bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synchronization of reproductive period among the two male forms and female of the damselfly Mnais pruinosa selys (Zygoptera: Calopterygidae)
Authors: Nomakuchi Shintaro , Higashi Kazunori , Maeda Makoto 
Published: March 2006

AbstractEcological parameters in a population of Mnais pruinosa were investigated in a mountain stream. In the study area, there were two forms of male with regard to wing color, the orange‐winged male (esakii) and the hyaline‐winged male (strigata), and only one female form with hyaline wings. Emergence of adults began in late April, and the flying season ended in late June. The time after emergence was spent in maturation, and the insects began to mate when they reached maturity. Longevity of adults was 17.6 days for esakii males, 18.4 days for strigata males and 21.9 days for females. There was little difference in emergence time, maturation period, survivorship curve and longevity among the two male forms and female. In other words, the period for reproductive activities was perfectly coincident among them. The factors influencing the synchronization of emergence were discussed.
Structure of primary Japanese beech (Fagus japonica maxim.) forests in the Chichibu Mountains, central Japan, with special reference to regeneration processes
Authors: Ohkubo Tasuhiro , Kaji Mikio , Hamaya Toshio 
Published: March 2006

AbstractThe floristic composition, structure and dynamics of three primary Fagus japonica stands were investigated in the Chichibu Mountains. F. japonica was dominant [RD(%): 64.9–87.0] and showed a slightly inverse J‐shaped DBH class distribution in the quadrats [No. of canopy stems (H>20m): 87–138/ha]. The stems of F. japonica for each size were distributed in the form of colonies, being scattered almost uniformly, and arranged in positive association with each other. Detailed examination of the bases of the stem groups forming colonies revealed that most of them originated from the bases of dead mother stems and that they were from common stools [No. of large stems (H>10 m) per stool: 6–11]. Among six major canopy gaps observed, only one included stems sprouting from the outer part of F. japonica stools, while all the others were occupied by individuals of species other than F. japonica. After tree‐fall, several undercanopy F. japonica stems remained. Thus canopy gaps in these forest stands recovered through the sprouting of remaining F. japonica stools or by new sprouting of F. japonica individuals adjacent to the gaps. However, it was considered difficult to fill canopy gaps only with sprouts when the distance between the center of a gap and that of a stool surpasses the crown vector. Such places that are not fully occupied by sprouts will be filled by individuals of other canopy and/or under‐canopy species.
A fitness function for optimal life history in relation to density effects, competition, predation and stability of the environment
Authors: Satou Shintarou 
Published: March 2006

AbstractA fitness function (function maximized under natural selection) is studied in a population model in which the growth of a population is suppressed by crowding, density‐independent continuous mortality (by euryphagous predators) and periodic disturbances. The dynamics of the population density between occurrence of disturbance can be expressed as, dN/dt=(F(N/K)−D)N, where N is the population density, K is the carrying capacity, D is the density‐independent continuous mortality, and F is the growth regulation factor described as a function of crowding (N/K). The period of disturbance is S. The survival rate under disturbance is u. It is concluded that the fitness function is (approximately) a product of competitive ability (C), carrying capacity, and degree of saturation, and is given by CKF−1(D−(lnu)/S). The degree of saturation is the inverse function of regulation factor (F) at the death rate due to predators and disturbance.I assume a population in which density is regulated only through survival. In this case, a low survival rate at the critical age‐group means a high value of CKF−1(D−(lnu)/S). Therefore, the reciprocal of the density‐dependent survival rate at critical age‐group is a measure of the fitness function. Using this measure, I predict the optimal age (body size) at first reproduction of a species of salamander. I also found that fitness calculated from observed values of l(x) and m(x) includes a tautology.When the concept of fitness function is compared with the ESS method, the latter is more flexible. However, there is a possibility that an ESS is at the minimum of fitness function.
Dispersal ecology of the maritime plants in the Ryukyu Islands, Japan
Authors: Nakanishi Hiroki 
Published: March 2006

