bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance and phenology of alpine herbs along a snow‐melting gradient
Authors: Kudo Gaku
Published: March 2006

Responses 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

Herbaceous 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

Annual 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

Spatial 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

The 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

A 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.
Marine ecosystem dynamics: Comparison of scales
Authors: Steele John H.
Published: March 2006

When marine and terrestrial ecological systems are compared at the same time scales, there are very great differences in their relations with their physical environments. Similarities arise when comparisons are made at different time scales. There are significant consequences for management.
Early herbaceous succession along a topographical gradient on forest clear‐felling sites in mountainous terrain, central Japan
Authors: Ohtsuka Toshiyuki , Sakura Tsuguo , Ohsawa Masahiko
Published: March 2006

Early successional patterns of herbaceous communities in forest clear‐felling sites were investigated along a topographical gradient, which included ridge, slope and valley habitat types, in warm‐temperate evergreen forest regions of central Japan for 5 years. Three dominant species with wind‐dispersed seeds played a major role in the succession: an annual, Crassocephalum crepidioides, a biennial, Erigeron canadensis, and a perennial, Miscanthus sinensis. Pioneer herbs that have a seed‐bank strategy, which are common in old field succession, were not found in the mountainous sites. The persistence of the annual or biennial dominants during the very early stages of secondary succession was different in the three topographical habitat types. In the ridge habitat, M. sinensis dominated from the first year state, and C. crepidioides and E. canadensis were less prominent. Crassocephalum crepidioides and E. canadensis became dominant as one moved down the slope. In the valley habitat, C. crepidioides dominated in the first year stage, was succeeded by E. canadensis in the second year, and then M. sinensis gradually replaced it in later years. As all three wind‐dispersed dominants simultaneously invaded in all the habitat types after clear‐felling, the different successional patterns along the topographical gradient might have resulted from differences in the establishment ability and the growth rate of the three dominants depending on the three habitat types.
Stand structure and dynamics of wave‐type Abies sachalinensis coastal forest
Authors: Sato Toshihiko
Published: March 2006

Stand structure and regeneration pattern were examined in Abies sachalinensis coastal forest in northern Hokkaido. In the forest a similar phenomenon to the wave regeneration in subalpine forests has been found. Wave regeneration has been reported for montane Abies forests in central Japan and North America. Differences and similarities between wave‐type stands in this coastal forest and wave‐regenerated montane forests were clarified.

The shift of dead tree zone, stand structure and regeneration pattern in wave‐type stands are the same as in subalpine wave‐regenerated forests. High density of individuals is considered to be an internal factor which causes stand‐level dieback and also enables the stands to persist in the severe environment in both forests.

A difference between wave‐regenerated forests and A. sachalinensis wave‐type stands is the number of dead tree zones, which is only one in wave‐type stands. Changes of regeneration patterns of Abies sachalinensis with environmental gradient from seaward to inland were related to this difference.
Influence of vegetation and soil types on the wheatbelt termite, Drepanotermes tamminensis (Hill), in the Western Australian wheatbelt
Authors: Park H. C. , Majer J. D. , Hobbs R. J.
Published: March 2006

A survey of the distribution and density of mounds of the harvester termite, Drepanotermes tamminensis (Hill), was carried out in the Durokoppin Nature Reserve, Western Australia in 1990. Vegetation and, to a lesser extent, soil type, appear to be important factors in determining density and distribution of termite mounds within the Reserve. A more detailed study of mounds in Wandoo (Eucalyptus capillosa) woodland and Casuarina (Allocasuarina campestris) shrubland indicated that the total number and size of mounds were significantly higher in the woodland than in the shrubland. The total wet weight biomass of D. tamminensis was calculated as 3.74 gm−2 (37.4 kg ha−1) in the woodland and 1.69 gm−2 (16.9 kg ha−1) in the shrubland. Thus, of the two favored habitats, Wandoo woodland appears to be more optimal for this termite species than the Casuarina shrubland.
Male emergence timing and mating success in the funnel‐web spider, Agelena limbata (Araneae: Agelenidae)
Authors: Masumoto Toshiya
Published: March 2006

