Does successive exposure of conifer seedlings to drought prepare them for subsequent extreme drought?

Foliar tissue carbon isotope discrimination (denoted δ13C) will be measured using isotope ratio mass-spectrometry, on a random subset of finely ground needle samples from across the combined water treatments (n=4). Details of the procedure are as follows. Four milligrams of needle tissue will be packed into 4 x 6 mm tins and analyzed at the UC Davis Stable Isotope Facility using a Costech ECS 4010 Elemental Analyzer interfaced to a Delta V advantage isotope ratio mass spectrometer through the ConFlo IV system. Elemental analyses will be conducted using evolutionary flash-combustion & chromatographic separation techniques with a furnace temperature of 1000° C and reduction oven temperature of 650° C. We will measure δ13C as ‰ values relative to the VPDB standard, following common practice. Four in-house standards (ISU Peptone, Costech Acetanilide, Glycine and DORM-3), calibrated against international standards (IAEA-N-1, IAEA-N-2, USGS-25, USGS-40, USGS-41, USGS-24, IAEA-600), will be used to create a two-point calibration curve to correct raw isotope measures.