In this study, we developed a system to predict the distribution of trees in a pure even-aged Hinoki (Chamaecyparis obtusa Sieb.) plantation, mainly using measurement data obtained from two experimental forests in the Tokai district of Japan and published data of the Forestry and Forest Products Research Institute of Japan (FFPRI) in Kinki, Shikoku and Kyushu districts. The system consists of a model to predict stand basal area, a model to estimate maximum density, and a model to predict diameter distribution succession. The system can predict the diameter distribution at the end of a growth period by the diameter distribution at the beginning of the growth period without tree height data. To validate the system, we compared the prediction and observation of stand variables (stand density and stand basal area) and statistics of diameter distribution (mean and standard deviation of diameter at breast height) using data from experimental forests in the Kanto district. We also compared the accuracy of the predictions of the system with those of an existing system that required tree height data. The results indicated that our system predicted stand variables and diameter distribution as precisely as the existing system, but without the need for tree height data. We conclude that our system would operate accurately in other districts to predict stand growth.

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The relative spacing index of a stand is expressed as a function of the average distance between trees and mean tree height. In the self-thinning law, mean and total plant weights are expressed as negative exponential functions of plant density in overcrowded pure stands. In this study, we analyzed the relationship between the self-thinning exponent and the relative spacing index for overcrowded pure stands of two species, Cryptomeria japonica D. Don and Chamaecyparis obtusa Endl. An allometric model that explains the difference in the self-thinning exponent among species was proposed based on allometric relationships between mean tree height and average distance between trees, and between mean tree height and mean stem volume. The resulting self-thinning exponent for total stem volume, obtained from the proposed model, was -0.938 for C. japonica and -0.560 for C. obtusa. These values were statistically identical to the exponents obtained from regressions of the relationships between stand density and total stem volume for the two species. Therefore, the proposed model was applicable to C. japonica and C. obtusa stands. The characteristics related to stem slenderness and relative spacing index determines self-thinning exponent based on the proposed model. The difference in allometric exponents of mean tree height to average distance between trees was found between the two species, but no difference in the exponents of mean tree height to mean stem volume was found. The results indicate that the difference in self-thinning exponents between two species is produced by characteristics related to relative spacing index, rather than by characteristics related to stem slenderness.

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Through the community forestry pilot projects, the Government of Cambodia has been working with various non-governmental organizations to conserve forest resources and improve the local economy. While understanding of community forestry in the world has grown in the last decade, there are still uncertainties about the extent, potential and conditions of community forestry development in Cambodia. This study examined the planning process of a community forestry project and evaluated its implementation based on the project participants' points of view. It was revealed that even if the project can be considered a success there remained some challenges and problems, which came as a result of unfavorable planning process. For future community forestry development, particularly on degraded forest areas, the study proposed a more promising framework of the planning process. This proposed planning process emphasizes the importance of extension work and monitoring and features a more self-reliant style of community forestry development. Currently, there are million hectares of forest areas where community forestry development should be carried out. To successfully expand community forestry in these areas through the proposed planning process, more foresters at all levels should be trained in community forestry, particularly in respect to facilitation skills needed to work with local communities.

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A socio-economic assessment of Eucalyptus plantations was undertaken in Suixi county, Leizhou Peninsula, P.R.China. Information was collected from officials of the Suixi Forestry Bureau and other agencies, and from interviews in a sample of six villages in the county. Eucalyptus plantations have been widely planted on the Leizhou Peninsula. The investigation showed that they play an important role in local environmental improvement, economic development, public infrastructure construction, and domestic energy supplies. But it was found that many plantations have suffered degradation through poor management. Some constraints to sustainable management of plantations, such as those relating to harvesting systems, land security and taxation, were found. Options for removing these constraints need to be further investigated.

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The sky factor, which is an estimate of relative illuminance used in the field of architecture, measured from digital hemispherical photography was compared with relative illuminance measured directly by illuminance meters. At fifty sample points selected randomly in ten stands, digital hemispherical photography was taken using a digital camera (Coolpix 900, Nikon) with an exclusive fish-eye lens (Fish-eye converter FC-E8, Nikon), and relative illuminance was simultaneously measured using illuminance maters (T-10, Minolta). The sky factor was significantly higher than relative illuminance (p<0.001), with the average and maximum differences being 17.191% and 24.995%, respectively. This suggested that the sky factor measured from digital hemispherical photography could not be directly used as an estimate of relative illuminance. However, there was a high correlation between sky factor (SF) and relative illuminance (RI) (r=0.971, p<0.001), and the regression line of SF against RI was SF=1.091RI+15.354 (r^2=0.953, p<0.001). The regression line between sky factor and relative illuminance could therefore be used in correcting the overestimation. In conclusion, although digital hemispherical photography would be a convenient means for estimating light environment, we should pay attention to the characteristics presented in this study to avoid the overestimation.

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