bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of overwintering Daphnia on spring zooplankton communities: An experimental study
Authors: Hanazato Takayuki , Yasuno Masayuki
Published: March 2006

To evaluate the influence of overwintering individuals of zooplankton on spring zooplankton communities, the dynamics of zooplankton communities with or without overwintering individuals were observed in experimental ponds from fall to spring. An insecticide, carbaryl, was used to regulate the overwintering individuals. In ponds which received insecticide applications in November or January, all cladoceran and rotiferan species were eliminated by the treatments and did not reappear until late March or early April, even when the chemical disappeared rapidly. The low water temperature may delayed the establishment of the populations from resting eggs. In these ponds, populations of various cladoceran and rotiferan species, which seemed to be originated from resting eggs, were built up in the spring. In control ponds, Daphnia ambigua or D. longispina overwintered as juveniles and adults and established a large spring population earlier than other cladocerans and rotifers overwintering as resting eggs. The latter zooplankters did not increase in the spring probably because their growth was suppressed by the preceding Daphnia species through competition. In nature, even if the number of overwintering individuals is small, they may have a potential to build up a large population earlier than the individuals hatching from resting eggs. As a result, the species which have overwintered as individuals seem to predominate in the spring and have a large influence on the spring zooplankton community.
Effects of herbivory by chrysomelid beetles on the growth and survival of Rumex plants
Authors: Suzuki Nobuhiko
Published: March 2006

The effects of herbivory by the guild of chrysomelid beetles on the growth and survival of Rumex plants were examined in relation to the distribution and size of the plants.

Gastrophysa atrocyanea never appeared on solitary plants whereas Mantula clavareaui showed even utilization of solitary and clumped plants. Galerucella vittaticollis utilized large solitary plants most frequently. In patches of the host plants, the frequency of withering of the aerial parts was higher on small plants. The regrowth rate was higher when the aerial parts withered in spring than in summer. In patches of the host plants, the regrowth rate was higher on small plants. On the other hand, it was lower on small solitary plants than on large solitary plants and small plants in patches. In large plants, no difference in survival rate was recognized between solitary and clumped plants, because both the frequency of withering of the aerial parts and the regrowth rate were lower in clumped than solitary plants. The high vigor against intense herbivory by the chrysomelid beetles brought on the delay in the phenology of Rumex plants. This shift permits in parts the existence of G. vittaticollis in mid summer. The temporal and spatial interactions between herbivore guild and the host plants were discussed.
Interspecific competition for seed production between two naturalized dandelions under different levels of fertilizer supply
Authors: Suehiro Kiyokazu
Published: March 2006

Two naturalized dandelions, Taraxacum officinale and Taraxacum laevigatum, were grown in mixed stands at various plant densities and mixing ratios with various levels of fertilizer supply until seeds were produced. The effect of fertilizer supply on the competitive relationship for seed production between the species was analyzed. In pure stands, the simultaneous effects of plant density and fertilizer supply on mean plant weight were formulated for each species. By introducing the density conversion factor, the results of plant weight growth in mixed stands were formulated successfully. T. laevigatum produced more seeds than T. officinale at the same plant weight. The relationship between mean plant weight and mean number of mature seeds produced per plant was also formulated for each species. Ratio diagrams were predicted with these formulas. The density conversion factors showed that T. officinale was always dominant over T. laevigatum for plant weight growth within a generation. The ratio diagrams showed that T. officinale became dominant over T. laevigatum for seed production with repeating generations at higher levels of fertilizer supply, but that the species with a larger ratio of plant density became dominant over the other species at lower levels of fertilizer supply.
Niche characteristics of Cladonia lichens associated with geothermal vents in Japan
Authors: Glime Janice M. , Iwatsuki Zennoske
Published: March 2006

To characterize the niche preferences of Cladonia species associated with geothermal areas, we sampled ten thermal areas in Japan. It appears from the current study and related studies that some members of the Cladonia genus can have a wide tolerance for both soil temperature and pH conditions. Cladonia mitis is the most abundant Cladonia and occurs throughout most of the vent system. Cladonia theiophila occurs most frequently at a soil pH of less than 3.5, but occurs mostly at lower soil surface temperatures (below 29°C). Cladonia floerkeana is very restricted in its distribution and is most abundant where the root zone temperature (15 cm) is above 70°C, the surface temperature is above 40°C, and the pH is 5–5.5. Tolerances to low pH, high soil temperatures, and low to moderate humidity permit Cladonia species to grow where vascular plants and even mosses cannot grow and thus they avoid the competition such plants would provide to these slow‐growing organisms.
Reproductive ecology of a freshwater amphipod, Jesogammarus suwaensis Morino, inhabiting Lake Suwa in central Japan
Authors: Kusano Harumi
Published: March 2006

The reproductive traits of Jesogammarus suwaensis Morino (1986) were estimated by field survey and rearing experiments. According to the relationship between clutch interval and water temperature, one clutch interval under 15°C corresponded to 212 degree days of the effective cumulative temperature. Thus a female could produce about three clutches during the reproductive period from November to early May in the field. Reproduction was somewhat inhibited at 20°C. The clutch size was positively correlated with female body length, and the regression coefficient was large (4.470 on log‐transformed data). Oviposition was somewhat synchronized in the field, and the proportion of paired females increased as their reproductive development approached oviposition. The precopula duration was estimated to be 60–80% of the clutch interval in the field. Positive size‐assortative mating was observed in precopula pairs and pairing males were usually larger than single ones.
A case study on the effects of a transmission‐line corridor on Sika deer habitat use at the foothills of Mt Goyo, northern Honshu, Japan
Authors: Takatsuki Seiki
Published: March 2006

