Seasonal change in the radiation budget of a forest floor was measured in a mixed forest located in Kyoto, Japan. The basal area at breast height in the survey forest was about 15.82m^2ha^<-1> for evergreen trees and 12.46m^2ha^<-1> for deciduous trees, respectively. The sky view factor was 16% and 22% at the survey site in the foliate and defoliate seasons, respectively. This small difference influenced the seasonal course of radiation budget of a forest floor, Namely, that net long wave radiation changed rapidly in leaving and falling days and that the maximum rate of net short wave radiation was measured in April. Distinctive characteristics of the radiation budget were recognized in the seasonal change that available radiation rates in daytime and night were almost equal in September and October

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We examined spatial correlation and factors influencing on seedling establishment for Abies sachalinensis and Quercus mongolica var. grosseserrata in a northern mixed forest, Japan. Negative spatial correlations between small trees and conspecific canopy trees for both A. sachalinensis and Q. mongolica var. grosseserrata were observed. While positive spatial correlation between small trees of A. sachalinensis and canopy trees of Q. mongolica var. grosseserrata was also observed. Most important factors on mortality of seedlings were grazing by mice or insects for Q. mongolica var. grosseserrata and dumping off by fungi for A. sachalinensis, respectively. Multiple regression analysis showed that neighborhood effect of A. sachalinensis had positive, and neighborhood effect and sapling density of Q. mongolica var. grosseserrata had negative effect on seedling survival of Q. mongolica var. grosseserrata. These results suggest that seedling establishment is hard to occur under conspecific canopy trees, and mortality factors are different among growth stage of saplings in a northern mixed forest.

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The survival of tree seedlings and the amount of dispersed and buried seeds were surveyed. Also, the possibility of plant recovery was discussed on the nearly bare site; which is the result of browsing and trampling by sika deer (Cervus nippon yezoensis) in the broad-leaved stands of Nakanoshima Island, Hokkaido. Tree seedlings disappeared by 70-90% in first twenty days of observation and by 90% within fifty days in all plots. Browsing was the most serious factor, causing more than 80% of seedling damage. The number of dispersed seeds was 238-5,820/m^2 and 21-394/m^2 in 1995 and 1996, respectively. The number of seed species was 11-22 and 7-19 in 1995 and 1996, respectively. A considerable number of viable buried seeds were found, 50-2,700/m^2, and they were composed of 8-20 plant species. Both dispersed and buried seeds contained a large percentage of woody plant species. The number of buried seeds, the number of species and the ratio of viable seeds varied among the study sites, and there were no clear differences between open sites and sites in which the deer were excluded by enclosures. Therefore, the trampling of the forest floor by sika deer did not greatly influence the survival of buried seeds. According to the results of this study, plant recovery is difficult under heavy use by sika deer, however, potential revegetation appears to be possible, for the present.

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The historical development of subalpine mesic meadows was examined on Mount Aizukomagatake which is in a Japanese snowy region. The age and size structure of Abies mariesii trees growing in and around the meadows were studied to discover the characteristics of vegetation dynamics in snowy subalpine areas. Soil profiles were observed to estimate growing conditions of A. mariesii trees and to reconstruct the long-term change in the meadow size. The results of the study suggest that the dynamism of subalpine meadows is affected by the temporal scale at which data are gathered. The meadows have reduced for the last millenniums. They have remained almost stable for the last 300 years, and have sometimes been invaded by A. mariesii saplings over the last 40 years.

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