Search

Ecosystems that offer several ecosystem services can be used as green infrastructure for human well‐being. In recent years, human activities have substantially engineered ecosystems to produce the desired ecosystem services. However, such efforts could lead to losses of other ecosystem services. Paddy fields are a seminatural ecosystem that can provide several ecosystem services other than rice production. Land consolidation in paddy fields aim to increase the efficiency of food production as a provisioning service, but it could depress the quality of wetland habitat as a supporting service. Recently, the Japanese government aimed to agricultural production with biodiversity conservation. Therefore, prioritizing a control strategy for future land consolidation is needed. Land consolidation work is effective for large areas and may incorporate the paddy field, previously a floodplain wetland that played a crucial role in regional biodiversity. However, land consolidation could result in the loss of this function. In this study, I investigated the spatial overlapping between land consolidation and paddy fields, which were previously natural floodplain wetlands in Kanagawa Prefecture, Japan. Here, terrain parameters and flow accumulation value (FAV), that can reflect wetland potential, along with the latest land use map, were used. The consolidation records in 1‐km cell for the whole of Kanagawa prefecture were used to test the hypothesis. Results showed that high FAV area with high wetland potential has large paddy fields and was heavily consolidated. Thus, there is need for drastic policy changes to align both food production and biodiversity in paddy fields in Japan. [ABSTRACT FROM AUTHOR]

Interspecific relationships between growth and survival are critical determinants of tree species diversity maintenance in forests. The trade‐offs between growth and survival in co‐occurring tree species are believed to arise along a continuum of life‐history strategies. For example, co‐occurring species range from those that grow slowly and survive well in resource‐poor environments to those that grow quickly but have low survival rates in resource‐rich environments. However, uncertainties remain regarding how growth–survival trade‐offs are related to species traits, tree sizes or environmental conditions.We examined how the relationships between species traits and growth–survival relationships shift in response to changes in stem sizes and across census periods with different climate conditions (frequency of strong winds, drought intensity) across 45 co‐occurring tree species based on 23 years of growth and survival records in a warm temperate rainforest on Yakushima Island, Japan. We developed hierarchical Bayesian models of relative growth and survival rates, including leaf traits, wood density and 95‐percentile maximum stem diameter as explanatory variables. We tested the relationships between estimated trait‐mediated growth–survival relationships and the indices of climate events during five census periods.Each trait's effects on growth–survival relationships differed across the five census periods in response to climate conditions. Interspecific growth–survival relationships affected by a single trait axis for leaves or wood tended to be negative. In contrast, those affected by the maximum stem diameter tended to be positive. Such trends increased with more frequent strong winds or more intense droughts. The single‐trait effects on growth–survival relationships were stronger for smaller sizes than for larger sizes. For all traits combined, we found a significant growth–survival trade‐off only for small‐sized stems in three of five census periods.Synthesis. Our results indicate that the effect of species traits on the growth–survival relationships depended on tree sizes, the census periods or both in response to the frequency or intensity of climate events. We argue the importance of incorporating spatial and temporal variations in environmental conditions into long‐term data from tree census to predict forest dynamics. [ABSTRACT FROM AUTHOR]

Habitat selection has a significant influence on animals' fitness, and has been well studied in various ungulates. A trade-off between the access to forage and to shelter often occurs for ungulates' habitat selections, which vary temporally. However, habitat selections for primitive ungulates with solitary and sedentary, such as the Japanese serow (Capricornis crispus), are poorly known. We examined habitat selection at the within-home range scale of the Japanese serow in a montane forest of Mt. Asama, central Japan, at two temporal scales, season and time of day (day or night), by radio-tracking. Serows selected shrub-rich habitats with steep slopes and avoided shrub-poor habitats with gentle slopes, and their selection showed little variation according to season. Shrub-rich habitats with steep slopes provide both abundant food and shelter against potential danger, which suggests that it is an adequate habitat for serows throughout the year. The habitat selection of serows had few differences according to time of day, which suggests that shrub-rich habitats with steep slopes are suitable for both feeding and resting (i.e., all times of day). Our results suggest that trade-offs between the access to forage and to shelter may be less likely to occur for serow's habitat selection, unlike other ungulates. [ABSTRACT FROM AUTHOR]

Dispersion–reproduction trade‐offs are important to explore the evolutionary mechanism of dispersal strategies and the adaptive significance of dispersion in insects. In our previous study, variations in hindwing length were found in Japanese populations of the leaf beetle Galerucella grisescens (Joannis) (Coleoptera: Chrysomelidae). They were distinctly divided into either long‐winged (LW) or short‐winged (SW) morphs in the field. The LW morphs were distributed widely in Japan, whereas the SW morphs were found in restricted areas in Honshu, the main island of Japan. We examined the possible existence of trade‐offs between dispersion and reproduction in G. grisescens by laboratory experiments. Larval duration and adult body size (head width) were not significantly different between LW and SW strains, but adult body weight was larger in some LW strains than in SW strains, most likely due to the size of hindwings and legs as well as to the development of flight muscles. Although the pre‐oviposition period was not significantly different among strains, female longevity and fertility were significantly higher in SW than in LW strains. Long‐winged individuals displayed flutter behaviours, suggesting their flight dispersal abilities, but SW individuals did not. Femurs of LW individuals were significantly longer on all legs compared to SW strains and the former walked faster than the latter. The present results indicate the presence of a dispersion–reproduction trade‐off in G. grisescens, in which SW strains have advantages in reproductive abilities and LW strains in dispersal abilities. [ABSTRACT FROM AUTHOR]

Much empirical data obtained across taxa is necessary to evaluate how variation in migratory costs and benefits can play a role in shaping the phenotypic and genetic patterns of reproductive investment between populations. Reproductive resources are allocated to both the size and number of eggs, and females may vary their allocation to each of these traits in response to increased movement capacity. In central regions of Japan, the rice plant skipper Parnara guttata guttata migrates in a southwesterly direction every year during late summer and early autumn ('migratory' population), but this migration is not observed in populations in southern or parts of western Japan ('resident' population). If migratory costs and benefits vary between these populations, they may cause their reproductive strategies to differ. Moreover, migration combined with a shift of reproductive allocation that evolved in one generation may influence the flight ability and patterns of reproductive allocation in the other generation in which migration has not evolved. In this study, a common-garden experiment was conducted to compare reproductive traits (egg size and number of eggs), flight ability and body size between these populations under two daylength regimes, at which different forms of adult P. g. guttata emerge. Under both daylength regimes the female adults of migratory populations had greater flight ability and tended to lay a greater number of eggs, which were on average smaller than the eggs laid by resident population females. A population-level difference in reaction norm elevation for flight ability and number of eggs was detected, but no interactions between population and daylength. The effects of the energetic cost of flight, adaptive constraints (e.g., genetic correlations and trade-offs), and the optimal strategy may explain the difference between populations of this species in the patterns of reproductive allocation to egg size and number of eggs. [ABSTRACT FROM AUTHOR]

The age structure, growth pattern, and reproductive traits of the southern red tabira bitterling, Acheilognathus tabira jordani, were investigated in a small pond in Toyama Prefecture, central Honshu, Japan. Analysis of 5,720 individuals over two years revealed the existence of three or four age groups in every month, and individuals born during the study years were observed after June. Individuals of two years of age and younger increased their body size in the spring and summer and maintained them in the winter, while individuals in the 3+ age cohort did not show noticeable increases in body size throughout the year. Based on the appearance of spawning-capable individuals, the oviposition period of the A. t. jordani population was estimated to range from late April to late August. Compared with the oviposition periods of populations in other regions, the period in the study area was delayed, probably as a result of lower water temperatures, especially in the summer. During the oviposition period, the proportion of spawning-capable individuals differed between age cohorts in both males and females; in younger individuals the proportion of ovipositors was higher in the early part of the oviposition period. Taking into consideration observed differences in growth and spawning patterns due to age, younger individuals appear to invest their acquired energy into their own growth, while older individuals invest it in spawning. The present study reveals that habitat conservation strategies for A. t. jordani should be determined for specific regions. [ABSTRACT FROM AUTHOR]