Forage biomass and habitat use of Sika deer (Cervus nippon) at a transmission‐line corridor were studied at the foothills of Mt Goyo, northern Japan. Summer forage biomass in the corridor was five times greater than in the adjacent Betula grossa forest. Among the plants that increased in the corridor, Sasa nipponica (a dwarf bamboo), an important forage plant for Sika deer, was predominant. Winter utilization of S. nipponica by Sika deer was slightly heavier in the corridor, and estimated removal of Sasa leaves was twice as great there as in the forest. However fecal pellets were more prevalent in the adjacent forest in winter. Sika deer seemed to use the transmission‐line corridor as a feeding site and the adjacent forest as cover as it reduces wind speed. A transmission‐line corridor is more beneficial than a large clear‐cut area because it provides more forest edges.
Effect of bryophytes on survival of conifer seedlings in subalpine forests of central Japan
Authors: Nakamura Toshihiko
Published: March 2006

Bryophytes form the major seedbed for coniferous trees in the subalpine forests of central Japan. Field experiments were conducted on the floor of a closed stand dominated by Tsuga on Mt Fuji to examine the seedling survival of Abies veitchii and Tsuga diversifolia in seven substrate types in relation to the morphological characteristics of the seeds and seedlings. Neither Abies nor Tsuga seedlings could survive on dwarf‐bamboo litter beyond 2 years after the seed rain. Abies seedlings survived not only in all types of bryophyte communities but also in larch litter. In contrast, the survival of Tsuga seedlings was restricted to communities of smaller‐statured bryophytes found on logs. The seeds and 1st year seedlings of A. veitchii were larger than those of T. diversifolia. Abies seedlings produced hypocotyls taller than any bryophyte community and radicles which were long enough to penetrate into the moist humus layer, whereas Tsuga seedling radicles presumably penetrate into humus only in bryophyte communities forming a thin mat on logs. The effect of bryophytes on survival of tree seedlings therefore depends on the relationships between the morphology of seeds and seedlings and the structure of bryophyte communities.
Home range and mating system of two sympatric field mouse species, Apodemus speciosus and Apodemus argenteus
Authors: Oka Teruki
Published: March 2006

The size and spatial distribution of home ranges in two sympatric field mouse species, Apodemus speciosus and Apodemus argenteus, were revealed by the capture‐recapture method in a temperate deciduous forest from June 1987 to June 1990. In A. speciosus, the home ranges of males were significantly larger tha those of females, and overlapped with those of other males and females during the breeding season. In A. argenteus, the home range of each male overlapped only that of a single female throughout the year. These results suggested that A. speciosus was promiscuous or polygynous and A. argenteus was monogamous.
Laboratory observations of prey behaviour for prey acquisition by a predator among three larval mosquitoes
Authors: Yasuda Hironori , Mitsui Takashi
Published: March 2006

The effect of prey behaviour on prey acquisition by a predator was examined in the laboratory, using three larval mosquitoes. Aedes albopictus was acquired by the predator, Toxorhynchites towadensis, at a higher rate than Orthopodomiya anopheloides. Toxorphynchites towadensis was a sit‐and‐wait predator. Aedes albopictus was more active than O. anopheloides. Orthopodomiya anopheloides ran away before the predator attacked, but A. albopictus did not. The escape ratio in O. anopheloides was higher than that in A. albopictus. These results suggest that the difference in the prey acquisition ratio by the predator between prey species is caused by different behavioural patterns of the prey to the predator.
Ecological characteristics of Agriophyllum squarrosum, a pioneer annual on sand dunes in eastern Inner Mongolia, China
Authors: Nemoto Masayuki , Lu Xiaoyun
Published: March 2006

A field survey was conducted in a semi‐arid region of Inner Mongolia, China, to clarify the ecological characteristics of Agriophyllum squarrosum (Chenopodiacea), which is an ephemeral in shifting sand dunes. The habitat of A. squarrosum is extremely unstable, that is, the surface substrate frequently shifts, the soil water‐content is highly variable and the site does not permit the growth of any other plant species. Agriophyllum squarrosum is able to invade as a pioneer because of the elongation of its fine roots, which are well adapted to dry sandy soil and able to penetrate deep soil layers containing moisture. The biomass and the pod numbers increased under conditions where enough water was supplied. However the biomass at sites where the wind was strong was relatively small.
Leaf carbon gain simulation for tree seedlings acclimatized to microsite light regimes of a temperate pine forest
Authors: Washitani Izumi
Published: March 2006

