Does the growth of old-aged forest decline? : Testing new and old hypotheses for application to forestry management.

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05695
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Nishizono Tomohiro 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (90353797)
• Co-Investigator(Kenkyū-buntansha): 福本 桂子 国立研究開発法人森林研究・整備機構, 森林総合研究所, 研究員 (30822712) ; 高嶋 敦史 琉球大学, 農学部, 助教 (40433099)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 高齢林 / スギ林 / 天然林 / 固定試験地 / 成長量

Outline of Final Research Achievements

Traditionally, forest growth was believed to peak during the young age stage and then decline over time, ultimately converging to zero (Hypothesis 1). Recently, however, there is growing support for the idea that growth continues steadily after reaching its peak, as long as the ecosystem remains undisturbed (Hypothesis 2). Studies in Japan also suggest a possible intermediate model (Hypothesis 3) between these hypotheses.
In this study, we tested these hypotheses using long-term monitoring data from Japanese cedar (Cryptomeria japonica) forests. We first investigated the presence of a growth peak during the young age stage using data from managed cedar plantations. Then, we examined whether growth rates decline and approach zero in the mature stage by analyzing data from both mature managed plantations and old-growth natural cedar forests. The results generally supported Hypothesis 3, indicating that forest growth patterns exhibit characteristics of both initial hypotheses.

Free Research Field

森林計画学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果は、森林の成長量の推移を規定する機構を理解することに貢献した。また，スギ林の伐期設定の指針に活用できる。