Bidirectional emission of organic compounds by decaying leaf litter of a number of forest-forming tree species in the northern hemisphere

The leaf litter of woody plants is an important, but insufficiently studied, source of volatile organic compounds (VOCs) in forest air, as well as the main source of dissolved organic carbon (DOC) for forest soil. This work is devoted to the determination of the molecular composition of litter -derived VOCs and DOC of four species of deciduous trees typical of boreal and mid -latitude forests: silver birch (Betula pendula), European hornbeam (Carpinus betulus), black alder (Alnus glutinosa), and aspen (Populus tremula). The qualitative composition of the compounds released from the litter was determined by gas chromatography with mass spectrometric detection. In the composition of VOCs of all four types of litter, both fresh and exposed during a six-month field experiment, 213 C1 -C16 compounds of various classes, including 83 photochemically active terpenes, were identified. Litterderived VOCs are a mixture of secondary plant metabolites and compounds of microbiological origin. In the composition of DOC leached by rainwater during the field experiment, the presence of 231 organic components was registered, 154 of which were identified. Most of them were carbohydrates, aliphatic acids and alcohols, which can be easily assimilated by soil microbes and affect biological processes with their participation. Thus, the important role of deciduous tree litter as a source of Corg, which plays an important role both in atmospheric processes and in soils, has been demonstrated.