Leaf carbon gain simulation was performed for Quercus serrata seedlings with previously reported 6 day photosynthetic photon flux density (PPFD) histograms from 20 understorey microsites of a pine forest (Washitani & Tang 1991). This simulation was performed with or without an assumption of the acclimatization of photosynthetic capacity (Pmax) to microsite light availability. A constant ratio of respiration rate to Pmax, within, the range of 0.07–0.1, was assumed as a constraint. In relatively well illuminated microsites with a diffuse site factor above 0.1, predicted optimal Pmax was about 5 μmol m−2 s−1, with the predicted mean daily net carbon gain being about 50 mmol m−2 day−1. Each of the predicted optimal Pmax and the simulated mean daily net carbon gains with a constant Pmax (5 μmol m−2 s−1) or the predicted optimal Pmax was linearly related to the microsite light availability index, diffuse site factor. Simulated net carbon gain was negative at diffuse site factors below 0.04, if the constant of Pmax was assumed. The predicted linear relationship between net carbon gain and diffuse site factor could provide an ecophysiological basis for the observed linear dependency of the relative growth rate of biomass of Q. serrata seedlings on the microsite diffuse site factor (Washitani & Tang 1991).
Seasonal change in specific needle weight of Pinus thunbergii
Authors: Kimura Makoto
Published: March 2006

To evaluate the reserve dynamics in pine needles, an index of specific needle weight (SNW; dry weight per unit length of needles) was provided. Developed needles of Pinus thunbergii did not show any additional elongation in their second year. Thus the seasonal change in SNW of developed needles was proved to indicate the dynamics of reserves in needles. SNW showed distinct seasonal change. It increased from autumn to carly spring, followed by a decrease by mid summer. This pattern of change was similar to the change in specific leaf weight (SLW) of evergreen broad leaves in temperate regions. It was concluded that the change in SNW indicated clearly the dynamics of reserves in needles, showing the accumulation in non‐growth seasons and the consumption in subsequent growth seasons. The decrease in SNW during the growth season was 10–15% of the maximum found in early spring.
Biomass and net production in a bamboo Phyllostachys bambusoides stand
Authors: Isagi Yuji , Kawahara Teruhiko , Kamo Kouichi
Published: March 2006

Biomass and net production were measured in a Phyllostachys bambusoides stand in Kyoto Prefecture, central Japan, which had carried out gregarious flowering in 1969 and has been recovering vegetatively. The culm density fluctuated around an average value of 12 040 ha−1 during the research period (1985–91). Annual recruirment and mortality rates of culms were 1340 and 1133 ha−1, respectively. The mean diameter at breast height increased from 7.28 cm in 1985 to 8.68 cm in 1991, and the biomass of culms increased from 71.3 to 111.6t ha−1 over the same time period. Branch and leaf biomasses were almost constant, 10.0 and 9.4t ha−1 on average, respectively. The leaf area index of the stand was 11.6 ha ha−1, which is one of the largest values found in Japanese forests. The belowground biomass of 32.6t ha−1 for rhizomes and 14.8t ha−1 for fine roots resulted in the smaller ratio of aboveground parts to the root system (2.38) than those determined for forest stands. The amount of litterfall, excluding culms and large branches, was large (9.13t ha−1 year−1), corresponding to those measured in equatorial stands. The aboveground net production was 24.6t ha−1 year−1, larger than the average value reported for forest stands under similar weather conditions.
Growth, morphology and leaf characteristics after simulated herbivory in Chinese subtropical evergreen saplings
Authors: Cornelissen J. H. C.
Published: March 2006

Growth, morphology and leaf characteristics were assessed in late spring following simulated autumnal defoliation in second‐year saplings of three Chinese subtropical evergreen tree species. Castanopsis fargesii showed strong compensatory growth in terms of plant biomass after removal of both 50 and 75% of leaf biomass and slight compensatory growth after 90% defoliation. Defoliated C. fargesii saplings had more leaves per unit shoot length than non‐defoliated saplings. New leaves on defoliated plants were smaller and had higher per area nitrogen content than new leaves on non‐defoliated plants. Pinus massoniana and Elaeocarpus japonicus showed strong and no compensatory growth, respectively, after 50% defoliation. The strong compensatory growth in P. massoniana and C. fargesii may partly explain why these species predominate in the early and late successional phases of evergreen broad‐leaved forests
Pressurized gas transport in two Japanese alder species in relation to their natural habitats
Authors: Grosse Wolfgang , Schulte Angela , Fujita Hiroko
Published: March 2006

Oxygen uptake measurements have shown that pressurized gas transport, resulting from the physical effect of thermo‐osmosis of gases, improves oxygen supply to the roots of the seedlings in two alder species Alnus japonica (Thunb.) Steud. and Alnus hirsuta (Spach) Rupr., which are both native in Japan. When gas transport conditions were established by irradiation of the tree stems the internal aeration was increased to a level nearly equal to the oxygen demand of the root system in leafless seedlings of A. hirsuta, but was higher in A. japonica so that excess oxygen was excreted into the environment. An increase of superoxide dismutase (SOD) activity, which protects plants from toxic oxygen radicals and post‐anoxic injury, has been observed in root tissues of A. japonica when the seedlings were flooded for 3 days. The increase of SOD activity, in concert with high gas transport rates, may enable this tree species to grow in wet sites characterized by low oxygen partial pressure in the soil and by varying water tables. A less effective gas transport, flood‐induced reduction of SOD activity in root tissues, and reduced height growth in waterlogged soil may be responsible for the fact that A. hirsuta is unable to inhabit wettland sites.
Difference of invasion behavior between two climax species, Castanopsis cuspidata var. sieboldii and Mechilus thunbergii, on lava flows on Miyakejima, Japan
Authors: Hiroki Shozo , Ichino Kazuo
Published: March 2006

