bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal variations of microsite light availability within a Miscanthus sinensis canopy
Authors: Tang Yanhong , Washitani Izumi , Iwaki Hideo 
Published: March 2006

AbstractPhotosynthetic photon flux density (PPFD) at 15 cm above the ground was measured at 20 microsites in gaps and grass patches within a Miscanthus sinensis Anderss community at 10 s intervals during 5 days every month from May to September 1989.Microsite light availability, which was characterized by daily total PPFD, sunfleck PPFD (PPFD above a threshold value of 50 or 400 μmol m−2 s−1) and the diffuse site factor, showed evident seasonal changes, with a marked reduction between June and July due to the rapid growth of the grass canopy. The monthly median value of daily total PPFD among the microsites decreased from 10.3 mol m−2 day−1 in May to 0.77 mol m−2 day−1 in September, with a reduction in the diffuse site factor from 31 to 4%. During the summer, the median value of the total time of sunflecks exceeding 50 μmol m−2 s−1 contributed 7–18% of measurement time, but the contribution of these sunflecks to daily total PPFD ranged from 29 to 59%.There was considerable microsite variation in light availability throughout the measurement period. Rank correlation analysis revealed that some microsites, such as those in gaps, consistently received more total PPFD, more sunfleck PPFD and had a higher diffuse site factor than those in grass patches. The diffuse site factor had a linearly positive relationship with daily total PPFD and total sunfleck PPFD for the 20 microsites during the measurement period, confirming that the diffuse site factor is a useful index for microsite light availability within M. sinensis canopies.
Dynamics of the fungal symbionts in the gallery system and the mycangia of the ambrosia beetle, Xylosandrus mutilatus (Blandford) (Coleoptera: Scolytidae) in relation to its life history
Authors: Kajimura Hisashi , Hijii Naoki 
Published: March 2006

AbstractThe dynamics of the fungal symbionts in the gallery system and the mycangia of the ambrosia beetle, Xylosandrus mutilatus, were studied in relation to its life history using both isolation experiments and scanning electron microscopy (SEM). In the galleries, Ambrosiella sp. was predominant during the larval stages but its relative dominance gradually decreased during the development of the larvae. In contrast, yeasts (mainly Candida sp.) and Paecilomyces sp. dominated continuously in the galleries after eclosion. Ambrosiella sp. was consistently stored in the mycangia in all adult stages, except in the teneral and overwintering adults when the other fungi were dominant. No fungal spores occurred in the mycangia of the adult beetles reared under aseptic conditions from the pupal stage, while only Ambrosiella sp. was stored in those reared from the teneral‐adult stage. These results suggest that: (i) Xmutilatus is associated with at least three fungal species, among which Ambrosiella sp. is the most essential food resource for development of the broods; (ii) immediately after eclosion, new female adults may take at least four associated fungal species, with no or incomplete selection, into their mycangia from the walls of the cradles; and (iii) conditions may well be produced in the mycangia of both matured and dispersing beetles whereby only the spores of Ambrosiella sp. can proliferate.
Photosynthetic and stomatal responses of Larix kaempferi seedlings to short‐term waterlogging
Authors: Terazawa Kazuhiko , Maruyama Yutaka , Morikawa Yasushi 
Published: March 2006

AbstractThe effects of short‐term waterlogging on net photosynthesis, stomatal conductance and shoot water status of 2 year old seedlings of Larix kaempferi (Lamb.) Carr. were studied under controlled environmental conditions. Waterlogging for 8 days induced significant stomatal closure and reduced net photosynthesis. After 3 days of waterlogging, stomatal conductance was reduced to 35% of that of non‐waterlogged plants, and net photosynthesis was reduced to 25% of the pre‐waterlogged level. At the beginning of waterlogging, slight shoot dehydration was observed. However during the latter stage of the waterlogging shoot dehydration disappeared and stomatal conductance and net photosynthesis increased. No adaptive morphological changes to waterlogging were observed in the stems and roots. Recovery of stomatal conductance and net photosynthesis after drainage was not observed within 11 days.
Comparison of ecophysiological responses to heavy snow in two varieties of Aucuba japonica with different areas of distribution
Authors: Kume Atsushi , Ino Yoshio 
Published: March 2006

