bluuebunny/crossref_metadata_2025_split huggingface dataset:
Canopy photosynthetic production in a Japanese larch forest. II. Estimation of the canopy photosynthetic production
Authors: Kurachi Nahoko , Hagihara Akio , Hozumi Kazuo 
Published: March 2006

AbstractSeasonal changes and yearly gross canopy photosynthetic production were estimated for an 18 year old Japanese larch (Larix leptolepis) forest between 1982 and 1984. A canopy photosynthesis model was applied for the estimation, which took into account the effect of light interception by the non‐photosynthetic organs. Seasonal changes in photosynthetic ability, amount of canopy leaf area and light environment within the canopy were also taken into account. Amount of leaf area was estimated by the leaf area growth of a single leaf. The change of light environment within the canopy during the growing season was estimated with a light penetration model and the leaf increment within the canopy. Canopy respiration and surplus production were calculated as seasonal and yearly values for the three years studied. Mean yearly estimates of canopy photosynthesis, canopy respiration and surplus production were 37, 13 and 23 tCO2 ha−1 year−1, respectively. Vertical trend, seasonal changes and yearly values of the estimates were analyzed in relation to environmental and stand factors.
A preliminary study of nectar production of the field cress, Rorippa indica, in relation to the age of its flowers
Authors: Muraoka Kazuyuki , Watanabe Mamoru 
Published: March 2006

AbstractFloral nectar production quantity and changes in sugar concentration of the nectar of Rorippa indica were investigated. Flowers were sorted by age. The small flower size was a major factor for the use of BCG test paper in nectar sampling. In flowers of the youngest age category, the nectar volume increased toward the night and decreased during the day. The amount of sugar in the nectar decreased with flower age. The sugar concentration was lower at night than daytime. The variability and changes in nectar concentration enabled various species of insects to forage for nectar.
Carbon stock and cycling in a bamboo Phyllostachys bambusoides stand
Authors: Isagi Yuji 
Published: March 2006

AbstractGross production and carbon cycling in a Phyllostachys bambusoides stand in Kyoto Prefecture, central Japan, were determined, and then a compartment model showing the carbon stock and cycling within the ecosystem was developed. Aboveground carbon stock was 52.3 tC ha−1, increasing at a rate of 3.6 tC ha−1 year−1. Belowground carbon stock was 20.8 tC ha−1 in the root system and 92.0 tC ha−1 in the soil. Aboveground net production was 11.2 tC ha−1 year−1. Belowground net production was crudely estimated at 4.5 tC ha−1 year−1. The gross production was estimated at 41.8 tC ha−1 year−1 by summing the amount of outflow to the environment and the increment in biomass. Leaves consumed 13.7 tC ha−1 year−1 by respiration; the rest (41.8−13.7=28.1 tC ha−1 year−1) was surplus production of the leaves and flowed into the other compartments. The amounts of construction and maintenance respiration of the aboveground compartments were 3.4 and 18.5 tC ha−1 year−1, respectively. The annual amount of soil respiration was 11.2 tC ha−1 year−1. Soil respiration levels of 4.3 and 3.1 tC ha−1 year−1 were estimated for the flow of root respiration and root detritus. The proportion of net to gross production was 37%, which fell within the range of young and mature forests. A shorter life span of culms, compared to tree trunks, resulted in smaller biomass accumulation ratio (biomass/net production) in the ecosystem, of 4.66.
The regeneration of pioneer tree species under browsing pressure of Sika deer in an evergreen oak forest
Authors: Shimoda Katsuhisa , Kimura Katsuhiko , Kanzaki Mamoru , Yoda Kyoji 
Published: March 2006

