The Tonomine site for grassland study is located a little west of the centre of Hyogo Prefecture. The site is covered with the seminatural grassland dominated by M. sinensis which is maintained for a long time by the farmers' burning. The annual mean temperature is 10.79℃ and the mean annual rainfall is 2,313mm. Investigation of the vegetation and soil was made in 1968 in the plots which were located linearly on the south facing slope, 13 degrees in average dip and 143m in sloping length. The largest standing crop (above-and underground) appeared in Plot 3 situated on the base of the slope. The aboveground standing crop in August at Tonomine (450g/m^2) is higher than that of Hachibuse (378g/m^2), Hyogo Prefecture and Kawatabi (236-375g/m^2,north-eastern JAPAN). The underground standing crop of Plots 1,2 and 3 is in the order of Plot 3>Plot 1>Plot 2. The seasonal variation of the root weight is remarkable in the layer 0-10cm in depth from the surface. In the plot having a good soil condition, the root weight varies considerably, even in the layer 20-30cm in depth from the surface. The underground/aboveground ratio in dry weight in the M. sinonsis type grassland varies with the sampling site and the season. In general, the ratio in the high yield plot is smaller than that in the low yield plot. Concerning the distribution of the volume percentage of soil, the air phase in June, July and August was considerably great. It seemed to be closely related to the aeration in the growing season. The aeration in the growing season, as well as the production of inorganic nitrogen from organic nitrogenous compounds and the increase of the availability of potassium are important as to the grass production. In the present paper, we report the result of some measurements made on the ionic exchange capacity of the root as the first step of the ion absorption to plant. The samples were collected from the layers 0-15,15-35 and 35-50 cm in depth from the surface and the diameter of the roots was classified into two classes (0.02-0.06 and 0.16-0.68mm). The ionic exchange capacity of the root of M. sinensis is almost in the range of 5-9 me. In general, the ionic exchange capacity of coarse roots is smaller than that of finer roots. The absorption of ion is related not only to the ionic exchange capacity of the roots, but also to the vigour and the respiration of the roots.
Experiments were conducted with the seeds of Indigofera cordifolia Heyne ex Roth to study their germination behaviour. Seeds possess seed-coat dormancy. Seeds pretreated with sulphuric acid for ten minutes and supplied with Red light give 100 per cent germination in 3 days. Seeds are slightly positively photoblastic. The optimum temperature for germination is 30℃. Inhibitory effect of Ultra violet and a phenomenon of photoreactivation by white light has been observed. Low temperature treatment induces secondary dormancy.
A moor called Harukoyachi is situated at an altitude of about 460m above sea level at the southeastern foot of Mt. Iwate, in the central part of Iwate Prefecture. Although this station is in the cool temperate forest zone, the secondary woods dominated mainly by Pinus densiflora, Quorcus serrata and Q. dentata etc. are developed around the moor at present. The sediments obtained from the moor were studied pollen-analytically. From the results of pollen analysis, six stages were recognized in the pollen diagram from the bottom to the surface. (1) Betula-Quercus stage (580-480 cm) (2) Quercus-Betula-Fagus stage (480-420cm) (3) Quercus-Fagus stage (420-240 cm) (4) Quercus stage (240-110cm) (5) Fagus-Cryptomeria stage (110-40 cm) (6) Pinus stage (40-0 cm) The first stage is characterized by the dominance of Betula ermanii, Quercus sp. (probably Q, mongolica var. undulatifolia) and Haploxylon Pinus. This stage, therefore, may correspond to the end of the Pleistocene or the beginning of the Holocene. The second stage is considered to be the transitional period from the sub-arctic forest stage to the cool temperate one. The third and the fourth stages are dominated by the cool temperate forest elements such as Fagus crenata, Quercus mongolica var. grosseserrata and Alnus sp. (probably A. japonica). It may be possible that the climate during the third and the fourth stages was milder and moister than the other stages. In the fifth zone, the cool temperate elements tend to decrease and Cryptomeria japonica becomes dominant for a while. The climate in this zone is somewhat cooler than that of the previous two stages. The destructions of natural forests by human activities and the following developments of secondary ones are reflected in the pollen diagrams of the sixth stage. The vegetational history mentioned above can be regarded as typical for the period from the Late glacial age to the present time in the lowlands of Northeastern Japan.
On a mesure la temperature du sol pendant la periode vegetative (mars-oct.) et pendant la periode dormante (oct-mars) par la methode de BERTHET, profitant de la vitesse d'invertation de sucre de canne qui est determinee par la temperature. Les tubes de verre contenant du sirop se'sont poses aux 46 localites dans la region. Aupres des valeurs mesurees aux memes localites par les thermometres, les valeurs par la methode de BERTHET sont plus hautes pendant la periode de maturation en ete et pendant la periode de dormance en hiver. On a estime le gradient vertical thermique de 1°/100m entre 600 et 1400m. La temperature du sol est fortement influencee par la relief et l'exposition. Dans la periode vegetative, la temperature s'eleve au versant nord-est par l'effet du soleil levant et au versant nord-ouest par celui du soleil couchant. Dans la periode dormante, chaque exposition montre le meme gradient vertical thermique, sans aucune difference comme pendant la periode vegetative. En hiver on a vu l'effet du soleil couchant an versant sud-ouest. La zonation vegetale dans les monts Kuzyu n'est pas claire, mais une bordure court entre l'altitude de 1000m et celle de 1400m. Les prairies a Miscanthus et les tourbiere aulnaies qui se developpent an-dessous de 1000m ont la temperature moyenne du sol de 25℃ dans la vegetative periode et celle de 10° dans la dormante. La vegetation rabougrie a Rhododendron kiusianum au-dessus de 1400m est moins chaude que 20° dans la periode vegetative et 8℃ dans la dormante. Les hetraies qui ne se developpent pas encore dans cette region volcanique pourraient se trouver entre ces deux conditions thermique.