We established 30 quadrats in 27 forests which have been preserved mainly around shrines and temples in the study area. Similarity indices, C_2 based on the number of trees and QS on the presence-absence of all species including the herb layer, were calculated between each pair of quadrats. Stand ordination by the principal component analysis, which used the two similarity indices, made it possible to classify the quadrats into two groups ; one is characterized by the occurrence of Cleyera japonica, and the other by the luxuriant growth of Camellia japonica. A weak but statistically significant correlation could be recognized between loadings of the quadrats on the second factor extracted from C_2-matrix and their altitudes, and between those of the first factor extracted from QS-matrix and their altitudes. Species ordination based on R_δ, an index of interspecific association, also suggested the existence of two species groups ; one is characteristic of the coast and low-lying land, and the other is of inland and mountain districts.
Vegetation of emerged shores and bottoms of irrigation ponds was studied by the BRAUN-BLANQUET approach. The Deinostemato-Eriocauletum hondoensis was described as a new association on the basis of releves collected from the ponds at altitudes between 190 m and 780 m in the western part of Hiroshima Prefecture. This association is characterized by the presence of Eriocaulon species and some other small herbaceous plants. The water of most ponds was clear and considered to be nutrient-poor. The Eriocaulion hondoensis (nov.) was erected as the higher unit of the Deinostemato-Eriocauletum hondoensis. This new alliance indicates some floristic connections with the Lindernion procumbentis and the Eriocaulo-Rhynchosporion fujiianae and also has an affinity to two European classes, the Isoeto-Nanojuncetea and the Littorelletea.
A phenological spectrum was presented for 64 tree and shrub species occurring in the primary forests and 33 other woody and herbaceous species in Chichijima Island. Long leaf flushing period in some species, flowering and fruiting occurring more than twice a year in several species and large intraspecific variations of phenology in many species indicated the tropical characteristics of phenology, while the phenological feature in the temperate zone was shown by some winter deciduous species. Three types of forest in the island, i.e. dry, rather dry and mesic forests, were different in phenology ; Leafing and flowering occurring from April to September were noticeable in the mesic forests with no droughty period, while the ratio of summer activities decreased and that of the phenological behaviors found from October to April increased in the dry forests with arid condition in the midsummer. Discrepancies in flowering time were observed among the congeneric species in some genera.
In Aomori prefecture, northen part of Japan, three indigenous and one naturalized Plantago species are distributed severally in particular habitats that have distinctly different substratums, especially in respect to physical compositions and consequently to the water status in the soil layer to which the Plantago roots distribute. P. japonica habitats are restricted to very wet depressions along the seaside, accumulated with sandy loam, where the water content in the root layer always retains much higher levels than field capacity due to the inflow of fresh water from the neighbourhood. P. asiatica lives on compact loam soil of which the available water content remains nearly constant at relative high values above 75 mm throughout the growing season. The habitats of P. lanceolata, a naturalized species, is confined to well drained waste grounds where the soil layer contains much sand, much gravel, or both. Accordingly, the available water content remains at values lower than 50 mm throughout the main growing period. Among habitats of P. camtschatica, the physical composition of the soil was largely different, such as compact loam soil at a very disturbed pathway, sandy loam at a moderately disturbed slope, and sandy gravel soil at a moderately disturbed seaside. Therefore, the water contents of three habitats of P. camtschatica ranged from 100 to 148,50 to 90,and 15 to 48 mm, respectively.
In the leafy phenology of ferns native to Hokkaido, there are summer-green, semi-evergreen, evergreen and winter-green types. Among them, summer-green is the predominant one in Hokkaido, the northern most island in Japan. Ferns such as Adiantum pedatum, Dryopteris austriaca and Woodsia polystichoides are typical summer-green ferns whose leavers unfold from late May to June and decay during October in the mature sporophyte. However, the leaves of young sporophytes can behave as if they were evergreens. In order to evaluate the stage of changing from evergreen-like to summer-green in the young sporophytes of summer-green ferns, the number of venation of the leaves (number of veins branching from the midrib) was used as a quantitative expression of the developmental age of the sporophytes. The maximal number of venation (NV) of the mature sporophytic leaf was 86 in W. polystichoides ; 60 in D. austriaca and 69 in A. pedatum. At the foot of Mt. Teine near Sapporo, the maximal NV of the young sporophytic leaves with greenness in winter was as follows : the first was 27,the second 28 and the third 35. The relative developmental age of NV of young leaves with greenness in winter to the maximal NV of mature leaves was 0.314,0.467 and 0.493 respectively. It was postulated that the summer-green characteristic is one of the adaptations to a cool climate in Japan, W. polystichoides was considered to be the most adaptive fern among the three summer-green ferns of Hokkaido.