The invasion behavior of two climax species, Machilus thunbergii Sieb. et Zucc. and Castanopsis cuspidata (Thunb.) Schottky var. sieboldii (Makino) Nakai, was studied on the 1874 and 1962 lava flows on Miyakejima, Japan. On the 1962 lava, zoochorous M. thunbergii appeared almost only under crowns of pioneering Alnus sieboldiana Matsum, while bolochorous C. cuspidata var. sieboldii occurred only along the borders of the lava. The three species, A. sieboldiana, M. thunbergii and C. cuspidata var. sieboldii, corresponded, in order, to the temporal sequence of invasion in the boundary forest and the spatial sequence from margin to center on the 1962 lava. Seed or fruit dispersion is important in primary succession in the case of large disturbances.
Resource allocation to sexual and vegetative reproduction in a forest herb Syneilesis palmata (Compositae)
Authors: Nishitani Satomi , Kimura Makoto
Published: March 2006

The balance between sexual and vegetative reproduction in Syneilesis palmata was examined in relation to environmental conditions and the amount of reproductive resources, which is defined here as the total quantity of dry matter invested in both modes of reproduction. The allocation balance was measured for individual plants of two populations, with different densities in an open habitat, for 2 years, and those of two other populations, under different light intensities in a plantation forest (forest floor and edge), for 3 years. Relative allocation to sexual reproduction decreased with increasing reproductive resources in all populations except for the forest edge, which showed a constant allocation balance. The high density population showed lower relative allocation to sexual reproduction than the low density population, irrespective of the amount of reproductive resources. However the between‐year comparison of the high density population suggested that under extremely high density, plants with a small amount of reproductive resources enhanced sexual reproduction, while plants with a large amount of reproductive resources reproduced vegetatively. On the forest floor, plants with small amounts of reproductive resources had higher relative allocation to sexual reproduction than the forest edge population, while plants with large amounts of reproductive resources had a somewhat lower one. The adaptive significance of such allocation patterns are discussed, based on qualitative data on the characteristics of both types of offspring.
Probable effects of CO2‐induced climatic changes on net primary productivity of terrestrial vegetation in East Asia
Authors: Ohta Shunji , Uchijima Zenbei , Oshima Yasuyuki
Published: March 2006

Changes in the net primary productivity (NPP) of natural vegetation of monsoon East Asia were simulated under three, doubled CO2‐climate scenarios (GISS, GFDL and UKMO). These three scenarios and baseline climate data were converted to grids of 1o×1o meshes. The gridded climatic data were used together with the Chikugo model to assess NPP under baseline and CO2‐doubling climates. The potential total net production (TNP0) of East Asia was climatically evaluated to be 154×108 t dry matter year−1. The climatic changes induced by a doubled CO2 concentration are predicted to increase the TNP0 by approximately 9–15%, depending on the climatic scenario. The estimated increase in TNP0 would be limited by the difference between the rate of shift of climatic zones and the rate of migration of vegetation formations.
Differences in sapling architecture between Fagus crenata and Fagus japonica
Authors: Yamamura Yasuo , Ishida Atsushi , Hori Yoshimichi
Published: March 2006

The ecological significance of architectural patterns for saplings of Fagus crenata and Fagus japonica co‐occurring in a secondary oak forest were evaluated by comparing the size and shape of leaves, trunks and crowns. Fagus japonica saplings were different from F. crenata saplings in some architectural properties: (i) the leaf area and specific leaf area were larger; (ii) the ratio of sapling height to trunk length was lower, indicating greater leaning of the trunk; and (iii) the projection area of the crown was larger and the leaf area index lower indicating less mutual shading of leaves. These architectural features indicated that F. japonica saplings were more shade tolerant than F. crenata and F. crenata saplings were superior to F. japonica for growth in height and could, therefore, utilize sunlight in the upper layer. An erect trunk in F. crenata and a leaning trunk in F. japonica may be important characteristics associated with the regenerations patterns of each species; regeneration from seedlings under canopy gaps in the former and vegetative regeneration by sprouting in the latter.
The ecology of a beech forest on Mt. Sanpoiwadake, Hakusan National Park, Japan II. The correlation of the subassociation within the Lindero membranaceae‐fagetum crenatae association and environmental parameters
Authors: Hukusima Tukasa , Kershaw Kennth Andrew
Published: March 2006

Detailed examination of a sample plot covered by the Lindero membranaceae‐Fagetum crenatae association on Mt. Sanpoiwadake, Hakusan National Park, revealed a number of correlations between the distribution of subassociations and environmental factors.

The subassociations on the south‐facing slopes receive deep snow cover in winter with rapid melting in the spring. They occur on porous, freely draining soils, typical of the general range of brown forest soils. Conversely, on the north‐eastern slopes there are widespread late‐snow patches which delay leaf development and expansion and which provide an abundant water supply well into early summer. Under these conditions, bleached soil horizons have developed with iron pan formation, resulting in poor soil drainage, strongly correlated with quite different plant communities.
Rhizome development of Phragmites australis in a reed community
Authors: Kudo Gaku , Ito Koji
Published: March 2006

Variations in the height, shoot density, biomasses of above‐ and below‐ground parts and rhizome distributions of Phragmites australis were investigated along a line‐transect in a reed community at Yufutsu Mire, Hokkaido. Relationships of performance of the reed plants to soil conditions and species compositions were also examined.

