Life table studies were carried out on the 28-spotted lady beetle in a suburb of Kyoto city, in 1970-72. Overwintered adults oviposited their eggs mainly in potato fields and the new adults of the first generation emerged in late June-early July. Egg mortality was 27% and was mainly attributed to physiological causes and cannibalism by larvae, while food shortage was the main cause of death during larval stages. Total mortality from egg to adult emergence was 90%. After the potato was harvested, the number of adults which immigrated from potato to the egg plant and other Solanaceae crops was so large that they were subjected to severe food shortage, dispersal and reduction in fecundity in consequence of overcrowding. In the second generation, egg mortality, ranging from 40-60%, was higher than in the first generation. This was largely due to egg cannibalism by adult beetles. Total mortality was 94-99.7% and a few adults emerged in early August. It is concluded that some density dependent intraspecific mechanisms, viz, regulation of fecundity, egg cannibalism, competition for food among larvae and adult dispersal, play a significant role in the population dynamics of the 28-spotted lady beetle.
Temperatures in Karamatsu-komori-ana Cave were very stable throughout the year. The farther from the entrance, the less the influence of open air temperature. The distribution pattern of air temperature in the cave was different in summer and winter. This difference can be explained by the three-dimensional form of this cave. Water temperature seemed to be affected by the position in the stream and the size of the pool. But fluctuation of water temperature was smaller than that of air temperature.
The present paper presents some interesting facts about this crab which was observed seasonally in Sagami Bay. The period of the good catch occurs twice a year, April-July and October-January. They mainly inhabit the littoral region at a depth of about 5 m throughout the year, and are very few or scanty on sea floor more than 20 m deep. The group of crabs measuring 30 mm in carapace width in June grows up to 55 mm in December and to 70-80 mm in April in the following year. The rate of growth tends to slow down in October towards winter. It is assumed that the spawning period is twice a year, from September to October, and from January to April. The latter period is especially long with a peak from January to March. The biological minimum size of this crab is thought to be about 43 mm in carapace width.
To study the ecological adsptation of the Japanese Hosta, the habitat preference and water economic characteristics of a number of species are determined and compared. Stomatal density and size, transpiration rate, drought resistance and relative growth rate in seedlings are investigated as indicators of adaptation to the soil moisture conditions of the habitat. The species which commonly occur under a diversity of soil moisture conditions, for example, H. sieboldiana, can readily adapt their water economies to a wide variety of environments, showing fairly high transpiration rates, rather high drought resistance and high relative growth rates. They can be regarded as unspecialized in life. On the other hand, with the exception of H. capitata, the species restricted to relatively dry habitats such as outcrops and rocky soils, for example, H. kikutii and H. longipes. have low transpiration rates and low relative growth rates in spite of high drought resistance. Finally, H. longissima, which is confined to wet places, exhibits low drought resistance, with a high transpiration rate and a somewhat high relative growth rate. The species which grow in limited habitats have rigid water economics, though each is well adapted to its particular environment. Thus, they may be considered ecologically specialized.
The Fujimidai Heights are located in the subalpine zone of Central Japan. The upper area of the heights has been used as pasture, being surrounded by the climax coniferous forest of Picea hondoensis and Abies veitchii. The climate of this area is cool and humid with a high annual precipitation of more than 2,400 mm. In this pasture four vegetation types are found. A Carex oxyandra community has developed on the moist and mesic land. A Festuca ovina community has developed on the dry ridge. Both the above are under heavy grazing and have thus developed as biotic plagioclimaxes from the wind-swept Sasaella sasaelloides community. Finally a Calamagrostis conoderuts var. langsdorfil community is found in the light grazing land and a Sasaella sasaelloides community has developed on the abandoried area. There are few pastures and meadows in the subalpine zone of Japan, but the Festuca ovina community under grazing and the Calamagrostls longiseta community under mowing are found in the Utsukushigahara Heights located in the subalpine zone with low annual precipitation. It is considered that the floristic composition of grassland vegetation in the subalpine and subarctic zone is affected not only by air temperature but also by the water condition of the habitat.
Some ecological investigations on breeding of an eleotrid goby, Odontobutis obscurus, were made under rearing conditions. Multiple spawnings in a male's nest by a fixed female were observed. The mating type is discussed from the viewpoints of residentiality and nest-guarding behaviour of the male parent fish. High sensitivity (high mortality and premature hatching) of deposited eggs to the exposure to indirect natural light may be related to the shaded spawning site of this species in its natural habitat. The noticeable tolerance of the newly hatched larvae against starvation was considered to be derived from their large body size and rather developed stage at hatching.
Polygonum cuspidatum is one of the pioneer perennials in the early stage of the voicanic desert succession on Mt. Fuji. The fate of P. cuspidatum seedlings was pursued during the growing season of 1973. Germination occurred twice, discretely, first early in May and second in the rainy season (Baiu) of June. Some of the seedlings which germinated in early May survived throughout the growing season. On the other hand, nearly all the seedlings that germinated in the middle of June died during the nine consecutive rainless days in summer. At the onset of the drought there was a large difference in the root development between the two groups of seedlings. From the study of the drying process of the gravelly soil layers, it was deduced that the water content of the upper part of the soil (0-5 cm) had dropped to a very low level by the end of this short drought period. It was surmised, therefore, that the seedlings with shsllower roots could not absorb sufficient water and died.
Reproduction of Microtus montebelli inhabiting cultivated lands was studied bi-monthly during the period from May, 1971 to March, 1972. The population was characterized by two main breeding seasons, in spring and fall, with sporadic breeding during winter. The average embryosize per pregnant female, based on 40 specimens captured during one year, was 5.1. The largest mean embryo-size appeared in September. The pattern of change in the male breeding rate and mean testis length showed similarities to that in female breeding rate, pregnancy rate and mean embryo-size. From the comparison of the breeding season in Kyoto with that in other localities, it is suggested that high temperature exerted a restraining influence on the breeding of the vole in summer. The seasonal change of embryo-size in Kyoto differed from that in Iwate. The reasons for the difference are discussed.