Field observations on the relationship between male mating success and emergence timing in the funnel‐web spider, Agelena limbata, were conducted. Agelena limbata is an annual species and adult males appear slightly earlier than adult females in July. As males deposit a copulatory plug at the female epigynum after copulation, copulation with virgin females is important to males. The number of copulations in males with virgin females, which strongly correlates with the longevity of males and the number of females that males courted, did not correlate with the emergence timing of males. Early emerged males and females were significantly larger in size than later ones, but the correlation coefficient between the emerged date and the cephalothorax width was not strong. Males that emerged earlier did not have any advantage in copulating with larger and more fecund females. Furthermore, virgin females first copulated on average 7.9 days after their final molt and the mortality rate of adult males increased after the final molt. These factors may favor the smaller degree of protandry in male emergence timing in A. limbata.
Seasonal change in the food habits of the Iriomote cat Felis iriomotensis
Authors: Sakaguchi Noriaki , Ono Yuiti
Published: March 2006

The food habits of the Iriomote cat Felis iriomotensis were studied by analyzing 177 feces collected monthly from 1987 to 1988. A total of 26 food items were identified. The frequency of lizards and frogs in the feces was higher than those of mammals and birds. The food habits changed greatly seasonally. Eumeces skinks were fed on most frequently, and found in the feces with a similar high frequency occurrence in March–April and July–September, while their proportion to the total number of food items was larger in March–April than in July–September. The cats fed on larg‐sized skinks, adult Eumeces kishinouyei, more in March–April than in other seasons. The number of skinks sighted in the course of a road census was greater from March to August, and large‐sized skinks were sighted more in March–April than in July–August. The cats fed selectively on large‐sized skinks in every season. Therefore, changes in the food habits depended on the food availability. Characteristics of food habits in the Iriomote cat are discussed in comparison with the food habits of other felids in temperate and tropical regions.
Optimal strategy of plant antiherbivore defense: Implications for apparency and resource‐availability theories
Authors: Yamamura Norio , Tsuji Nobuyuki
Published: March 2006

Plants produce chemicals as methods against animal herbivory. Such chemical defenses are classified into two major categories: (i) quantitative defenses with massive production of indigestible substances; and (ii) qualitative defenses with production of poisonous substances. A mathematical model was developed that identified factors that favored the evolution of quantitative defenses. Selecting an annual plant for simplicity, the allocation of photosynthetic production between growth substances and defense substances was considered. If the plant invests more in defense substances, it can protect itself more efficiently from herbivory but with a reduced growth rate. If it invests more in growth substances, the contrary holds. Using Pontoryagin's maximum principle, the following results were obtained: (i) the plant should conduct quantitative defenses when the growth rate (G), reflecting resource‐availability, is low and the growth period (T) is long as well; (ii) if the plant invests in quantitative defenses, the optimal proportion of defense substances (χ*) should be higher as G is smaller, but it is independent of T; and (iii) the value of χ* is not monotone for the effectiveness of defense substance (A), but has a maximum at an intermediate value of A. Predictions of the model partly supported both Feeny's apparency theory, claiming that apparent plants or their parts for herbivores should quantitatively defend themselves, and Coley's resource‐availability theory, claiming that plants with rich resources should invest in growth rather than defense.
Population dynamics of the whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), in Java, Indonesia, with special reference to spatio‐temporal changes in the quantity of food resources
Authors: Hirano Kohji , Budiyanto Erma , Swastika Nyoman , Fujii Koichi
Published: March 2006

Six monitoring plots were established in the northern part of West Java, Indonesia, to clarify the factors that influence population fluctuations of the whitefly, Bemisia tabaci. Yellow sticky traps were used to monitor adult populations. To examine the relationship between the population fluctuations and the quantity of food resources, the quantity of food resources of B. tabaci (i.e. soybean and mung bean) was also investigated routinely in each subdistrict where the experimental plot was located. The maximum number of adults per trap in each sowing season showed a similar noticeable seasonal trend in all experimental plots. Climatic factors did not have a major role to play in population fluctuations. The number of adults per trap in each experimental plot tended to increase when the quantity of food resources in each subdistrict increased. The changes of the quantity of food resources seemed to influence the population fluctuations. It is suggested that the operation of regulatory processes in population density is influenced largely by both the distance between habitat patches and the amplitude of temporal fluctuations of the quantity of food resources. An explanation for why the time lag between fluctuations of the quantity of food resources and the number of individuals of B. tabaci occurred is discussed. Based on their flight ability and intrinsic rate of natural increase, B. tabaci is considered not to be a serious pest in the environment where the host plants are grown discontinuously in time and space.
Root respiration rate before and just after clear‐felling in a mature, deciduous, broad‐leaved forest
Authors: Nakane Kaneyuki , Kohno Takahiro , Horikoshi Takao
Published: March 2006

