It has proved difficult to monitor the state of plantations by field observations due to the high costs involved, although the extent of unsuccessful plantations has been increasing. The objective of this study was to develop a method to estimate the survival rates of planted trees in young Sugi (Cryptomeria japonica) and Hinoki (Chamaecyparis obtusa) plantations by analyzing LANDSAT TM (Thematic Mapper) data. Our hypothesis was that the survival rate of planted trees, which was regarded as closely correlated with canopy coverage of planted trees, could be represented by the digital number of bands or intensity of some index of remote sensing data. The study sites were young plantations (4 to 12 years old) in Kyushu University Forests in Miyazaki which is located in southern Kyushu, Japan (32°22′10″N, 131°10′40″E), within the cool-temperate deciduous zone. Plantations were divided into aspect classes as the minimum units of this study. The method had two main parts. 1) Interpreting survival rates of planted trees on a pair of aerial photographs. 2) Analyzing the relationships between TM data and the survival rates of trees under two models, MODEL I using NDVI (Normalized Difference Vegetation Index) and MODEL II using the TM band 3 digital number (DN) for detecting the difference in spectra between planted trees and grass. The results showed that: 1) there were big differences in the survival rates according to aspect, and northern slopes had relatively high survival rates compared with southern slopes. 2) It was difficult to estimate the survival rates of planted trees by NDVI. 3) The relationship between survival rates and DN in TM band 3 showed strong negative correlation with a coefficient of determination of 0.643. Thus, DN in TM band 3 appears to be preferable for estimating the survival rates of planted trees. This study thus indicated that TM band 3 approach would be the most effective monitoring method for plantations in inaccessible mountainous regions.

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New Zealand has the potential to become a stable wood supplier to help Japan overcome its projected future difficulties in obtaining wood resources. The basis for this is New Zealand's increasing timber production from monocultural plantations consisting mainly of radiata pine. Presently, Japan uses radiata pine mainly for packaging, with some for plywood production. However, considering the fact that radiata pine is used for many different purposes in New Zealand, it might be possible for Japan to further expand its range of use. The possible areas to improve utilization of New Zealand wood in Japan involve wood used for construction, and civil engineering. However, because it might be difficult to use radiata pine as non-dried pure timber in these areas due to its low quality, such as its relative weakness, processing it into engineering wood is more likely. Considering the utilization of engineering wood imported from New Zealand to Japan, it is likely that New Zealand will face keen international competition in the near future and therefore its market share might not be sustainable. Hence it is critical that both countries cooperate on the issue of improving the technology used for processing radiata pine into engineering wood in order to improve its utilization in Japan.

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A fast growing population and the need for food and forest products coupled with the great demand for wood and rapid economic development in the developing world have brought sustainable forest management under continuous uncertainty. Deforestation in the developing world has been relatively high. But recently, it has been more widely recognized that over-exploitation of forest products and non-forest products is prejudicing the sustainability of the world's forests. Cambodia has been chosen as a case study to test this hypothesis regarding sustainable forest management. There are two main types of forests in Cambodia, namely dryland and edaphic forests, covering a total area of 10.59 million ha or 58% of the total land area. It had been reduced from 12.32 million ha in 1973 as a result of wars and political instability over the last 25 years. Against a background of government instability, great domestic and foreign demands for wood in recent years have resulted in Cambodia's forests being over-exploited. To prove this, a selective 25-year felling cycle system used by F Company was analyzed with the aid of various statistical tools. The analysis shows that although the growing stock of F's evergreen forest is as low as 82 m^3/ha due to illegal logging, the company has exploited 7 m^3/ha or 9% of the total stock. This was 6 percentage points higher than the sustainable cutting rate of Cambodia's evergreen forest. This supports the hypothesis of over-exploitation. The result also shows that there is still a large number of residual trees with diameter less than 45 cm, which are available for extracting over the next 25 years if they are properly managed. Strong enforcement mechanisms for forest monitoring and control are needed to stop illegal logging, to prevent over-exploitation and to manage the residual trees for long-term availability of forest resources.

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Even-aged pure forest stands of Japanese cedar (Cryptomeria japonica D. DON) and Japanese cypress (Chamaecyparis obtusa ENDL.) were statistically stratified into upper and lower strata using the discriminant analysis method. The mean height of the stratified upper trees was defined as the "upper tree height (H_u)", and the relationship between H_u and mean tree height (H_m) was analyzed. A strongly positive correlation was observed between H_u and H_m, and well-fitting empirical equations for H_m and H_u were derived for Japanese cedar stands as: H_u=1.091H_m (r=0.979) and for Japanese cypress stands as: H_u=1.056H_m (r=0.997). The upper strata in Japanese cedar and Japanese cypress stands were considered to be composed of 67% and 58% of the total number of trees, respectively. These equations or component ratios could be used in estimating upper tree height.

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The discriminant analysis method (DAM), which is a method for analyzing forest stratification, was qualitatively compared with a method using symmetric type difference diagrams (SDM) by applying both methods to four types of actual forest stands. The number of strata determined by DAM and SDM were different. Using SDM, cases of forest stands that could not be successfully stratified into several strata were observed, and the number of strata and boundaries between the strata could not be objectively determined. On the other hand, forest stands could be stratified into several strata not subjectively but objectively with DAM. However, it could not be judged with DAM whether a forest stand is composed of one stratum or two strata, whereas this was possible with SDM. From these results, it cannot be concluded which method is superior to the other since they have different advantages and disadvantages. It is therefore considered important to choose the appropriate method or to combine the two methods depending on the purpose of analysis.

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