AbstractThe effects of Sika deer (Cervus nippon) browsing on the regeneration of pioneer species were studied in relation to canopy gaps in a warm temperate evergreen oak forest in Kasugayama, Nara City. Four study sites, three in canopy gaps and one under a closed canopy, were selected and each divided into fenced and unfenced plots. Under the closed canopy, seedlings of all the pioneer species died irrespective of browsing pressure. However, in the canopy gap sites, seedlings of the pioneer species could establish and grow well. The seedling survival ratio in the fenced plots in the canopy gaps was >60% 1 year after germination. However, in the unfenced plots, only <20% of the seedlings survived 1 year, with all dying within 3 years after germination. Thus, the regeneration of pioneer trees in this forest was strongly inhibited by deer browsing. Successful regeneration of a pioneer, Zanthoxylum ailanthoides, occurred for several years even after two major wind disturbances during the past 90 years. This may be due to less browsing pressure from the deer.
Comparative analyses on food habits of Japanese marten, Siberian weasel and leopard cat in the Tsushima islands, Japan
Authors: Tatara Masaya , Doi Teruo 
Published: March 2006

AbstractFood habits of three sympatric carnivore mammals in the Tsushima islands of Japan were studied during 1986–91. Scats of the Tsushima marten (n=1236), the Siberian weasel (n=218) and the Tsushima leopard cat (n=350) were collected monthly and the food items were determined by scat contents analysis. Marten was omnivorous showing a high level of diversity of food throughout the year. The important foods for marten were fruits and berries from spring to autumn, insects in summer and autumn and small mammals all year round. Leopard cat preferred to hunt wood/mice and birds, and remained a flesh meat specialist throughout the year. Weasel was intermediate between marten and leopard cat, but was slightly biased towards the flesh meat eater. The three carnivores do not compete against one another for food, except for small rodents. A conflict for food between leopard cat and weasel was suggested to be more intense than that of other combinations based on diet overlapping. Marten may be characterized as an opportunistic generalist. When interspecific competitors existed, or human disturbance to the habitat occurred, the preferential flexibility of the marten to alternative food resources might become more advantageous than the other two species.
Effects of leaf blade narrowness and petiole length on the light capture efficiency of a shoot
Authors: Takenaka Akio 
Published: March 2006

AbstractEffects of the length: width ratio of a leaf blade and petiole length on shoot light capture were studied with computer simulation. Both a larger length: width ratio and longer petiole contributed to larger light capture per unit leaf area due to a reduced aggregation of leaf area around the stem. Other conditions being equal, shoots with narrow leaves and no petioles and those with wide leaves with petioles showed similar light capture as long as the mean distance of the leaf blade from the stem was the same. In shoots with a short internode and/or distichous phyllotaxis, however, narrow leaves contributed more to avoiding mutual shading than wide leaves with petioles. The predominance of light coming from a higher angular altitude also favored narrow leaves. The possible consequences of these results in the adaptive geometry of plant architecture are discussed.
Female reproductive cycles in the northernmost populations of the two gekkonid lizards, Hemidactylus frenatus and Lepidodactylus lugubris
Authors: Ota Hidetoshi 
Published: March 2006

AbstractLepidodactylus lugubris, a parthenogenetic gekkonid lizard of possible tropical origin, occurs on Kita‐Daitojima Island of the Ryukyu Archipelago and lays eggs almost throughout the year. The oviposition season of the sympatric population of another primary tropical, but bisexual gecko, Hemidactylus frenatus, is confined to between April and September. Laboratory experiments indicate that the hatching ratio of the egg reduces with the decrease of incubation temperature in both species. Some eggs of L. lugubris develop at 14°C of ambient temperature, wheras eggs of H. frenatus always die at temperatures of 18°C or lower. Examinations of stomach contents and fat body mass in the monthly samples suggest that food availability is not severely low for the geckos even during the winter, rejecting the previous assumption that food stress suppresses vitellogenesis in H. frenatus. No other environmental factors that may induce reproductive seasonality as phenotypic physiological responses were detected either. Tropical populations of H. frenatus and L. lugubris are known to lack distinct annual reproductive cyclicity. Thus, it is probable that the East Asian H. frenatus has evolved the winter quiescence of reproduction, presumably due to the poor embryonic tolerance of low temperatures. The absence of such seasonality in the sympatric L. lugubris seems to be attributable to its clonal nature which predicts the low genetic variability of the population from the colonization stage.
Classification and ordination of communities of soil arthropods in an urban park of Osaka City
Authors: Natuhara Yoshihiro , Imai Chobei , Takeda Hiroshi 
Published: March 2006

