森林生態系サービス総合評価のための生態系プロセスモデルの改良と気候変動および森林管理によるサービス変化の分析

抄録

    Process-based ecosystem models simulate carbon, nitrogen and water cycles connected to ecosystem services such as wood biomass provisioning service (WPS), carbon sequestration service (CSS) and flood control service (FCS) in forests. They are potentially applicable to the comprehensive assessment of forest ecosystem services and their changes under climate changes and/or a variety of forest management. In this study, thinning and self-thinning processes were implemented to modified Biome-BGC (Machimura et al., 2016) to calculate timber volume and stand density changes by forest management. Moreover, we adjusted model parameters to reproduce the timber volume and stand density recorded in the yield table for Chamaecyparis obtusa private plantation in Hyogo as a case study. The improved model and adjusted parameters could reproduce the timber volume and stand density of 1 to 80-year stand. We analyzed changes of WPS, CSS, FCS and timber volume growth (TVG) under climate change (RCP8.5) and several forest management cases in Hyogo. Among different rotation periods (60, 80 and 120 years), WPS by middle rotation period (80 years) was the largest and was best for woody biomass production. In contrast, the long rotation period (120 years) showed the largest FCS, the largest TVG and only 2% smaller WPS than middle rotation period, therefore this management practice was suitable for controlling flood and getting high-value timber. This example demonstrated that the improved model can analyze the tradeoff relationship between services and it is applicable to a comprehensive forest management considering ecosystem changes by climate change and practices.