The block slope is the major land-forms which determine vegetation patterns in the subalpine zone. We surveyed vegetation pattern, micro-topography, and the surface materials on the block slope located around Sensui Pass in the South Japan Alps, in order to examine the site factors causing the vegetation pattern on block slope. The plant communities on the block slope were physiognomically classified into three types: the forest type with a continuous canopy of Abies veitchii, A. mariesii, etc., the scrub type with a continuous vegetation cover of Tuga diversifolia, Pinus pumila, etc., and the desert type with patches of scrub. The desert type was classified into two subtypes by patch size: the large patch subtype and small patch subtype. The forest type was found on slopes affected by temporal dissection, or around the knick lines and small ridges. The scrub type and the desert type with large patches were distributed on the lobes in the middle and lower part of the block slope. The desert type with small patches was distributed on the frontal side of lobes and linear troughs. The inorganic interstitial fine materials were found most frequently on the forest type and less frequently on both the scrub type and the desert type with large patches. On the desert type with small patches, a fine grain substance layer was not found, and the colonizing trees were dwarf growth-form. We concluded 1) that the difference in conditions of the surface materials causes the vegetation pattern on block slope and 2) that the presence or lack of inorganic interstitial fine materials has contribution to the establishment and development of the plant communities.

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The vegetation in the moor on the summit of Mt. Hiragatake, located on the boundary between Gunma and Niigata prefectures, has been changing due to an invasion of non-moor vegetation. In order to investigate how the recent climate change influenced this change, we examined the annual fluctuation of the tree-ring width of Pinus pumila around the moor and its correlation with the meteorological data. The results show that the most influential factor is the summer temperature; the tree-ring width decreased with an increase in the temperature. Rainfall, particularly in spring, has a significantly positive effect on the tree-ring width, although it is not noticeable. The negative effects of higher temperature on the growth of P. pumila contradict the previous reports. We believe that this occurred because the root of P. pumila could not develop sufficiently in the wet environment of the moor, resulting in greater water stress on the leaf. Therefore, the lower temperature shift is believed to be the factor causing the invasion of P. pumila in the moor.

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The expansion process of Castanopsis forests in the Higashiyama hill area, in the eastern part of Kyoto City, was investigated by aerial photograph analysis. First, we made a crown distribution map of Castanopsis trees using a digital orthoimage of an aerial photograph taken in early May, 2004. Next, based on this crown distribution map, the expansion process of Castanopsis trees was made clear by analyses of aerial photographs taken in 1961, 1975 and 1987. Also, we conducted a field survey to find Castanopsis trees under the canopy layer in order to predict of the expansion of the Castanopsis forest in future. The results are as follows: 1) The distribution of Castanopsis trees has expanded since the 1960s. 2) The total crown area of Castanopsis trees was 6.9ha in 1961 and 32.1ha in 2004.3) On the east side slope of the study area, there were few canopy trees of Castanopsis in 2004.4) Castanopsis trees exist under the canopy layer on the east slope. The decrease in the use of wood for fuel by the fuel revolution in the 1960s would have advanced the succession of the forests in general and the expansion of Castanopsis forests in particular. Also, the dieback of pine trees by the spread of the pine wilt disease after the 1970s would have accelerated the succession. The Castanopsis forests may expand to the east slope in future.

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Two species of fern, Urajiro (Gleichenia japonica Spr.) and Koshida (Dicranopteris linearis Burm. f.), often grow to form an extremely dense undergrowth in coniferous plantations, especially in Hinoki cypress (Chamaecyparis obtusa Endl.) plantations on more or less poor soil. They are considered to be a serious obstacle to the forest management aiming at labor-saving and improvement of public functions of forests in which coniferous plantations are left untouched after heavy thinning and shifted naturally to mixed forests of coniferous and broad-leaf trees. In this context, characteristics of the sites dominated by the two ferns was described quantitatively in order to demarcate those sites unsuitable for the management mentioned above. Undergrowth vegetation of Hinoki cypress plantations was divided into two types, "Urajiro-Koshida type" and "Others", based on the combined coverage of the two ferns. Site index, chemistry of the surface soil, and topography of the stands were contrasted between the two types. Relative frequency of the Urajiro-Koshida type was clearly higher among the stands of lower site index (<14.0), although separation of the two types in terms of site index was not complete. Higher acidity (pH(H_2O)<5.0), lower contents of exchangeable Ca, Mg and K, higher content of exchangeable Al and higher C/N were characteristic of the Urajiro-Koshida type. Clear-cut ridge-shaped slope was the typical topography of the Urajiro-Koshida type. Based on these findings, we proposed the following site conditions as unsuitable for the forest management mentioned above: site index of Hinoki cypress lower than 14.0, pH(H_2O) of the surface soil lower than 5.0, and topography of clear-cut ridge-shaped slope.

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Previous researches have been revealed that, in beech (Fagus crenata) forests, bad crop year likely to occur due to heavy insect attack when flower density in current year is not more than 10 times as much as those of the previous years. Thus, if the maximum flower density (Fmax) which is constant for all beech stands exists, a hypothesis can be proposed i.e. when female flower production reach up to more than 1/10 of Fmax in current year, the next year must result in a bad crop year. This suggests that we can predict the seed crop of two years later. Literature and field surveillance study investigating maximum flower and seed production in each of 25 beech forest suggested that Fmax should be 1200/m^2. Additionally, when 120 (Fmax1/10) flowers were produced, the next year tends to result in a bad crop year with high probability. This indicates that we can predict bad crop of two year later by winter bud examination, which enable us to plan more effectual forest restoration by natural regeneration or planting operation.

