Plant-derived Secondary Organic Material in the Air and Ecosystems

Biogenic secondary organic aerosol (SOA) and deposited secondary organic material (SOM) are formed by oxidation of volatile organic compounds (VOCs) emitted by plants. Many SOA compounds have much longer chemical lifetimes than the original VOC, and may accumulate on plant surfaces and in soil as SOM because of their low volatility. This suggests that they may have important and presently unrecognized roles in plant adaptation. Using reactive plant terpenoids as a model we propose a three-tier (atmosphere-vegetation-soil) framework to better understand the ecological and evolutionary functions of SOM. In this framework, SOA in the atmosphere is known to affect solar radiation, SOM on the plant surfaces influences the interactive organisms, and wet and dry deposition of SOM on soil affects soil organisms.