The timber certification system, discussed by several international organizations, is an important subject in sustainable forest management. This paper reports the results of an oral questionnaire survey I conducted at the Ministry of International Trade and Industry and several other organizations to elucidate the details of the forest certification by the International Standards Organization (ISO) and the characteristics of the system. Initially, the ISO standards mainly concerned the size and weight of the industrial products. However, based on the proposal of sustainable technologies by the industrial sector at the Earth Summit in 1992, and the effectuation of the ISO14001 (EMS) aimed at environmental management in 1995, the scope of the standards now includes the production activities of organizations. At the same time, a group of Canadian and Australian forest producers proposed to organize a working group to discuss the draft of the technical report form. The final draft of the document was adopted in 1998. The characteristics of the ISO14001 include the following three points : 1) the mining of raw materials is included in the scope of the standards, 2) bio-diversity is included as an item in the evaluation of the effect on the environment, and 3) public participation is required for the establishment of the standards and indicators. Therefore, the ISO certification is considered to contribute to sustainable forest management.

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In the 20 years since the introduction of contract arrangements for profit-sharing reforestation, the total contract forest area has reached 34,558 ha. Approximately 120,000 people have invested 60 billion yen as tending costs for artificial forests. In recent years, however, the number of contracts has been decreasing. As there are now fewer invited contracts for non-national forests, the nature of this system for facilitating the participation of public investors is changing. In cases in which contracts have expired, the dividends account for only a half of the investments, and the owner of the contract forest distributed all of his dividends to investors. While this was mainly due to the marked drop in timber prices and the increase in logging costs, it was also caused by an overestimation of standing tree volume and final cutting volume at the time the contracts were signed. The total contracted area for profit-sharing reforestation represents 0.3% of all artificial forests in Japan, and the use of investments is not limited to forest practice. Judging from the trend of forestry management after the establishment of the profit-sharing reforestation system, this system may not have played a significant role in the stabilization of forestry management and promotion of forest practice. As an increasing number of contracts will expire in the near future, there will be many problems associated with investments falling below par value, logging of large contract areas and realization of actual public participation. This system is now at a major turning point.

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Yield tables are prepared by all prefectures and are used to update Shinrinbo data for private forests in Japan. Therefore, the yield table is the most important source of data for the forest database. The characteristics of the yield tables of Cryptomeria japonica , Chamaecyparis obtusa and broad-leaved species in all twenty-eight prefectures in Western Japan were analyzed based on the parameters of the Richards growth function. Richards function fitted all yield tables very well. Parameter m , denoting the shape of growth pattern, was smaller than 1 for all yield tables, which means that all yield tables showed a Mitscherlich growth pattern. Both total means of parameter k and m denoted nearly equal values in Cryptomeria japonica and Chamaecyparis obtusa. A slightly positive relationship was observed between parameter A and the total yield value in the yield-table for national forests between districts, but no relationship was observed between parameter A and prefectural forest productivity within each district. The mean value of parameter A , denoting the maximum yield table volume, were 589.3, 451.6 and 172.7m^3/ha for Cryptomeria japonica, Chamaecyparis obtusa and broad-leaved species, respectively ; the mean age at the maximum mean increment of stand volume, 38.3, 40.1 and 31.8 years, respectively, and the mean maximum value at that age 8.9, 6.4 and 2.9m^3/ha respectively.

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We examined the effects of the following three conditions on estimating canopy openness with colour hemispherical photographs : the distance between exposure sites, resolution of scanning film and zenith angle of cutting hemispherical photographs. First, four plots were established in broad-leaved natural forests dominated by beech (Fagus crenata BLUME) and color pictures of the canopy were taken with a fish eye lens there. Next, the photographs were scanned with a film scanner and the images were separated into sky and canopy by supervised classification. Moreover, canopy openness was estimated under various conditions for each plot and errors of estimates were calculated from standard errors of averages. In conclusion, the distance had little to do with canopy openess ; the resolution under 680dpi decreased the error, although the error was almost constant over 680dpi ; the zenith angle did not affect canopy openness.

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