Soil respiration was measured throughout the year (June 1992 to May 1993) in a mature, deciduous, broad‐leaved forest and an adjacent, clear‐felled stand which was made in November 1991, in Hiroshima Prefecture, west Japan. The same soil temperature and soil moisture content as those in the forest stand were maintained in two frame boxes covered with sheets of white netting in the clear‐felled stand to observe soil respiration. A herbicide was applied to the cut end of all stumps in one of the two frame boxes in order to kill the root system. There was no significant difference in the aboveground biomass and soil environmental conditions between the forest and the frame boxes in the clear‐felled stands. The difference in soil respiration rate between the forest and the frame box, in which the root system was killed by the herbicide, was considered to be due largely to the contribution of root respiration. Taking into consideration CO2 evolution due to the decomposition of roots killed and the change in A0 layer respiration rate after clear‐felling, the proportion of root respiration to the total soil respiration before clear‐felling was estimated to be 51% annually, which coincides closely with those values estimated previously in mature forests by other methods. The difference in the soil respiration rate between the two frame boxes (one with killed roots and the other with undisturbed roots) suggested that the annual root respiration rate just after clear‐felling dropped to about two‐thirds (70%) of that before clear‐felling.
Comparisons of nutrient recovery and specific leaf area variation between Carex lasiocarpa var. occultans and Carex thunbergii var. appendiculata with reference to nutrient conditions and shading by Phragmites australis
Authors: Onimaru Kazuyuki , Yabe Kazuo
Published: March 2006

The distribution of two sedge species was studied in two mires which differ in abiotic environments and in distribution of Phragmites australis. Carex lasiocarpa var. occultans dominated in nutrient‐poor valley mire, and Carex thunbergii var. appendiculata dominated in nutrient‐rich flood plain subject to water fluctuations. Phragmites australis grew well in nutrient‐rich conditions. The distribution of C. lasiocarpa showed a strong negative correlation with P. australis coverage, whereas C. thunbergii coverage was not affected by P. australis. The leaf area per dry leaf mass (specific leaf area: SLA) of C. thunbergii increased with shading by P. australis, but that of C. lasiocarpa was stable. The SLA flexibility of C. thunbergii to light interception might enable this species to invade P. australis patches in nutrient‐rich environments. The residual nutrient ratio of nitrogen and phosphorus (the ratio of the residual nutrient content at the end of the growing season to peak nutrient content) in the vegetative ramet of C. thunbergii was 1.7 times higher than that of C. lasiocarpa. This low residual ratio may indicate effective nutrient recovery to storage organs. The effective nutrient recovery in C. lasiocarpa might enable this species to grow even in nutrient‐poor environments. However, it may be difficult for C. lasiocarpa to expand its habitat to nutrient‐rich areas where P. australis dominates as it is not shade tolerant.
Culm recruitment, dry matter dynamics and carbon flux in recently harvested and mature bamboo savannas in the Indian dry tropics
Authors: Tripathi S. K. , Singh K. P.
Published: March 2006

