It is necessary to dry woody biomass used for fuel of boilers. We examined the decreasing rate of moisture contents by transpirational drying of Japanese cedar logs with bark. Two meter long logs of Japanese Cedar were stacked up into triangle or quadrilateral on paved collecting place and dried from December to September. As a result, the moisture content decreased from about 140% to 40% through drying for 9 months. There was no difference in drying rate between the triangle and quadrilateral stack. The surface logs dried twice as fast as inside ones regardless of ways of piling logs. The moisture differences inside logs were higher in the inner logs of piles than the surface ones. Besides, bias of moisture content occurred because of the environment of stacking logs. It is necessary to interchange surface logs with inner ones, when surface log’s average drying speed declines.

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Effects of thinning for 21 years (or 20 years) in a 45 year-old secondary forest dominated with Quercus crispula and Fagus crenata were examined in Misasa forests of Field Science Center, Faculty of Agriculture, Tottori University. In this experiment, we adopted a method of crown thinning. The mean growth increment (GI) or rate (GR) per year of total basal area was higher in thinning or thinning+fertilization plots than in the control (non-thinned) plots. However, the fertilization alone was not effective. From the relationship between the diameter at breast height (DBH) just after thinning and mean GI or GR of the basal area of individual stems, the effect of thinning was clear in small or middle sized stems in which the big stems with a DBH of more than 25 cm increased after thinning (thinning+fertilization) compared with the control plots. The high-rate thinning of the stems in the large DBH class contributed to the increase of big stems. The effect of thinning on the growth of Quercus clispula, Fagus crenata and Betula grossa was clear, but not in the case of Acanthopanax sciadophyloides or Cornus controversa. Several stems of the latter 2 species died in the thinning and thinning+fertilization plots, but not in the control plots. In the Quercus crispula, the mean number of epicormic shoots per stem and the stand volume after 21 years of thinning showed a significant negative correlation. It is concluded that high- and even-rate thinning of stems in the large DBH species comprising the crown canopy promoted the thickening growth of individual stems and total volume in the stand contributing to control of the development of epicormic shoots.

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Hydrological observations for 3 water-years, along with soil surveys and investigations of stand condition have been conducted in three catchments formed from tuff of the Tertiary layer (upper, middle, and down) of the Nagasaka experiment in Akita prefecture to identify the effects that differences in stand condition and soil properties had on runoff characteristics. Each catchment was covered with more than 40-year-old stands of planted Cryptomeria japonica. The growth and stem density of Cryptomeria japonica, and the ratio of other species invading the plantation differed among the catchments; such that the forest cover percentages also differed among the catchments. The annual water losses of the catchments showed remarkable individual differences; 724 mm (upper), 861 mm (middle), and 548 mm (down). It was thought that some of these differences occurred because of differing rates of evapotranspiration between the catchments. The annual water loss of the middle catchment was much greater than the annual potential evapotranspiration using the Hamon formula (640 mm), suggesting that deep percolation occurred. The water-holding capacity of each catchment based on the soil survey was 104 mm (upper), 132 mm (middle), and 121 mm (down). The ordering of the water-holding capacities among the three catchments was the same as that for the basin capacity. It was postulated that the shape of the discharge-duration curve of each catchment could be explained by differences in evapotranspiration and the basin capacity.

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We studied the pollination system of a shrub, Aucuba japonica Thunb, by conducting a pollinator exclusion experiment (bagging and artificial pollination) and an observation of floral visitors. The fruit set was lower in the bagging treatments (either 1 mm or 3 mm mesh) than that under natural condition. Artificial pollination treatment with the bagging, however, did not decrease the fruit sets. Moreover, there was no difference in the fruit sets between 1 mm and 3 mm mesh treatments. These results suggest that A. japonica is mainly pollinated by insects. The main floral visitors were Coleoptera, mainly Cantharidae and Curculionoidae, and Nematocera, such as Sciaridae. It is concluded that A. japonica depends on opportunistic visitations by small generalist insects for pollination.

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In this study, we developed software to measure tree heights with the iPhone. A smartphone such as the iPhone sometimes has an accelerometer, by which the inclination of the device can be measured. Therefore, you can measure tree heights using an iPhone with an accelerometer, applying the principles of trigonometry. iPhones have excellent user interface, making it possible to manage, display, edit and calculate the measuring data. Thus, it is not necessary to input and calculate the measuring data on a personal computer after measuring. Moreover, the measuring data can be transmitted using wireless LAN or cellular phone circuit. Thus, productivity of field surveying in forests can be improved by using software to measure tree heights on an iPhone.

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This paper reviews recent advances in studies on the causes of tropical deforestation. It indicates that there has been a reevaluation of the importance of shifting cultivation, population growth, poverty, and road construction which were given as the main causes. It has broadly been believed that population growth and poverty are the driving forces behind tropical deforestation, mostly through shifting cultivation. This idea was examined thoroughly during the 1990s and 2000s. Agricultural expansion is the main factor contributing to tropical deforestation. Empirical evidence now shows that the expansion of commercial and export crops has a greater impact than shifting cultivation. The effects of population pressure and poverty on deforestation are still controversial despite having been the subject of many empirical studies. Evidence supports the notion that road construction has a strong impact on deforestation. It is pointed out that road construction reduces transportation costs and raises agricultural profitability (land rent) in tropical rural areas. This then accelerates deforestation. Von Thnen’s model showing the relationship between land rent and land use has been argued as being a powerful concept to explain deforestation. However the model’s shortcomings must be made up for by other theories.

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