In the main island of Okinawa, inflow of "reddish soil" caused by development projects has damaged the ecosystems of coral reefs. The conversion of hillslopes into farmlands and housing areas and the construction of roads in woodlands have been reported to be the causes of soil erosion. However, the effect of felling on soil erosion has not been elucidated. To determine changes in soil erosion rates after forest clearing, the amounts of soil movement in a cutover basin on the main island of Okinawa were measured. The results of measurements showed that 1)the amount of soil movement in the cutover basin was greatly decreased when most of the surface of the slope was covered by understory vegetation; 2)the amount of soil movement differed according to soil type, with the largest soil movement occurring in the case of surface gleyed red and yellow soils, the second-largest soil movement occurring in the case of yellow soils, and the least soil movement occurring in the case of red soils.

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To clarify the dynamics of dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) with vertical movements of rainfall in a small watershed of established Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Sieb. and Zucc.) plantation, DON, dissolved inorganic N (DIN), DOC in precipitation, throughfall, stemflow. A_0-percolation, soil water, spring water and stream water were investigated. DON and DOC in order of high concentrations were in A_0-percolation>throughfall>precipitation, and was rapidly in low concentration in soil water. The concentration of DOC decreased more along spring water and stream water. Annual fluxes of DON were 5.5kgha^<-1> in throughfall, 11.1kgha^<-1> in A_0-percolation, and only a little (under 0.9kgha^<-1>) in stream water. Annual fluxes of DOC were 139, 185, and 6.4kgha^<-1>, respectively. From throughfall to A_0-percolation, the percentage of DON to total dissolved nitrogen (TDN=DON+DIN) and the amount of NH_4-N decreased, and the amount of NO_3-N increased. The amount of DOC flux increase in throughfall minus A_0-percolation was smaller than that in precipitation minus throughfall. These results suggested that both the productivity of DON and DOC, and the activity of microbes for decomposition and nitrification in A_0-layer were high. The annual output of TDN from watershed was 13.8kgha^<-1>, and the percentage of DON/TDN was lower than 7%. The annual output of DOC was 6.4kgha^<-1>, which was smaller than those from the watersheds in Europe and North America. These results suggested that DON and DOC do not play an important role in N and C discharge from stream water in the established cedar and cypress plantation forests in Japan.

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Large-scale forestation in arid areas is looked upon as one possibly countermeasure against global warming. Because it has never done, the methodology and the effect of the forestation are being considered in Leonora. Western Australia, where mean annual rainfall is approximately 200mm. An estimation of biomass in some ground-truth points and the application of remote sensing are essential to evaluate the effect of carbon sequestration by the forestation. Therefore in this study, the biomass was estimated in 13 representative plant communities in Leonora. The biomass of plants was estimated by destructive samples and complete enumeration in each site. Grass was weighed by Quadrat method. The conclusions were as follows. 1) In the destructive samples, dry weight of each component part was strongly correlated to projected foliage area, and the correlation was regular even in different species. Judging from these results, the biomass in the research area could be estimated by the application of remote sensing. 2) The biomass in the most sites was much heavier than in typical arid areas, and it was about 14kg/m^2 in an Eucalyptus forest, 6〜7kg/m^2 in dense Acacia forests and 0.5〜5kg/m^2 in sparse Acacia forests, respectively.

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Leaf areas of Fagus crenata were measured at 26 native beech forests in the Nagano region, Central Japan. Six trees were subjectively selected at each site and 100 fallen leaves were randomly sampled under the canopy of each trees. Gradient of leaf area was highly correlated with the distance from Japan Sea rather than climatic factors such as snow depth, precipitation, and temperature. Therefore, the gradient of leaf area was assumed less affected by the present climatic regimes. It was rather hypothesized that the hybridization occurred between the larger leaf provenances growing in the Japan Sea side and the smaller one in the Pacific Ocean side in the inland area of the Nagano region.

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