NAKANE, Kaneyuki (Dept. Biol., Fac. Sci., Osaka City Univ., Osaka). 1978. A mathematical model of the behavior and vertical distribution of organic carbon in forest soils. II. A revised model taking the supply of root litter into consideration. Jap. J. Ecol., 28 : 169-177.The model proposed in the preceding paper (NAKANE & SHINOZAKI, 1978) was further improved by adding root litter as another source of soil organic matter. The new model simulated the vertical distribution of soil organic carbon concentration in terms of the rates of humus supply from the A_0-layer and the dead roots and of the downward transfer of humus along a soil profile. It fitted satisfactorily the data obtained in a few climax forests of Japan. The results of the fitting showed that the annual mortality of fine roots was between 10% and 20% of their biomass, and that the rate of root litter supply was equivalent to about 20% of that of the aboveground littetfall in warm-temperate and cool-temperate broadleaf forests of central Japan. It was also shown that the preceding model could be derived from the new model as a special case.
SUZUKI, Tadashi (Dep. Biol., Fac. Sci., Tokyo Metrop. Univ., Tokyo). 1978. Area, efficiency and time of foraging in Polistes chinensis antennalis PEREZ (Hymenoptera, Vespidae). Jap. J. Ecol., 28 : 179-189. Foraging activity for flesh of Polistes chinensis antennalis PEREZ (Hymenoptera, Vespidea) was investigated in the field. It was observed that the foraging areas of some colonies in the same field overlapped each other. Some foraging areas of workers of the same colony were overlapped but some were distinct in direction or distance from the nest. The size of the foraging area of a worker was about 120 m^3 on a featureless grassland. Foundresses tended to fly out of the nest in various directions while workers flew relatively in definite directions. The foraging efficiency in terms of the number of successful trips for flesh was larger for workers than for foundresses, but not so different in terms of time. The time taken for a single trip for flesh by workers was longer than by foundresses. This fact may be responsible for the difference in the foraging efficiency in terms of the number of successful trips and consequently in the fidelity of flight direction from the nest. Returns to the remaining flesh of female wasps were also observed.
SASTROUTOMO, Soetikno S., IKUSIMA, Isao and NUMATA, Makoto (Lab. Ecol., Fac. Sci., Chiba Univ., Chiba). 1978. Ecological studies of waterhyacinth (Eichhornia crassipes Mart. Solms) with special emphasis on their growth. Jap. J. Ecol., 28 : 191-197. Ecological studies of waterhyacinth (Eichhornia crassipes) were conducted in the laboratory as well as in the field. The productivity at the Hanami river, Chiba was decreased in winter in terms of fresh weight and dry weight. Some of the rhizomes still had a good growing ability if placed in a high temperature (25℃). Therefore, it is possible that they can survive the winter in the field of central Japan. The relative growth rate(RGR)^^^- and the doubling time (DT) of waterhyacinth in summer were 5 times higher and 4 times shorter than those in winter respectively, and with addition of fertilizer (10kg NPK/ha) were 8 times higher and 5 times shorter respectively. Besides temperature, the nutrient status of the water was also an important factor for the growth of waterhyacinth.
SAITOU, Takashi (Inst. Biol. Sci., Univ. Tsukuba, Ibaraki). 1978. Ecological study of social organization in the Great Tit, Parus major L. I. Basic structure of the winter flocks. Jap. J. Ecol., 28 : 199-214. The winter flocks were normally found from late September to early March and could be classified into two types, according to the composition of flocks : basic flock and compound flock. The basic flocks were constant in membership throughout the winter as far as all the members survived until the following spring, whereas the compound flocks were formed through the aggregation of basic flocks. The basic flocks had neither a particular sex composition nor a specific age composition. They did not originate from the family flocks, nor formed through the aggregation of pairs. However. the basic flocks had a basic structure in which a previous breeding pair formed the nucleus and young birds associated with it. The size of basic flocks varied from two to sixteen and was determined by the number of young associated with the nucleus. The members of basic flocks kept strictly together during winter and the basic flocks never divide into sub-unit as a flock, so it is considered that the basic flock is the social unit of the Great Tit in the non-breeding season. like the pair in the breeding season.