AbstractAucuba japonica varieties are common evergreen understory shrubs in Japan. Aucuba japonica var. borealis is distributed on the Sea of Japan side of Honshu and Hokkaido where heavy snow cover lasts for more than 3 months in winter. Aucuba japonica var. japonica is distributed in areas with shallow or no snow on the Pacific Ocean side of Honshu and Shikoku. The ecophysiological characteristics of var. borealis were compared with those of var. japonica to examine the effects of heavy and long‐term snow cover on the life cycle of var. borealis. Shoots of both varieties were shaded in crushed ice for 110 days, but their photosynthetic activities, chlorophyll contents and the chlorophyll a/b ratio was not affected. The leaves of var. borealis were no less frost tolerant than those of var. japonica. In spite of the difference in environmental factors, both varieties had similar characteristics in seasonal changes of photosynthesis, respiration and chlorophyll a/b ratio. These results suggest that var. japonica could survive in areas with heavy snow where it does not normally occur. Leaf net production (LNP) was estimated based on the microclimatic data and seasonal photosynthetic and respiration rates. The difference in the annual LNP between the two varieties was equivalent to the difference in the LNP during the snow season. One of the major effects of snow cover is to interrupt and reduce the production period of var. borealis.
Light environment and carbon gain of understory herbs associated with sunflecks in a warm temperate deciduous forest in Japan
Authors: Koizumi Hiroshi , Oshima Yasuyuki 
Published: March 2006

AbstractSeasonal variation in the light environment on the forest floor of a deciduous forest was investigated with special reference to sunflecks. Diurnal variations and seasonal changes in frequency and irradiation period of the sunflecks (sunfleck duration) were measured. The hourly total sunfleck duration varied seasonally; that is, 30–40 min in spring and autumn and about 15–20 min in summer. There was no large variation in the hourly sunfleck duration during daytime hours (from 9.00 to 15.00 h). The emergence frequency of sunflecks was 1.3–4.8 per h with two peaks, one in the morning and one in the afternoon. The mean duration of a sunfleck, however, showed a characteristic daily pattern with a peak around noon. Sunfleck duration was long around noon, ranging from 12 to 18 min, and short around 10.00 and 14.00 h, ranging from 6 to 10 min. Using the light photosynthesis curves of Pyrola japonica and Syneilesis palmata (Koizumi & Oshima 1985), the contribution of sunflecks to the dry matter production of these understory species was evaluated. It was shown that the sunflecks contributed 7–10% of the carbon gain in S. palmata, but only 2–3% of that in P. japonica.
The effect of long wave ultraviolet radiation (UV‐A) on the photosynthetic activity of natural population of freshwater phytoplankton
Authors: Kim Dong‐Sup , Watanabe Yasunori 
Published: March 2006

AbstractThe effect of ultraviolet radiation on diel changes and depth profiles of phytoplankton photosynthesis was studied in four temperate freshwater lakes. Photosynthetic oxygen production was determined by incubating lake water in light and dark bottles under various weather conditions. Half the light bottles were wrapped with sheets of vinyl chloride film to exclude light with wavelengths shorter than 400 nm. The inhibition of photosynthesis due to UV‐A (320–400 nm) was observed during most of the daytime and was very strong around noon on both sunny and cloudy days. On sunny days, when the surface waters of the highly eutrophic Lake Suwa and Senzoku Pond were dominated by dense Microcystis populations, cumulative daily production at the surface, estimated from the incubation of bottles from which UV‐A was excluded by the vinyl film, were about double the rates obtained from glass bottles in which UV‐A was present. The UV‐A inhibition was detected from the surface to ca 20 cm depth in hypereutrophic lakes and at depths greater than 50 cm in mesotrophic lakes. Analysis of the photosynthesis‐irradiance (P‐I) relationship obtained in the present study shows β, a parameter that describes photo‐inhibition, is higher in the presence of UV‐A than in its absence. This indicates that UV‐A is the major cause of photo‐inhibition of phytoplankton photosynthesis.
Respiration for maintenance and growth in Reynoutria japonica ecotypes from different altitudes on Mt Fuji
Authors: Mariko Shigeru , Koizumi Hiroshi 
Published: March 2006