Change of the cycling of soil organic carbon was calculated mathematically on a daily basis by a simulation model in several types of matureforest disturbed by human activities such as cutting undergrowths or raking litters on the forest floor. The results of the calculations indicated that there was little effect of cutting undergrowths (excluding the herbaceous layer) on the cycling of soil organic carbon, while raking litters caused a significant decrease in the accumulation of not only A_0 layer but humus in the mineral soil. It was also suggested that the more frequent the raking of litters became or the lower the decomposition rate of A_0 layer became, the more sterility of the forest soil increased. However, after stop of the disturbances, especially raking of litters, the accumulation of soil organic matter calculated by the simulation model recovered its loss rapidly. These results of calculation also could be predicted by a simulation model constructed on an annual basis.
The total community respiration rate was estimated in undisturbed stands in the Pasoh Forest Reserve, Negeri Sembilan, Malaysia. Dark respiration rates were determined with a large number of detached samples of leaves and woody parts taken from plants of various sizes ranging from a 55m-tall emergent tree to undergrowth herbs. Respiration rates in leaves tended to decrease toward the lower layers of the forest canopy, the mean leaf respiration rate per tree thus increasing with increasing tree size. Respiration rates of woody parts depended on both their diameter and the size of the tree they were taken from. Inter-species differences were relatively small in both cases. A procedure for assessing the total respiration of a tree solely from its DBH was formulated taking all these factors into consideration. Combining the formulation with a DBH census, the rate of total respiratory consumption of dry matter by the whole community was estimated at 75.2 t ha^<-1>y^<-1>, of which 94% was accounted for by trees (DBH≥4.5 cm). Leaf, branch, trunk, and root parts contributed, respectively, 50%, 21%, 15%, and 15% to the total tree respiration.
Various soils from the Tama basin (Japan), including volcanic and alluvial soils with different vegetations and land-uses, were incubated until the rate of CO_2 evolution showed constant values. The rates of CO_2 evolution Y (mg C/kg dry soil/hr) of the incubated soils were highly correlated with the amounts of dissolved organic carbon (DOC) X (mg C/kg dry soil) in soil solution obtained by the centrifugation (13,000 g, 4℃, 40min) ; and the regression equation, Y=0.298X^<1.09> (sample number n=65,correlation coefficient r=0.954), was obtained at temperature t (℃) 25. Increase in temperature increased the rate Y and vice versa, but did not change the amount X significantly. Assuming that the temperature coefficient Q_<10> is 2,and substituting the base of natural logarithm for e, the regression equation is rewritten as Y=0.053・e^<0.069t>・X^<1.09>, by which the rate Y of any incubated soil in the Tama basin can be predicted from the two factors, temperature t and the amount X. There was good agreement of the predicted rates Y with the measured rates Y of several soils incubated at various temperatures. On the assumption that the DOC was the respiratory substrate for the soil microbes, it was suggested from the equation that the turnover rate of DOC varies with the temperature t and the amount X. For example, the turnover rate per hour at 25℃ was 0.298 (turnover time, 3.36 hrs) when the amount X was 1,and 0.367 (2.72 hrs) when the amount X was 10.
The growth of individuals until sexual maturity in the prawn Macrobrachium nipponense was comparatively investigated between the estuarine and upper freshwater populations of a river. The growth of upper freshwater individuals was noticeably depressed, but most of the females seemed to spawn at one year of age like the estuarine females at nearly the same breeding season. The males were presumed to participate in spawnings at two or more years of age at both sites. The undelayed oviposition in the upper freshwaters despite their depressed growth was considered to be due to their maturity at small body size. The relatively early maturity to size is supposed to be a specific life history trait of the upper freshwater population.
Ropalidia fasciata (F.) females rub the basal tuft of the terminal gastral sternite against the petiole of the nest. Foundresses of mature single-foundress colonies (with pupae and/or final-instar larvae) rubbed more frequently than those of young single-foundress colonies (with eggs and/or first-instar larvae). The close temporal association of rubbing with licking on the petiole is likely to contribute to keep the chemical barrier against ants. Departure of the foundress from the nest was much frequently preceded by the rubbing behavior on a single-foundress colony than on a multiple-foundress colony.
Pollen analysis at Nonbara bog (34°27′N lat., 131°48′E long.; 520m alt.) shows two major ecotonal shifts : (1) from the full-and late-glacial cool-temperate coniferous forest [Abies firma, Picea polita, Tsuga sieboldii and Pinus (Haploxylon)] to the early postglacial deciduous broadleaf forest [or, deciduilignosa, Quercus (Lepidobalanus), Fagus crenata, F. japonica, Ulmus, Tilia, Juglans and Pterocarya] about 12,000 years ago ; and (2) from this deciduilignosa to the Cryptomeria japonica forest with some warm-temperate laurilignosa species (mainly Cyclobalanopsis and Castanopsis) 7,000 years ago. It took a few thousand years for each of these vegetational replacements because newly arrived climax species increased logistically toward their respective asymptotes with the low intrinsic growth rate (less than 0,006 yr^<-1>), even if declining plant populations reached rapidly their lower abundance levels.