Work

Unexpectedly high aldehyde emissions from stems of six major European tree species

Year: 2026

Type: article

Abstract: Volatile organic compounds (VOCs) are of great relevance for atmospheric chemistry as they are involved in ozone and secondary aerosol (SOA) formation, hence, affecting regional air quality. Tree stems represent an important but usually overlooked ecosystem component contributing to the budget of biogenic VOCs (BVOCs) in forests. Here, we quantified stem BVOC exchange from six major European tree species – Quercus robur, Fagus sylvatica, Larix decidua, Pseudotsuga menziesii, Abies alba and Picea abies – in a mixed temperate forest in southwestern Germany. BVOC exchange rates were determined in late spring and early summer 2025. Across all tree species studied, 25 BVOCs were consistently exchanged between stems and the atmosphere. BVOC composition of all trees was dominated by aldehydes (≥ 60% of total BVOCs exchanged), followed by monoterpenes, aromatics and alkanes. In contrast to deciduous trees, conifers showed considerable higher emission of monoterpenes. Multivariate analyses revealed species-specific emission patterns particularly for Q. robur and F. sylvatica. To compare tree stem BVOC emission to leaf BVOC emissions at the ecosystem scale, we upscaled sabinene emissions based on leaf area index (LAI) and stem surface area, respectively. At the ecosystem scale, stem sabinene fluxes from F. sylvatica accounted for ~0.2% of foliar emissions, based on the approximation that the surface area of stems amounts to ca. 29% of the total leaf area. This estimate demonstrates that stems might substantially contribute to total BVOC exchange in temperate forests, underscoring the need to incorporate species-specific stem fluxes into ecosystem-scale emission models.

Source: Agricultural and Forest Meteorology

DOI: 10.1016/j.agrformet.2026.111193