AbstractRespiration for maintenance and growth of Reynoutria japonica ecotypes from altitudes of 700 and 2420 m on Mt Fuji were measured in two controlled thermal conditions. The maintenance respiration of the high‐altitude ecotype at both 15 and 25°C was significantly (1.7‐fold) higher than that of the low‐altitude ecotype, whereas growth respiration was independent of both ecotype and temperature. The temperature coefficient (Q10) of the maintenance respiration was about 1.9 in both ecotypes. The results show that there is ecotypic differentiation in the performance of maintenance respiration. It is suggested that the high maintenance respiration of the high‐altitude R. japonica ecotype is advantageous in severe upland environments but disadvantageous in a warm lowland climate in terms of carbon economy.
Protandry in the parasitoid Cardiochiles nigriceps, as related to its mating system
Authors: Hirose Yoshimi , Vinson S. B. , Hirose Yasuko 
Published: March 2006

AbstractA laboratory study was conducted of the emergence times and mating success of Cardiochiles nigriceps Viereck (Hymenoptera: Braconidae), a larval parasitoid of the tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), and in view of this information, the parasitoid's mating system was explored. Observations on laboratory populations of C. nigriceps confirmed the occurrence of two types of protandry, i.e. seasonal and diurnal; males emerged 2 days before females in a generation, and emerged about 1 hr before females on a given day. An experiment on mating success showed that newly emerged females are not receptive to males that emerged 1 hr earlier, but that these males and females often mate successfully after 1 more hr. The experiment also showed that 1‐ to 5‐day‐old males are more successful than 1‐hr‐old males in mating with 0‐ to 1‐hr‐old females. Thus, it is argued that males emerging on a given day have a disadvantage in competition for mates with males that emerged days earlier, and that this disadvantage may serve as a selection pressure toward diurnal protandry.A monogamous mating system for females of C. nigriceps is suggested because sexual selection would be expected to be strong in species exhibiting both seasonal and diurnal protandry. A possibility of a sibling mating system in C. nigriceps is questioned partly because newly emerged females are unreceptive to males that emerged 1 hr earlier and partly because this parasitoid is solitary in what is considered highly dispersed hosts in the field.
Growth and turnover of microbial biomass during the decomposition of organic matter(Polygonum cuspidatum) in vitro
Authors: Tateno Masaki 
Published: March 2006

AbstractAir‐dried fresh and dead specimens ofPolygonum cuspidatumwere incubated for 250 days in the laboratory, and the growth and turnover of microbial biomass‐C in the organic matter were studied. The biomass‐C in the fresh leaf and fresh stem attained maximum levels on day 14 and day 7, respectively, and then settled down to stable levels. In the dead leaf and dead stem, increase in biomass‐C ceased by day 4 and the biomass‐C levels did not change thereafter. The turnover time of the biomass‐C was estimated from the amount of biomass‐C and the release rate of CO2‐C. The turnover was rapid in the early period of incubation. Then the turnover time became longer and after incubation for 70 days the values approached those in natural soils (longer than 16 days). During the incubation period, nitrogen was not mineralized in any organic matter. In the dead leaf and dead stem, asymbiotic nitrogen fixation activity increased after incubation for about 40 days and disappeared by the end of the incubation period, whereas nitrogen fixation was hardly detected in the fresh leaf and fresh stem.
Relationship between specific leaf area of a Cryptomeria japonica foliage shoot segment and its diameter
Authors: Katsuno Masumi , Hozumi Kazuo 
Published: March 2006

