bluuebunny/crossref_metadata_2025 huggingface dataset:
An ecological study of soils in the highlands of western Tibet II. Vertical change from 3900 m to 5450 m in elevation
Authors: Iwatsubo Goro , Zheng Xilan , Shidei Tsunahide
Published: March 2006

Abstracts

Two kinds of soil study were carried out in the south‐western Tibet region of China. Changes in soil properties with elevation were examined from the snout of a glacier at 5450 m above sea level down to a village (Burang) at 3900 m. The area close to the glacier was devoid of vegetation, probably because of the coldness. With a decrease in elevation, the landscape changed from desert to sparse Artemisia steppe, and below 4750 m, to a thorn‐bush steppe dominated by Caragana spp. which continued down to the village (where the annual precipitation was 169 mm). Organic C, total N and cation exchange capacity (CEC) all increased with decreasing elevation down to 4700 m due to the increase in warmth, but the parameters decreased below 4700 m, reflecting the increase in aridity. Almost no carbonate was detected in areas above 4700 m, but below this elevation it increased exponentially, also reflecting the increase of aridity. Available P tended to decrease with both the decrease in elevation and the increase in carbonate.

The vertical distribution of soil parameters was investigated in the soil profiles of dry and wet plots at 4700 m. Organic C, total N, and CEC decreased with increasing soil depth. Their values were higher in the dry plot than in the wet plot. In the dry plot, carbonate increased with depth. Total P was found to be similar in both the wet and dry plots, but there was less available P in the soil of the dry plot, reflecting the abundance of calcium carbonate.
Development of ecology in Japan, with special reference to the role of Kinji Imanishi
Authors: Itô Yosiaki
Published: March 2006

The development of ecology in Japan, especially after the Meiji Restoration (1868), is briefly reviewed. Pioneering studies of Hiratsuka, on the calorimetric budget of a silkworm population, and Motomura, on the relation between numbers of species and individuals in biotic communities, are noteworthy. A critical examination of his role in ecology in Japan reveals Kinji Imanishi to have played pivotal roles in leading Japanese population ecologists to realize the importance of dispersal in population regulation, and leading to the worldwide revival of field primatology. Although Imanishi's later (popular) writings, in which he completely negated the role of competion and natural selection, have justifiably drawn much criticism, his earlier critique of the competition‐Almighty paradigms may be re‐evaluated in the light of recent discussions on interspecific competition and community equilibrium.
Forest ecosystems of east and southeast Asia in a global perspective
Authors: Kira Tatuo
Published: March 2006

Owing to the influence of the Tibeto‐Himalayan Highland, the east‐and southeastcoastal zone of the Asian continent lacks the subtropical dry belt, which elsewhere in the world separates temperate forest areas from the humid tropics. Thus forest climates with sufficient rainfall cover coastal areas of the Western Pacific from subarctic eastern Siberia to equatorial SE Asia, giving rise to a sequence of five forest formations. The warmtemperate evergreen (lucidophyll) forest formation is peculiar to this region and represents the east‐coast counterpart of Mediterranean sclerophyll forest, which develops under the west‐coast climate with a different pattern of seasonal rainfall distribution.

The characteristics of the five formations and their latitudinal distribution were briefly described as being related to climatic environments. Certain ecosystem properties such as floristic diversity and the rate of organic matter decomposition were found to be very sensitive to thermal gradients, whereas the responses of plant biomass, primary productivity, etc. to changes in thermal climate were less apparent.
Gap characteristics and gap regeneration in a subalpine coniferous forest on Mt Ontake, central Honshu, Japan
Authors: Yamamoto Shin‐Ichi
Published: March 2006

Gap characteristics and gap regeneration were studied in three mature stands belonging to different community types in a subalpine coniferous forest on Mt Ontake, central Honshu, Japan. Gap disturbance regimes were remarkably similar among stands studied; percentage gap area to surveyed area, gap density and mean gap size were 7.3–8.5%, 17.8–20.0 ha−1 and 40.8–42.5 m2, respectively. The gap size class distributions were also similar and showed a strong positive skewness with a few large and many small gaps; gaps <40m2 were most frequent and gaps >200m2 were rare. Forty‐five to 66% of gaps were due to the death of single canopy trees. Canopy trees more often died leaving standing dead wood (40–5.7%) or broken trunks (43–49%). Shade tolerant Abies mariesii and Abies veitchii, frequently, and Tsuga diversifolia, less frequently, regenerated in gaps, from advance regenerations recruited before gap formation. Picea jezoensis var. hondoensis may regenerate in gaps, from new individuals recruited after gap formation. The breakage of dense Sasa coverage and the mineral soils exposed by the uprooted plants that form gaps might provide regeneration opportunities for shade intolerant Betula. Of the important species limited to the ridge site, Chamaecyparis obtusa, frequently, and Thuja standishii, infrequently, regenerated from plants already in situ. Regeneration of Pinus parviflora was not seen. Based on the gap characteristics and gap regeneration behaviour of each species described, stand dynamics in each stand are discussed.
Temporal changes in food resources, parental feeding and breeding success of Heron Island silvereyes, Zosterops lateralis chlorocephala
Authors: Eguchi Kazuhiro
Published: March 2006