AbstractThe dispersal ecology of seventeen maritime species, which are dominant and/or characteristic species of coastal communities on the Ryukyu Islands, was studied. The species were Calophyllum inophyllum, Canavalia maritima, Clerodendron inerme, Guettarda speciosa, Hernandia sonora, Hibiscus tiliaceus, Ipomoea gracilis, I. pes‐caprae, Messerschmidia argentea, Pandanus odoratissimus, Pongamia pinnata, Scaevola frutescens, Sophora tomentosa, Terminalia catappa, Thespesia populnea, Vigna marina and Wedelia biflora. The structure and size of disseminules and their buoyancy and viability in seawater were examined in the laboratory. The disseminules of these seventeen species have morphological characteristics for buoyancy, and tests showed that these species could be dispersed by sea currents. Drift disseminules on the drift line, seedlings on the hightide line, and young plants of woody species in the herb zone were observed, being abundant on the coasts of the Ryukyu Islands. The Kuroshio Current carries these disseminules from islands where these species form part of the tropical coastal vegetation.
Role of bottom sediments in sustaining plankton production in a Lake ecosystem — Experimental demonstration using enclosed water bodies in a shallow eutrophic Lake
Authors: Sakamoto Mitsuru , Hayashi Hidetake , Otsuki Akira , Aoyama Kanji , Watanabe Yasunori , Hanazato Takayuki , Iwakuma Toshio , Yasuno Masayuki 
Published: March 2006

AbstractUsing large enclosures set in Lake Suwa, experimental studies were conducted to examine the effects of bottom sediments on plankton production in a natural lake ecosystem. Successive changes in biotic and abiotic components in two types of enclosure with and without bottom sediments were surveyed throughout a one‐month period in the early fall of 1985. Remarkable differences were found between the two types of enclosure with regard to the time courses of abundance of chlorophyll, PON, PP, TN, TP and zooplankton as well as those of POC/PON and POC/Chl ratios and primary production rate in terms of mg N m−2 day−1. Quantitative examination of the major causes of these differences revealed that the release of nitrogen and phosphorus from the bottom sediments was significantly effective for sustaining the active production of phytoplankton cells with a high nitrogen and phosphorus content, subsequently resulting in active zooplankton growth.
Sexual difference of lifetime movement in adults of the Japanese skimmer, Orthetrum japonicum (Odonata: Libellulidae), in a forest‐paddy field complex
Authors: Watanabe Mamoru , Higashi Takayoshi 
Published: March 2006

AbstractThe mark‐and‐recapture method was used to study the lifetime movement of the Japanese skimmer, Orthetrum japonicum, in a forest‐paddy field complex in the warmtemperate zone of Japan. The flight season was from mid April to late June. The age structure showed that the maiden flight occurred towards the forest from the emergence sites (paddy fields) for both sexes. The insects returned to the paddy fields after maturation. The total number of skimmers estimated in the whole survey area was about 1000–2000, of which about 200 males were found in the paddy fields. The average lengths of the immature and reproductive periods were about 10 and 20 days in both sexes, respectively. Most mature males tended to stay in the paddy fields and showed territorial behavior, while most mature females moved frequently between the forest and the paddy fields. The average extent of each territory was about 19 m2, being established mainly in the shady paddy fields. Few males were sneakers. The available habitat throughout the life span for the skimmers was both the paddy fields and the forest.
A Markov approach for describing post‐fire succession of vegetation
Authors: Isagi Yuji , Nakagoshi Nobukazu 
Published: March 2006

AbstractVegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described using a stationary Markov model. In this region, vegetation types of Miscanthus‐Pleioblastus grassland, Lespedeza‐Mallotus scrub, Pinus‐Rhododendron forest and Crassocephalum‐Erechtites community have been identified, and these show cyclic succession under the influence of fires.The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages and limitations of applying Markov models to studies of vegetation succession are also discussed.
Summer dietary compositions of sika deer on Yakushima Island, southern Japan
Authors: Takatsuki Seiki 
Published: March 2006