AbstractTo assess the effect of management of a park on soil arthropods, communities of Oribatida and Collembola were analyzed at 11 sites of different vegetation in Tsurumi Park, an urban park of Osaka City. The type of canopy layer and soil density strongly affected the community parameters, such as species diversity. Ordination revealed that soil density, contents of organic matter, and shrub layer were important for variety in the oribatid community; the shrub layer was important for the collembolan community. Species richness of both arthropod groups was highest in a mixed forest and lowest on bare land, while the abundance of Collembola was highest on a lawn site. Areas of a common vegetation type had a similar oribatid community;Trichogalumma nipponica dominated in deciduous forests, Eohypochthonius crassisetiger in mixed forests and one of coniferous forests. On the other hand, collembolan communities did not correspond with the vegetation. Sminthurinus sp. was collected from every site, and the most abundant species was Cryptopygus thermophilus that exhibited an outbreak on lawn sites. A significant correlation existed between species diversities but not between abundances of Oribatida and Collembola.
Abundance patterns of soil micro‐arthropods at aPinus pumilascrub in an alpine range of central Japan
Authors: Hijii Naoki 
Published: March 2006

AbstractSeasonal changes in abundances of major soil micro‐arthropods were assessed at aPinus pumilascrub in an alpine range of central Japan during a period with no snow coverage. The total abundance showed a peak in late August, reaching no less than 140 000 m−2, which was comparable to that in an evergreen coniferous plantation in the cool‐temperate zone. Collembola was the most dominant group of soil micro‐arthropods, comprising about 50% of the total, followed by oribatid mites (Acari [O]) occupying 20%. Annual mean air temperature was no more than 2.1 °C and the daily fluctuation in temperature was less in soil layers. The thickness of the A0layer reached 9–10 cm and soil organic matter accumulation was estimated to be 45–58 ton dry weight ha−1. The large amount of litterfall and organic matter accumulation in the soil, comparable to those of sub‐alpine evergreen coniferous forests, and a lower decomposition rate due to severe environmental conditions, suggest the relative importance of litter processing by soil micro‐arthropods such as Collembola and Acari, especially in alpine regions.
Aboveground net production and dry matter allocation of Pinus pumila forests in the Kiso mountain range, central Japan
Authors: Kajimoto Takuya 
Published: March 2006

AbstractAboveground net production rates of the subalpine stone pine (Pinus pumila) forests in central Japan were estimated by the summation method; net production was defined as the sum of annual biomass increment and annual loss due to death. In the two pine stands of different scrub heights, P1 (200 cm) and P2 (140 cm), aboveground biomass reached 177 and 126 ton ha−1, respectively. Leaf biomass was about 14 ton ha−1 in each stand. The estimates of aboveground net production during the 2 year period (1987–1989) averaged 4.1 and 3.7 ton ha−1 y−1 in P1 and P2, respectively, which were at the lowest among the pine forests in the world. Two indices of efficiency of energy fixation, that is, the ratio of net production to the total radiation during a growing season and the ratio of net production to total radiation per unit of leaf weight, were evaluated. Both efficiency indices for the two P. pumila stands fell in the range obtained for other Japanese evergreen conifer forests. This suggested that the low annual net production of the stone pine stands were mainly due to a limitation in the length of the growing season. The pine forests were also characterized by a small allocation (about 17%) of aboveground net production into biomass increment, in comparison with other evergreen conifer forest types. Annual net carbon gain in the P. pumila forests was suggested to be largely invested in leaf production at the expense of the growth of woody parts.
Seedling establishment ofPolygonum cuspidatumandPolygonum weyrichiivar.alpinumat high altitudes of Mt Fuji
Authors: Maruta Emiko 
Published: March 2006