The influences of the temporal change in food supply on the parental feeding effort and breeding success of silvereyes, Zosterops lateralis chlorocephala, was investigated on Heron Island, Australia. Food supply (arthropods and figs) declined as the breeding season progressed. The parental feeding rate and growth of nestlings were lower when food supply was poor. When available, dominant pairs fed their young more figs and fewer arthropods than lower ranking pairs. Dominant pairs raised heavier young than lower ranking pairs when food supply was poor, while there were no significant differences between them when food supply was rich. When food supply was rich, pairs delivering greater amounts of arthropods reared nestlings better, whereas feeding more figs did not improve growth of nestlings. When food supply was poor, pairs spending a longer time at the nest reared nestlings better.
The effect of missing rings on stand‐age estimation of even‐aged forests in northern Hokkaido, Japan
Authors: Takaoka Sadao
Published: March 2006

The effectiveness of estimating stand age from increment core samples taken at stump height (20 cm above ground) was tested in an even‐aged stand of Betula ermanii that had regenerated after a forest fire in 1945 in Hokkaido, Japan. Careful cross‐dating revealed that annual rings were missing in 11 cores out of a total of 42 cores sampled, and that all these missing rings occurred in the outermost part of the core. These facts indicate that precaution has to be taken in selecting trees from which cores are to be sampled. The present work also revealed that those trees with missing rings have a characteristic appearance, with a thinner stem and less crown foliage than normal trees with complete rings. It was also found that even if this appearance test failed, the possibility of missing rings could be detected from a declining growth pattern, with extremely narrow rings on the increment core which normal trees did not show.
Myrmecochorous adaptations of Corydalis species (Papaveraceae) in southern Japan
Authors: Nakanishi Hiroki
Published: March 2006

Dispersal morphology based on the myrmecochorous adaptations for predator avoidance of seven Corydalis species including two varieties are investigated in southern Japan. Three types of myrmecochory were distinguished: myrmecochory with autochory (diplochory), the explosive ejection of seeds followed by ant transportation; myrmecochory with vegetative reproduction, seed‐transportation by ants and reproduction by tuber; and pure myrmecochory, seed‐transporting by ants only. Diplochory occurs in one winter annual plant, which has explosive capsules, a smooth seed surface, a small elaiosome, long pedicels and large bracts. Myrmecochory with vegetative reproduction occurs in two perennials that reproduce by tuber, although they also produce a small number of seeds with a medium‐sized elaiosome. the pedicels and bracts are medium in size. Pure myrmecochory occurs in five annuals or biennials that are characterized by a rough seed surface with a large elaiosome, comparatively high seed production, short pedicels and only small bracts. Diplochory is exhibited by only one species distributed widely throughout Japan. Myrmecochory with vegetative reproduction is exhibited by species mainly distributed in cool‐temperate northern Japan, while true myrmecochory is exhibited by the majority of Corydalis species in warm‐temperate Japan.
Phytosociological study on natural summer‐green forests in Korea
Authors: Takeda Yoshiaki , Nakanishi Satoshi , Choe Dumun
Published: March 2006

Two phytosociological associations, Corylo‐Quercetum mongolicae and Lespedezo‐Quercetum serratae, were recognized as natural summer‐green forests in the cool‐temperate zone of Korea. They belong to the alliance, Rhododendro‐Quercion mongolicae and Lespedezo‐Quercion serratae, respectively. The former alliance occurs in northern areas of the cool‐temperate zone and the latter develops in southern areas. Both alliances belong to the phytosociological ranking order, Acero‐Quercetalia mongolicae. In contrast to Korean cool‐temperate, summer‐green forest associations, the Japanese ones, such as Fagus crenata or Quercus mongolica var. grosseserrata associations, belong to the order, Saso‐Fagetalia crenatae.
Larval survival of the phytophagous ladybird, Epilachna yasutomii (Coleoptera, Coccinellidae), on the blue cohosh, Caulophyllum robustum (Ranunculales, Berberidaceae), grown under different environmental conditions
Authors: Shirai Yoichi
Published: March 2006

Larval survival of four local populations of Epilachna yasutomii in the southern part of Nagano Prefecture was evaluated on leaves of blue cohosh, Caulophyllum robustum, growing at two different sites, Takatoh and Nakatachi. Based on larval survival on leaves of Takatoh C. robustum, Takatoh E. Yasutomii was clearly distinguishable from the three populations in the Minami‐Shinano area (Akasawa, Nakatachi and Tenryu). Takatoh E. yasutomii developed successfully to emergence on C. robustum from both sites, while Minami‐Shinano populations showed a very low survival rate when given Takatoh C. robustum. Under controlled plant growth conditions, larval survival of Akasawa E. yasutomii was significantly reduced when given C. robustum leaves, from either site, exposed to direct solar radiation, which suggested that larval survival was influenced by environmental conditions at the growing sites rather than genetic differences between the plant populations. In contrast, Takatoh E. yasutomii developed well on C. robustum leaves from either site exposed to direct solar radiation. Takatoh E. yasutomii appears to have some defensive mechanism that allows it to overcome a substance deterring larval development, which increases in leaves exposed to direct solar radiation.
Spatial and temporal heterogeneity in population dynamics of citrus aphids at a regional scale
Authors: Lapchin Laurent , Guyot Hervé , Brun Pierre
Published: March 2006

