Comparing concentration-based (AOT40) and stomatal uptake (PODY) metrics for ozone risk assessment to European forests

Alessandro Anav, Alessandra De Marco, Chiara Proietti, Andrea Alessandri, Alessandro Dell'Aquila, Irene Cionni, Pierre Friedlingstein, Dmitry Khvorostyanov, Laurent Menut, Elena Paoletti, Pierre Sicard, Stephen Sitch, Marcello Vitale

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Abstract

Tropospheric ozone (O3) produces harmful effects to forests and crops, leading to a reduction of land carbon assimilation that, consequently, influences the land sink and the crop yield production. To assess the potential negative O3impacts to vegetation, the European Union uses the Accumulated Ozone over Threshold of 40 ppb (AOT40). This index has been chosen for its simplicity and flexibility in handling different ecosystems as well as for its linear relationships with yield or biomass loss. However, AOT40 does not give any information on the physiological O3uptake into the leaves since it does not include any environmental constraints to O3uptake through stomata. Therefore, an index based on stomatal O3uptake (i.e. PODY), which describes the amount of O3entering into the leaves, would be more appropriate. Specifically, the PODY metric considers the effects of multiple climatic factors, vegetation characteristics and local and phenological inputs rather than the only atmospheric O3concentration. For this reason, the use of PODY in the O3risk assessment for vegetation is becoming recommended. We compare different potential O3risk assessments based on two methodologies (i.e. AOT40 and stomatal O3uptake) using a framework of mesoscale models that produces hourly meteorological and O3data at high spatial resolution (12 km) over Europe for the time period 2000-2005. Results indicate a remarkable spatial and temporal inconsistency between the two indices, suggesting that a new definition of European legislative standard is needed in the near future. Besides, our risk assessment based on AOT40 shows a good consistency compared to both in-situ data and other model-based datasets. Conversely, risk assessment based on stomatal O3uptake shows different spatial patterns compared to other model-based datasets. This strong inconsistency can be likely related to a different vegetation cover and its associated parameterizations.
Original languageEnglish
Pages (from-to)1608 - 1627
Number of pages20
JournalGlobal Change Biology
Volume22
Issue number4
DOIs
Publication statusPublished - 1 Apr 2016
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

Cite this

Anav, A., De Marco, A., Proietti, C., Alessandri, A., Dell'Aquila, A., Cionni, I., Friedlingstein, P., Khvorostyanov, D., Menut, L., Paoletti, E., Sicard, P., Sitch, S., & Vitale, M. (2016). Comparing concentration-based (AOT40) and stomatal uptake (PODY) metrics for ozone risk assessment to European forests. Global Change Biology, 22(4), 1608 - 1627. https://doi.org/10.1111/gcb.13138