Harvesting tree selection based on age structure and survival analysis of natural forest

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06142
• 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: The University of Tokyo
• Principal Investigator: Hiroshima Takuya 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (40302591)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 天然林 / 生存時間解析 / 択伐 / 選木 / 樹齢 / レジストグラフ

Outline of Final Research Achievements

In this study, we conducted survival analyses of tree populations in natural forest from various perspectives such as multiple time periods, multiple plots, and multiple tree species, and examined methods for applying the results to actual natural forest management.
As an overview of the results, (1) we established a method for evaluating the maturity of natural forests by applying survival analysis to tree populations. (2) We found differences in survival curves between conifer and broadleaf tree species in natural forests. (3) Using the survival curves of conifers and broadleaf trees estimated above, we conducted a simulation of long-term variation in tree age distribution and found the shape of steady state of the distribution.

Free Research Field

森林科学

Academic Significance and Societal Importance of the Research Achievements

本研究は、これまで適用事例が極めて限られていた、天然林の樹木個体群を対象とした生存時間解析を、長期間かつ豊富な樹木サンプルに対して行い、解析結果を実際の天然林管理へ応用するための手法を提案した。具体的には、上記①、③の成果より、森林の成熟度を評価した上で、②の成果を応用して、針葉樹、広葉樹の平均寿命（針葉樹72年、広葉樹80年）を推定した上で、樹齢情報を胸高直径情報（針葉樹31cm、広葉樹36cm）に換算し、天然林択伐における伐採木の選定条件としての応用可能性を見出した。