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On the floodplains of gravel-bed rivers in Central Honshu, we can often observe deciduous broad-leaved forests dominated by Quercus serrata. In order to clarify ecological characteristics of these Quercus serrata forests, we surveyed species composition and substratum of the ground surface on the floodplains of the Sabi, Daiya, and Komu river. The substrata were sandy alluvial deposits in all stands, showing those Quercus serrata forests were established after river flooding and accumulation of sandy deposits. Riparian Quercus serrata forest stands had different species composition compared with coppice forest stands around each river. Riparian stands included elements of ravine forest dominated by Zelkova serrata, whereas they were lacking Ericaceae species and tall herb species that were common in coppice forest. WI are about 85℃・month and CI are less than -10℃・month respectively in the studied areas. This means that the areas are located in intermediate warm-temperate zone. Therefore, we concluded that the Quercus serrata forest established on flood-plain was regarded as a type of riparian forests of gravel-bed rivers in low elevation area of the Central Japan.

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We discussed rate of mineralized nitrogen changing through soil profile and their seasonal changes in the soil of small catchments under Sugi (Cryptomeria japonica) and broad leaved forest at North Kanto region. We determined rate of nitrogen mineralization in the soil under field condition using resin core method. Rate of mineralized nitrogen in the soil decreased from lower to upper slope positions. We also cleared that rate of nitrogen mineralization has positive correlation with sum of soil temperature during incubation. An estimated annual amounts of mineralized nitrogen in the soil of a mid slope position was highest among the site, 176.6kgN ha^<-1>yr^<-1>, and those at in a lower slope position was small, 124.6kgN ha^<-1>yr^<-1>. Proportion of mineralized nitrogen in the subsoil, from 20 to 50cm depth, to 0 to 50cm depth is 41% at lower slope, 30% at mid slope and 43% at upper slope position. Amounts of mineralized nitrogen were high in summer. In this duration, 31 to 45% of mineralized nitrogen through a year was mineralized, but 10 to 32% was mineralized in winter. There were possibilities that mineralized nitrogen during winter will leach to the stream water because of fewer uptakes by trees in this season, and be useful for the nutrient source for uptake by trees at the begging of growing season if mineralized nitrogen will remain in the soil until spring also. Therefore, we must study the role of subsoil on nitrogen cycling and dynamics of mineralized nitrogen of winter season in detail.

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The comparative examination of the distribution of mangrove vegetation, submergence situation, total Na concentration of soil, salinity and oxygen reduction potential of surface water were conducted in secondary mangrove forests (BT1) and abandoned fishponds (BT2), located in Lagay village of Lamon Bay in Luzon Island, Philippines. From relationship between appearance of mangrove tree species and submergence days, eligible distribution ranges for growth were clarified which were indicated by submergence and non-submergence days. Submergence/non-submergence days of Rhizophora apiculata (Ra) is 24-21 days/3-4 days per month, Ceriops tagal (Ct) is 22-17 days/4-7 days, Lumnitzera littorea・Scyphiphora hydrophyllacea (Ll・Sh) is 21-13 days/5-9 days, Avicennia officinalis (Ao) is 13-9 days/9-16 days, Heritiera littoralis・Intsia retusa etc. (Hl・Ir) is 9-0 days/16-30 days. In the abandoned fishponds, mangrove vegetation was not observed. The submergence/non-submergence days of abandoned fishponds is 30 days/0 days per month, it was recognized that mangrove vegetation could not easily recover naturally in such place. Distribution range of mangrove tree species in the secondary mangrove forest is influenced by difference of submergence/non-submergence days through the total Na concentration of soil, salinity and oxygen reduction potential of surface water. On the other hands, in the abandoned fishpond, value of total Na concentration of soil and value of oxygen reduction potential of surface water is influenced by disturbance of land condition of 20 years ago.

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Damage to naturally regenerated forests by sika deer Cervus nippon was examined in Southern Japan Alps in Shizuoka in Shizuoka Pref. from 2000 to 2002. One hundred twenty one forest trees in two rectangular plots (20m×30m) were mainly shared by Betura ermanii (n=51), Acer shirasawanum (n=32), Fraxinus apertisquamifera (n=20) and Sorbus commixta (n=10), which accounted for almost whole trees (about 93%). During three years, the rate of bark stripping damage by sika deer to S. commixta was 90% (n=9), but none of other tree species suffered from their damage. The rate of antler scrubbing damage to trunk was 90.0% (n=9) in S. commixta, 34.4% (n=11) in A. shirasawanum, 30.0% (n=6) in F. apertisquamifera and 5.9% (n=3) in B. ermanii. There were significant differences in the rate of bark stripping and antler scrubbing damage among the four species. Furthermore, there was no significant difference in diameters at breast height (DBHs) among the four species, and the distribution of their DBHs classes were overlapped. Therefore, it suggests that the rate of damage among the four species did not result in thickness of DBHs of their species. Because S. commixta suffered from two type of damage much more than other species, it suggests that sika deer selected S. commixta.

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[in Japanese]

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