The primary interest of forest owners is the amount of income that will be derived from forest operations. Before cutting operations are carried out, the quality and quantity of the wood yield need to be estimated as accurately as possible. To calculate the pro?t from a future cutting operation, the upper diameters (example of 4-m above the ground) of the stems of trees in the stand need to be estimated. The aim of this study was to estimate these diameters by applying a relative stem taper curve. The equation was developed based on diameter at breast height (DBH) data in order to eliminate the effect of root spread. The curve equation is a third-order polynomial based on data from 571 sugi (Cryptomeria japonica D. Don) trees measured between 1996 and 2004; the equation ?t the data well (R²>0.99). There are more than 60 local varieties of sugi, and relative stem taper curve equations were developed for 8 of these varieties. By applying the relative stem taper curves, forest managers can estimate the upper stem diameter and log yield before cutting trees.

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Accessibility to cloud-free optical sensor images is essential for large-area monitoring of land and forest cover changes. In this study, the acquisition probabilities of cloud-free images were analyzed using MODIS cloud mask products from 2000 to 2008 in Southeast Asia. The daily cloud masks were summarized into monthly acquisition probabilities for cloud-free images over the period at a spatial resolution of 1km. The mean annual acquisition probability profiles were extracted averaging nine years' observation. Unsupervised clustering was conducted for zoning of the acquisition probabilities using the mean annual profiles. Annual variations in the acquisition probabilities were examined by the standard deviations calculated for each month and comparisons of the mean annual profiles of the whole period and individual years. The distributions of annual acquisition probabilities in forested areas were different in each country. These results suggested that selection of suitable methods and data allowing for the spatial and temporal differences in the acquisition probabilities is necessary for periodic large-area monitoring.

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We evaluate an applicability of the hemispherical photography for estimating leaf area index (LAI) in a stand of bamboo, Phyllostachys pubescens Mazel ex Houz. In the P. pubescens stand, ten successive thinning regimes were conducted, and the repetitive hemispherical photography was performed before and after each thinning. LAI estimated from the photographs was then compared with that estimated by the allometric technique. There was a significant correlation between LAI estimated by these two methods, suggesting the applicability of the hemispherical photography. However, LAI estimated by the photographic method was signi?cantly larger than that estimated by the allometric method. The discrepancy of the estimated LAI might be due to the bias caused by the culms and branches taken in photographs. The Monte Carlo simulation indicated that at least, but not more than, 12 hemispherical photographs per plot with 25 m² in area were necessary for stable estimation of LAI in a stand of P. pubescens. In conclusion, the hemispherical photography should be accepted as an effective alternative for estimating LAI in a stand of P. pubescens.

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