5:15 PM - 7:15 PM
[ACG52-P08] Dendro-ecological analysis for past extreme tree-growth reduction events and their resilience components over northern high-latitude regions
Keywords:Tree ring, ITRDB, Resilience, High latitudes of the Northern Hemisphere
Terrestrial forest ecosystems in northern high-latitude regions, although crucial to the global carbon cycle and climate system, are vulnerable to climate change. Global warming has contributed to the increase in forest decay and mortality rates in this region. This study aimed to examine past extreme tree-growth reduction (EGR) events and the associated resilience components by using the tree-ring width index (RWI) data from 675 International Tree-Ring Data Bank (ITRDB) sites across the northern high-latitude regions. Few significant regional differences existed in the observed frequency of EGR events over the past several hundred years; however, the resilience components exhibited large spatial variations with significant regional differences. The site-averaged resilience (Rs) over the entire analysis period was lower in North America than in Europe, suggesting a possible higher vulnerability to EGR events in North America. The high vulnerability in North America was not attributed to the large reduction in growth during the EGR event but to the small amount of recovery (Rc) after the events. As no significant temporal changes were observed with respect to the resilience components over the four analysis periods, that is, (i) pre-1700, (ii) 1701–1800, (iii) 1801–1900, and (iv) post-1901, the resilience components estimated in this study could be considered as representative values for each region, and the pattern of regional difference was relatively uniform from past to present and possibly into the future. These results are crucial to understand future tree and forest dynamics in the high latitudes of the Northern Hemisphere, particularly regarding risks associated with tree decline and mortality due to climate extremes and other disturbance factors.