A screening analysis of foliar terpene emissions of 36 rainforest tree species in French Guiana and their relationships with seasonality

Key message

Inventory and seasonal variation of terpene emissions from tropical trees in French Guiana: implications for environmental and ecological roles.

Abstract

A limited understanding of foliar terpene emissions from different tree species is prominent in diverse tropical forests. We conducted a study in French Guiana, screening BVOC emissions from 36 tropical woody species. We focused on 32 species in the dry season and 33 in the wet season, documenting terpene emissions for the first time in some of these tree species. Our findings show that 93.8% emitted terpenes in the dry season, while only 33.3% did so in the wet season. Terpene emissions ranged from 0.01 to 80.9 μg g⁻¹ h⁻¹ in the dry season and 0 to 11.7 μg g⁻¹ h⁻¹ in the wet season, consistent with previous reports. We identified and quantified 23 terpene compounds, including 19 monoterpenes and 4 sesquiterpenes. Additionally, 2 non-terpenoid compounds were detected: 2,2,4,6,6-pentamethylheptane (with no detected emissions in the dry season) and toluene. Among the monoterpenes, the most abundant were α-terpinolene, limonene, α-pinene, β-ocimene, and sabinene. As for sesquiterpenes, β-caryophyllene, α-caryophyllene, and α-copaene were observed during the dry season, while during the wet season, α-terpinolene predominated, followed by limonene, α-pinene, sabinene, β-caryophyllene, and α-copaene. Isoprene was detected in most of the species studied in both seasons. Sesquiterpene emissions displayed a notable phylogenetic pattern, whereas total terpenes and monoterpenes did not; however, total terpenes and monoterpenes exhibited a significant seasonal influence. Our study demonstrates that seasonality strongly influences BVOC production in tropical trees, with higher emissions in the dry season. These findings imply that various factors and conditions influence tree emissions in this tropical forest, affecting their ecological, environmental, and climatic roles, as well as the implementation of atmospheric chemistry models.