Culm recruitment, standing crop biomass, net production and carbon flux were estimated in mature (5 years after last harvest) and recently harvested bamboo (Dendrocalamus strictus (Roxb.) Nees) savanna sites in the dry tropics. During the 2 study years bamboo shoot recruitment was 1711–3182 and 1432–1510 shoots ha−1 in harvested and mature sites, respectively. Corresponding shoot mortality was 66–93% and 62–69%, respectively. Total biomass was 34.9 t ha−1 at the harvested site and 47.4 t ha−1 at the mature site. Harvesting increased the relative contribution of belowground bamboo biomass. Annual litter input to soil was 2.7 and 5.9 t ha−1 year−1 at the harvested and mature sites, respectively. The bulk of the annual litterfall (78–88%) occurred in the cool dry season (November to February). The mean litter mass on the savanna floor ranged from 3.1 to 3.3 t ha−1; at the harvested site wood litter contributed 70% of the litter mass and at the mature site leaves formed 77% of the litter mass. The mean total net production (TNP) for the two annual cycles was 15.8 t ha−1 year−1 at the harvested site and 19.3 t ha−1 year−1 at the mature site. Nearly half (46–57%) of the TNP was allocated to the belowground parts. Short lived components (leaves and fine roots) contributed about four‐fifths of the net production of bamboo. Total carbon storage in the system was 64.4 t ha−1 at the harvested site and 75.4 t ha−1 at the mature site, of which 23–28% was distributed in vegetation, 2% in litter and 70–75% in soil. Annual net carbon deposition was 6.3 and 8.7 t ha−1 year−1 at harvested and mature sites, respectively.
Nitrogen translocation via rhizome systems in monoclonal stands of Reynoutria japonica in an oligotrophic desert on Mt Fuji: Field experiments
Authors: Adachi Naoki , Terashima Ichiro , Takahashi Masayuki
Published: March 2006

Mechanisms which enable Reynoutria japonica, a dominant pioneer herb, to be successful in maintaining large stands in an oligotrophic volcanic desert on Mt Fuji were investigated with special reference to its nitrogen acquisition. Reynoutria japonica forms circular stands, each of which comprises only one genet. As a stand develops outwards, the number of aerial shoots per unit area decreases in the center. Shoots grow vigorously in the peripheral area where the available nitrogen from soil and precipitation (about 2.4 g m−2 year−2) was much less than total nitrogen in the shoots (6.1–9.1 g m−2). Leaf nitrogen content per unit mass was also greater in the leaves of the peripheral shoots. When rhizomes extending radially from the center to the periphery were severed, the dry mass of shoots in the periphery diminished by 75% on a ground area basis. In the periphery, leaf nitrogen content also reduced significantly and no flowers were produced. When fertilizer was applied to the peripheral shoots with severed rhizomes, neither growth, survival nor flower production of the shoots was significantly smaller than the control levels. In these shoots, it is also found that the nitrogen content in the youngest leaves decreased for about 1 month and then increased to above that in the control leaves. These results suggest that (i) nitrogen accumulated in the central part is translocated to peripheral shoots via rhizomes, and that long‐distance translocation enables the stands to develop outwards, and (ii) aerial shoots in the periphery utilize the nitrogen translocated by rhizomes in the beginning of the growth season, whereas once the shoots have established, they begin to take up nitrogen with their own roots. Since the peripheral shoots are in sunnier environments than the shoots inside the stand, the acropetal nitrogen translocation via rhizomes will raise the production efficiency of a whole stand.
Adaptation of stomatal response of Camellia rusticana to a heavy snowfall environment: Winter drought and net photosynthesis
Authors: Kume Atsushi , Tanaka Chikako
Published: March 2006

The adaptation of Camellia rusticana, an evergreen broad‐leaved shrub found in areas of heavy snowfall in Japan, to heavy snowfall environments, and the mechanisms by which it is damaged in winter above the snow, were investigated. The stomatal response and photosynthetic characteristics of C. rusticana were compared to those of Camellia japonica found in areas of light snowfall. In field conditions, the mean net photosynthesis of C. rusticana at photon flux density (PFD) over 200 μmol m−2s−1 (Pn(>200). was 50% larger than that of C. japonica, but in both light saturated and CO2 saturated conditions, the O2 evolution rate (Pc) of C. rusticana was not different from that of C. japonica. Mean leaf conductance at PFD over 200 μmol m−2s−1 (gl(>200)) was about 100% larger than that of C. japonica in the field. The Pn(>200)) was 50% ratio of C. rusticana was 37% higher than that of C. japonica which suggests that C. rusticana's larger Pn(>200) can be explained by its larger gl(>200). When C. rusticana trees wintering underneath the snow were projected above it, the leaves of these plants showed serious drought within five days in non‐freezing conditions. Their Pc and the maximum stomatal conductance decreased by half and did not recover. The leaves of C. rusticana showed larger gl(>200) and a less sensitive stomatal response to the decrease of leaf water potential than that of C. japonica. The stomata characteristics of C. rusticana caused larger net photosynthesis than that of C. japonica during the no snow period, and caused the need for snow cover in winter as protector from winter drought.
Carbon dioxide evolution of an upland rice and barley, double cropping field in central Japan
Authors: Nakadai Toshie , Koizumi Hiroshi , Bekku Yukiko , Totsuka Tsumugu
Published: March 2006

