Frontiers in Forests and Global Change (Dec 2022)
Emissions of isoprenoids from dominant tree species in subtropical China
Abstract
Emission factors (Es) are among the major sources of uncertainty in regional or global emission estimates of biogenic volatile organic compounds (BVOCs). Tropical vegetation contributes approximately 70% of global BVOC emissions, yet in situ measurements of BVOC emissions from tropical tree species, especially naturally grown mature trees, are quite limited. In this study, BVOC emissions from twenty mature trees (15 evergreen broad-leaved and 5 evergreen needle-leaved) were measured using dynamic chambers, and the emitted BVOCs were collected using sorbent tubes and speciated with a thermal desorption-gas chromatography/mass spectrometry system (TD-GC/MS). Twenty BVOC compounds including, isoprene, 14 monoterpene (MT) species and 9 sesquiterpene (SQT) species were quantified to calculate their Es. The results showed that Eucalyptus urophylla had the largest Es of isoprene (26.47 ± 3.70 μg g–1 h–1) among all the measured trees, followed by Ficus hispida (20.74 ± 1.78 μg g–1 h–1), Syzygium hainanense (20.49 ± 1.36 μg g–1 h–1), Casuarina equisetifolia (18.70 ± 2.91 μg g–1 h–1), and Mangifera indica (11.71 ± 7.04 μg g–1 h–1). α-Pinene, β-pinene, and limonene were the most abundant MTs, of which the largest Es were observed for Magnolia denudata (8.33 ± 2.05 μg g–1 h–1), Castanopsis hystrix (5.29 ± 3.24 μg g–1 h–1), and Magnolia denudata (3.11 ± 1.07 μg g–1 h–1), respectively. The Es of SQTs for the measured trees were lower than 0.50 μg g–1 h–1 except for Magnolia denudata (1.10 ± 0.41 μg g–1 h–1). β-Caryophyllene was the most common SQT, with Magnolia denudata having the highest Es of 0.09 ± 0.03 μg g–1h–1. The localized Es for dominant tree species could be used to update BVOC emission factors for typical vegetation types and help improve BVOC emission estimates in typical subtropical regions and narrow their uncertainties.
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