Assessment of species‐specific growth‐mortality relationships using tree‐ring data

CAILLERET, M., J. MARTÍNEZ-VILALTA; OJEDA, V (+MUCHOS OTROS)

Estoril

Conferencia; STReESS COS Annual Meeting Estoril; 2014

·          Tree mortality is a keyfactor influencing forest functions and dynamics, but our understanding of thephysiological mechanisms leading to mortality and the associated changes in treegrowth rates are still limited. ·          Here, we compiled aglobal tree ring-width database from sites where dead and living trees weregrowing together (2,970 dead and 4,224 living trees growing at 190 sites), and comparedthe juvenile and recent growth rates between trees that died and those that surviveda given mortality event. ·          We observed a general decreasein radial growth before death. The magnitude and duration of the reduction werehighly variable (1-200 years), with longer and stronger reductions forgymnosperms, shade- and drought-tolerant species, and trees that died fromcompetition (relative to drought-induced mortality). Angiosperms and trees thatdied due to biotic agents (especially bark beetles), however, showed atypically short growth reduction. Also, there was no consistent trade-off between juvenile growth and mortality risk.·     Growth reductionsbefore mortality are nearly universal, but their magnitude and duration arespecies- and site-specific. This variability provides valuable information onthe nature of the mortality process, with abruptchanges in growth shortly before death revealing hydraulic failure and/or barkbeetle attack, and long-term growth declines indicating carbon depletion.