| 要旨トップ | 目次 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

一般講演（ポスター発表） P0-106 （Poster presentation）

#### Spatiotemporal Variability of Extreme Tree-Growth Reductions and Resilience Components: Comparative Study across Northern High-Latitude Regions

*Shunsuke TEI（Hokkaido Research Center FFPRI）

Forests in the northern high latitudes are increasingly affected by extreme climatic events, such as droughts and heavy precipitation, whose frequency is expected to rise under ongoing global warming. In this study, we conducted a large-scale spatiotemporal analysis using tree-ring width data from numerous forest sites distributed across the Northern Hemisphere high latitudes to assess tree vulnerability to climate extremes. We defined incomplete recovery as events in which more than half (≥50%) of trees at a given site failed to recover to at least 80% of their pre-disturbance growth within five years following a growth-reducing disturbance. We evaluated the occurrence probability of incomplete recovery and its dominant climatic drivers, considering growth reductions associated with drought and wet conditions as well as with cold and warm temperature extremes.
Our results show that, compared with the period 1900–1949, the probability of incomplete recovery increased at many sites across North America and Eurasia after 1950. The dominant climatic drivers of incomplete recovery varied across regions and time periods: in recent decades, the proportion of sites primarily constrained by dry conditions increased markedly in North America, whereas cold conditions became increasingly dominant in Eurasia. Furthermore, during post-disturbance recovery processes, the relative contribution of recovery growth (Rc) increased after 1950 compared with 1900–1949 only under wet conditions, while its contribution became relatively smaller under cold, dry, and warm conditions. These results indicate that the recent increase in incomplete recovery risk is driven less by a decline in recovery capacity itself than by the increasing severity of growth reductions during disturbance events—that is, the magnitude of growth decline (Rt) has become a more critical limiting factor.

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