A quick method of evaluating aphid infestations on young clementine trees is developed. It uses visual abundance classes. This method is used to compare the population dynamics of two aphid species in 11 orchards in Corsica (France). The curves describing the succession of the abundance indices on each sampling tree between April and July are compared using principal component analyses.

The first three factorial axes illustrate the intensity, precocity and flatness of the infestation curves. For each species, a significant between‐orchard variability is demonstrated by comparing the mean factorial coordinates of the sampling trees of the different orchards. The validity of such methods for analyzing the demographic strategies of phytophagous and entomophagous insects at a large scale is discussed.
Reproductive ecology of a cleistogamous annual, Impatiens noli‐tangere L., occurring under different environmental conditions
Authors: Masuda Michiko , Yahara Tetsukazu
Published: March 2006

Demographic and reproductive schedules were compared among five populations of a cleistogamous annual, Impatients noli‐tangere L., occurring in habitats with contrasting moisture and/or light environments. In all populations, flowering extended for 2–3 months during which light environment and mortality changed. Seasonal patterns of growth and mortality were significantly different among the five populations studied. The beginning and duration of flowering and the ratio of chasmogamous flowers to cleistogamous ones were also significantly different among populations. An experiment was conducted under different light conditions (open and closed) to separate the genetic and environmental components of the variation in reproductive traits observed among populations of I. noli‐tangere. Transplanted plants showed significant among‐population variation in flowering time, as is observed in natural populations, suggesting genetic differentiation among populations of this species. On the other hand, the ratio of chasmogamous flowers did not differ among plants transplanted from three populations. Based on these results, the authors suggest that facultative cleistogamy is a conditional strategy under seasonally changing environments.
A simple model of interactive pollutants
Authors: Yeung David W. K.
Published: March 2006

This study presents a model of two interactive pollutants in which the natural rate of regeneration of each pollutant is affected by the quantity of the other pollutant present in the atmosphere. The behavior of pollution accumulations in the natural unintervened system is characterized. With human intervention, it is shown that while a sustainable environment can be obtained, a deteriorating environment may also arise. There is a unique continuous boundary beyond which the environment is non‐revitalizable.
Effects of Sika deer on the regeneration of a Fagus crenata forest on Kinkazan Island, northern Japan
Authors: Takatsuki Seiki , Gorai Takuji
Published: March 2006

Kinkazan Island, a sanctuary island that has been conserved for over 100 years, is inhabited by a Sika deer population of high density (60 km−2). A Fagus crenata forest, a climax forest of this region, was composed of only large sized trees (30–60 cm diameter breast height) and lacked young trees. However, many saplings were found inside a deer proof fence, indicating this forest had a potential to produce seedlings. They were tentatively protected by shrubs of Leucothoe grayana var. glabra, an upalatable ericaceous shrub, but did not exceed the shrub height. Heavy browsing by the deer suppressed recruitment of saplings of F. crenata. The forest will be reduced without population control of the deer.
Canonical correspondence analysis of early volcanic succession on Mt Usu, Japan
Authors: Tsuyuzaki Shiro , del Moral Roger
Published: March 2006

Canonical correspondece analysis (CCA) was applied to explore revegetation patterns during early succession on Mt Usu. Vegetation was buried by deposits of ash and pumice from 1 to 3 m in depth from the 1977–78 eruptions. Three habitats were selected: tephra, tephra in gully and original surface. Plant density and plant cover data were analyzed separately. Environmental factors consisted of five quanticative variables (organic matter, elevation, distance from colonizing source, erosion and deposition of volcanic deposits) and three nominal variables (habitat types: tephra, tephra in gully and original surface). Canonical correspondence analysis showed that the original surface played a special role in vegetation development because the old topsoil supplied both nutrients and seed‐bank species. The CCA also suggested that the environmental factors that influence plant density and cover differ. Distance from colonizing source affected plant density while erosion affected cover. Using CCA, factors could be distinguished that influenced seedling establishment from vegetation expansion and vegetation recovery dynamics could also be more clearly interpreted.
Successional leafhopper assemblages: Pattern and process
Authors: Hollier J. A. , Brown V. K. , Edwards‐Jones G.
Published: March 2006

