Terpene content in the air of younger and older forests in southeastern Poland: implications for forest therapy

The aim of the study was to investigate differences in terpene content level in the air within younger and older forests of the same species. Conducted from July 18 to October 2 in Nemoral Scots pine and Central European submontane beech forests, air samples were collected using portable aspirators with Tenax TA sorbent tubes. The compounds were identified and quantified using gas chromatography with flame ionization detection. Results showed that older forests emitted more volatile organic compounds (VOCs) than younger ones. Regardless of forest age or species, α-pinene was the most prevalent terpene, accounting for 7.4-12.9% of total VOCs. Other terpenes, such as β-pinene and camphene, were found in lower concentrations (1.7-12.7 times less). In Scots pine, higher α-pinene concentrations were observed in older forests, while younger forests had higher levels of 3-carene and α-terpinene. For beech, higher concentrations of camphene and β-pinene were found in younger forests. In nearly half of the cases, TVOC values and terpene concentrations showed moderate variability (25-45%), with high variability (> 45%) recorded in the remainder. Considering the quantitative and qualitative structure of terpenes, an older pine forest would be most suitable for supporting the treatment of respiratory diseases.