AbstractDependency of specific leaf area (SLA) on shoot diameter (x) was studied for Cryptomeria japonica foliage shoot segments about 5 cm in length taken from 18 branches at different height levels on 3 trees in August 1987. The leaf area of a shoot segment (S) was defined as half the sum of the needle area (s) estimated by the allometric relationship between s and needle length. The dry weight of woody tissue (Ww) and needles (Wn) of a segment and its S were divided by the segment length (L) to give linear densities as Ww/L, Wn/L and S/L, respectively. The densities were related to x by power‐form equations. S/L values tended to be constant around 1.2 [cm2 cm−1] within the discussed range of x, while Ww/L and Wn/L values clearly increased with x. The approximately reciprocal relationship between average needle area (s) and linear density of the number of needles supported the fact that S/L values were roughly constant regardless of x. SLA and SNA were defined as S/(Ww+Wn) and S/Wn, respectively. The SLA‐x relationship expected from the average value of S/L and the Ww/L‐x and the Wn/L‐x relationships was well fitted to the observed decrease in SLA with increasing x. SNA also decreased as x increased. Variations in SLA and SNA among the shoot segments with similar x were not systematically related to their height levels. An empirical equation with a maximum value of x (Xmax) was also proposed in order to formulate the SLA‐x relationship.
Seasonal growth and biomass of Trapa japonica Flerov in Ojaga‐Ike Pond, Chiba, Japan
Authors: Kunii Hidenobu 
Published: March 2006

AbstractIn order to determine the seasonal growth and biomass of Trapa japonica Flerov, field observations were carried out at Ojaga‐ike Pond, Chiba, Japan, during 1979 and 1980. In spring, the plant showed exponential growth (c. 0.080 g g−1 day−1) and shoot elongation was as rapid as 10 cm day−1. The plant attained its maximum biomass (380.5±35.1 g m−2) in late August, and about 50% of this was concentrated in the topmost 30‐cm stratum (645.7±33.1 g m−3); maximum total stem length exceeded 6m. The plant produced large (500–800 mg per fruit), but small numbers of nut‐like fruit (maximum, 5 fruits per rosette). Defoliation occurred almost linearly with time at a rate of 30.6 leaves m−2 day−1; annual net leaf production was estimated to be about twice as large as the seasonal maximum leaf biomass. While the number of leaves per rosette showed moderate seasonal change, rosette density, rosette area and leaf dry weight changed considerably during the year. From the negative log‐log correlation between mean total leaf dry weight per rosette and rosette density, density‐dependent rosette growth was assumed. The cause of the wide spread of this species in aquatic habitats is briefly discussed in terms of its seed size and morphology.
Population dynamics of Japanese serow in relation to social organization and habitat conditions. II. Effects of clear‐cutting and planted tree growth on Japanese serow populations
Authors: Ochiai Keiji , Nakama Satoru , Hanawa Sin‐ichi , Amagasa Toshifumi 
Published: March 2006

AbstractPopulation responses of Japanese serow (Capricornis crispus) to clear‐cut logging and planted tree growth were studied by a direct count of the number observed in three areas, Takiyama (305 ha), Gentouziro (270 ha), and Tanokashira (324 ha), near Wakinosawa Village, Aomori Prefecture, Japan, during 1976–89. At Takiyama, a mature mixed forest of Thujopsis dolabrata var. hondai and Fagus crenata decreased from 73 to 39% coverage of the area due to clear‐cutting during 1978–83. The serow population maintained a relatively low stable density (3–6 individuals per km2) until 1985–87, and increased 5–10 years after the clear‐cutting, reaching 9–10 km−2 in 1988. At Gentouziro and Tanokashira, young plantations of Japanese cedar (Cryptomeria japonica) covered about half of each area. The population densities between 1980 and 1983 were relatively high (14–19 km−2), but declined thereafter, reaching 10–14 km−2 in 1988–89. These results indicated that the density increase resulted from an improvement of food supply due to growth of scrub following the clear‐cutting, and that the density decline resulted from a habitat change due to growth of planted Japanese cedar and a decrease in the food supply. In Wakinosawa Village, serow density began to increase 5–10 years after forest cutting, and the high population density, about three‐ or six‐fold larger than that in mature forest, is expected to be maintained for about 20 years after logging.
Altitudinal variations in germination and growth responses of Reynoutria japonica populations on Mt Fuji to a controlled thermal environment
Authors: Mariko Shigeru , Koizumi Hiroshi , Suzuki Jun‐ichirou , Furukawa Akio 
Published: March 2006