Auchenorrhyncha (leafhopper) faunas of a series of experimental plots of different successional age were recorded by vacuum sampling. There were clear successional trends in the assemblages. The life‐history strategy of the dominant species changed during succession; the mobile and multivoltine or bivoltine species, which overwinter as adults or nymphs, are replaced by less active, univoltine or bivoltine species which overwinter as eggs. Leafhopper assemblages clearly responded to the changes in plant species composition and vegetation structure during succession; however, disentangling the relative importance of the various factors requires further experimental manipulation.
Prey selection by a spider wasp,Batozonellus lacerticida(Hymenoptera: Pompilidae): Effects of seasonal variation in prey species, size and density
Authors: Endo Tomoji , Endo Akira
Published: March 2006

Prey selection by a spider wasp,Batozonellus lacerticida, was investigated at the riverside of the Toyohira River in Misumai, Sapporo, Hokkaido over 7 years from 1981 to 1987. Seventeen species of araneid spiders were found in the study area and six of them were hunted by the wasps. Most (97.3%) of the 223 prey records obtained were of three species,Araneus macacus, A. marmoreusandA. pinguis. Nesting activity of the wasps continued until mid‐August in 1981, 1982 and 1986, but stopped in July in 1984, 1985 and 1987. The length of nesting period was related to whether the wasps successfully switched prey species fromA. macacustoA. marmoreusandA. pinguisandA. pinguisor not Switching seemed to occur at the phase when density ofA. macacusremained high, depending on the density of largerA. marmorusandA. pinguis. This switching had large effects on species composition and size distribution of actual prey. Chesson's index α calculated at every 10 day period revealed that the wasps preferredA. macacusto the two other species and large prey to medium and small ones. The effect of prey density on preference depended on whetherA. macacuswas present or absent. In the presence of it there were only slight differences in preference among various conditions of prey density. However, whenA. macacuswas absent, densities of bothA. marmoreusandA. pinguishad some complementary effects on preference. The importance of prey size selection by pompilid wasps, and implications of density effects on preference are discussed.
Photoperiodic control of larval development in the semivoltine cockroach Periplaneta japonica (Blattidae: Dictyoptera)
Authors: Shindo Jun‐ichi , Masaki Sinzo
Published: March 2006

Periplaneta japonica is semivoltine, entering early diapause in any (except the first) larval instar before the last, and late diapause in the last instar. Early diapause was induced under a short day of 13 h or less at 28°C, and under both short and long daylength (12–16 h) at 20°C. The shorter the daylength and the lower the temperature, the younger the instar was entering early diapause. Early diapause was terminated by a long day (16 h) or a high temperature (28°C), after which larvae grew faster in short days than in long days until the last instar, when they again entered diapause, always in short days and frequently in long days. This late diapause was terminated also by an increase in daylength and was always followed by adult emergence. In this case, 13 and 14 h daylengths after exposure to 12 h daylength were as effective as 16 h daylength. Ourdoor samples collected in late autumn, winter and early spring at Hirosaki (40.5°N) comprised two distinct size groups, corresponding with the early and late diapause instars. Based on these results, the seasonal development strategy and intriguing aspects of the photoperiodic response in this cockroach are discussed.
Stand structure and carbon metabolism of coppice forests at a heavy snowfall climate region of central Japan. I. Dynamics of stand structure during 14 years
Authors: Yoneda Tsuyoshi , Hamabata Etsuji , Ogawa Husato
Published: March 2006

The coppice stands under the climatic conditions of Warmth Index (WI)≧85°C·month, and Coldness Index (CI)≦−10°C·month could be classified into a Quercus serrata type and Carpinus types at a heavy snowfall climate region of central Japan. The latter types tended to be more distributed on steeper slopes rather than the former. An analysis of tree forms and growth rates of species could reveal the characteristic of this habitat and vegetation type. The growth rates of stem diameter of dominant species on a gentle slope were higher than ones on a steep slope. However, the dominant species on the steeper slope had plasticity to basal bend with sustentacular roots, which is one form of tolerance of heavy snowfall on steep slopes. Average mortality during 14 years was 26%, irrespective of the gradient of a slope. More than one‐third of dead shoots were induced by direct damage, while cracked or broken pieces of a stem were from heavy snowfall. The shoot density at smaller diameter classes tended to be higher at a stand having high horizontal variance of canopy surface caused by basal bend of big shoots. A frequency distribution function of individual tree weight (w), f(w)=pw−3/2, could be obtained at each coppice stand by statistical analysis. The value of a parameter p, a packing factor, tended to be higher at stands on steeper slopes consisting of largely bent shoots and was constant irrespective of the growth.
Comparative study of leaf carbon gain in saplings of Thujopsis dolabrata var. hondai and Quercus mongolica var. grosseserrata in a cool‐temperate deciduous forest
Authors: Hashimoto Ryoji , Shirahata Manabu
Published: March 2006

