Seasonal Dynamics and Composition of Biogenic Volatile Organic Compounds in Different Forests

Understanding seasonal patterns of forest biogenic volatile organic compounds (BVOCs) is essential for clarifying their ecological functions and potential health benefits. In this study, BVOC samples were collected from ten representative forest stands in Caoyutang Forest Park across four seasons using adsorption tube sampling coupled with thermal desorption–gas chromatography/mass spectrometry (TD-GC/MS). Pronounced spatial and temporal variations in BVOC composition and relative abundance were observed among different forest stands. The number of detected BVOCs varied considerably among seasons, following the order autumn > winter > spring > summer, while relative BVOC abundance was highest in autumn and lowest in spring. Thujopsis dolabrata stands showed relatively high BVOC relative abundance in spring, whereas several mixed forest stands exhibited greater compound richness and relative abundance during autumn. Seasonal shifts in dominant BVOC groups differed among forest stands, with esters becoming prominent in Cunninghamia lanceolata–Hydrangea mixed stands during summer, while aromatic hydrocarbons and alkanes dominated many stands during winter. Across all samples, alkanes and esters represented major compound classes, whereas aromatic hydrocarbons, aldehydes, and esters contributed substantially to relative abundance. A total of 10 terpenoid compounds were identified, with camphene representing one of the major components, and a higher relative abundance of terpenoids was observed in Abies firma stands. Principal component analysis indicated distinct compositional patterns among Cunninghamia lanceolata-dominated mixed stands, highlighting the influence of associated tree species and stand structure on BVOC profiles. This study elucidates spatial and seasonal BVOC patterns of BVOC composition in relation to forest structure, providing a scientific basis for planning forest therapy bases and selecting therapeutic plant species in landscape design.