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In this study, a weeding-duration model for Larix kaempferi plantations was developed that employs a generalized linear model. The number of years that weeding is necessary is the response variable, and elevation, slope, maximum snow depth, annual precipitation, geological type, soil type, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geological type, soil type, slope aspect, and vegetation type are categorical data. We assumed a Poisson distribution for the response variable. The link function was log. Among the models that could be developed from these variables, we chose the model with the smallest Akaike's information criterion (AIC). The weeding-duration model can be written as follows: years that weeding is necessary = Exp (-0.0172833 9 site index ? 0.0014053 9 maximum snow depth (cm) ? 1.7417731). The results of this study imply that weeding of Larix kaempferi plantations is needed for more years as the maximum snow depth increases and fewer years as the site index increases. This model is useful for cost-benefit analyses of afforestation or reforestation with Larix kaempferi.

To obtain the relationship between the structure and reflectance of winter maritime stratocumulus cloud tops, observations using an aerial stereophotographic method were carried out from January 1989 to January 1991 in the area off Wakasa Bay in the Japan Sea, and around the Amami Islands in the Pacific Ocean. The relationship between cloud top heights and the reflectance of the cloud was first investigated, and a positive correlation was found to exist. An especially high correlation was obtained for the clouds over the Amami Island data. Next, the relationship between the cloud area ratio and the reflectance of the cloud top surface was examined. Results indicated that in areas of low reflectance, the cloud top heights were relatively low and widely distributed. The cloud tops were sharp and jagged in shape. In contrast, in areas of high reflectance, high cloud top heights were found, being uniform on the average. Their shapes were flat and trapezoidal in comparison with the jagged nature of the other clouds.For the clouds north of the Amami Islands, the cloud top heights were lower than those found in other cases. The difference between the maximum and minimum cloud top heights was more than 400m and the values of reflectance were greater than those in the other observations. The difference in the reflectance of the clouds over the Amami Islands may result from the difference between the liquid-water paths.

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