Multi-temporal survival analysis of tree population in natural forest: Case in Chiba prefecture.

抄録

Survival analysis of tree populations is an important method applied to forest science researches such as prediction of dead trees, comparison of mortality trends by tree species, and assessment of tree mortality decline by insects and pathogens. The purpose of this study was to conduct multi-temporal survival analysis of a tree population in a natural forest stand. The study site was the permanent plot, of 0.26 ha, established in the secondary forest dominated by Abies firma, Tsuga sieboldii, and Quercus serrata at the University of Tokyo Chiba Forest in the southeastern part of the Boso peninsula, Japan. We set the two observation periods of 2000-2009 and 2012-2021, and collected tree age data for both living and dead trees in the two periods. The non-parametric survival probabilities were estimated and then their curves were compared in the two periods. The results showed that the survival curve significantly declined in the second period owing to the massive Oak Wilt diseases.