TAKAHASHI Yayoi (1-22-23,Nishiki-cho, Tachikawa-shi, Tokyo) & HAYASHI Ichiroku (Sugadaira Montane Research Center, The University of Tsukuba). 1978. An experimental study on the development of berbaceous communities in Sugadaira, Central Japan. Jap. J. Ecol. 28 : 215-230. An observation on the establishment and replacement of species was made in stands of seral stages. The pioneer stage of secondary succession was dominated by Echinochloa crus-galli var. crus-galli and Digitaria violascens whose seeds are heavier than those of othoer species with seeds buried in the soil of the initial stand. These species, however, were replaced by Rumex acetosella, Erigeron canadensis, E, annuus and Artemisia princeps in the second year, even though the soil of this stand contained many buried seeds of the dominants of the pioneer stage. The standing crop and net production were 621.1 g/m^2 and 681.3 g/m^2 year in initial stand and 682.4g/m^2 and 630.0 g/m^2/year in the second-year stand, respectively. The energy efficiency in the pioneer and second-year stands was 1.02 and 0.96 percent, respectively. In the inital stand, 57 percent of assimilated matter was distributed to the above ground parts and 25 percent of it was invested in seeds. In the second-year stand, investment of matter to the above ground parts was 46 percent of total assimilated matter, of which 6 percent was devoted to the seeds.
KAWANISHI, Masaoki & LEE, Won Ho (Nat. Inst. Genet., Mishima). 1978. Food preferences of Drosophila simulans and D. melanogaster. Jap. J. Ecol., 28 : 231-235. Food preferences of the two sibling species, Drosophila simulans and D. melanogaster, were examined using three kinds of fruit juices. D.simulans prefers apple and grape juices, while D. melanogaster prefers orange juice. However, D. simulans has been almost eliminated from the mixed species cage populations with foods of apple or grape juice in about 150 days.
FUNAKOSHI, Kimitake & UCHIDA, Teru Aki (Zool. Lab., Fac. Agr., Kyushu Univ., Fukuoka). 1978. Studies on the physiological and ecological adaptation of temperate insectivorous bats. II. Hibernation and winter activity in some cave-dwelling bats. Jap. J. Ecol., 28 : 237-261. Cave-dwelling bats seasonally change their roosts. In winter Rhinolophus ferrumequinum nippon, R. cornutus cornutus and Miniopterus schreibersi fuliginosus are found in places with different ambient temperatures and humidities. Body temperatures of hibernation bats approximate the ambient ones. Arousal during the hibernation is mainly caused by endogenous rhythm or physiological requirements. As hibernation advances, arousal frequency drops, activity rhythm is retarded, and activity duration shortens gradually. Loss of body weight and stored fat is more in the first half of hibernation period than in the latter half. The larger bat, R. f. nippon, selects a wide range of environment for hibernation roosts. Its arousal frequency and loss rate or weight are low. The reverse is the case with the smaller bat, R. c. cornutus. The intermediate-sized bat, M. s. fuliginosus, forms huge, dense clusters, and their function is to keep down its body, temperature and weight loss during the hibernation. With scanty food sources in winter, some species (e. g., R. f. nippon) will hibernate deeply almost regardless of the change of ambient temperature, others arouse and feed occasionally (R. c. cornutus) or frequently (M. s. fuliginosus) during the hibernation period.
ARAI, Tetsuo (Lab. Entomol., Fac. Agr., Hirosaki Univ., Hirosaki). 1978. Effects of group size on the wing form in Gryllodes sigillatus WALKER (Orthoptera : Gryllidae). Jap. J. Ecol., 28 : 263-267. Occurrence of the macropterous form in Gryllodes sigillatus WALKER was observed under various conditions of crowding and available area. When the available area was kept constant and the number of insects per container (=group size) was varied, the larger the group size the higher was the incidence of macropterous adults. When the available area was varied in proportion to the number of insects, the result showed a tendency similar to the above mentioned, even though the area per insect was the same. But when insects of the same group size were compared under different conditions of available area, the incidence of macropterous adults was similar in every case. It seems, therefore, that the occurrence of macropterous adults is under the control of the group size effect.