Changes in terpenes of three kinds of pine needles during litter decomposition

Abstract

This study was designed to evaluate changes in the terpene composition of 3 types of pines (Pinus densiflora, Pinus thunbergii and Pinus rigida), while decomposing their leaf litter. Needle litters were placed at two different organic layer depths, one on the surface and the other beneath the litter layer. Changes in the terpene composition of this litter were detected using a gas chromatograph-mass spectrometer. Among the monoterpenes acquired from the fresh needles of P. densiflora and P. rigida, α-pinene (12.05% and 19.87%, respectively) was the major one, followed by β-pinene (2.90% and 14.07%). However, from the needles of P. thunbergii, β-pinene (20.77%) was the major one, followed by α-pinene (10.79%). Among the sesquiterpenes detected in P. densiflora, trans-caryophyllene (3.12%) was the highest composition compound, whereas germacrene-D (6.09%) for P. thunbergii and 1,6-cyclodecadiene (7.41%) and endo-1-bourbonanol (7.41%) for P. rigida were the highest content compounds. However, the total amounts of terpenes decreased sharply by 40-85.4% in all three types of pine needle after 90-120 days of the experiment. The concentration of each terpene differed during decomposition, and the majority of compounds disappeared from beneath the litter layer. It was determined that three types of reducing patterns of each compound appeared on the rate of loss of concentration during decomposition; one pattern decreasing sharply during the initial period, another pattern steadily or slowly decreasing, and a newly detected pattern at low concentration occurring during decomposition.

Characteristics and distribution of terpenes in South Korean forests

“…Jiri are located at similar latitudes, 35°04′N and 35°3 7′N respectively, thus, these results indicate that monoterpene emission from P. densiflora may be affected by the latitude of the location where the trees have grown in the summer. Despite some variations in monoterpene ratios, other studies also confirmed that three monoterpenes from P. densiflora, α-pinene, myrcene, and β-phellandrene are dominantly emitted regardless of location or season in Korea , Jo and Kim 2010, Son et al 2012. The dominant emission of the three monoterpenes from P. densiflora was also observed in studies conducted overseas: an emission experiment performed with cultured P. densiflora in a greenhouse in Japan demonstrated high emission of α-pinene, myrcene, and β-phellandrene (Yokouchi and Ambe 1984).…”

Profiling Patterns of Volatile Organic Compounds in Intact, Senescent, and Litter Red Pine (Pinus densiflora Sieb. et Zucc.) Needles in Winter

“…The shed of aged or damaged needles in pine stands is important for the release of VOCs from the forest floor (Isidorov et al, 2003. Even when senescent or dead, pine needles contain high levels of terpenes and other precursors of the oxidized volatile compounds, formed as a result of enzymatic reactions (Isidorov et al, 2010;Jo and Kim, 2010;Zhang et al, 2018). Coniferous litter is also a good source of secondary metabolites that are released during chemical or biological decomposition processes.…”