Ozone (O3) is the most phytotoxic air pollutant in the Mediterranean region, where climatic conditions favor its formation and persistence during spring and summer. The negative effects of O3 on the physiology and biomass growth of several forest species have been well documented in the last decades. However, some divergences exist between the effects observed on Southern Europe forests and the expected effects estimated with the current flux-based dose-response (D-R) relationships. This discrepancy is likely to be explained by the inadequacy of the current D-R functions, which have been defined with experiments conducted in Northern and Central Europe, to estimate the effect on the Mediterranean forest trees and/or their higher O3 tolerance. In order to address this issue, this study presents a reanalysis of the available O3 exposure experiments performed on deciduous broadleaved tree species in the Mediterranean area and the proposal of new critical levels to improve the O3 risk assessment in this region. A database of 5 different experiments, performed in Spain and Italy, including 5 tree species was collated. The studied species were: Q. pyrenaica, Q. faginea, Q. robur, P. nigra (“Jean Pourtet” clone) and P. maximowiczii Henry×P. berolinensis Dippel (Oxford clone). All the experiments were performed with seedlings or cuttings growing in Open-Top Chambers exposed to different O3 levels (with charcoal-filtered air as control treatment). The length of the experiments varied between a minimum of 2 months and a maximum of 1.5 years. Two different parameterization were used for the stomatal conductance (gs) model: one species-specific based on the “local” gs measurements performed in each experiment, and the other “generic” based on the “Deciduous Mediterranean broadleaved” parameterization described in the Mapping Manual of the UN/ECE. The two different parameterizations (local and generic) were used to calculate the Phyotoxic Ozone Dose (POD1) and to derive the D-R functions for the aboveground biomass. The D-R function built with the generic parameterization of gs was not statistically significant, while the local parameterization yielded a statistically significant (p=0.0057) relationship. According to this result different POD1 critical levels were calculated on the latter D-R relationship considering an effect threshold of 2%, 4% and 5% decrease in the annual relative yield (RY) of shoots biomass. The effects were calculated starting from a reference biomass estimated for an average POD1 using 10 ppb of O3 as constant concentration (POD1_10). Fluxes with constant 10 ppb O3 were calculated for each experiment and averaged, and the corresponding RY was used as the reference RY for defining critical levels. The obtained values (9, 16 and 19 mmolO3 m-2, for 2, 4 and 5% biomass loss, respectively) indicate that the Mediterranean deciduous trees could be more tolerant to O3 than trees growing in more humid biomes, and that different O3 critical levels should be used for ozone risk assessment in Europe depending on vegetation types.

Dose-response relationships for ozone effect on aboveground biomass of deciduous broadleaved tree species in Mediterranean environment / Gerosa, G.; Bussotti, F.; Calatayud, V.; Alonso, R.; Pollastrini, M.; Calvo, E.; Bermejo, V.; Monga, R.; Finco, A.; Marzuoli, R.. - ELETTRONICO. - (2017), pp. 21-21. (Intervento presentato al convegno 30th Task Force Meeting tenutosi a Poznan, Polonia nel 14-17 Febbraio 2017).

Dose-response relationships for ozone effect on aboveground biomass of deciduous broadleaved tree species in Mediterranean environment.

BUSSOTTI, FILIPPO;POLLASTRINI, MARTINA;
2017

Abstract

Ozone (O3) is the most phytotoxic air pollutant in the Mediterranean region, where climatic conditions favor its formation and persistence during spring and summer. The negative effects of O3 on the physiology and biomass growth of several forest species have been well documented in the last decades. However, some divergences exist between the effects observed on Southern Europe forests and the expected effects estimated with the current flux-based dose-response (D-R) relationships. This discrepancy is likely to be explained by the inadequacy of the current D-R functions, which have been defined with experiments conducted in Northern and Central Europe, to estimate the effect on the Mediterranean forest trees and/or their higher O3 tolerance. In order to address this issue, this study presents a reanalysis of the available O3 exposure experiments performed on deciduous broadleaved tree species in the Mediterranean area and the proposal of new critical levels to improve the O3 risk assessment in this region. A database of 5 different experiments, performed in Spain and Italy, including 5 tree species was collated. The studied species were: Q. pyrenaica, Q. faginea, Q. robur, P. nigra (“Jean Pourtet” clone) and P. maximowiczii Henry×P. berolinensis Dippel (Oxford clone). All the experiments were performed with seedlings or cuttings growing in Open-Top Chambers exposed to different O3 levels (with charcoal-filtered air as control treatment). The length of the experiments varied between a minimum of 2 months and a maximum of 1.5 years. Two different parameterization were used for the stomatal conductance (gs) model: one species-specific based on the “local” gs measurements performed in each experiment, and the other “generic” based on the “Deciduous Mediterranean broadleaved” parameterization described in the Mapping Manual of the UN/ECE. The two different parameterizations (local and generic) were used to calculate the Phyotoxic Ozone Dose (POD1) and to derive the D-R functions for the aboveground biomass. The D-R function built with the generic parameterization of gs was not statistically significant, while the local parameterization yielded a statistically significant (p=0.0057) relationship. According to this result different POD1 critical levels were calculated on the latter D-R relationship considering an effect threshold of 2%, 4% and 5% decrease in the annual relative yield (RY) of shoots biomass. The effects were calculated starting from a reference biomass estimated for an average POD1 using 10 ppb of O3 as constant concentration (POD1_10). Fluxes with constant 10 ppb O3 were calculated for each experiment and averaged, and the corresponding RY was used as the reference RY for defining critical levels. The obtained values (9, 16 and 19 mmolO3 m-2, for 2, 4 and 5% biomass loss, respectively) indicate that the Mediterranean deciduous trees could be more tolerant to O3 than trees growing in more humid biomes, and that different O3 critical levels should be used for ozone risk assessment in Europe depending on vegetation types.
2017
Proceeding of the 30th Task Force meeting ICP Vegetation
30th Task Force Meeting
Poznan, Polonia
Gerosa, G.; Bussotti, F.; Calatayud, V.; Alonso, R.; Pollastrini, M.; Calvo, E.; Bermejo, V.; Monga, R.; Finco, A.; Marzuoli, R.
File in questo prodotto:
File Dimensione Formato  
Finalbookofabstractsforweb.pdf

accesso aperto

Descrizione: Atti congresso
Tipologia: Pdf editoriale (Version of record)
Licenza: Open Access
Dimensione 2.98 MB
Formato Adobe PDF
2.98 MB Adobe PDF

I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1083731
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact