This paper provides a prediction of the future timber production for the next 5 periods (25 years). The prediction is based on the analysis of present harvesting behaviors in four rural towns in the Okukuji River watershed in Fukushima Prefecture. First, a questionaire survey was made to both investigate attitudes and viewpoints of the forest owners and analyze their harvesting behaviors in this watershed. The results are as follows: 1) Owners who have thinned their forests carry out thinning at regular intervals. Many owners who have carried out final felling also intend to receive extra income. 2) Many owners who answered the questionaire think that they will cut their plantation at about standard felling age, while only a few think they will cut at an older felling age. 3) When cutting, many owners do not keep a particular felling age in mind. Next, log yield tables were constructed under standard tending regimes and thinned-log products were predicted taking accessibility and log prices into consideration. Finally, a timber production forecast was carried out by log length and top-diameter class for both thinning and final felling based on the yield tables and the present age-class distributions.

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Forest aesthetics have recently become an important public demand. This paper introduces an improved method for assessing the landscape of artificial production forests (Japanese cedar stand). The method was based on the derivating the multiple regression analyses between stand composition variables and visual desirabilities which were obtained through psychological experiments using color slides. Of the thirteen stand composition variables that were applied to the analyses, the level of pruning and cleanliness of the stand, the stand age and the amount of shrub layer were found to be statistically significant in the regression model. This result was indicative of the present level of forest landscape assessment in artificial stands of Japanese cedar.

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Lognormal distribution functions were theoretically derived and then proposed as mathematical models to describe the diameter and height frequency distributions. A two-parameter lognormal distribution function f(W), [numerical formula] was derived to model even-aged stands, where W is the diameter or height, and μ and σ are constants. The following combined lognormal distribution function g(W), [numerical formula] was derived to model multi-storied stands, under the assumption that the diameter or height frequency distribution in multi-storied stands are composed of several age-class distribution. In this paper, a two-component, combined lognormal distribution function g(W), [numerical formula] was proposed to medel two-storied stands, where W is the diameter or height and all other variables are constants. The method used to estimate the σ parameters in g(W) is briefly summarized below. The two-parameter lognormal distribution model was applied to 24 observed diameter frequency distributions and 22 observed height frequency distributions. The combined lognormal distribution model was applied to 4 observed diameter and 4 observed height frequency distributions in selected Ate (Thujopsis dolabrata SIEB. et ZUCC var. hondai MAKINO) forests. Agreement between the obserbed and the expected frequencies was checked with the chi-square test. The two-parameter lognormal distribution model yielded data that agreed well with the observed frequency distributions with the exception of 2 in cases out of 24 in the diameter model and 4 cases out of 22 in the height model. The combined model yielded data that agreed with every observed data point in the diameter frequency distribution but to only 3 data the points in the height frequency distribution. The proposed models may be useful for analyzing the diameter and height frequency distributions of even-aged and two-storied stands.

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