气候变化领域集成服务门户

Recent studies suggest that forest vulnerability to tree mortality has increased as a result of extreme climate events such as severe drought and heavy rain. However, little is known about the mortality processes, particularly when they are induced by heavy rain. A dendroecological analysis was conducted on living and dead trees in a Siberian larch forest using the chronologies of 30 years of radial growth and carbon isotope (Delta C-13) discrimination. The analysis demonstrates the relationship between heavy rain and larch tree mortality. Radial growth and Delta C-13 patterns in dead trees at a wet subsite diverged from those of living trees only during the heavy rain period in 2005-2007. On the other hand, the radial growth and Delta C-13 patterns in dead trees at the dry subsite diverged from those of living trees after severe drought events in 1998 and in 2002-2003. At the wet subsite, the heavy rain was intense enough to push the larch trees past their mortality threshold, whereas previous drought conditions also contributed to tree mortality at the dry subsite. Our results demonstrated that the process of larch tree mortality differs with site-specific topographical soil moisture conditions, even when synchronous tree death occurs in a specific year of climatic extremes.