Properties of PEARSON's type VII distribution were examined by applying this distribution to data on the frequency distribution of individual weight in Cryptomeria japonica and Larix leptolepis stands. These stands satisfied the TADAKI's model of natural thinning. Limited by the TADAKI's model, all the coefficients of the distribution density function of individual weight were formulated by empirical equations of the population density of trees. These empirical equations leaded a mathematical model for describing the frequency distribution of individual tree weight in forest stands restricted by the TADAKI's model of natural thinning. This model of the frequency distribution of weight depended on a normalized distribution density function of tree weight and was specific to every set of the coefficient values of TADAKI's model.
Soil respiration was measured throughout the year before and after clear-felling in a mature red pine (Pinus densiflora) forest in Hiroshima Prefecture, west Japan. The same environmental conditions as those before the felling such as light intensity, soil temperature and soil moisture content were maintained after the felling by using a frame box covered with sheets of black netting to observe soil respiration. The balance of the soil respiration rates between the two conditions before and after the felling was considered roughly to lean forward the contributions of root respiration, because the root system of the pine dies and its respiration ceases after felling. Taking into consideration CO_2 evolution due to the decomposition of roots which died as a result of the felling and the change of soil organic carbon flows after the felling, the proportion of root respiration rate in the soil respiration rate was estimated at 47-51% annually, which closely coincided with the value estimated indirectly by the cycle of soil carbon observed in primeval forests. This finding suggests that root respiration occupies about half of soil respiration in the mature forest ecosystem irrespective of the type of forest.
Development processes of two sapling populations in different aged gaps in a climax beech forest at Mt. Moriyoshi, Akita Prefecture, northeastern Japan, were studied using a revised method of stem analysis along with counting bud scars. The ages of the gaps were estimated at 7-11 and 24-29 years from the growth analysis of the saplings inside them. The beech populations in the gaps were composed of saplings which had emerged about 10 years before and after the gap formations. The older or larger saplings tended to grow faster with lower mortalities than the younger and the smaller ones. Also, advance regenerated saplings had many advantages of growth and survival.
Group size and composition of Sika deer (Cervus nippon) were examined on Kinkazan Island, northeastern Japan, from 1973 to 1977. Mean group size on the island was 3.8 with a range of 1-48. This value was larger than those obtained in other localities of Japan, which was probably due to the more open habitats on the island. Group size was larger in grassland (mean, 4.6 ; range, 1-48) than in woodland (mean, 2.3 ; range, 1-17). Most of the groups (82.4%) were segregated into buck or doe groups. The buck group was smaller in size (mean, 1.7 ; range, 1-7), with solitary bucks occupying 68.0% of the group, while the doe group was larger (mean, 2.9 ; range, 1-23). Seasonal changes were as follows : (1) In spring, the mean group size and the proportion of mixed group increased ; (2) The proportion of doe group increased in summer ; and (3) The proportion of buck group increased in autumn, but since most of the bucks (94.4%) were solitary, the mean size was smallest for the year.
To estimate the primary production in an Antarctic region, photosynthetic activity of moss communities was measured with an infrared gas analyzer at Syowa Station, east Antarctica, in January 1982. At the same time, air and moss temperatures and light intensity were measured. The moss community was composed of Ceratodon purpureus, Pottia heimii and Bryum pseudotriquetrum. The relations between gross photosynthetic rate and temperature, and/or light intensity were discussed.
To acquire fundamental knowledge of the dynamics of an arboreal arthropod community in a forest ecosystem, five surveys were carried out from Oct. 6,1979 to May 11,1981 by the smoking method, using permethrin, in a 24-year-old Chamaecyparis obtusa plantation. The collected arthropods were composed of animals belonging to from 13 to 16 orders. Density of the total arthropods ranged about 1200 to 2400 inds./m^2,and it reached its maximum in Nov. 1980,mainly due to the increase of Acarina. The total biomasses, whose main component was Lepidopteran larvae biomass, fluctuated between about 70 and 180 mg d.w./m^2,and reached their maximum in July 1980. Various patterns of seasonal fluctuations both in individual numbers and biomass were observed among the order groups. Acarina and Collembola were overwhelmingly dominant groups in numbers, and they occupied 60-95% of the total arthropod numbers throughout the surveys. Lepidopteran larvae were the most abundant group, occupying 20-63% of the total arthropod biomasses. Washing the trap sheets with appropriate liquids after fumigation was suggested to be one of the key helps in the exact collection of the arboreal microarthropods, such as Acarina.
The ecological structure of a moth community has been analyzed on the basis of the data obtained by a light-trap survey at eight trap stations of four different vegetations in Tomakomai Experiment Forest in 1978. The moth faunas at eight trap stations are compared by a cluster analysis (UPGMA) concerning 44 abundant species. The eight stations are grouped into three clusters, each of which is regarded as a different environment for moths. The 44 abundant species are classified into seven associations for their habitat preferences. The correspondence between environments and associations is examined, and discussed in relation to larval food habits of component species in each association.
Species composition and density of Dictyostelid cellular slime molds in Phragmites communis communities in the Kushiro moor were investigated by means of a clonal isolation technique. Seven species, Dictyostelium mucoroides BREFELD, D. minutum RAPER, D. purpureum OLIVE, D. lacteum VAN TIEGHEM, D. discoideum RAPER, Polysphondylium violaceum BREFELD and P. pallidum OLIVE, were isolated from the thirteen soil samples. Absolute densities, relative densities and frequencies of the cellular slime molds in the soil samples were determined. From the present results and others reported previously, all taken in the Kushiro moor and its surrounding areas, it was suggested that distribution of cellular slime molds was related intimately to the vegetation of the site where soil samples were collected for isolation of cellular slime molds. Absolute density was lowest in the high moor. The relative densities of cellular slime molds of the four vegetation types, high moor, Phragmites communis community, alder forest and Quercus mongolica var. grosseserrata-Betula platyphylla var. japonica forest, showed patterns unique one another.
To clarify the factors controlling the establishment of the alpine desert community, I investigated the periglacial stone movement and denudation of slope materials on the leeward slope where a Cardamine nipponica community is developed. As a result of the study, it was known that the rate of the periglacial downward movement and the amount of denudation on the studied slope averaged 14.8 cm and 0.9 cm per annum, respectively. It was deduced that the unstable conditions of the slope, such as denudation and deposition of slope materials, resulting from their periglacial movement continues to limit the invasion and establishment of general plants, and that the slope can support only specified plant species adapted to the alpine desert. Furthermore, the adaptation of the subterranean organ of plants to the slope instability was observed and divided into three types.
To elucidate the mode of the ecotypic differentiation of Plantago asiatica L., the phenology and growth of seedlings of the seeds collected from various sites in Japan were compared. As the result, a summer green type and an evergreen type of P. asiatica were recognized. The seedlings of the summer green type ceased their growth in a greenhouse at 20-25℃ and 9 hr day length, however, the seedlings of the evergreen type did not under the same conditions. Under the photoperiod of 16 hr light and 8 hr dark at 6±2℃, the growth of the seedlings of the summer green type was depressed more than those of the evergreen type. The summer green type of P. asiatica distributes in the summer green forest zone, the subalpine coniferous forest zone and the northern mixed conifer and deciduous broad leaved forest zone. The evergreen type of P. asiatica distributes in the evergreen broad leaved forest zone and the subtropical rain forest zone. The summer green type overwinters probably in the dormant state, whereas the evergreen type overwinters in the growing state.