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Using δ13C and δ18O measurements to assess climate controls on insect-related tree mortality in south-central Alaska
Presented by Dr. Adam CSANK on 17 May 2013 from 10:30 to 10:50
Type: Oral Presentation
Session: Isotopes in Dendrochronology II
Track: Isotopes in dendrochronology
Here we test whether trees killed by spruce beetles show a water stress response prior to death using tree-ring chronologies and isotopic measurements from live and dead trees. Growth and δ13C in surviving trees was only weakly correlated with spring-summer temperatures until roughly 10 years before the beetle outbreak, both growth and δ13C in the dead trees was correlated with temperatures for several decades. Approximately 10 years prior to death, growth in the dead trees became decoupled from temperature. This is in contrast to δ13C values, which show a stronger temperature response 10 years prior to death. At sites where δ18O was more sensitive to precipitation surviving trees showed a more clear climate- δ18O response. Water stress response explains both the isotopic values and the decoupling of temperature and growth in trees that were killed during the outbreak and also indicate that certain trees may be physiologically pre-disposed to mortality events by nature of their environmental response.
Room: Salon D