The purpose of this article is to determine whether there is a trade-off between the growth and the stability of Japanese prefectural tax revenues. This article employs long-term income elasticity as a measure of growth and short-term income elasticity as a measure of stability and estimates the correlation coefficients between growth and stability in a cross-sectional manner. Our results indicate that there are trade-offs between the growth and stability of local corporate and consumption taxes, but there is no clear relationship between growth and stability for other taxes. [ABSTRACT FROM AUTHOR]

In conifer plantations, enhancement of species diversity has become an important management goal. Although thinning is a useful method to enhance diversity, determining optimum thinning intensities may be rather complicated because of potential trade-offs among a broad array of management goals (e.g., recovery of biodiversity, increasing individual tree sizes, increasing net primary production, saving management costs). To evaluate the optimum thinning intensity by analyzing these relationships, we conducted a thinning experiment with three different thinning intensities-unthinned, 33% thinned, and 67% thinned-in a Cryptomeria japonica plantation in 2003, and investigated the number, diameter at breast height (DBH), and diversity of hardwoods (height > 1.5 m) in 2008, and the growth of conifers over five years. In hardwoods, the number of individuals, number of species, mean DBH, and total basal area were greatest in the 67% thinned treatment, irrespective of successional status. However, Shannon's diversity index did not differ among the three treatments due to a disproportionate increase with thinning intensity in the abundance of a mid-successional species, Cornus controversa. Diameter growth of conifers was also highest in the 67% thinned and lowest in the unthinned treatment, whereas the reverse was true for stand volume increment. These results suggest that intensive thinning is a reliable method to convert conifer plantations into conifer-hardwood mixed forests at canopy level much more quickly and consistently than weak thinning, although primary production is to some extent reduced. If forest managers prefer sustainable timber production of conifers rather than full recovery of diversity, weak thinning may be suitable. [ABSTRACT FROM AUTHOR]

To investigate whether or not oviposition on substrates other than host plants (e.g., non-host plants, abiotic materials) would affect the evolution of egg size in phytophagous insects, we studied the winter cherry bug, Acanthocoris sordidus ( Thunberg) ( Heteroptera: Coreidae), as a model organism for its interpopulation variation in oviposition preference. The rate of oviposition off host plants is much higher in the Amami Island population than in either the Kyoto or Kochi populations. We compared egg size and number among the three local populations from Kyoto, Kochi, and Amami Island. In addition, to evaluate the adaptive significance of larger eggs for offspring in terms of searching for host plants, we examined the relationship between egg size and first-instar body size. We also searched for a relationship between egg size and starvation tolerance in the second instars because first instars can develop to second instars without food intake, and thus the substantial host-searching stage is the second instar, when females lay their eggs off host plants. Females from the Amami population produced fewer larger eggs than females from either the Kyoto or Kochi population. Regardless of the local population, the body size of first instars that emerged from larger eggs was larger, and the second instars originating from larger eggs had a higher starvation tolerance. The larger body size and higher starvation tolerance should enable nymphs to disperse further, which may enhance the probability of successfully reaching host plants. These results suggest that egg size in A. sordidus may be determined in relation to its oviposition habits to maximize reproductive success, resulting in interpopulation variation in egg size. [ABSTRACT FROM AUTHOR]