Three types of rhizome development were recognized in reed plants; (1) the central part of the reed community, characterized by well developed rhizomes and dense aerial shoots, (2) the intermediate part, characterized by development of rhizomes along both the peat and surface layers and very dense aerial shoots, and (3) the marginal part, characterized by development of rhizomes only along the peat layer and sparse aerial shoots.

Observation showed that rhizomes in the surface layer actively produced aerial shoots, whereas rhizomes in the peat layer contributed to the spreading of their distribution range. With the growth of rhizomes, organic debris originating from dead rhizomes and roots accumulated in the mineral soil to promote organic soil formation. In dense parts of the reed stand, species composition was poor because of the shading and litter accumulation by reed plants. The effects of microtopography and water level on the establishment of reed seedlings were also considered.
Population dynamics of Daphnia rosea in a small eutrophic pond
Authors: Shei Ping , Iwakuma Toshio
Published: March 2006

The population dynamics of Daphnia rosea were studied in a small, eutrophic fish‐free pond during November 1986–November 1987. D. rosea showed two density peaks in 1987, a high peak in spring and a slightly lower one in autumn, but they disappeared in mid‐ and late summer when a smaller cladoceran, Ceriodaphnia reticulata, dominated.

The rapid decline in density of D. rosea in mid‐May and the low density in June/July were preceded by or coincided with a period of increased male density, the appearance of ephippial females, smaller body length of adult females, decreased brood size, and increased frequency of empty brood chambers, all of which indicate a worsening food situation. The rapid density decline of D. rosea in mid‐May was considered attributable neither to increasing water temperature, nor predation by the dipteran Chaoborus flavicans, but to insufficient food conditions for the maintenance of stable reproduction. Although edible phytoplankton was abundant in June/July, the general food situation was not suitable for D. rosea due to blooms of the large‐celled dinoflagellate, Ceratium hirundinella, which probably inhibited the feeding activity of D. rosea. The C. hirundinella blooms might also be important for the shift of the dominant herbivore from the larger D. rosea to the smaller Ceriodaphnia reticulata in August/September.
Foraging behavior of Ural owls (Strix uralensis) in a patchy environment: The importance of acquired information
Authors: Nishimura Kinya
Published: March 2006

How the allocation of searching investiment by Ural owls (Strix uralensis) in a patchy and fluctuating environment is affected by prior information was experimentally studied. The owls searched among four patches, two with prey and two without prey. During the five days, the positions of two prey patches were randomly assigned daily (random treatment) and for the other five days, they were fixed (fixed treatment). In experiment I, the sequence of treatments was from random to fixed. In experiment II, the sequence of treatments was reversed. The choice of prey present patch was affected by acquired information which owls acquired during one night (short term), a treatment period (medium term), and throughout the experiment run (long term). They predicted the positions of the prey patches, to some extent, in the first choice in one night in the fixed treatment by the experience of previous days. The searching time per visit was also affected by previous information. Owls searched prey patches longer than empty patches. In the random treatment, the giving up time in prey patches was variable, while in the fixed treatment, it was longer and fixed. Although owls could use information on the environment where they had searched to make a decision of foraging behavior, they were not able to choose prey patches accurately. The information which was acquired during the treatment period and throughout the experiment run affected the gain from prey. The changes in gain were not caused by the encounter rate but by the proportion of attack success.
Population dynamics of japanese serow in relation to social organization and habitat conditions. I. Stability of Japanese serow density in stable habitat conditions
Authors: Ochiai Keiji , Nakama Satoru , Hanawa Sin‐Ichi , Amagasa Toshifumi
Published: March 2006

The density of a Japanese serow (Capricornis crispus) population, which has been in stable habitat conditions and free from hunting and predation, was investigated by direct observation of serows at Kusoudomari (336 ha), Wakinosawa village, Aomori Prefecture, Japan, during 1977–89. The vegetation, composed of mature mixed forest of Thujopsis with deciduous trees (43.2%), secondary forest of deciduous trees (23.4%) and a plantation of coniferous trees (30.0%) showed little change during the study period. The serows were counted 17 times each winter for 14 consecutive years. The serow population maintained a stable density with a mean of 12.5 individuals km−2 (SD=1.4) ranging from 8.6 to 14.6 km−2. The ratio of the proportion of kids (<1 year old) to serows more than 1 year old decreased, but density did not decrease during the study period. Though extremely severe winters with heavy snowfall in 1984–86 caused a decline in serow density, the density recovered within a few years. It was considered that the stability of the serow density resulted mainly from the stable food supply and the lack of human disturbance, such as forest cutting in the habitat. Stable population density for a long period is probably related to the social organization of the serow.
Botanical and chemical composition of rumen contents of Sika deer on Mt Goyo, northern Japan
Authors: Takatsuki Seiki , Ikeda Shoshichi
Published: March 2006

