m in Nabeta Bay, Shimoda, pacific coast of Japan, was investigated over a period of about 3 yr. Gross primary production of the community (Pg) and community respiration (R) showed maxima at 10 and 13 months after immersion, and then Pg decreased significantly at all depths, whereas R was reduced only at the lower two depths. A parameter of community biomass, chlorophyll a (Chl. a), showed a similar successional change to Pg. Five other parameters, i.e. dry mass (DM), ash dry mass (ADM), ash‐free dry mass (AFDM), organic carbon (C) and organic nitrogen (N) increased significantly throughout succession, at least at the uppermost depth, but decreased significantly in the period 13–37 months after immersion at the lowest depth. Successional changes in five indices reflecting community maturity, i.e. the ratios of estimated daily gross primary production/estimated daily respiration (Pg/R), gross primary production/organic carbon (Pg/C), gross primary production/chlorophyll a (Pg/Chl. a), organic carbon/organic nitrogen (C/N) and Margalef's pigment diversity (D430/D665), also differed among the depths, especially at 37 months after immersion. Succession at the upper two depths appeared to progress toward a mature state, as opposed to retrogression to an immature state at the lower two depths. This difference in successional changes in these 13 parameters between depths agrees with the prediction of Margalef (1968) and Odum (1969), despite the tendency for Pg/R to be more heterotrophic in an open system.