To elucidate the effects of clear-cutting and following reforestation on snowmelt runoff, we analyzed statistically the daily hydrological observation data from 1939 to 2005, also daily air temperature and daily snow depth in the Kamabuchi experimental watershed, where paired-catchment studies had been conducted, in northern Japan. Our analysis revealed that snowmelt runoff during the snowmelt season of the clear-cut watersheds (No. 2 and 3) tended to increase after clear-cutting and then decreased gradually. The time needed to return to the previous state was about 30 years after planting. Differences in snowmelt runoff compared with the prelogging periods tended to increase as annual snowfall and spring average air temperature increased, probably due to snow interception by the forest canopy in winter and evapotranspiration in spring, respectively. Although snowmelt runoff seasons tended to begin earlier after clear-cutting than the prelogging periods, the ending dates after cutting were almost the same or only slightly late. These results indicate that clear-cutting increases water resource availability in the spring in terms of water quantity and the duration of snowmelt runoff, but it is concerned that clear-cutting cause snowmelt-flood. Furthermore, it is necessary to carefully evaluate the results of No. 2 watershed, because the practice history was unusual.

We conducted dropping experiments of the root ball of sugi (Cryptomeria japonica D. Don) cuttings grown in paper pots in order to compare the destructive strength of root balls with those of container-grown root balls reported in a previous study. Only small amount of soil medium was detached from paper pot-grown root ball in most droppings in spite of similar or lower root coverage of root ball surface (CRBS) compared to containerized root ball. Generalized linear models performed also demonstrated less soil detachment of paper pot-grown root balls than containerized root-balls under various CRBS and water content, indicating high effectiveness of paper pot in protecting the root balls of cuttings.

Using coupling periods of 5 days, Nobuchi (1976) showed empirically that male Monochamus alternatus could obtain mature sperm at around 5 days old and 1-day-old females undergoing the coupling could lay fertilized eggs later. Nobuchi's experiment contained important information for comprehending fertilization and oviposition potential, but had not been retested. In this study, 48 pairs of male and female M. alternatus less than 5 days old were left for 15 hours at 25°C (15L9D), and each female alone was given a log for oviposition 3-4 times at approximately 5-day intervals. Then, eggs and their hatchings under the bark of each log were examined on the logs 18-55 days after oviposition. Hatchings were observed on the logs given to 10 females, originated from the rearing pairs including 1-day-old females or 3-day-old males. This study supports the finding shown in Nobuchi's experiment and suggests that males and females less than 5 days old have the potential to complete their mating behavior under natural conditions and produce fertilized eggs.

A time study of chipping operations of unutilized forest biomass using a combination of a grapple loader and a chipper was carried out. The material to be chipped was composed mainly of 4-m-length logs that were piled up in the yarding alongside a forest road. An analysis of the relationship between the volume gripped by the grapple loader and the productivity of the chipping operation showed that productivity was maximized when the gripped material volume was 0.56 m³/cycle. Productivity decreased when the gripped volume was larger than 0.56 m³/cycle, because it could not be placed appropriately on the conveyor of the chipper and the swallowing time of the chipper was too long when the gripped material was long and the amount of material was too large. When the investigated chipping operation was performed with a gripping material volume of 0.56 m³/cycle, it was estimated that the total operation time could be significantly reduced by an average of 19％ (386 s). These results suggest that productivity may be optimized by considering the optimum gripping material volume when chipping relatively long logs.

Tropical deforestation has become a global environmental issue and a major source of greenhouse gas emissions. Therefore, efforts to reduce deforestation have been actively promoted worldwide through climate change mitigation schemes. However, results of these efforts have fallen far below initial expectations. Concerns, such as economic damages to local people in the tropics have also been observed. The reason for the disappointing results is proposed to be that the underlying causes of deforestation are not well understood, thereby resulting in the selection of inappropriate strategies. Therefore, this study aimed to clarify the causes of deforestation, show the mechanisms of deforestation's occurrence and control, and propose sustainable solutions based on previous studies from around the world and the author's empirical research in Southeast Asia. The highlights are as follows: 1) the main proximate causes of deforestation are related to increase in agricultural rent (agricultural profitability); 2) poverty is the chief underlying cause of deforestation; 3) deforestation mechanisms can be explained via three factors―agricultural rent, poverty, and forest scarcity; 4) the mainstream of current efforts are strategies to decrease agricultural rent, which can be effective to reduce deforestation, but unsustainable without considering the high costs and social impacts; 5) poverty reduction strategies can be sustainably effective in reducing deforestation; and 6) global efforts to combat deforestation need a shift in focus from agricultural rent reduction strategies to poverty reduction strategies.