Canadian Forest Service Publications

A synthesis of radial growth patterns preceding tree mortality. 2016. Cailleret, M.; Jansen, S.; Robert, E.M.R.; Desoto, L.; Aakala, T.; Antos, J.A.; Beikircher, B.; Bigler, C.; Bugmann, H.; Caccianiga, M.; Čada, V.; Camarero, J.J.; Cherubini, P.; Cochard, H.; Coyea, M.R.; Čufar, K.; Das, A.J.; Davi, H.; Delzon, S.; Dorman, M.; Gea-Izquierdo, G.; Gillner, S.; Haavik, L.J.; Hartmann, H.; Hereş, A.-M.; Hultine, K.R.; Janda, P.; Kane, J.M.; Kharuk, V.I.; Kitzberger, T.; Klein, T.; Kramer, K.; Lens, F.; Levanic, T.; Linares Calderon, J.C.; Lloret, F.; Lobo-Do-Vale, R.; Lombardi, F.; López Rodríguez, R.; Mäkinen, H.; Mayr, S.; Mészáros, I.; Metsaranta, J.M.; Minunno, F.; Oberhuber, W.; Papadopoulos, A.; Peltoniemi, M.; Petritan, A.M.; Rohner, B.; Sangüesa-Barreda, G.; Sarris, D.; Smith, J.M.; Stan, A.B.; Sterck, F.; Stojanović, D.B.; Suarez, M.L.; Svoboda, M.; Tognetti, R.; Torres-Ruiz, J.M.; Trotsiuk, V.; Villalba, R.; Vodde, F.; Westwood, A.R.; Wyckoff, P.H.; Zafirov, N.; Martínez-Vilalta, J. Global Change Biology 23(4):1675-1690.

Year: 2016

Issued by: Northern Forestry Centre

Catalog ID: 37526

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1111/gcb.13535

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Tree mortality is a key factor influencing forest functions and dynamics, but our understanding of the mechanisms leading to mortality and the associated changes in tree growth rates are still limited. We compiled a new pan-continental tree-ring width database from sites where both dead and living trees were sampled (2970 dead and 4224 living trees from 190 sites, including 36 species), and compared early and recent growth rates between trees that died and those that survived a given mortality event. We observed a decrease in radial growth before death in ca. 84% of the mortality events. The extent and duration of these reductions were highly variable (1–100 years in 96% of events) due to the complex interactions among study species and the source(s) of mortality. Strong and long-lasting declines were found for gymnosperms, shade- and drought-tolerant species, and trees that died from competition. Angiosperms and trees that died due to biotic attacks (especially bark-beetles) typically showed relatively small and short-term growth reductions. Our analysis did not highlight any universal trade-off between early growth and tree longevity within a species, although this result may also reflect high variability in sampling design among sites. The intersite and interspecific variability in growth patterns before mortality provides valuable information on the nature of the mortality process, which is consistent with our understanding of the physiological mechanisms leading to mortality. Abrupt changes in growth immediately before death can be associated with generalized hydraulic failure and/or bark-beetle attack, while long-term decrease in growth may be associated with a gradual decline in hydraulic performance coupled with depletion in carbon reserves. Our results imply that growth-based mortality algorithms may be a powerful tool for predicting gymnosperm mortality induced by chronic stress, but not necessarily so for angiosperms and in case of intense drought or bark-beetle outbreaks.

Plain Language Summary

Forests are affected when trees die, but we cannot yet predict which trees will die and why. This study looked at over 4000 live trees and about 3000 trees that died, and we compared how all these trees grew. We measured the width of the annual growth rings of both live and dead trees; we completed these measurements at 190 different places all around the world where both live and dead trees once grew together. Usually, right before a tree died, it grew more slowly, which was evident because its annual rings were narrower. Trees grew more slowly for anywhere from 1 to 200 years, depending on the type of tree (whether it has leaves or needles), and how easily the tree could tolerate growing conditions such as very little light or water, and whether or not they had been attacked by bugs at some point during their lives. Rates of growth before trees died varied quite a bit, but trees usually grew at least a bit more slowly before they died. It did not seem to matter whether or not a tree that died grew slowly or quickly relative to the other trees around it when it was young. Following drought, trees die either because the “pipes” inside their trunks that carry water (called xylem cells) burst when it is dry and they die suddenly, or because the tiny holes in their leaves (called stomata) stay closed for too long and the trees can not make enough of their own food (called photosynthesis), and they slowly starve to death. Both of these types of events can happen. Our analyses show that the changes in growth level before death might provide useful insights into the processes underlying tree mortality.