Stand dynamics was studied over 13 years in a cool-temperate conifer-hardwood forest, northern Japan. A total 30 hardwood species and one conifer, Abies sachalinensis, larger than 1.5 cm DBH were recorded. The total stand density was 1677 trees ha at the beginning, decreasing to 1184 trees ha (30% reduction) over the study period, but the total stand basal area was almost unchanged (about 49 m ha). This large reduction in total density was mainly due to the death of saplings and infrequent recruitment. Number of recruits gradually decreased with time, while that of dead trees was constant. Cause of death of small trees was mainly due to suppression by tall trees. Skewness of the DBH frequency distribution varied among the species. A less skewed frequency distribution (i.e., few number of saplings) was shown by shade-intolerant species such as Populus maximowiczii and Betula maximowicziana, and a more skewed frequency distribution (i.e., large number of saplings) by shade-tolerant species such as Acer mono and Tilia japonica. DBH frequency distribution changed to less skewed patterns with reduction of density in most species during the census period. Rank of shade tolerance positively correlated with tree density and skewness, and negatively correlated with mean DBH. Skewness also positively correlated with recruitment rates. Furthermore, rank of shade tolerance positively correlated with seed size. These results suggest that shade-intolerant species regenerated immediately after disturbances by wide dispersal of small seeds, but their recruitment was interrupted after that. By contrast, shade-tolerant species were able to recruit even after the ceasation of recruitment of shade-intolerant species, but suffered severe mortality due to the increasing shading with the progress of stand development. This study suggests that the stand is still developing, with changes in species composition and size structure, and that species differences in shade tolerance and seed size are important for the stand structural changes. [ABSTRACT FROM AUTHOR]

Abstract Cyperus esculentus is an exotic clonal (or pseudoannual) weed in Japan, and its range is steadily increasing. To investigate its interclonal variation and phenotypic plasticity in response to water availability, five clones of C. esculentus , collected from different sites in Japan, were grown singly in pots placed outdoors under dry and wet conditions. All the traits examined showed considerable variation among the five clones. However, two clones from Tochigi were similar to each other; thus, they might have originated from the same founder population. The clone from Ibaraki was quite different from the others. Therefore, it is suggested that the Japanese populations of C. esculentus might have resulted from multiple introductions of genotypes from geographically separated and, hence, genetically differentiated, source populations. All the clones also showed considerable plasticity in response to water availability. Clones with a larger ramet number had a greater plasticity, whereas tuber size was invariant across water treatments. Highly plastic traits had generally low interclonal variation in plasticity. All the clones had high productivity and produced more ramets and tubers under wet conditions than under dry conditions. Moreover, water availability could partially regulate the mode of its reproduction; wet conditions favored tuber production (vegetative propagation) while dry conditions favored sexual reproduction. A number of trade-offs occurred between the traits of clonal growth, storage and sexual reproduction, indicating that allocation among the competing functions/organs is mutually exclusive in plants. The results obtained here suggest that C. esculentus is more likely to invade wet habitats than dry habitats. [ABSTRACT FROM AUTHOR]

The growth rate, reproduction, recruitment and feeding of four spatangoid species in the Okiislands in the Japan Sea were investigated over five years. Nacospatangus alta, which inhabits unstable surface sediments, grows rapidly, reaches sexual maturity early, and has a short life span, indicating that it should be a ruderal, whereas Metalia spatagus and Brissus agassizii, which inhabit relatively stable deep sediment, grow slowly, reach sexual maturity late, and have a long life span, suggesting that they are stress-tolerators. Lovenia elongata, however, inhabits unstable surface sediment but has an exceptional life history; it grows rapidly, but does not reach sexual maturity early and has a long life span, likely because the specific morphology of its spines and tubercles allow it to cope with surface disturbances caused by storms. Lovenia elongata seems to be a competitive ruderal. A trade-off between test formation and gonad development may occur; N. alta constructs a fragile test with very thin plates, allowing the echinoid to allocate energy to increasing test size and developing the gonad to sexual maturity within a year. Lovenia elongata, with thick plates supporting the specific stout spines and tubercles, needs 2 years to reach sexual maturity with a similar rate of test growth to that of N. alta; M. spatagus and B. agassizii construct robust tests with thick plates, presumably necessary for these species, which burrow and live deep in sand under high pressure from surrounding sand. These echinoids do not reach sexual maturity until over 2 years of age. The flexible trade-off related to stress and disturbance associated with burrowing depth in different habitats allows the spatangoids to have different life-history strategies.