Carbon dioxide evolution rates from a double cropping, upland rice and barley field were determined in central Japan from June 1992 to May 1994, and regression models were developed to predict soil respiration rate. Diurnal patterns of hourly soil respiration rates (SRh) showed a similar trend with those of soil surface temperatures. Daily soil respiration rate (SRd) obtained by integrating SRh varied from 0.3 to 15.6 g CO2m−2for the 2 years. In the summer cropping period, SRd was positively correlated with daily mean soil surface temperature and negatively correlated with volumetric water content in soil. Moreover, this relationship was able to be expressed as a multiple‐factor model with an Adj‐R2of 0.925. On the other hand, in the winter cropping period, SRd was able to be represented by a single factor model using soil surface temperature with an Adj‐R2of 0.854. Based on these relationships, seasonal changes in soil respiration rate were estimated. Total soil respiration rates in 1992 and 1993 estimated for the summer cropping period were 1260 g CO2m−2and 1094 g CO2m−2, and for the winter cropping period 624 g CO2m−2and 676 g CO2m−2, respectively. It was considered that the lower values during the summer cropping period in 1993 depended on lower soil surface temperature and higher soil water content.
Optimal brood size and its limiting factors in the Rufous Turtle Dove Streptopelia orientalis
Authors: Kameda Kayoko
Published: March 2006

Optimal brood size and its limiting factors of the Rufous Turtle Dove, Streptopelia orientalis, were studied at the campus of the University of Tsukuba, Japan, during the breeding season in 1990–92. The dove usually lays two eggs in a nest. I made nests of a brood size of one and three by transferring a hatchling from one nest to the other, and compared their fledging success, factors of breeding failure, weight and tarsus length at fledging, growth rate and nestling period with those of a brood of two. The index of fitness (fledgling weight multiplied by average number of fledglings per nest) was almost the same in broods of two and three. However, the highest variation in fledging weight within the brood and the extension of nestling period were observed in broods of three, which caused the extension of inter‐brood interval and consequently the smaller number of broods in the total breeding season. Therefore, broods of three would not have an advantage in producing more offspring than broods of two. Crop milk production had an effect on the growth of nestlings in the early phase of the nestling period, but the rapid growth in the granivorous phase compensated for the growth delay of the smallest nestling in broods of three. Small brood size and a large number of broods in a season would also be more effective under high predation pressure.
Ecological relationships between seedling emergence and litter cover in the earliest stage of plant succession on sandy soil
Authors: Nakamura Toshihiko
Published: March 2006

The relationships between seedling emergence and litter cover were studied in the earliest successional stage of a plant community. During a period of 3 years, changes in vegetation cover and species composition were assessed on three permanent quadrats with virgin sandy soil substrates A successional pattern from summer annual grasses to winter annual herbacoeus plants to biennial and perennial plants was confirmed, and invasion and replacement of the component species were conspicuous. The spatial distributions of seedlings and litter were heterogeneous in winter, and some patches consisting of both seedlings and litter were observed. There was a strong positive correlation between distribution patterns of seedlings and litter; seedling density increased with increasing litter cover. The results suggest that the litter cover of the previous stage plays an imporrant role in promoting successional changes in the early stage of plant succession.
The effect of herbivore density on host plant mediated interactions between two insects
Authors: Masters Gregory J.
Published: March 2006