Botanical and chemical compositions of the rumen contents of 58 Sika deer on Mt Goyo, northern Japan, collected from summer of 1988 to spring of 1989, were analyzed. Sasa nipponica, a dwarf bamboo, was important in summer (35.0%) and winter (61.4%), but it decreased to 5.6% and was replaced by browse leaves in fall, and to 28.0% and was replaced by dead leaves, twigs and bark of woody plants in winter. Crude protein was 20–25% lower in the washed fraction than in the gross fraction. It was highest (16.2%) in summer and lowest (8.6%) in winter. High protein content in summer and fall foods was attributed to forb and browse leaves. Seasonal fluctuation in protein content in the foods of these Sika deer was greater than red deer on Rhum, Scotland and smaller than wapiti in Yellowstone National Park, Wyoming, USA. Climatically, winter severity of Mt Goyo is intermediate between the two localities, which seems to explain the seasonal fluctuation of the protein level. Crude fiber was ca 33% in the ‘washed’ fraction, and did not change seasonally.
Examination of the method for measuring soil respiration in cultivated land: Effect of carbon dioxide concentration on soil respiration
Authors: Nakadai Toshie , Koizumi Hiroshi , Usami Youzou , Satoh Mitsumasa , Oikawa Takehisa
Published: March 2006

An acceleration of soil respiration with decreasing CO2 concentration was suggested in the field measurements. The result supporrs that obtained in laboratory experiments in our previous study. The CO2 concentrations in a chamber of the alkali absorption method (the AA‐method) were about 150–250 parts/106 lower than that in the atmosphere (about 350 parts/106), while those observed in the open‐flow IRGA method (the OF‐method) were nearly equal to the soil surface CO2 levels. The AA‐method at such low CO2 levels in the chamber appears to overestimate the soil respiration. Our results showed that the rates obtained by the AA‐method were about twice as large as those by the OF‐method in field and laboratory measurements. This finding has important consequences with respect to the validity of the existing data obtained by the AA‐method and the estimation of changes in the terrestrial carbon flow with elevated CO2
Photosynthesis of bract and its contribution to seed maturity in Carpinus laxiflora
Authors: Hori Yoshimichi , Tsuge Hiromi
Published: March 2006

Light saturated net photosynthesis was measured in bracts and leaves of Carpinus laxiflora, the major species in secondary forests in cool and intermediate temperate zones in Japan. The maximum net photosynthesis of leaves and bracts was essentially constant from May to early August and decreased gradually thereafter. For bracts, it was 3.2 μmol m−2s−1, approximately half that for the leaves. The photosynthesis of bracts would thus appear to contribute significantly to seed maturity. The estimated production of bract based on the photosynthesis would make seeds (3 mg dry weight) mature for 37 days, assuming all photosynthate of the bracts to have been distributed in the seeds only. This was quite consistent with the growth curve for the seeds. A mast year phenomenon is discussed in relation to bract photosynthesis and leaf number.
Field measurements of nitrogen‐fixing activity of intact saplings of Alnus maximowiczii in the subalpine zone of Mt Fuji
Authors: Tsutsumi Hiroshi , Nakatsubo Takayuki , Ino Yoshio
Published: March 2006

Nitrogen‐fixing (acetylene‐reducing) activity of intact saplings of Alnus maximowiczii was measured under natural conditions in the subalpine zone of Mt Fuji. The nitrogen‐fixing activity was detected from the middle of June when expansion of leaves had just begun to the end of October when the shedding of leaves was almost completed. Diurnal changes in the activity were almost parallel with those of ground temperature. The measured nitrogen‐fixing activity was related to ground temperature and total leaf area. Using this relation, annual nitrogen fixation was estimated from the data of ground temperature and leaf area measured in the field. The amount of annual nitrogen fixation was almost the same as that of nitrogen used for annual growth. It was concluded that nitrogen fixation by nodules made a considerable contribution to the nitrogen economy in the saplings of A. maximowiczii.
Fecundity and oviposition in three skimmers, Orthetrum japonicum, O. albistylum and O. triangulare (Odonata: Libellulidae)
Authors: Higashi Takayoshi , Watanabe Mamoru
Published: March 2006

Females of three skimmers, Orthetrum japonicum, O. albistylum and O. triangulare, were captured in forests and paddy fields. They were dissected and examined for the number of submature and mature eggs. Orthetrum japonicum and O. albistylum continuously developed eggs throughout their reproductive period. The volume of mature eggs in O. albistylum was the smallest among the three species. The number of mature eggs in ovaries decreased from morning to afternoon, suggesting that all of them oviposited around noon. The number of mature eggs laid by O. japonicum, O. albistylum and O. triangulare was estimated at about 400, 800 and >2000 a day, respectively.
Nitrogen cycling in an Antarctic ecosystem 2. Estimation of the amount of nitrogen fixation in a moss community on East Ongul Island
Authors: Nakatsubo Takayuki , Ino Yoshio
Published: March 2006

Nitrogen fixation by cyanobacteria in a moss community on East Ongul Island (69°00'S 39°35′E), Antarctica was investigated using the acetylene reduction method.

The mean acetylene reduction rate at 10°C and 200 μE·m−2·s−1 photosynthetically active radiation was 7.12 nmol C2H4 per square centimeter of moss community per hour. The effects of temperature, radiation, desiccation and rehydration on the acetylene reduction rates were examined.