AbstractSeedling establishment ofPolygonum cuspidatum(Seib. et Zucc.) andPolygonum weyrichii(F. Schmit) var.alpinum(Maxim.), dominant early‐successional species in a volcanic gravel area on Mt Fuji, Japan, was compared for current‐year seedlings at 2500 m a.s.l. The rate of survival in the first winter after germination at 2500 m was 2% and 24% forP. cuspidatumandP. weyrichiiseedlings, respectively, and correlated with the upper distribution limit of each (2500–2600 m forP. cuspidatum; 3200–3300 m forP. weyrichii). The critical size for survival was 12 mg dry weight for overwintering current‐year seedlings of both species. At 2500 m, the percentage of seedlings that attained the critical size for survival at the end of the first growing season was 19% and 85% forP. cuspidatumandP. weyrichii, respectively. Growth curves indicated that the larger‐seeded characteristic ofP. weyrichiicontributed to larger end‐of‐season size and resulted in higher rate of seedling survival at 2500 m, compared with smaller‐seededP. cuspidatum. Current‐year seedlings ofP. weyrichii, at least up to 3250 m, attained the first year annual growth critical for overwintering and therefore for successful seedling establishment, due to the large‐seeded characteristic. At the top (3770 m) beyond the upper distribution limit ofP. weyrichii, most seedlings raised artificially failed to attain the critical size for survival in the first growing period due to the reduced growing period. Failure of seedling establishment would thus appear to restrict the distribution of the species at altitudes higher than 3300 m.
A mass‐mortality of Sika deer on Kinkazan Island, northern Japan
Authors: Takatsuki Seiki , Suzuki Kazuo , Suzuki Ikuo 
Published: March 2006

AbstractA Sika deer (Cervus nippon) population had been maintained at a level of around 600 head on Kinkazan Island (960 ha), northern Japan during the 1970s and the early 1980s. However, in the spring of 1984 which followed an uncommonly cold winter, a mass‐mortality occurred and about half of the deer population died. A total of 293 recovered carcasses indicated that many had died during a short period (late March and mid‐April). More carcasses were found in the lower altitudinal areas than expected numbers relative to area sizes, suggesting that the deer had moved down from the higher areas to avoid snow. Rumen contents of the carcasses contained much low quality food. Malnutrition caused by the exceptional coldness and late snow was considered to be the factor responsible for mortality.
Role of interspecific competition in the coexistence of Apodemus argenteus and A. speciosus (Rodentia: Muridae)
Authors: Sekijima Tsuneo , Sone Koichi 
Published: March 2006

AbstractReciprocal‐removal experiments with two replicates were conducted to test for the role of interspecific competition in the coexistence of Apodemus argenteus and A. speciosus. Population density, rate of appearance of new (unmarked) individuals, reproduction, survival rate and habitat use were monitored during pre‐ and removal periods. In both removal experiments, the removal of A. argenteus had little effect on A. speciosus, while that of A. speciosus affected several population characteristics of A. argenteus. Namely, the removal of A. speciosus shifted the distribution of A. argenteus to the habitat with a denser shrub cover in one experiment. Also, the removal increased the population densities and appearance rates of new individuals of A. argenteus in another experiment. Interspecific interactions between the two species appeared to be a one‐way action from A. speciosus to A. argenteus. In removal periods in both experiments, the rates of appearance of new individuals in each species were the highest on the grid where that species was removed. These results suggest that, though interspecific competition occurred between the two species, intraspecific competition had greater effects than interspecific competition on the abundance and habitat use of A. argenteus and A. speciosus. This implies that the fundamental niches of A. argenteus and A. speciosus differ potentially, which may play an important role in the coexistence of the two species.
Forest canopy structure analyzed by using aerial photographs
Authors: Nakashizuka Tohru , Katsuki Toshio , Tanaka Hiroshi 
Published: March 2006

AbstractA method was developed using aerial photographs to analyze forest canopy structure. Digital elevation models of both the land and canopy surface in a mesh of 5 m intervals were made from aerial photographs taken in winter (without tree leaves) and summer (with leaves), respectively, in a 60 ha area of temperate deciduous forest. The difference between the two elevation values at each point was regarded as the canopy height, and a canopy height profile was constructed. The estimated canopy structure was compared with that obtained by ground observations in a 6 ha part of the study area. Large gaps (>100 m2) were adequately detected by the method, and the gap size distribution obtained was similar to the one observed on the ground. The method was found to be effective in analyzing the forest canopy structure of large areas, but it is not suitable for the detection of small gaps.
Gap characteristics and gap regeneration in subalpine old‐growth coniferous forests, central Japan
Authors: Yamamoto Shin‐Ichi 
Published: March 2006