Recent work suggests that foliar‐ and root‐feeding insects can interact in a novel plus‐minus fashion. However, the effects of herbivores may be different at different densities. This paper describes two laboratory experiments investigating the effect of increasing insect density on plant performance and the host‐plant mediated interaction between a leaf‐mining fly and root‐feeding chafer larvae. Above‐ and below‐ground insect herbivory decreased plant performance. The effects of the root feeder were, for some parameters, different between the two densities of chafer larvae. Leaf mining significantly decreased the performance of the chafer larvae, while root herbivory was found to increase the pupal weight (related to fecundity) of the leaf miner. The effects of root herbivory suggest that the relationships between herbivore density and plant performance may be curved as the greater chafer density had no significant increased effect on the plants or foliar‐feeding insects.
Shoot growth phenology of co‐existing evergreen and deciduous species in an oak forest
Authors: Dhaila S. , Singh S. P. , Negi G. C. S. , Rawat Y. S.
Published: March 2006

Shoot growth phenology was compared for the saplings of evergreen and deciduous woody species sharing the same microsite. Growth initiation occurred earlier in evergreens (among co‐stratal species) while deciduous species completed their growth earlier. Shoot growth rate was significantly greater (P<0.01) for deciduous trees than evergreen trees. The amount of shoot elongations and shoot diameter was also significantly greater (P<0.01) for deciduous trees than evergreens. On the other hand, among shrubs the amount of shoot elongation and shoot diameter was greater for evergreens but the rate of elongation and diameter was more or less similar for both. The duration of shoot elongation and shoot diameter was significantly longer in evergreens than the deciduous species. Leaf packing (number of leaves per shoot) was significantly more dense in evergreen trees (P<0.01) than in deciduous tree species. Leaf packing was more dense in evergreen than deciduous shrubs but the difference was not significant. Leaf area (per individual leaf) at full expansion was significantly greater (P<0.01) in deciduous species. Leaf dry mass and specific leaf mass in the initial stage was significantly greater for evergreen species than for deciduous species. The number of buds/10 cm of shoot was higher in evergreens. However, the per cent mortality was also higher in them.
Characteristics of small‐scale heterogeneity in light availability within a Miscanthus sinensis canopy
Authors: Tang Yanhong , Washitani Izumi
Published: March 2006

To examine the small‐scale variations in light and space availability, photon flux density (PFD) at 20 cm aboveground was measured at 2 cm intervals along each of four 160 cm horizontal transects under an overcast sky condition in a Miscanthus sinensis Anderss grass canopy. Two characteristics were identified for the variation patterns of PFD penetration along transects; the predominant variations of PFD penetration prevailed at the scales usually larger than 10 cm, and the point‐to‐point fluctuations occurred everywhere. Spatial autocorrelation coefficients of PFD penetration along transects were highly positive (>0.5) over the lag distances from 2 to 6 cm, while those of the point‐to‐point fluctuations exhibited a random series. Spectrum analysis showed a higher spectrum density at the lower frequency, that is, at the higher periodicity, which indicated that the variation of PFD penetration was mainly due to the patchy distribution of grass canopy. PFD‐available spans along the transects and contour maps were examined to evaluate the microsites fulfilling both PFD and space requirements in the growth of Quercus serrata Thunb. seedlings. More than 75% of the spans with PFD penetration constantly exceeding 0.04 were shorter than 8 cm, which suggests that a large proportion of high PFD spots may not be used by Q. serrata seedlings in the grass canopy because of the limitation of availability in space. The spatial heterogeneity of PFD at small scales may be of great importance in the succession of M. sinensis grass communities.
Ontogenetic niches of a planktonic copepod in Lake Biwa studied on a fine temporal scale
Authors: Kawabata Keiichi
Published: March 2006

Eodiaptomus japonicus was collected in the north basin of Lake Biwa, Japan, on six dates from 11 to 25 June 1987. Temporal changes in its vertical distribution and reproduction indices were small, but those in its abundance were large. Mortality was high in the naupliar stage I and from copepodid stage III to adult stage. The latter fact and low proportion of females in adulthood suggest heavy predation by fishes which prefer larger prey. Eodiaptomus japonicus showed ontogenetic vertical migration within the epilimnion. The direction of the migration was upward in the early naupliar stages and downward in the late naupliar and early copepodid stages. Both migrations resulted in raising mortality in the corresponding or succeeding stages, probably expressing the behavioral constraints of E. japonicus.
Age‐sex differences in the diets of Sika deer on Kinkazan Island, northern Japan
Authors: Padmalal U. K. G. K. , Takatsuki Seiki
Published: March 2006