A simple predictive model was constructed in order to estimate the amount of nitrogen fixed in the field. Using this model, the daily amount of nitrogen fixation was calculated from microclimatic data (temperature and radiation) measured in the experimental field at Syowa Station on East Ongul Island between 1983 and 1984. The cumulative amount of nitrogen fixation in the growing season during this period was estimated to be 329 mg N per square meter of moss community.

It is suggested that nitrogen fixation by cyanobacteria in the moss community is important as a nitrogen source for the community growth on East Ongul Island.
Regeneration process of coniferous forests in northern Hokkaido I. Abies sachalinensis forest and Picea glehnii forest
Authors: Suzuki Eizi , Ota Kasio , Igarashi Tsuneo , Fujiwara Koichiro
Published: March 2006

Regeneration of natural forests was studied in the Nakagawa Experiment Forest of Hokkaido University using age distribution surveys made by the clear felling method. In Plot 1 (30 m × 65 m), Abies sachalinensis dominated the canopy layer but there were also a few Betula ermanii trees. Sasa senanensis densely covered the forest floor. Most of the canopy trees were from 122 to 195 years old. Seedlings younger than 50 years old of A. sachalinensis were found on fallen logs and root bases. There were, however, few trees from 50 to 120 years old. The present canopy trees seemed to have regenerated after competitive pressure from old canopy and Sasa disappeared 180 years ago. Plot 2 (50 m × 100 m) on serpentinite soil was dominated by Picea glehnii. Sasa kulirensis covered the floor but not as densely as S. senanensis in Plot 1. The ages of P. glehnii ranged from 1 to 586 years old, and the age distribution of A. sachalinensis was L‐shaped. A small gap in the canopy formed about 290 years ago, and it gradually extended. Conifers regenerated continuously in the extending gap but B. ermanii did not. One hundred thirty years ago, part of Plot 2 was again destroyed and A. sachalinensis and B. ermanii regenerated. Thus, two types of regeneration were found. One regenerated both conifers and Betula after a sudden disturbance of canopy layer or death of Sasa, and the other, under an extending gap, regenerated only conifers.
The impact on the Senjogahara ecosystem of extreme run‐off events from the river Sakasagawa, Nikko National Park
Authors: Hukusima Tukasa , Kershaw Kenneth Andrew , Looney John Henry
Published: March 2006

Vegetational data from Senjogahara moor, Nikko National Park, Japan have been analysed using two contrasting but parallel multivariate approaches as a basis for future studies. The plant communities objectively defined using a divisive polythetic classificatory approach (TWINSPAN) have been successfully overlayed on an ordination of the same data using detrended correspondence analysis (DCA). The results reveal a vegetational mosaic reflecting differential levels of flood damage to the vegetation and its subsequent rates of recovery, in a space‐time continuum. The results from the TWINSPAN classification show that 13 plant communities are present in the sample area and these correlate closely with complete absence, slight, or extremely heavy disturbance. The form of the disturbance as either channel erosion or alluvial depositional features is shown to also correspond quite closely with the vegetational types and is reflected in the ordination axes derived from DCA.
Analysis of development of a subalpine Abies stand based on the growth processes of individual trees
Authors: Kimura Makoto , Kimura Wakio , Honma Satoru , Hasuno Tomohisa , Sasaki Teruko
Published: March 2006

The progress of growth of a subalpine young Abies veitchii and A. mariesii forest during 25 years was analyzed on the basis of measurements of the processes of height growth of about 230 trees in a quadrat where the old canopy had been completely destroyed by a typhoon in 1959. The original forest floor sapling population had consisted of trees shorter than 2 m. Saplings grew faster after the breakage of the canopy than before, A. veitchii growing faster than A. mariesii. During the 25 years of growth, a few well developed trees exceeded 6 m in height, while others remained around only 1 m or less. Some small trees, mostly A. veitchii died at sites of high density. A bimodality in the distribution of tree height had developed with a trough at about 2.5 m, differentiating the trees into canopy and suppressed populations. Canopy trees grew with wide variation of rates, while most of the suppressed trees showed little recent growth. No difference was found in recent growth rates between the two canopy Abies species. Differences in height growth rates among individual canopy trees were analyzed on the basis of their horizontal crown overlapping. Competition models evaluating the difference in height between trees with overlapping crowns were shown to be effective. The height growth rate of a canopy tree appeared to be controlled by both the closely grown taller trees and the local density of trees including those shorter than the subject tree.
Interspecific competition and coexistence of the two chrysomelids, Gastrophysa atrocyanea motschulsky and Galerucella vittaticollis baly (Coleoptera: Chrysomelidae), under limited food resource conditions
Authors: Suzuki Nobuhiko
Published: March 2006

Field experiments were conducted in order to investigate the mode of exploitation of food resources and the mechanism of coexistence of mixed larval populations of the two chrysomelids, Gastrophysa atrocyanea and Galerucella vittaticollis, under limited food resource conditions. The larval survival rates seemed high enough to assure coexistence when hatchlings of the two species were released in 1∶1 and 1∶3 ratios on a host plant. However, the survival rate became almost nil for both species when a 3∶1 ratio was employed, suggesting asymmetrical interspecific competition.

