bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production and population ecology of Phyllospadix iwatensis Makino. II. Comparative studies on leaf characteristics, foliage structure and biomass change in an intertidal and subtidal zone
Authors: Yabe Tohru , Ikusima Isao , Tsuchiya Takayoshi 
Published: March 2006

AbstractA seagrass in Japan, Phyllospadix iwatensis Makino, is distributed in the lower intertidal zone and upper subtidal zone making a dense population on the Choshi coast, Japan. Intertidal P. iwatensis is able to receive sufficient light for photosynthesis but experienced severe exposure to the air, which decreased a large amount of aboveground biomass in April to June (i.e. the daytime exposure season). Subtidal P. iwatensis was never exposed throughout the year and the aboveground biomass increased gradually over the daytime exposure season. However, the maximum aboveground biomass and shoot density of the subtidal plant never exceeded that of the intertidal plant. The dense foliage, large aboveground biomass and high shoot density of both intertidal and subtidal plants is likely to be an adaptation to heavy water movement, but the subtidal plants always received insufficient light for photosynthesis as a result of having dense foliage, particularly in turbid water. In choppy and swell sea, P. iwatensis did not seem to be adapted to growing in the subtidal zone where there was shortage of light.
Topographic variations of soil properties and stand structure in aPinus thunbergiiplantation
Authors: Enoki Tsutomu , Kawaguchi Hideyuki , Iwatsubo Goro 
Published: March 2006

AbstractSoil properties and above‐and belowground forest structure were studied across various topographies in a 20‐year‐oldPinus thunbergiiParl. plantation on Mt Tanakami, Japan. The soil properties and stand structure varied greatly with slope position fromridge top to valley floor. Soil thickness, fine soil content and soil moisture content were greater in lower slope positions. The amount of organic carbon in the forest floor was greater in upper slope positions. The organic carbon content in the mineral soil was slightly greater in lower slope positions. These changes in soil properties suggested an upslope decrease in decomposition rate and water and/or nutrient availability. The aboveground structure ofP. thunbergiiwas more developed at lower slope positions. The mean stem diameter, height and volume ofP. thunbergiiincreased downslope with decreasing tree density. However, fine root biomass increased greatly upslope. This inverse relationship between tree height and fine root biomass indicated morphological plasticity ofP. thunbergiiin exploiting environmental heterogeneity. Variations in soil‐plant interactions in the stand along various topographies caused spatial heterogeneity in the accumulation pattern of organic matter in plants and the soil.
Resource availability and growth responses to defoliation in seedlings of three early‐successional, tropical, woody species
Authors: Lim W. H. L. , Turner I. M. 
Published: March 2006

AbstractA growth experiment was conducted using seedlings of three early‐successional, tropical, woody species:Dillenia suffruticosa (Dilleniaceae), Macaranga heynei (Euphorbiaceae) and Trema tomentosa (Ulmaceae). These species are characteristic of different positions along a soil fertility gradient in Singapore, with D. suffruticosa being the least and T. tomentosa the most demanding of high nutrient availability. The seedlings were grown in vermiculite at either low or high nutrient availabilities supplied by watering with different concentrations of a commercial plant food. Half the seedlings were subjected to a 50% defoliation at the start of the experiment by cutting off the distal half of each leaf. After 9 weeks the plants were harvested. Macaranga heynei and T. tomentosa seedlings showed no significant difference in parameters of growth such as total dry weight and total leaf area between the defoliated and control seedlings. The seedlings compensated completely for the loss of leaf area. Dillenia suffruticosa did show significant reductions in growth in some parameters due to defoliation, and these were more pronounced under the high nutrient treatment. These findings support the hypothesis that plants characteristic of resource‐rich sites can readily recover from herbivory through fast growth, probably associated with a rapid turnover of leaves, whereas species of resource‐poor habitats cannot easily replace losses due to herbivory and are adversely effected by defoliation.
Different responses of pollinating bees to size variation and sexual phases in flowers of Campanula
Authors: Inoue Ken , Maki Masayuki , Masuda Michiko 
Published: March 2006