Dietary differences in the ages and sexes of Sika deer (Cervus nippon) were studied on Kinkazan Island, northern Japan from October 1990 to July 1991. Larger deer consumed more graminoids than smaller deer except in spring, and less dicotyledonous leaves in all the seasons. Fecal nitrogen concentrations were lower in larger deer than in smaller deer in all the seasons. The age‐sex differences in foods were smaller in summer and winter when foods were most abundant and scarce, respectively, while they were greater in spring and autumn when food availability was intermediate.
Maximum yield and the C‐D effects in natural white birch stands
Authors: Shibuya Masato
Published: March 2006

The competition‐density effect for natural Japanese white bitch (Betula platyphylla var. japonica) stands, located in the northern part of Hokkaido Island, was examined for various growth stages to establish mean tree weight‐density relationships over a considerable extent of stand growth of white birch. Aboveground yields of investigated stands ranged from 16.0 to 161.7 t·ha−1, and it was recognized that maximum aboveground yield of this species was about 160 t·ha−1. Constants A and B of the reciprocal equation of the C‐D effect, 1/w=AN+B (w, mean tree weight; N, tree density), were related to mean height classes of birch stands. Constant B was related to the entire mean height classes as the allometric relationship. On the other hand, constant A had an allometric relationship to mean height classes under 16 m, but became fixed over the 16 m class. White birch stands can come up to the maximum yield approximately at the stage of the 16 m class. The asymptotic tendency seemed to be appropriate for constant A‐mean height class relationship. The maximum yield of white birch stands was predicted by the asymptotic value of A. The trend of mean tree weight‐density relationships with stand growth also changed with constant A. It was considered that maximum yield was an important characteristic for practical applications of the C‐D effect to agriculture and forestry.
Efflux of carbon dioxide from snow‐covered forest floors
Authors: Mariko Shigeru , Bekku Yukiko , Koizumi Hiroshi
Published: March 2006

The release of CO2 from the snow surface in winter and the soil surface in summer was directly or indirectly measured in four cool‐temperate deciduous broadleaved and evergreen needle forests. The closed chamber method (CC‐method) and Fick's diffusion model (DM‐method) were used for the direct and indirect measurements, respectively. The winter soil temperatures from the soil surface to 10 cm depth were between 0 and 2°C. The concentration of CO2 within snowpack increased linearly with increasing snow depth. The average effluxes of CO2 calculated from the gradients of CO2 concentration in the snow using the DM‐method ranged from 20 to 75 mg CO2 m−2 h−1, while the CC‐method showed the average effluxes of 20 to 50 mg CO2m−2h−1. These results reveal that the snow thermally insulates the soil, allowing CO2 production to continue at soil temperatures a little above freezing throughout the winter. Carbon dioxide formed in the soil can move across snowpack up to the atmosphere. The winter/summer ratio of CO2 emission was estimated to be higher than 7%. Therefore, the snow‐covered soil served as a source of CO2 in the winter and the effluxes represent an important part of the annual CO2 budget in snowy regions.
Arthropod communities in a Japanese cedar (Cryptomeria japonica D. Don) plantation: Abundance, biomass and some properties
Authors: Hijii Naoki
Published: March 2006

Arboreal arthropod communities were censused by insecticidal knockdown in a plantation of Japanese cedar, Cryptomeria japonica, in central Japan from April 1983 to February 1985 at intervals of two months. All arthropods sampled were allocated to higher taxonomic groups or guilds and the composition of the communities was analyzed with respect to abundance, biomass and their seasonal trends. The total densities fluctuated seasonally from 200 to 3500 m−2; corresponding biomass values ranged from 7 to 600 mg fresh weight m−2. Maximum density and biomass generally occurred in summer and were minimum in winter. The consistently dominant guild in terms of abundance were the detritivores, mostly comprising Collembola and oribatid mites, accounting for 36–93% of all arthropods; phytophages, predators and detritivores were major guilds in terms of biomass, showing average proportions of 27%, 23% and 20%, respectively.