Seasonal courses of leaf CO2 gas exchange in a growing season were examined in saplings of Thujopsis dolabrata var. hondai and Quercus mongolica var. grosseserrata in a cool temperate deciduous forest. Between the two tree species there were no large differences in the light compensation point of leaf photosynthesis, except for the season of new leaf expansion. However, light‐saturated rates of net photosynthesis were obviously high in T. dolabrata var. hondai. Evergreen T. dolabrata var. hondai saplings had large photosynthetic production in two seasons, before the emergence of new foliage and after foliage fall of the overstory deciduous trees, because of the significantly high solar radiant energy penetrating under the forest canopy during the seasons. Saplings of deciduous Q. mongolica var. grosseserrata were heavily shaded throughout the growing season by foliage of the overstory trees, which resulted in a low daily surplus production. The annual surplus production of leaves in the growing season was estimated to be 2300 mmol CO2 m−2 in T. dolabrata var. hondai and −100 mmol CO2 m−2, slightly negative, in Q. mongolica var. grosseserrata. These results supported the high survivability of T. dolabrata var. hondai saplings and the high mortality of Q. mongolica var. grosseserrata in the deciduous forest.
Sex expression, sex change and fruiting habit in an Acer rufinerve population
Authors: Matsui Kiyoshi
Published: March 2006

Three hundred and thirty‐eight plants of Acer rufinerve Sieb. et Zucc. were monitored in a secondary deciduous forest for 5 years in terms of their sex expression and fruiting habit. Two types of flowers, functionally male and female, were recognized. The adult population consisted of constant males, inconstants and constant females. Constant males, plants that bore exclusively male flowers throughout the study period, accounted for 87% of the adult population. Thirty‐four inconstant plants (11%) changed their sex in various ways. Constant females which accounted for only 2% of the population, were significantly smaller plants than the other two morphs, and suffered greater mortality. Fruit set was consistent and generally high for plants bearing female flowers. Thirteen juvenile plants out of 17 began reproduction during the 5 years, and all became male. For inconstant plants, fluctuation in sex expression tended to be more frequent and/or greater in magnitude for smaller plants. However, there was no evidence of the directional sex transition predicted by the size advantage hypothesis. Plant health and the successional stage of the stand should be taken into account as well as resource allocation problems to explain the proximate mechanisms of sex expression.
Effect of competitor abundance on feeding territoriality in a grazing fish, the ayu Plecoglossus altivelis
Authors: Iguchi Kei'ichiroh , Hino Teruaki
Published: March 2006

The grazing fish, ayu, Plecoglossus altivelis Temminck & Schlegel, establishes feeding territorialiry during the young stage. The population density fluctuates from year to year by more than a hundredfold, but the determinant of territory size is less well known. The feeding territoriality of ayu was examined under simulated habitat conditions where fish density was manipulated and food resources were renewable. Fish competed for algae attached to the substrata and were divided into residents with territories, and floaters without territories. By experimental alteration of fish density the number of residents increased with density and rerritory size decreased with density. Floaters intruded into territories in a school to feed on algae, which induced overt aggression of the resident and reduced the productivity of algae growing there. Both the intruding frequency of floaters over territorial areas and their feeding pressure on algae increased at higher floater density. Floaters functioned to shift cost‐benefit relationships for various territory sizes. They acted as food competitors to restrict territory size below a maximum through competitive interference. Although the growth rate of residents was inversely related to fish density, residents grew faster than floaters in each group. Under a given set of competitor abundances, economic defensibility determined territory size.
Spatial structure of avifauna along urban‐rural gradients
Authors: Natuhara Yosihiro , Imai Chobel
Published: March 2006

We examined the pattern of species composition of breeding birds along urban‐rural gradients in the Osaka Prefecture, western Japan. We recorded the proportion of nine types of land‐use and the presence/absence of each of 76 breeding birds in 5 km square quadrats on a map of the Prefecture. The proportion of woodland and farmland which increased from urban to rural areas were two major enviornmental gradients according to Principal Component Analysis of the nine types of land‐use. Ordination by Canonical Correspondence Analysis (CCA) showed that the breeding bird distribution differentiated along the two major clines, woodland and farmland. The avifauna changed successively along these environmental gradients. There were no discrete boundaries of the distribution of bird species groups. We tentatively classified five groups of quadrats on the ordination plane of the sample score. The geographic position of these five groups on a map preserved the environmental gradient, but showed that water (seashore and river) was a stronger influence on bird species composition than land‐use pattern. Although the diversity of land‐use seemed to raise species richness in the third group, the less diverse, woodland‐rich group contained as many species as the third group. Four groups of bird species, and one group in which species occurred in more than 90% of the quadrats, were classified in the CCA‐ordination plane. The occurrence of these bird groups correlated with land‐use; the first group with woodland area, the second with scatter woodland, the third with farmland and the fourth with seashore.
Stand dynamics during a 12 year period in an old‐growth, cool temperate forest in northern Japan
Authors: Namikawa Kanji
Published: March 2006