AbstractTo examine the response of pollinating bees to size and sexual phases of flowers, we constructed an artificial population of Campanula having large flower variation and presented it to potentially pollinating bees in nurseries. The pollinating bee groups (halictid, megachilid and bumble bees) responded differentially to both the flower size and to the sexual phases of the flowers. Whereas visitation rate of megachilid bees increased with the flower size, those of halictid bees and bumble bees did not show particular trends; for example, bumble bees visited almost all of the flowers consistently. Visitation frequencies to male‐and female‐phased flowers were significantly different between megachilids at Tokyo and halictids. This study indicates that pollinator attraction could not solely explain the evolution of the flower size in Campanula, and that other factors such as pollen transfer efficiency, should be considered.
Habitat preference, food habits and growth of juveniles ofLates angustifronsandLates mariae(Pisces: Centropomidae) in Lake Tanganyika
Authors: Kondo Takaki , Abe Naoya 
Published: March 2006

AbstractHabitat preference of juveniles ofLates angustifronsandLates mariae, endemic fish species in Lake Tanganyika, was investigated in the field and in the laboratory. Both species settle on the grass bed after the post‐larval pelagic phase.L. angustifronspreferred the short grass bed composed ofVallismeriasp., whileL. mariaepreferred the tall grass bed composed ofPotamogeton schweinfurthii. L. angustifronsalways rested near the root, keeping a position parallel to the bottom; dark cross bands on the body may be advantageous as camouflage in the short grass bed. On the other hand,L. mariaealways stayed in mid‐water, keeping a head‐down position parallel to a leaf or stem of grass; such posture and longitudinal stripes on the body may be advantageous as camouflage in the tall grass bed. Both species were more active at night, and fed mainly on atyid shrimps.Lates angustifronsshifted its main food from shrimps to fish with growth, as was suggested inL. mariae. Difference in the habitat preference may play an important role in their coexistence.
Responses in spatial organization to manipulations of the food resource in polygynandrous alpine accentors
Authors: Nakamura Masahiko 
Published: March 2006

AbstractThe alpine accentorPrunella collarisis a territorial and polygynandrous mating species. The breeding unit is a group consisting of about seven members who share a group territory which contains all the resources necessary for living. Each female holds a small territory around her own nest within the larger group territory. Supplemental food in the form of millet seed was provided for a total of 23 group territories to test the hypothesis that the abundance and distribution of food influences the size of a female's territory and her dispersion pattern which, in turn, determine the mating system. Both males and females had regular access to the feeders, but females and groups provided with feeders did not have smaller territories than those without feeders. No groups were divided into two by offering extra food. Provision of extra food resulted in an increase of group size but did not alter the sex ratio. All members, including new settlers, were sexually active and the sexual relationships among the members of a group were still multiple matings. Food addition did not prompt the fed females to choose nest sites nearer the feeder. Nest sites were restricted to particular rocky slopes and non‐vegetated areas which were invariably free from snow each year due to the effects of strong winds and the topography. Females showed a nest‐site fidelity for successive years. The reason why supplemental food had no effect on the territory size or dispersion of female alpine accentors is discussed.
Production and population ecology of Phyllospadix iwatensis Makino. I. Leaf growth and biomass in an intertidal zone
Authors: Yabe Tohru , Ikusima Isao , Tsuchiya Takayoshi 
Published: March 2006

AbstractIn an intertidal zone on Choshi coast, Japan, Phyllospadix iwatensis Makino emerges at daytime in spring and summer, while at night time in winter. The plants therefore experience seasonally different stresses caused by emergence, for example, intense light, ultraviolet rays, extreme temperature and desiccation, all of which the plants are unable to avoid during daytime emergence. Seasonal changes in the biomass and LAI suggest that the optimum periods for growth of P. iwatensis would be in March when the emergent period is short or nil and light availability is high while water temperature is not too low. Dense foliage and low canopy height of P. iwatensis in the intertidal zone relieve the plant from the stresses in emergent periods and from the disturbance caused by strong water movement in some coastal areas with active wave action.
The effect of color polymorphism on mortality in the aphid Macrosiphoniella yomogicola
Authors: Agawa Hiroko , Kawata Masakado 
Published: March 2006

