Projection of impacts of climate change on windthrows and evaluation of potential adaptation measures in forest management: A case study from empirical modelling of windthrows in Hokkaido, Japan, by Typhoon Songda (2004)

A windthrow refers to the uprooting and overthrowing of trees by the wind. Typhoons are a major cause of windthrows in Japan and are predicted to intensify under global warming. This study aimed to estimate the impact of climate change on windthrows and evaluate possible adaptation measures for sustainable forest management. We incorporated Typhoon Songda (2004) simulation experiments under current and pseudo-global warming (2075–2099, RCP 8.5 scenario) conditions with windthrow modelling in four natural and four artificial (Abies sachalinensis, Pinaceae) forests of Hokkaido. Unexpectedly, pseudo-global warming conditions decreased windthrow probabilities compared with current conditions for both forest types, presumably because wind speeds of the simulated typhoon weakened in Japan’s high-latitude regions. Our results indicate that reconversion of artificial forests into natural forests largely decreased windthrow probability, providing a potential adaptation measure for improved forest management. To fully understand the range of climate-change effects on windthrow in Japan, future studies should use different climate scenarios and data from other typhoons, geographical regions, and forest types.