AbstractThe authors examined altitudinal variations in the thermal responses of seed germination and seedling growth in Reynoutria japonica (=Polygonum cuspidatum) under controlled environmental conditions. Seed populations were collected from different altitudes on Mt Fuji in Japan. The mean seed weight of the upland populations (above 1500 m) was significantly (1.5‐fold) heavier than that of the lowland populations (below 1400 m). Under the lowest temperature regime of 15/10°C (day/night) the upland populations showed a significantly higher percentage and speed of germination than the lowland populations; this was not significant under higher temperature regimes. These results indicate that the germination traits of the upland populations on Mt Fuji are favorable for colonization in their cold habitats (low temperature and short growing season). Growth and shoot development were compared between the seedlings grown from seeds collected at altitudes of 700 and 2420 m. The upland seedlings showed a significantly larger biomass and leaf area than the lowland seedlings at 15°C, but there was no difference at 25°C. The difference in biomass at 15°C was attributed to the difference in seed weight. The upland seedlings produced a significantly larger number of branches with smaller and more numerous leaves at both 15°C and 25°C. these developmental traits of the upland seedlings were considered to represent the adaptation of the life form to upland environments. It was concluded that the R. japonica populations along an altitudinal gradient on Mt Fuji can be classified into two ecotypes, whose distribution border lies at an altitude of about 1400–1500m. In this study, the seed weight and germination traits of two R. japonica seed populations collected in Chiba Prefecture were briefly compared with those of the lowland populations on Mt Fuji.
Pine forest structure in a human‐dominated landscape system in Korea
Authors: Kamada Mahito , Nakagoshi Nobukazu 
Published: March 2006

AbstractTo elucidate the characteristics of spatial heterogeneity in a human‐dominated landscape, vegetation and community structure of pine (Pinus densiflora and P. rigida) forests were studied at rural Teokseong‐ri in Chollanam‐do, in the southwestern part of Korea. Daily removal of undergrowth for firewood affects the stratification and species composition in the community. In general, stratification of the pine forest develops in proportion to its distance from the main habitat of farmers, involving the residential and cultivated land. In pine forests near the main habitat of farmers, sun‐demanding herbaceous plants grow well, while in remote forests, Fagaceous plants such as Quercus serrata, Q. actissima and Castanea crenata grow well. This zonation results from the fact that removal of undergrowth is greater in the forest near the main habitat of farmers, than in the remote forest. Construction and maintenance of graveyards, however, prevents development of stratification of the forest even in remote stands.
Male‐male competition and mating success in the orb‐web spider, Nephila clavata, with reference to temporal factors
Authors: Miyashita Tadashi 
Published: March 2006

AbstractSeasonal occurrence patterns of adults of both sexes, intensity of male‐male interactions, and mating success in the spider, Nephila clavata, were examined in the field. Adult males began to attend female webs about 2 weeks before female maturation. Large adult males were abundant in the early breeding season, but small males increased later in the season. From the distribution of males among female webs and size relationship of males within a web, male‐male interactions seemed to be more intense when most females were still subadult. This was verified by a field experiment in which males were artificially introduced to female webs that were attended by other males. It was found that the probability of introduced males remaining on subadult female webs was lower than that on adult webs. As mating occurred mostly in the period shortly after the female final molt and first male sperm precedence was known in all spiders reported so far, intense male‐male competition on subadult female webs seemed to be reasonable. Male longevity had an important influence on the mating success of males with just‐molted females. Mating success was also affected by the relative body size of males present in a given period. Since larger males occupied the position closest to females within a web and stayed there longer, relative body size appeared to influence mating success through male‐male competition. Female body size at maturation declined with time; hence, males that attained sexual maturity earlier had the advantage of mating with larger and more fecund females. Therefore, early maturation as well as larger size seem to be two important trairs influencing the reproductive success of males.
Germination of Rubus palmatus var. coptophyllus and R. microphyllus seeds buried in soil for 7.5 years
Authors: Suzuki Wajirou 
Published: March 2006

AbstractSeeds of two Rubus species, R. palmatus var. coptophyllus and R. microphyllus, buried for 7.5 years in soil were subjected to germination tests to investigate their germinability and germination traits. Most of the retrieved seeds were viable, and germinated at the alternating temperatures of 20/30°C in both light and dark. The two Rubus species showed similar responses of germination to temperature and light, although the final percentages of germination were slightly higher in R. palmatus var. coptophyllus. These characteristics of seed dormancy and germination would be involved in the species' utilization of ephemeral habitats created by unpredictable and infrequent disturbances.