AbstractWe examined body color polymorphism in the aphid Macrosiphoniella yomogicola from July to September 1993. We classified body color into eight types: green 1, green 2, red 1, red 2, white, orange, yellow and mist. The frequencies of body color varied with time and among patches of the host plant, yomogi (Artemisia spp.). Color diversity within a shoot was calculated using the Shannon diversity index. Of five usable data sets, three showed negative relationships between color diversity and mortality. The regression coefficients for two of these relationships were significant. No significant relationship between mortality and the number of aphids was found. The color diversity was not significantly related to a particular body color found on a yomogi shoot. Color polymorphism may be maintained because selection may favor a high color diversity on the host plant shoot.
Establishment and maintenance of the breeding territory in the polygynous great reed warbler
Authors: Ezaki Yasuo 
Published: March 2006

AbstractSettlement of male great reed warblers in the breeding ground was highly asynchronous at Lake Biwa in Japan. It took over 1 month from the appearance of the first male to a saturation in number of males. In resource‐defense‐polygyny, males are expected to try to defend as large an area as possible in the optimal habitat. In fact, a small number of the earliest settling males divided up the breeding ground almost completely as territories among themselves and these were later reduced in size with the addition of later settlers. The reduction was not due to a seasonal decline of aggressiveness on the part of the owners but to a higher level of intrusion pressure by later arriving males. The neighbor‐neighbor relationship, once established, was rather stable. Home range overlap was small and territorial contacts were few between neighbors. Territorial boundaries seem not to shift despite the addition of new males as long as the neighbors were the same. The stable relationships between neighbors are expected to help the earlier resident to maintain his large and good territories throughout the breeding season and hence polygyny is favored in this species.
Size dependency of gametophytes decay in Athyrium brevifrons Nakai during spring desiccation
Authors: Sato Toshiyuki 
Published: March 2006

AbstractGametophyte populations in Athyrium brevifrons were analysed with respect to population size and surviving area (%) of individual thalli in a transplant garden at Sapporo during 5–26 April 1983, to study the safe‐microsite for gametophyte establishment in nature. Spores dispersed in August 1982 germinated and grew into thalli of various widths (<10 mm); 10.3% of the thalli matured by early October 1982. Maturation was attained by gametophytes of width 4–7 mm. The number of gametophytes gradually decreased with increasing width. By April 1983, 20.5% of total gametophytes were mature with a mode of 5–6 mm in width. The relative number of gametophytes with surviving area of 2–20% increased and that of 85–100% decreased in accordance with collection days delayed until after snow‐melt. Surviving area (%) on gametophyte of all widths decreased with decreasing soil moisture contents. In particular, immature gametophytes of 2–4 mm width showed a significant correlation (P<0.01) between soil moisture content and relative number of gametophytes with 0–20% surviving area and mean surviving area (%) of every width of thalli. The spring desiccation might be a factor that reduces or limits gametophyte populations in nature.
Succession of sessile organisms on experimental plates immersed in Nabeta Bay, Izu Peninsula, Japan V. An integrated consideration on the definition and prediction of succession
Authors: Hirata Tetsu 
Published: March 2006

