To clarify the effect of edaphic factors on the annual production in the M. sinensis type grassland, a series of investigations were carried out by the authors for the last four years at Kawatabi and Tonomine. The present report deals with the relationship among the standing crop of plants, the components of humus, seasonal change of soil moisture, amount of inorganic nitrogen and soil respiration. The amount of the minerals such as potassium and magnesium, etc. in the fulvic acid of the humus in the plot having a high standing crop was more than that of the plot having a lower standing crop. On the other hand, the presence of a considerable amount of Al in the fulvic acid was shown in the low yield plots. The seasonal variation of the soil moisture in the high yield plot was small. Generally, the soil moisture of the upper layer (0-30 cm) was constantly kept at a high level. On the contrary, the soil moisture of the upper layer decreased from July to October in the low yield plots. The plot having a deep humus soil layer and favorable soil moisture content had NH_4-N and HO_2-N a little more than those of the other plots. These were conditioned to contain water in 60 per cent of the maximum water holding capacity and placed in a thermostat at 30℃ for 3 weeks. Thereafter, quantitative analysis was made on the amount of NH_4-N and NO_2-N. This amount may be considered as potential available nitrogen. The amount of NO_2-N was scarce, but that of NH_4-N was extremely great, in general. The produced amount of CO_2 and the accumulation of exchangeable calcium in Plot 3 were larger than in the other plots. There seems to be a considerable amount of available nitrogen in the soil for the vigorous reproduction of micro-organisms.
Two sites of volcanic ash deposit were studied by polien analysis : Site I being a Miscanthus-grassland dominated by Arundinaria pygmasa, on the flat top of an undulating platean surface, 870 m above the sea-level, and Site II a Quercus crispula-Symplocos coreana-Circaea alpine-forest along the valley at the foot of Mt. Mimata, 1140 m above the sea-level. The pollen flora is influenced by the present vegetation down to the limit of 10 cm from the surface in site I, and 15-25 cm in site II, which are indicated by the presence of Cryptomeria introduced to this volcanic region by man. The deposition of volcanic ash has made the habitat drier and exerted an influence on the historical development of the plant-communities. The vegetation was anihilated at least twice in the past. In site I (grassland) no progressive stage deeper than the present one has been recognized. In site II (colluvial forest soil) The Ulmion has changed to the present oak forest dehydrated by the ash deposits. When the pollen spectra of the volcanic ash soils in the Kuzyu-volcanoes and the glacial deposits in Europe are compared, which have occurred probablly contemporaneously, a good analogy is susceptible, and one can conclude that in Kuzyu the Ulmion has much declined against the prospecting Pinion.
Life history, reproduction and population structure of an amphipod, Orchestia platensis (KROYER) were investigated in the forest of Kiyosumi, Chiba Prefecture. The breeding period of O. platensis in Kiyosumi was from May to October. Newborn animals appeared in May, and from June to August, clear growth of the new-born animal was found. Pregnant rate of the adult female of the amphipod was 40 per cent in September, and the average rate throughout the breeding period was 25.3 per cent. The relationship between the size of the female and number of eggs produced by the female is, Y=0.021X^<2.717> where Y is the estimated number of eggs produced, X is the size of the female in head and peraeon length. An adult female, 31 mg in body weight, of O. platensis had 10 eggs in her brood pouch, the percentage of these eggs to the mother was 18.7 per cent in terms of biomass, and 24.1 per cent in terms of energy. The reproduction efficiency of an individual (E_<rp>) in terms of energy is defined as, [numerical formula] Reproduction efficiency of an individual for O. platensis was 19.4 per cent, and those for three isopods were from 28 per cent to 33 per cent.