AbstractSummer food habits of Sika deer (Cervus nippon yakushimae) on Yakushima Island, southern Japan, were studied focusing in particular on Pseudosasa owatarii, a dwarf bamboo native to the island. Fecal analyses showed that the food habit of the Sika deer on Yakushima island was plastic: the dietary composition was dominated by graminoids (ca. 90%), particularly P. owatarii (50%–60%) in the bamboo grassland of the P. owatarii zone above the timber line, whereas leaves and non‐leafy parts of woody plants were important in the crytomeria forest and evergreen broad‐leaved forest below the timber line. The maximum culm age of P. owatarii was 8.5 yr, but the majority of leaves (97.8%) were younger than 2.5 yr. Since the weight contribution of the leaves is great (27.7%) and the turnover rate is high, the P. owatarii grassland affords a good foraging place for the Sika deer on Yakushima Island.
Role of rhizomes in tussock formation by Carex thunbergii var. Appendiculata
Authors: Nishikawa Yoko 
Published: March 2006

AbstractSeveral types of tussock formed by Carex thunbergii var. appendiculata were compared with respect to the growth pattern of their rhizomes at various developmental stages at Benten Marsh in Yufutsu Mire, Hokkaido, Japan. The rhizomes were classified into three types based on their function: 1, very short rhizomes; 2, intermediate‐length rhizomes which grow upwards to raise the shoot base; 3, long rhizomes which grow horizontaly to spread the plant. The extent of development of the tussock and the total length of rhizomes per shoot was inversely related with the number of Type 3 rhizomes, and positively related with Types 1 and 2 rhizomes. The tussock was made of dead roots, dead rhizomes and much litter, which provided a substitute for soil for the rhizomes and absorbing roots. The growth conditions of the Carex changed from aerobic and eutrophic to anoxic and oligotrophic with tussock development. It is concluded that the tussock is adaptive to anoxic conditions.
Germination ecology of coastal plants in relation to salt environment
Authors: Mariko Shigeru , Kachi Naoki , Ishikawa Shin‐ichi , Furukawa Akio 
Published: March 2006

AbstractResponses of seed germination to salinity were examined using 37 species collected from salt marshes, cliffs, and fore (unstable) and hind (stable) sand dunes along Japanese coasts. For comparison, seed germination of nine inland species was also examined. The soil salinities in salt marshes ranged from 150 to 300 mmol/L NaCl, whereas those in fore and hind dunes ranged from 0 to 150 mmol/L NaCl, with a few exceptions. Cliff soils showed relatively high salinities up to 300 mmol/L NaCl. Ciff and foredune soils that encountered a typhoon and storm showed high salinities >300 mmol/L NaCl. Salt tolerance in seed germination of coastal plants was ordered by comparing the responses of percentage and rate of germination to salinity conditions up to 200 mmol/L NaCl, being in the order of salt marsh>cliff>foredune≅hind dune≅inland. Thse results indicate that salt tolerance in seed germination of coastal plants is closely related to the salinity conditions of their habitats. Germination experiments under favorable conditions showed that a high percentage of the seeds of salt marsh species germinate rapidly, those of diff species germinate slowly and those of foredune species exhibit a low percentage and low rate of germination. It seems that these germination characteristics contribute to the success of germination at the ‘safe site’ and the subsequent survivorship of emerged plants in their natural habitats.
Canopy photosynthetic production in a Japanese larch stand. I. Seasonal and vertical changes of leaf characteristics along the light gradient in a canopy
Authors: Kurachi Nahoko , Hagihara Akio , Hozumi Kazuo 
Published: March 2006

AbstractIn an 18 year old Japanese larch stand, leaf characteristics such as area, weight, gross photosynthetic rate and respiration rate were studied in order to obtain basic information on estimating canopy photosynthesis and respiration. The leaf growth courses in area and weight from bud opening were approximated by simple logistic curves. The growth coefficient for the area growth curve was 0.155–0.175 day−1, while that for the weight growth was 0.112–0.117 day−1. The larger growth coefficient in area growth caused the seasonal change in specific leaf area (SLA) that increased after bud opening to its peak early in May at almost 300 cm2 g−1 and then decreased until it leveled off at about 140 cm2g−1. The change in SLA indicates the possibility that leaf area growth precedes leaf thickness growth. The relationship between the coefficients a and b of the gross photosynthetic rate (p)‐light flux density (1) curve (p=bI/(1+aI)) and the mean relative light flux density (I′/I0) at each canopy height were approximated by hyperbolic formulae:a=A/(I′/I0)+B and b=C/(I′/I0)+D. Leaf respiration rate was also increased with increasing I′/I0. Seasonal change of gross photosynthetic rate and leaf respiration rate were related to mean air temperature through linear regression on semilogarithmic co‐ordinates.
Performance and phenology of alpine herbs along a snow‐melting gradient
Authors: Kudo Gaku 
Published: March 2006