AbstractSuccessional changes of sessile organisms over about 3 years 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, were investigated from their species composition, percentage cover, and the structure, metabolism, biomass and maturity of the community for the purpose of verifying the hypothesis of succession by Margalef (1968) and Odum (1969). The process of succession was divided into five stages from a cluster analysis based on Horn's (1966) similarity in community structure. The five stages were characterized from dominant, species and 18 community attributes in terms of structure, metabolism, biomass and maturity. With the advance of stages, two large‐sized, long‐lived species, the kelp Eisenia bicyclis and the oyster Crassostrea nippona, dominated; 18 community attributes showed a directional succession ending in a constant community structure, low community metabolism, accumulation of community biomass except chlorophyll a and an enhanced degree of community maturity. This directionality in succession of community attributes was valid for the prediction of Margalef and Odum, despite a tendency for estimated daily energy budget to be more heterotrophic in such an open system. From these results, it was suggested that the definition of succession by Odum (1969) should be interpreted as the regularity in shift of dominant species, not individual species, and as the control of system by feedback mechanism developing with succession rather than community‐controlled mechanism.
Overlapping territories of Pseudosimochromis curvifrons males and other herbivorous cichlid fishes in Lake Tanganyika
Authors: Kuwamura Tetsuo 
Published: March 2006

AbstractMales of the herbivorous cichlid fish Pseudosimochromis curvifrons established mating territories 3–10 m in diameter, which included both spawning and feeding sites. Territorial males attacked conspecific males and also other species. Only conspecific males were chased out of the territories. Territorial males attacked other species at the spawning sites while courting or waiting for females and at other sites in their territories while patrolling and foraging. Attacks against herbivorous species were more frequent than against non‐herbivores since herbivores were much more abundant. Territories of four abundant herbivorous cichlids largely overlapped the territories of P. curvifrons males. Symbiotic relationships were not detected between the species. Instead, they were aggressive towards each other but coexisted by segregating feeding sites in the overlapping areas. The aggressive coexistence of P. curvifrons males with other herbivores may have resulted from the energetic costs of defending their relatively large territories against all food competitors. Interspecific food‐resource partitioning may also have facilitated the coexistence.
Optimal seasonal timing of univoltine and bivoltine insects
Authors: Iwasa Yoh , Yamauchi Atsushi , Nozoe Shinji 
Published: March 2006

AbstractThis study examines the optimal seasonal timing of the life cycle for univoltine and bivoltine insects, assuming that resource availability has a peak in the middle of a year and is symmetric around it. Results show that if the growth rate increases in proporrion to the bodyweight, bivoltine life cannot be optimal. If the growth rate is a power function of the bodyweight with a power smaller than unity, a symmetric bivoltine solution can be the optimal provided that the resource availability has a plateau in the middle of the season. If the resource availability has a sharp peak, the optimal pattern is an asymmetric bivoltine solution in which the larval periods of two generations differ in length. The bivoltine life cycle is more likely to be superior to the univoltine one if: growth is fast, suitable growing season is long, biomass loss during nonlarval stages is small, and egg size is small.
Importance of communal foraging grounds outside the reed marsh for breeding great reed warblers
Authors: Ezaki Yasuo 
Published: March 2006

AbstractForaging habitat selection of breeding great reed warblers was studied at a shore of Lake Biwa. The foraging grounds of parent warblers during the nesting period were not restricted to the breeding territory of the reed marsh, their nestling habitat. The paddy field outside the reed marsh was used communally by them throughout the breeding season. Females with early stage nestlings did not visit the paddy field whereas when nestlings were older than 3 days, more than half of their total food was collected there. Females with nests adjacent to the paddy field tended to exploit the paddy field more often than those with nests distant from it. Monogamously mated females tended to exploit the paddy field more often than polygynously mated females. Food collected in the paddy field was larger than that in the reed marsh and parent birds were prepared to travel longer distances to exploit the rich source of food in the paddy field. The importance of the communal foraging ground outside the reed marsh as a background of the polygynous mating system of this species is discussed.
Gap‐detecting mechanism in the seed germination of Mallotus japonicus (Thunb.) Muell. Arg., a common pioneer tree of secondary succession in temperate Japan
Authors: Washitani Izumi , Takenaka Akio 
Published: March 2006

