Photosynthetic optical signals studying biogenic volatile organic compound emissions in Scots pine and English oak saplings under drought or warming

Biogenic volatile organic compounds (BVOCs), primarily emitted into the atmosphere by terrestrial vegetation through biochemical processes, have key ecological functions in protecting vegetation from biotic or abiotic stresses. However, accurately quantifying and predicting changes in BVOC emissions in response to long-term environmental changes large spatial scales remain challenging. The appropriate tools for observing the BVOC emissions at large scales are still missing. Remote sensing of optical signals is a promising solution to fill spatial knowledge gap. We hypothesize that the carotenoid-related vegetation index, such photochemical reflectance index (PRI), is a promising method to investigate BVOCs emitted by plants based on their functional links with carotenoids and photosynthetic activity. We conducted a leaf-level experiment in greenhouse during the summer of 2022 to investigate how the relationships between PRI and BVOC emissions change in response to drought or heat stresses in Scots pine and English oak saplings during the peak of growing season. We aim to address the following questions: (1) What factors control the relationships between PRI and BVOC emissions in response to mild/extreme drought or heat; (2) Will these controlling factors differ between vegetation species or BVOC emission types (e.g., isoprene and monoterpenes)? (3) Can PRI or other carotenoid-related vegetation indices capture the changes of BVOC emissions in response to drought or heat stresses? We will present our preliminary results. The expected outcomes will give new insight into leaf-level mechanistic links between PRI and BVOC emissions for plants in response to climate drought or warming.