AbstractResponses of plants to the length of the growing season were studied in an alpine snow‐bed by setting five plots along a snow‐melting gradient. Performance and phenology were compared between the plots for five herbaceous species (Peucedanum multivittatum, Primula cuneifolia, Veronica stelleri var. longistyla, Solidago virga‐aurea var. leiocarpa and Potentilla matsumurae). Performance characteristics measured were flower height, leaf height, leaf number, flower number and fruit number. In the late exposed plots with short snow‐free periods, fruit‐set was reduced in many species due to the decrease in flower number and/or the short growing season for fruit development. Veronica stelleri var. longistyla and Solidago virga‐aurea var. leiocarpa, which decreased in flower and leaf numbers due to the short snow‐free period, were sensitive to the short growing season. Peucedanum multivittatum was vigorous in the late exposed plots, but its slow flowering and fruiting prevented the fruit‐set from developing in the last exposed plot. Primula cumeifolia and Potentilla matsumurae, quick flowering species that maintained their flower number throught the snow‐melting gradient, were considered the most successful species in late exposed habitats.
Buried seed population in the herbaceous lomas on Loma Ancon in the coastal desert of central Peru
Authors: Ohga Nobuhiko 
Published: March 2006

AbstractHerbaceous lomas in the Peruvian coastal desert, of South America establish in spring, and its habitat is limited to the southern or southwestern slopes along the coast that are affected by thick fog. The time of appearance, the duration and the thickness of the fog vary greatly from year to year, so the lomas can grow only in habitats with enough water to, sustain seed germination and plant growth. This paper studies the species composition and density of the buried seed population, of the herbaceous lomas of Loma Ancon in order to clarify the mechanisms of the lomas' establishment. The mean number of species with viable seeds was about, 12 spp. m−2 and that of dead seeds was about 22 spp. m−2. The dominant species were Solanum tuberiferum, S. pinnatifidum and Nolana humifusa, both in viable and dead seeds. Viable seed density was about 5000–8000 seeds m−2, which is comparable with the seed densities of other herbaceous communities. Dead seed density was about 15000–27000 seeds m−2, or nearly three times the viable seed density, because the rate of decomposition was slow in the extremely dry conditions. The net increase of viable seeds by seed production was estimated at about 5000 seeds m−2 in 1980, and the increase in the number of dead seeds was 2200 seeds m−2.
Peculiarities of sexual reproduction inFagus crenataforests in relation to annual production of reproductive organs
Authors: Saito Hideki , Imai Hideyuki , Takeoka Masaji 
Published: March 2006

AbstractAnnual production rates of reproductive organs inFagus crenataforests in the lower area of the species' range were studied using 10 litter traps in 1980–1986. The production rates of dispersed pollen were estimated by multiplying the number of fallen male inflorescences per ha per year by the mean amount of pollen per inflorescence before anthesis. Large annual fluctuations in the production rates of male and female inflorescences were recognized, whereas their annual trends were synchronized with each other. Pollen production rates were within the range 1.0–6900 (mean: 1630)×109ha−1yr−1, the maximum/minimum ratio attaining 7000.F. crenatawas the lowest producer of pollen among seven tree species studied: the number of pollen grains equivalent to a single ovule was in the range 6.0–14×104. Furthermore, the mean dry weight of a single pollen grain (3.77×10−5mg) was higher than for wind‐pollinated species. Three factors seemed to cause the low seed fertility ofF. crenata. The dry‐matter production rate in the best seed year reached 3252 kg ha−1yr−1, of which pollen accounted for 259 kg ha−1yr−1. Unproductive years with less than 10% of the maximum production occurred four times in a 7‐yr period. In such years there were fewer male and female inflorescences, and more fruit dropped as a result of insect damage. Lower nut dissemination would play an important role in suppressing any increase in nut predators, and fewer flowers would be produced to avoid wastage of photosynthates in a cool‐temperate climate.
Microsite variation in light availability and seedling growth of Quercus serrata in a temperate pine forest
Authors: Washitani Izumi , Tang Yanhong 
Published: March 2006