Biomass ratios of predators to prey were generally high in some canopy communities, suggesting the importance of predation pressure in regulating the population levels of arthropods in forests. Average individual size of predators was approximately proportional to that of prey, irrespective of tree locality. Soil arthropod communities maintained densities approximately 102–103 times as large as the corresponding canopy communities throughout the year. The seasonal variations in abundance were much greater in canopy than in soil communities.
Survival and growth of konara oak (Quercus serrata Thunb.) seedlings in an abandoned coppice forest
Authors: Matsuda Kozue
Published: March 2006

Survival and growth of konara oak (Quercus serrata) seedlings were examined on the forest floor of a konara oak coppice stand in Mitaka, Tokyo, for 5 yr (1976–1980) after exclusion of human management. Attention was mainly focused on a large cohort derived from a bumper acorn crop in 1975. Seedlings began to branch in the second year, although some did not branch during the whole 5‐yr period. Branched seedling showed higher survival and greater weight in 1980 than unbranched seedlings. Many of the branched seedlings had lost an orthotropic leader shoot and spread their branches laterally, suggesting a response for efficient light‐capture. As for unbranched seedlings, a size relationship between leaf area and stem length developing every year was dependent on the shoot size. A small shoot gave priority to enlargement of leaf area, whereas a large shoot gave priority to stem elongation. Yearly variations in seedling mortality and stem elongation were related to the amount of precipitation. Both the initial height and leaf area of germinated seedlings were positively correlated with their survival and weight after five years. Five‐year survival of seedlings showed a positive correlation with light intensity at the growth site but a negative correlation with the extent of leaf predation. Sprouts of shrub species grew vigorously and became much taller than the oak seedlings in the 5‐yr observation period. The characteristics of forest‐floor seedlings were discussed in relation to the regeneration of konara oak forests in general.
Spatial heterogeneity of photosynthetic photon flux density in the canopy of Miscanthus sinensis
Authors: Tang Yan‐Hong , Washitani Izumi , Tsuchiya Takayoshi , Iwaki Hideo
Published: March 2006

Spatial variation in photosynthetic photon flux density (PPFD) was investigated in detail at different heights within the canopy of a Miscanthus sinensis grassland to evaluate the light environment of microsites for establishment of heliophilic tree seedlings. Highly heterogeneous patterns of light distribution were revealed within the apparently uniform grass canopies, especially under direct light. The frequency distribution patterns of relative PPFD (RPFD) were compared among different solar and sky conditions. With increasing height in the canopy, the mean RPFD value and standard deviation (SD) increased, while the skewness and kurtosis of the distribution decreased. The mean RPFD and SD were higher, especially at higher solar elevation angles, under direct light than those under diffuse light conditions. The frequency distribution of RPFD was more platykurtic under direct light and at higher solar elevation angles.
Climate and vegetation in China III water balance and distribution of vegetation
Authors: Fang Jing‐yun , Yoda Kyoji
Published: March 2006

Distributions of 29 vegetation types in China as a function of climatic humidity or aridity were analysed using Thornthwaite's system, by employing meteorological records from 671 stations in China. The annual potential evapotranspiration and the humidity/aridity indices were calculated for every station, and distribution maps of water deficiency, water surplus and moisture index (Im) were constructed. The Im map showed that arid areas (Im<0) occupied about 56% of the country. The effect of the difference in soil water storage capacity on Thornthwaite's indices was examined, and Im values were found to differ little, although some differences were observed in actual annual evapotranspiration, water deficiency and water surplus values. Correlations between Im values and distributions of 29 vegetation types, identified from a vegetation map with a scale of 1/4000000, were investigated. The distributions of desert, steppe, woodland, deciduous forest and evergreen forest corresponded to Im values of below −40, −40–−20, −20‐0, 0–60 and over 60, respectively. In addition, climatic factors delimiting the northern distribution of evergreen broadleaf forest were investigated, and it was clarified that the northern limit was restricted by combined hydrothermal conditions, and not by the low temperature in winter.