In 1979 and 1991, trees over 2.0 m high were measured and mapped together with their crown projections to clarify stand dynamics and shifts in canopy dominants during this period, in a permanent plot of 0.525 ha in an old‐growth, cool temperate mixed forest of Mt Moiwa, Central Hokkaido, northern Japan. During this period, an abundant recruitment of trees was observed after some canopy trees were felled by a typhoon in 1981 leaving gaps in the canopy. Vigorous recruitment was observed for Tilia japonica, Acer mono and Prunus ssiori. These species had different regeneration sites in relation to canopy state. Neither Ulmus japonica nor Kalopanax pictus had any recruits during the 12 year period even in gaps. The equilibrium composition of tree species projected from transition probability analysis also implied the above shift of dominant species during the 12 year period in the plot and suggested that the present forest is not in an equilibrium state.
Soil macro‐invertebrates and litter disappearance in a Japanese mixed deciduous forest and comparison with European deciduous forests and tropical rainforests
Authors: Tsukamoto Jiro
Published: March 2006

Soil macro‐invertebrates and rate of litter disappearance were studied in a ridge plot with moder (mor) humus and a bottom plot with mull humus on a slope in a temperate mixed deciduous forest in Kyoto, Japan (J). The results were compared with those from two German beech forests (G) representative of European deciduous forest mor and mull. Between‐plot differences in biomass of total saprophagous animals was much smaller in J than in G, which is dominated by earthworms. Susceptibility to soil acidity and zoogeographical distribution of earthworms were suggested to be related to this situation. Biomass of soil macro‐invertebrates and litter turnover rate were compared among J, G and three types of tropical rainforests in Malaysia (M) in relation to climatic conditions. Taking into account among‐site differences in temperature and moisture, which affect microbial activity and in biomass of saprophagous macro‐invertebrates especially earthworms, the following order of importance of soil macro‐invertebrates in determining the rate of litter disappearance was suggested: G>J>M. Based on the comparison of biomass of earthworms among European deciduous forests, Japanese deciduous forests and tropical rainforests, as well as on the presence or absence of anecic earthworms in these forests, it was suggested that this ranking could be generalized to European deciduous forests > Japanese deciduous forests > tropical rainforests. It was pointed out that this order was the opposite of the gradient in evapotranspiration rate existing among these regions.
Age‐specific life history tactics in organisms with determinate growth: Optimal models for non‐optimal behavior?
Authors: Thomson David L.
Published: March 2006

Among organisms with determinate growth, optimization models predict that reproductive effort should increase as individuals approach old age, but the assumptions of these models may be inappropriate because the senescence that generates the necessary selective pressure may be not itself be optimal. Population genetics models were constructed to examine whether genes for age‐specific changes in reproductive effort could invade a population in which senescence was maintained at equilibrium levels by a balance between mutation and selection. In asexually reproducing organisms, it was found that strategies of increasing reproductive effort could not normally invade the population. In sexually reproducing organisms, however, recombination was found to be important and genes for age‐specific changes in effort could spread in the population under most circumstances.
A model of litter harvesting by the Western Australian wheatbelt termite, Drepanotermes tamminensis (Hill), with particular reference to nutrient dynamics
Authors: Park H. C. , Orsini J. P. G. , Majer J. D. , Hobbs R. J.
Published: March 2006

A series of papers have been published which describe the influence of vegetation and soil type on the Western Australian wheatbelt termite, Drepanotermes tamminensis (Hill), and also on its litter harvesting levels and contribution to the soil nutrient budget. This paper integrates these findings by means of a computer simulation model. The model consists of three modules which respectively describe the dynamics of litter on the ground, the dynamics of litter within termite mounds and how these in turn influence nutrient loads within the habitat. The outputs of the model suggest that this litter harvesting termite plays an important role in the nutrient dynamics of the area and it provides an estimate of the unmeasured variable, litter consumed in mounds by termites, which is consistent with measurements for other termite species with similar feeding habits.
Reconstruction of Ropalidia fasciata nests by progeny females after a typhoon and its significance in the social evolution of wasps
Authors: Itô Yosiaki
Published: March 2006

A strong typhoon, Typhoon 13, which swept through Okinawa on 2 and 3 September 1993, knocked down 57 to 61 of 97Ropalidia fasciata nests. Thirty‐five colonies soon reconstructed their nests, and these nests produced 54±46 adults per nest during the remaining two and a half months before winter. The number of females involved in nest reconstruction was 21.3±15.7 per nest. The frequency of foraging activity was significantly higher in nests being reconstructed than in normal nests. As only one out of 205 foundresses marked in spring was found in early September, most cases of nest reconstruction were considered to be made exclusively by females that emerged during the spring and summer of 1993 (progeny females). All of the reconstructed nests but one produced adult females. Many females (31%) collected from the two reconstructed nests were inseminated. As all the reconstructed nests became vacant by early January, indicating completion of the colony cycle, and a large number of nests were established in the spring of 1994, females emerging from reconstructed nests in 1993 probably become foundresses in 1994. Ropalidia fasciata is considered to be, at least partially, bivoltine in Okinawa. The significance of these facts for the evolution of multi‐queen social systems in the Polistinae is discussed.
Food habits of sika deer on the Boso Peninsula, central japan
Authors: Asada Masahiko , Ochiai Keiji
Published: March 2006

