We investigated the effect of storage CO₂ flux on evaluating RE (ecosystem respiration), GPP (gross primary production), and NEE (net ecosystem exchange) using 3 years of continuous data by eddy-covariance measurement. In the case of estimating carbon budget without consideration of the storage CO₂ flux, large underestimations in RE and GPP were caused especially during snow-free periods. Those bias errors reached 10% of annual cumulative RE and GPP. The daytime respiration estimated by the temperature dependency of nighttime NEE may cause the underestimation of RE and GPP. By considering the simplified CO₂ storage flux estimated by CO₂ concentration time series at the height of the eddy-covariance measurement (F_sc), the estimation accuracy in RE and GPP was drastically improved and the bias errors in RE and GPP were less than 2% of annual cumulative RE and GPP. The errors in NEE were less than 6.4% of annual cumulative NEE. In addition, RE, GPP, and NEE estimated by considering F_sc were similar in seasonal and inter-annual variation as compared with those estimated by considering F_s. Therefore, we conclude that we can detect the seasonal and inter-annual variation of RE, GPP, and NEE with enough accuracy for inter-comparison analyses without vertical CO₂ profile measurements, if F_sc coincides well with F_s, such as for our study site.

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Khilmi’s self-thinning model of a Gompertz function is a practical model, but generally it is difficult to estimate a self-thinning parameter. The purpose of this paper is to estimate parameters with existent material. First, we attempt to estimate the parameters by a supposition used to express a self-thinning curve on a stand density control diagram. The result was as follows: the self-thinning parameter is only concerned with height curve parameters. If height curve is expressed with a Gompertz function, the self-thinning parameter is equal to the time coefficient. In addition, when a height curve is expressed with a Richards function, the same result was gotten with a supposition. Then we tested this result with Spurr et al.’s self-thinning data and Usoltsev’s yield table. When we applied stand density and height for growth function independently, we couldn’t confirm a relationship between the self-thinning parameter and the time coefficient of the height curve. However, when we applied stand density with fixed parameters except end density, AIC of the model didn’t increase. Finally, we compared Khilmi’s self-thinning model expressed by these parameters with a self-thinning model on a stand density control diagram—Tadaki’s model. These two curves are close to each other before crossing the full density curve.

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We analyzed the relationships between the growth direction of creeping shoot in Japanese ivy (Hedera rhombea) and the light conditions experimentally. As a result, the creeping shoots (≥ 10 mm in length) of the ivy clearly showed negative phototropism clearly. The negative phototropism led the shoot horizontally and vertically into the dark space strictly along the negative gradient of spatial light intensity. The growth rate of the shoot decreased according to the reduction of light intensity, but negative phototropism still occurred under the weaker light conditions (20 μmol m² s¹). Therefore, negative phototropism in the creeping shoots of this species must be understood as the active response of searching for a dark space instead of the response of avoiding a strong light. When a creeping shoot searches for an effective tree as a climbing support under heterogeneous light conditions such as forest floors, this negative phototropism would provide an ecological function to lead a shoot apex to the most shady tree base which can be a climbing start point.

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To clarify the factors affecting the survival and growth of Salix gracilistyla growing along rivers, 20 cm long cuttings (1-year-old) were planted on a gravel bar along a river of which survival, shoot length, and herbivory by caterpillars or hares were examined. Flooding duration on the ground surface showed a negative effect on survival at the early stage after planting, but showed a positive effect three months later. Caterpillar herbivory showed a positive effect on survival while hare grazing did not. For sprouting tree species, herbivory on shoots may contribute to survival of cuttings indirectly by reducing transpiration surface area. Only flooding duration affected positively the shoot length at the end of the growing period. At the early stage of establishment, S. gracilistyla cuttings would find it difficult to survive at a low elevation with longer flooding duration, while about three months later, survival and growth would be promoted under longer flooding duration. Herbivory would promote indirectly the survival of plants with high sprouting ability growing at a river side. Flooding duration at the ground surface would affect plant survival differently depending on the growth stage.

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The moisture reduction in split logs of Japanese cypress (Chamaecyparis obtusa) and evergreen oak spp. (Quercus glauca) were evaluated under some conditions differentiated in split sizes (one quarter or one eighth) and drying circumstances (paved or unpaved, roofed or unroofed). Japanese cypress dries out more rapidly than oak: the days required to reach 30% moisture content (dry base) were about 14-80 days in cypress of 90% initial moisture content compared to 40-over 200 days in oak of 68.3-78.3% initial moisture content. Drying on paved ground was more effective than that on unpaved ground whether it were under a roof or not (cypress on paved: 14 days and on non-paved: 80 days, oak on paved: 40-90 days and on non-paved: over 200 days). Split size effect was more enhanced in oak. The benefit of natural seasoning under any conditions was realized only within the first one or two months. Under natural seasoning with unroofed conditions, there was little benefit in a long drying period for split logs in terms of rainfall.

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Realized genetic gains of initial height growth caused by within-family selection of the F₁ seedling seed orchard for Kunugi (Quercus acutissima) plus trees were compared with predicted ones. Predicted genetic gains for 50% within-family selection of the F₁ seedling seed orchard were a 3.4% increase in height growth based on 4-year height growth data. This F₁ seedling seed orchard consisted of 22 open-pollinated families. Realized genetic gains, which were 4.0% in height growth, were evaluated by analyzing 5-year height growth data collected from the F₂ seedling seed orchard. This F₂ seedling seed orchard comprised 6 open-pollinated F₂ families and 6 open-pollinated F₁ families. The realized genetic gains were comparable to the predicted ones. The mean height of the F₂ family population outperformed that of the F₁ family population, and the gains were statistically significant. The results of this study confirmed the efficiency of the seedling seed orchard procedure for Kunugi plus trees.

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A review of the literature in terms of forest tourism and recreation in the1980’s and 1990’s was done using the FOLIS database. This result shows that there are twelve kinds of research topics which were started during the 1980’s and 1990’s. They are studies on 1. forest policy for recreation and tourism, 2. forest recreation/tourism in other countries, 3. nature conservation and recreation/tourism, 4.visitor use, 5. historical analyses of forest recreation/tourism, 6. evaluation of forest recreational/tourism functions, 7. resort development and forests, 8. owners, managers, and citizens in terms of forest recreation/tourism, 9. economic analyses of forest recreation/tourism in terms of public benefit, 10. psychological or physiological research, 11. recreation/tourism activities in forest areas, and 12. therapy and universal design. In this study these twelve topics were reviewed and discussed.

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