Under the J-Credit Scheme, the amount of certified carbon credits generated from forest management (forest credits) has been increasing every year. However, many of them remain unsold. In this study, we aimed to clarify the characteristics and motivations of forest credit buyers and to examine issues to activate forest credit trading. We sent questionnaires to 179 forest credit buyers from six forest management projects in Niigata Prefecture, of which 96 responded. Most of the forest credit buyers were small and mid-sized companies that aimed to contribute to the local forest. The amounts of credits they bought were also small, mostly less than 5 t-CO2. Most of the buyers were encouraged to buy forest credits by either prefectural officials, the credit creators, or intermediaries (coordinators) such as local banks. Among these, coordinators were effective in obtaining new buyers and expanding sales channels. However, many of the buyers who were encouraged by coordinators bought only small amounts of credits and were less willing to continue buying. In contrast, buyers who actively learned about forest credits without being encouraged by others were more willing to continue buying larger amounts of credits. Thus, in order to activate forest credit trading, it would be effective to increase efforts to motivate buyers who were encouraged by coordinators, and to increase opportunities to catch the attention of companies that are willing to contribute to the forest environment.

Japanese oak wilt (JOW) is an epidemic disease transmitted by an insect vector, the oak platypodid beetle Platypus quercivorus. Splitting a dead tree is one of the best approaches to prevent spreading JOW because this method is not only highly effective in the extermination of the beetles but also in the availability of infested trees for fuel. However, this approach has high costs for on-site work to prepare firewood and is restricted to the Quercus genus available for fuel. Here, we investigated whether the number of newly emerged adults decreased by leaving the split logs of the infested Quercus serrata and Lithocarpus edulis in the forest. The dead trees of both species were brought to the study site, each cut into 30 cm lengths. These logs were split in half and eighth, and intact logs were prepared. We placed these logs into each trap to collect adults and measured the weight of split logs to predict water contents. In Q. serrata, the number of adults in eighth-split logs significantly decreased than those of half-split logs and intact logs. The predicted water contents of eighth-split logs were significantly low compared with those of others. In L. edulis, the number of adults collected from half- and eighth-split logs significantly decreased than those of intact logs, but the predicted water contents were not different between half- and eighth-split logs. Our results indicated effective pest control even if at least eighth-split logs of both tree species were left on the forest floor.