FIG 1.

Terpenic compounds content (μg/g DW) (DW, dry weight) present in Norway spruce wood upon storage. FW_C represents freshly cut spruce wood, SW_C denotes commercially available spruce timber felled 3 to 4 years ago, and OW_C represents old wood that was cut circa 120 years ago. Values are the average of two independent analytical determinations of compound concentrations in pooled homogenized (n = 6) samples of wood. Error bars represent the uncertainty (U) of the whole analytical procedure, including extraction and GC-MS (gas chromatography coupled with mass spectrometry) instrumental analysis. U is based on relative standard deviation (RSD) obtained from 9 independent determinations of compounds concentration in one homogenized wood sample. U is calculated using the equation U = 2 × RSD.