The rumen contents of sika deer (Cervus nippon Temminck) on the Boso Peninsula, central Japan, were analyzed to identify local, sexual and age‐specific differences in food habits. Graminoids and woody plants were the primary foods throughout the year. In winter, the use of evergreen broad leaves increased. The food habits of sika deer on Boso Peninsula were intermediate between those of populations inhabiting northern and southern Japan. Acorns, mainly Lithocarpus edulis Nakai, were consumed in fall and winter with a peak in October. Since the availability of acorns is not influenced by foraging in previous years, it can be regarded as a stable food supply and hence may be important for deer on the Boso Peninsula. The local difference between the Amatsukominato (AT) area, having a large plantation of Lithocarpus producing acrons, and the Kamogawa‐Katsuura (KK) area, having a small plantation of Lithocarpus, was recognized; seeds and fruit were consumed more in AT than in KK in fall and winter. Males consumed more seeds and fruit than females at both sites in fall. This can be attributed to sexual differences in nutritional requirement.
Effects of disturbance and size structure on the regeneration process in a sub‐boreal coniferous forest, northern Japan
Authors: Kubota Yasuhiro
Published: March 2006

The stand structure and disturbance history in a sub‐boreal coniferous forest dominated by Picea jezoensis, Picea glehnii and Abies sachalinensis were investigated in four study plots set up in Taisetsuzan National Park, Japan. The effect of stand characteristics on the growth and mortality rates of understory trees was examined. Although all the stands showed inverse J‐shape d.b.h. (diameter at breast height) distributions, the age structure and disturbance history differed amongst the stands. The stands with wide d.b.h. distribution (i.e. large CV and skewness) were more uneven‐aged than those with narrow d.b.h. distribution (i.e. small CV and skewness). The disturbance‐return interval based on the model of Hett and Loucks was 31 to 65 years. The gap ratio in the canopy was also different among the stands. These suggest that the variations in stand structure represent different occurrences of natural disturbances. Furthermore, the structural features such as size structure, canopy gap ratio and density of canopy trees also affected the growth dynamics of understory trees (≥2 m in height and <10 cm in diameter at breast height). The growth and mortality rates of understory trees changed with the canopy gap ratio and canopy tree density. The understory trees of stands with wide canopy d.b.h. distribution had higher growth and canopy recruitment rates than those of stands with narrow canopy d.b.h. distribution, contributing to the maintenance of continuous stand stratification. The understory trees of stands with narrow canopy d.b.h. distribution showed lower growth and higher mortality rates than those of stands with narrow canopy d.b.h. distribution, leading to the formation of a single‐canopy structure. It is suggested that natural disturbance governs the regeneration process in the future by affecting the growth and mortality patterns of understory trees through the stand structure (size and age structure, canopy tree density, canopy gap ratio).
The pollination ecology of Bletilla striata (Orchidaceae)
Authors: Sugiura Naoto
Published: March 2006

Anthecological observations of an orchid Bletilla striata were carried out in Kobe, Japan. The purplish pink flowers were visited by 26 species of insects belonging to Hymenoptera, Diptera and Lepidoptera, although the flower did not offer food rewards of any kind. Candidates for pollination were seven species of aculeate Hymenoptera with a body size that well fitted the space in between the column and labellum. The most effective candidate was the male of the longhorn bee Tetralonia nipponensis, judging from its abundance and legitimate intrafloral behavior. The female of T. nipponensis and the other six species also contributed to promote out‐crossing, but to a lesser extent than the male T. nipponensis, since they occasionally exhibited illegitimate intrafloral behaviors for pollination and also, their flower visitation rate was lower.
Impact of overgrazing on seed predation by rodents in the Thar desert, northwestern India
Authors: Wada Naoya , Narita Kenji , Kumar Suresh , Furukawa Akio
Published: March 2006

We compared the vegetation structure, rodent density and seed loss rate between protected and disturbed sites affected from grazing by cattle, goats and sheep, in the Thar desert of India. A perennial tussocky grass Lasiurus sindicus Hent. was largely dominant in the protected site, while L. sindicus was rare and replaced by undershrub species Aerva pseudotomentosa Blatt. & Halb. and Crotalaria burbira Buch.‐Ham. in the overgrazed site. In the grazed site, plant coverage was low, but the density of rodent burrows and the frequency of rodent captures were significantly high as compared to the protected site. Corresponding with the density of desert rodents, seed predation was significantly higher in the grazed site than in the protected site. These results suggest that overgrazing by large mammals has strong effects on plant succession by altering not only the species composition and abundance of plant community, but also the habitat suitability for seed‐eating rodents.
Stochastic population dynamics of clonal plants: Numerical experiments with ramet and genet models
Authors: Eriksson Ove
Published: March 2006