AbstractGap characteristics and gap regeneration were studied in three old‐growth stands of subalpine coniferous forests in the northern Yatsugatake and the northern Akaishi mountains, central Japan. With the results of the present study and those of a previous study conducted in another locality, general features of gap characteristics and gap regeneration behavior of major tree species in subalpine coniferous forests of central Japan were summarized and discussed. Of the total 237 gaps investigated in the 14.48 ha of forested area, the percentage gap area to surveyed area, gap density and mean gap size were 7.3%, 17.2 ha−1, and 43.3 m2, respectively. The gap size distributions were similar among stands and showed a strong positive skewness with a few large and many small gaps; gaps <40m2 were most frequent and those >200 m2 were rare. Gaps due to the death of multiple canopy trees comprised 44.7% of the total ones. Canopy trees died in various states; standing dead (42.6%) or trunk broken (43.7%) were common and uprooted (12.2%) was an uncommon type of death of canopy trees. These figures indicate that general features of gap characteristics in this forest type are the low proportion of gap area and the high proportions of small gap size and multiple‐tree gap formation. In general, shade‐tolerant Abies frequently, and Tsuga, infrequently, regenerate in gaps from advance regenerations recruited before gap formation, while Picea and shade‐intolerant Betula possibly regenerate in gaps from new individuals recruited after gap formation. Gap successors of conifers occurred in a wide range of gap size and did not show the clear preference to species specific gap size. In old‐growth stands without large‐scale disturbance (≥0.1 ha in area) of subalpine coniferous forests of central Japan, major tree species may coexist with their different gap‐regeneration behaviors and, probably, different life history traits.
Feeding, reproductive and locomotor activities in diapausing and non‐diapausing adults of Drosophila
Authors: Matsunaga Katsutoshi , Takahashi Hiroshi , Yoshida Takao , Kimura Masahito T. 
Published: March 2006

AbstractFeeding, reproductive and locomotor activities of four Drosophila species were studied under short and long daylengths at 15°C. A short daylength induced firm reproductive diapause in experimental strains of D. subauraria and D. triauraria from northern Japan, but very shallow diapause in those of D. lutescens and D. rufa from southern Japan. A subtropical strain of D. triauraria had no diapause. The influence of diapause on feeding activity was detected only in aged (> 12 day old) females; that is, the feeding activity was lower in diapausing females than in non‐diapausing ones. Females that do not produce eggs would not require so much energy. On the other hand, young adults of the study species exhibited a high feeding activity and rapidly increased bodyweight irrespective of sex and the diapause state. They would need nutrition to build up their adult body. In males, the feeding activity decreased with age irrespective of the diapause state. Males would not require so much energy for reproductive activity. Diapausing males became heavier than non‐diapausing males, perhaps because they accumulated triacylglycerols in fat bodies. However, female bodyweight did not differ by the diapause state, perhaps because diapausing females accumulated triacylglycerols and reproducing females had eggs in their ovaries. In D. triauraria, diapausing individuals exhibited somewhat lower locomotor activity than non‐diapausing ones.
A 5 year study of litter decomposition processes in aChamaecyparis obtusaEndl. forest
Authors: Takeda Hiroshi 
Published: March 2006

AbstractDecomposition of needle litter in aChamaecyparis obtusaforest was studied over a 5 year period using a litter bag method. Organic matter, nitrogen and carbon mass and faunal abundance were monitored. The pattern of weight loss was represented by three phases: the initial leaching of carbon and nitrogen (0–3 months), nitrogen immobilization (3–15 months), and nitrogen mobilization (15–60 months). The decomposition rate of needle litter was expressed by Olson's decomposition constant (k) which was−0.113 over a 5 year period. The decomposition rate decreased with the advance of decomposition processes. The role of soil fauna in the decomposition process was assessed by comparing decomposition rates between the control and defaunated plots. In the leaching phase, soil animals had no significant role in the decomposition processes. During the immobilization phase, soil animals contributed to the immobilization processes through their grazing activities, and there were significant differences in weight loss between the control and defaunated plots. In the mobilization phase, saprovorous soil animals such as Collembola and Acari contributed to the mobilization processes by feeding on decomposing litter. Decomposition processes observed in this study were compared with other similar studies.