AbstractGermination responses of Mallotus japonicus (Thumb). Muell. Arg. seeds to temperature revealed a gap‐detecting mechanism in the seed germination of the species. Among various constant and alternating temperatures examined in the range from 12–40°C, only very limited temperature regimes were found to be favourable for seed germination, specifically, alternating temperatures between 18–32°C and 28–40°C. A single several‐hour higher‐temperature (32–40°C) treatment could also induce the germination of seeds which had been imbibed for several days at a constant temperature in the range of 20–26°C, suggesting that there is a process requiring higher temperature among the overal germination processes. Seeds located at or near the surface of denuded soil would have a good chance of experiencing such a temperature change when several rainy days are followed by fine weather, while seeds beneath close vegetation would not. On the other hand, the pressence or absence of light or a simulated ‘canopy ligh’ had little effect on the germination. Therefore, it was concluded that the seeds of M. japonicus have a ‘gapdetecting mechanism’ in the form of a higher‐temperature requirement of a certain process involved in the overall germination processes.
Production dependence of vegetative propagation in Disporum smilacinum A. Gray
Authors: Hori Yoshimichi , Yokoi Tomoko , Yokoi Yota 
Published: March 2006

AbstractThe dependence of vegetative propagation on the production of individual plants was examined in Disporum smilacinum A. Gray on the basis of shading experiments and field surveys. This species typically showed four types of reproductive behavior: sterile plants producing one plantlet (no propagation), sterile plants producing more than two plantlets (vegetative propagation), fertile plants producing one plantlet (sexual reproduction) and fertile plants producing more than two plantlets (both sexual reproduction and vegetative propagation).The propagation of D. smilacinum was clearly related to the annual net production of each individual plant. The probability of a mother plant producing more than two vegetative propagules (plantlets) increased with net production of the plant in the current year. The number of propagules per plant and runner length increased with net production.It was possible to explain the types of reproductive behavior of this species on the basis of both the initial plant size before sprouting and its net production during the growing season. There was a critical initial plant size for sexual reproduction and a critical level of production for vegetative propagation.
The effect of tubificids and chironomids on particle redistribution of lake sediment
Authors: Fukuhara Haruo 
Published: March 2006

AbstractThe effects of chironomid larvae, Chironomus plumosus, and tubificid worms, Limnodrilus spp., on particle redistribution in lake sediment were investigated experimentally using pots containing sediments obtained from Lake Suwa, Japan. The chironomids and tubificids increased the water content of surface sediment. The chironomid larvae had no effect on particle size distribution, while tubificids continuously accumulated small particles on the surface sediment through their selective feeding activity. Particles larger than 0.125 mm were buried at a sediment depth of 6 cm. In Lake Suwa, long diatom frustules, large plant debris and blue‐green algal flocs were found to accumulate in the deeper layer of the lake sediment inhabited by tubificids at high density.
Den distribution and den use by the red fox Vulpes vulpes japonica in Kyushu
Authors: Nakazono Toshiyuki , Ono Yuiti 
Published: March 2006

AbstractThe distribution of dens and den use by the red fox was studied in Kumamoto Prefecture between 1968 and 1982. A total of 80 dens were classified into natal, residential, and temporarily‐visited dens. Natal dens comprised 12.4% of all dens. Relative proportions were quite stable for a long period. This indicates a constant number of reproducing females in the area for a considerable length of time. Seasonally the utilization of den showed three peaks in February, May and October. The peaks coincided well with the peaks of reproductive activity of female foxes. The results of multiple regression analysis of distribution of dens with respect to selected environmental parameters around densites indicated that the fox selectively utilize open land, rather than densely vegetated areas. The persistence of dens, the selective utilization by foxes of open land and the sizes of dens were all related to the breeding activities of female foxes inhabiting the area. Reproductive females usually used plural dens (“den group”) in one reproductive season. The numbers of those females occuring in the area were maintained at a steady level for fairy long periods. These indicate that the existence of a stable social relationship between females mediated through occupancy of “den groups.”