Wasted food consumption was much higher in G. atrocyanea larvae. The population of G. atrocyanea seemed to be regulated more by intraspecific competition, while on the other hand, the population of G. vittaticollis was considered to be more likely affected by the interspecific competition with G. atrocyanea, depending on the initial ratio and density of the two species.
Responses of dry weight growth under SO2 stress in an SO2‐tolerant plant, Polygonum cuspidatum
Authors: Natori Toshiki , Totsuka Tsumugu
Published: March 2006

The effects of exposure to 0.5–0.7 ppm SO2 for about one month on the dry weight growth and net photosynthesis of Polygonum cuspidatum were investigate. Furthermore, the carbon and nitrogen concentrations in each plant organ were measured. The results obtained showed no significant decrease in the total dry weight of SO2‐treated plants in comparison with controls. On the other hand, the leaf area (LA) and/or leaf dry weight of SO2‐treated plants were increased, and the root dry weight (RW) was decreased, in comparison with controls. The leaf carbon assimilation rate (CAR) in SO2‐treated plants was slightly decreased in spite of a clear decrease in net photosynthesis, and the value of (SW+RW)/LA (SW stem dry weight) was decreased in comparison with controls, thus minimizing the reduction in CAR. Furthermore, the ratio of total leaf carbon absorption (leaf area x CAR) to total root nitrogen absorption (root dry weight x nitrogen assimilation rate) in SO2‐treated plants was similar to that in controls. From these results, it can be concluded that an increase in leaf area and/or leaf dry weight and a decrease in root dry weight in P. cuspidatum under SO2 stress may be induced in order to compensate for the decrease in CAR and to maintain the ratio of total leaf carbon absorption to total root nitrogen absorption in the early stage of vegetative growth.
Germination responses to temperature responsible for the seedling emergence seasonality of Primula sieboldii E. Morren in its natural habitat
Authors: Washitani Izumi , Kabaya Hajime
Published: March 2006

Temperature requirements for the breaking of seed dormancy and germination in Primula sieboldii E. Morren and the annual surface‐soil temperature regime in one of its natural habitats were investigated in order to clarify the germination responses determining the seedling emergence seasonality of the species. In a grassland nature reserve in an abandoned flood plain of the Arakawa River, natural seedling emergence of the species was shown to be restricted to mid‐ to late‐spring before the closure of seasonal vegetational gaps, when the daily mean soil surface temperature reached about 15°C, accompanied by large daily fluctuations of about 10°C. Mature seeds collected in late June were never able to germinate at any constant temperature in the range of 8–40°C unless they had been previously subjected to moist‐chilling treatment. The proportion of seeds which were released from dormancy increased with increasing duration of the moist‐chilling treatment at 2°C, 70–85% of seeds becoming germinable at 16–28°C after 12 weeks of pretreatment at 2°C. The thermal time required for the germination of the thus‐pretreated seed population was 905–1690 Kh with a base temperature of around 5°C. Fluctuating temperatures between 24°C and 16 or 12°C had a remarkable dormancy‐breaking effect, inducing considerably quick germination in most of the seeds previously subjected to 2°C moist‐chilling for 8 weeks.
A Qualitative Study of Health Professionals' Views Regarding Provision of Information About Health‐Protective Behaviors During Genetic Consultation for Breast Cancer
Authors: Rees Gwyneth , Young Mary‐Anne , Gaff Clara , Martin Paul R.
Published: March 2006

This study aimed to explore health professionals' views and practice regarding the provision of information about health‐protective behaviors (e.g., exercise, alcohol consumption, diet) during genetic consultation for breast cancer. Ten genetic counselors participated in three focus groups, and seven medical specialists were interviewed in a focus group or individually. Data was analyzed using the constant comparative method. Findings suggested that health professionals held differing, often opposing, views about the value of health‐protective behaviors for women at increased risk of breast cancer. The content and extent of information provided about health‐protective behaviors varied widely, and participants expressed a need to form consensus regarding information provision both within and across clinics. The main barriers to providing information regarding health‐protective behaviors included the lack of research evidence regarding the impact of these factors and higher priority of other information need to be provided in the limited consultation time. Participants generally did not consider it their role to promote health‐protective behaviors, and were concerned about the psychological impact of providing information about behavioral risk factors during genetic consultations.
2005 National Society of Genetic Counselors Presidential Address: Raising Our Voice
Authors: Callanan Nancy
Published: March 2006

This Presidential Address was given at the annual education conference of the National Society of Genetic Counselors in Los Angeles, California, USA on November 14, 2005
An Extension of Multiple Correspondence Analysis for Identifying Heterogeneous Subgroups of Respondents
Authors: Hwang Heungsun , Dillon William R. , Takane Yoshio
Published: March 2006

An extension of multiple correspondence analysis is proposed that takes into account cluster-level heterogeneity in respondents’ preferences/choices. The method involves combining multiple correspondence analysis and k-means in a unified framework. The former is used for uncovering a low-dimensional space of multivariate categorical variables while the latter is used for identifying relatively homogeneous clusters of respondents. The proposed method offers an integrated graphical display that provides information on cluster-based structures inherent in multivariate categorical data as well as the interdependencies among the data. An empirical application is presented which demonstrates the usefulness of the proposed method and how it compares to several extant approaches.