EXPLO3RVOC · Ecophysiological control by Mediterranean forest ecosystems on the exchange processes of ozone and reactive Volatile Organic Compounds with a polluted atmosphere

Multipurpose and biodiverse forest ecosystems in the Mediterranean area have to deal with the negative effects of climate change and a strong human pressure, often represented by gaseous emission transported to the vegetation through polluted air sheds. In the polluted lower atmosphere ozone is formed in the presence of sunlight through photochemical reactions of volatile organic compounds (VOC) and oxides of nitrogen, which can have biogenic (foliar and soil emissions) or anthropogenic (e.g. combustion processes) sources.Plants are natural sinks for ozone and therefore phytoremediate the atmosphere. On the other hand, ozone is the main oxidant for plants and humans. The uptake of ozone by plant ecosystems is attributed to both stomatal (ozone enters leaves through stomata and is detoxified) and non-stomatal sinks (ozone is deposited on plant/soil surfaces or reacts with VOC in the gas-phase). The scientific program foresees experiments on key representative Mediterranean forest species with the intent to study environmental control on plant ecophysiology, and responses of plants in terms of ozone and VOC exchanges with the atmosphere. In the field, experimental stations will be equipped and advanced micrometeorological techniques will be used to measure stomatal and non-stomatal sinks of ozone and reactive VOC at canopy-scale in the soil-plant continuum, as well as different sources of VOC, and their reaction products in the atmosphere. Laboratory “in-vivo” investigations will finely describe leaf physiological responses to environmental variables, including exposure to different levels of ozone concentrations. Novel techniques will be applied to study the emission of constitutive and induced VOC emissions, quantifying endogenous emissions of oxidation products of VOC with Reactive Oxygen Species produced inside the leaves by ozone and temperature stress. The project would help understanding the complex interactions between Mediterranean forests and the atmosphere.