Dynamics of ramer and genet populations were analyzed by use of stochastic matrix models. Based on field data, population development and extinction rates during 50 simulated years were estimated for ramet populations of three species Potentilla anserina, Rubus saxatilis and Linnaea borealis. Only small initial populations (below 125–250 ramets), experienced a detectable risk of extinction within this time interval. For P. anserina and R. saxatilis, population increase occurred in some simulations despite negative average growth rates. A model for stochastic genet dynamics was constructed by combining field data and hypothesized parameter values. Growth rate and population structure were insensitive to variation in disturbance intensity and frequency, whereas variation in recruitment affected population structure but only to a minor extent growth rate. Decreasing recruitment causes extinction of genet populations, but the time‐scale for the decline is in the magnitude of centuries for initial genet populations of about 1000 individuals. Dynamics of genets in clonal plants thus incorporate processes occurring on widely different scales. Some implications of the results for models of population dynamics in long‐lived clonal plants are discussed.
The number of species occurring in a sample of a biotic community and its connections with species‐abundance relationship and spatial distribution
Authors: Kobayashi Shiro , Kimura Katsuhiko
Published: March 2006

Connections among species‐abundance (i‐mi), species‐frequency (i‐Fi), and species‐sample size (Sn‐n) relationships were examined on the basis of the mapping data of a natural forest in Thailand. The spatial distribution of individual trees without any discrimination of species was nearly random. Provided that the spatial distribution of each species was random, the i‐mi and the i‐Fi relationship was reconstructed from each other in terms of the total number of species (S) and the total number of individuals (N) in the data. The number of species (Sn) in a subsample consisting of n individuals was then obtained from the i‐Firelationship. Logarithm of Sn increased with log n and showed a convex curve through the origin. The values of diversity indices based on N and S(or n and Sn) were affected by sample size. These trends were further examined on the basis of 944 data sets of biotic communities and three mathematical models of an S‐N relationship. The properties of species‐area relation were discussed in the light of these results.
Field evidence of plastic growth responses to habitat heterogeneity in the clonal herb Ranunculus repens
Authors: Waite Stephen
Published: March 2006

Stolon internode lengths were measured on plants of the clonal herb Ranunculus repens growing in a hay meadow which was subject to disturbance by mole (Talpa europaea) activity. Within the site three habitat types were recognized: closed grassland, the open ground of fresh molehills and the grass‐molehill boundary. The lengths of stolon internodes of R. repens differed significantly in each of the three habitats. The shortest internodes occurred on stolons on the open molchills. The longest occurred in the closed grassland habitat. The type of habitat in which parent ramets were rooted did not significantly influence the length of internodes on their daughter stolons. The length of a stolon internode was determined by its immediate surrounding habitat type. Consecutive internode lengths on a given stolon showed considerable plasticity, shortening significantly as stolons spread onto molehills from surrounding habitats, and increasing significantly as stolons advanced from a molehill into the surrounding closed grassland habitat. These results are consistent with the proposition that under favorable conditions (on the molehills, where resources are expected to be more abundant, and competition absent) internode lengths shorten and the plant forages intensively, whereas under conditions of low resource availability (in the closed grassland, where competition occurs) internode lengths increase, allowing R. repens to forage extensively. Such morphological plasticity may promote more efficient exploitation of resource‐rich sites and more rapid vacation of resource‐poor sites.
Field tests of a balloon‐suspended trap system for studying insects in the canopy of tropical rainforests
Authors: Fukuyama Kenji , Maetô Kaoru , Kirton Laurence G.
Published: March 2006

A system of suspending traps from a movable balloon was developed and tested on pollinating and wood boring Coleoptera in a tropical rainforest canopy in Pasoh Forest Reserve, Peninsular Malaysia. The balloons, 2.5 m in diameter, were filled with helium gas for levitation and moored in different directions by three pieces of thin rope. Traps in which benzyl acetate and ethanol were used as attractants for the pollinators and wood borers, respectively, were suspended from the balloon at different heights. The trapping results show that the balloon system can be used for studying canopy insects and their vertical distribution on a spatial and temporal scale.
The influence of microclimatic conditions on potential photosynthesis of Usnea sphacelata: A model
Authors: Bölter Manfred , Kappen Ludger , Meyer Michael
Published: March 2006

At a boulder on a hill near Casey Station, Wilkes Land, sensors for light, temperature and humidity were installed facing the four cardinal directions. The measurements lasted for about two months of the summer season 1985/86. The data recording was carried out at intervals of 6 minutes for all probes by automatic recording instruments.

Data analysis was carried out with special regard to the biological effects of the parameters analyzed. These data of the microclimatic features taken from its original place of growth were used to a regression model of potential photosynthetic activity of Usnea sphacelata, which is a characteristic species of this area.

Although the individual time courses of the above mentioned parameters show long periods of favourable conditions for possible growth and metabolic processes, the combined analysis of these variables considering threshold values for metabolism shortens these time spans drastically. Thus, cross relationships within the physical descriptors and their effects on the actual values of photosynthesis as well as respiration become evident. They are illustrated by the results of models on photosynthesis and respiration of U. sphacelata regarding the different cardinal directions.