Effect of environmental humidity on monoterpene emissions from Chamaecyparis formosensis heartwood

Abstract Chamaecyparis formosensis is a high-value wood species widely recognized as an excellent raw material for furniture and wooden structures. Wood-framed constructions made from C. formosensis emit a more intense fragrance during rainy weather than on sunny days, suggesting that environmental humidity may influence the release of aromatic compounds from the wood. This study aimed to evaluate the effect of environmental humidity on the emission of monoterpene components from C. formosensis . Heartwood samples were placed in environments with different humidity levels (11, 46, 63, 83, and 99%) for 8–18 days. Monoterpene components from the heartwood were collected using the solid-phase microextraction (SPME) technique and analyzed using gas chromatography-mass spectrometry (GC–MS) to determine their chemical composition and content. SPME–GC–MS analysis results revealed that the major monoterpene components in the heartwood were cis -myrtanol (37.95%) and a mixture of myrtenal and myrtenol (31.01%). In both open and closed environments, the emission of monoterpene components from heartwood was significantly higher at high humidity levels (83% and 99%) than that at low humidity level (11%). This finding indicates that humidity markedly influenced the emission of monoterpene components. Furthermore, under dynamic humidity conditions where humidity increased from 40 to 80%, the emission of monoterpene components from heartwood rose significantly with increasing humidity. Conversely, when humidity decreased from 80 to 40%, the emission of monoterpene components also declined. These results confirm that the emission of monoterpene components from C. formosensis heartwood is strongly affected by environmental humidity, with higher humidity levels promoting greater release of monoterpene components.