Assessing the risk of tropospheric ozone phytotoxic effect on Southern European Mediterranean environments: a review with emphasis on vineyards
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abstract
Tropospheric ozone in Southern Europe has an increasing tendency in association with
a greater incidence of warm summers and heatwaves. As there is already much
evidence of the negative effects that current ambient ozone has on vegetation, there is
a need for consistent risk assessment methods. Ozone plant exposure-based
parameters have been used extensively to support decision-making. However, these
parameters have been also criticised, as they do not relate with the actual dose of ozone
entering the plant. Moreover, in Mediterranean environments, they often overestimate
the risk as thresholds are exceeded without corresponding evidence of damaging
effects. To overcome these limitations, dose-based approaches were developed. These
approaches have a stronger biological basis as they are based on estimates of the
amount of ozone molecules that diffuse into the leaf cells through the stomata. However,
they have also limitations, as detoxification processes or non-stomatal uptake are not
often taken into consideration. This work presents a review regarding ambient ozone
effects on vegetation and the indices used to assess phytotoxic risk in southern
European Mediterranean plant communities and crops. Emphasis is given to the
grapevine as three southern European countries (Spain, Italy and Portugal) are major
wine producers concentrating more than 20% of the area under grapevines globally.
These countries hold a long winemaking tradition associated to renowned
denominations of origin (DOs). Therefore, there is concern regarding climate change as
a potential threat to wine typicity in these areas, most of the work focusing on
atmospheric variables, bioclimatic and climate change indices only. Results from the
DOUROZONE project are presented with the aim to analyse the implications climate
change can have in a significant Portuguese wine region such as the Douro Demarcated
Region (DDR) including ozone-related indices as a novelty among other more frequently
used bioclimatic and climate change indices.