AbstractSpatial heterogeneity in light availability for tree seedlings under the canopy of a temperate pine forest was studied. Six‐day measurements at 10‐s intervals revealed a great variety in the temporal patterns of photosynthetic photon flux density (PPFD) and histograms among observation days and microsites; mean daily total PPFD relative to full sun varied from 1.5% to 10.4% depending on the microsites. The occurrence and duration of PPFD above 80 μmol m−2 s−1, which might reflect sunfleck activity, varied greatly among the microsites. However, several simple empirical relationships were found between some parameters characterizing microsite light availability and sunfleck activity; the diffuse site factor was correlated well with other parameters, including daily total PPFD, daily totals and daily summed durations of high PPFD above any examined threshold level, and its contribution to daily total PPFD. Diffuse site factors which were obtained for 700 microsites within an area of 28 m2 on three different occasions during the growing season showed high correlations within the microsite. Based on the regressed relationship between the relative growth rate of current‐year seedlings of Quercus serrata and the microsite diffuse site factor and the results of area‐survey measurement of the diffuse site factor, an estimation was made of the abundance of potential ‘safe‐sites’ for seedling growth of the species; the ‘safe sites’ were estimated to cover 40% and 0% of the total area of the sunny and shady sites of the forest, respectively.
Effect of streaked shearwater Calonectris leucomelas on species composition of Persea thunbergii forest on Kanmurijima Island, Kyoto Prefecture, Japan
Authors: Maesako Yuri 
Published: March 2006

AbstractThe effects of trampling and burrowing by streaked shearwaters were studied on the Persea thunbergii forest in Kanmurijima Is. The vegetation data were analysed using both the phytosociological tabulation method and principal component analysis (PCA). The vegetation ordination on the first axis reflected the environmental gradient from light to heavy disturbance by the streaked shearwater, and the vegetation ordination on the second axis represented the gradient from the latter phase of forest succession to retrogressive succession. The position of the three vegetation groups in the ordination diagram successfully explained the relation between the habitat and the species composition. The disturbance caused by activities of the streaked shearwater such as burrowing and trampling causes a decrease of species, especially character species of Camellietea japonicae, and also causes retrogressive succession: patches of Mallotus japonicus develop and many heliophytes occur.
An ecological study of soils in the Highlands of western Tibet I. Soils along an iso‐altitudinal transect across western Tibet
Authors: Iwatsubo Goro , Zheng Xilan , Shidei Tsunahide 
Published: March 2006

AbstractA variety of soil studies were carried out along a 920‐km transect running SE to NW from near the border with northern Nepal, through the Western Tibet Highlands (soils sampled at six locations at an elevation of about 4200 m), to the Takla Makan Desert. This transect, which parallels the China‐India border, covers a range of aridities. Annual precipitation decreased exponentially (from 169 mm to ca. 50 mm) north‐westwards along the transect. The humidity index also decreased exponentially to the desert zone in the Western Tibet Highlands, and decreased further in the Takla Makan Desert because of the high temperature in the latter area. Vegetation changed from Caragana thorn‐bush steppe, through Artemisia sparse steppe, to desert. Soil properties were studied in relation to the humidity index. Organic C, total N, cation exchange capacity, and very low C/N ratio values (a maximum of 12.8) of soils decreased with the decrease in humidity index. In contrast, carbonate, pH (KCl), and sulfate increased exponentially. Available P and ammonia content were inversely related to the abundance of carbonate, whereas nitrate increased where carbonate was abundant. Illite was the most abundant of the clay minerals, followed in order by kaolinite and montmorillonite.