LIFE15 ENV/IT/000183
Results
What we learned from MOTTLES to date
MOTTLES network allows an epidemiological assessment of POD–based critical levels for the protection of forests from O3.
Based on the results of the first MOTTLES dataset, we can see that:
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our network is representative of a large range of O3 pollution: click here to view the table with ozone metrics
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O3 is a harmful key factor for forest health, because trees showing visible foliar O3 injury were more defoliated and showed a lower annual radial growth than trees with no visible O3 injury: click here to view the correlation between ozone metrics and forest indicators
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the metrics used for the protection of forests in Europe (Directive, ICP) are well correlated to the metrics calculated on the basis of the real duration of the growing season (MOTTLES) and are thus representative of the actual exposure/flux;
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AOT40 and POD0 are uncoupled, in that high values of AOT40 often corresponded to low POD0 values and vice–versa. As POD is considered a more biologically–meaningful metric, AOT40 cannot be recommended as an optimal metric for forest protection from O3;
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visible foliar O3 injury is better related to POD0 than crown defoliation and radial growth, and can be recommended as the best plant–response indicator of tree responses to O3 under field conditions;
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monitoring visible foliar O3 injury in the LESS is a better approach than recording the same injury in the ITP. These results are useful to monitoring experts and environmental policy makers.
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Third annual MOTTLES survey (2019)
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From the middle of August to the beginning of September 2019 the third field campaign for forest data was conducted: crown defoliation and visible ozone injury were assessed at forest sites in Italy, France and Romania by the 3 surveyor teams of MOTTLES.
Second annual MOTTLES survey (2018)
Assessments of crown conditions (i.e. discoloration, defoliation) and of visible foliar ozone-induced injury were carried out at 17 forest plots during summer 2018 (August-September). Data will be then related with the ozone metrics calculated on the basis of direct measurements at those sites.
First field campaign: crown defoliation and visible ozone injury assessment at plots in Italy, France and Romania (2017)
Every year, visible injury & crown conditions (radial & height growth, crown transparency), meteorological station control & phytosociological survey are carried out.
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For the harmonization of methodologies of the three MOTTLES surveyor teams, an intercalibration training course for O3 visible injury was organized in collaboration with ICP Forests in Romania in September 2016 as workshop open to interested scientists (DOWNLOAD THE REPORT). Moreover, a data validation and inter-comparison exercise was carried out in Castelporziano during the first progress meeting (DOWNLOAD THE REPORT).
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Assessments of crown conditions (i.e. discoloration, defoliation) and of ozone-induced injury have been carrying out at 17 forest plots during the summer 2017 (July-September). The ICP-Forests methodologies of survey were discussed and adapted to MOTTLES. Common field protocols and survey documents for crown assessment were developed for use of all MOTTLES surveyors.
The monitoring system
The monitoring network of MOTTLES is completed and active since summer 2017, it consists of 9 plots in Italy, 4 in France and 4 in Romania selected from two main European networks: ICP Forests and MERA network.
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Find here more details about sites.
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Each site is made up an Open-Field station (OFD) for ozone and meteorological measurements and an In-the-plot station (ITP) for radial growth and soil parameters records.
Thanks to a data acquisition systems, hourly records are transmitted by GPRS to a central office (CNR), for storage and Technicians of CNR and CREA are responsible of the good functioning of the stations.
Work at the free-air ozone FACE (FO3X) for leaf-level measurements
The FO3X facility is used to validate visible injury, reproducing it in potted plants of selected species and for parameterizing the stomatal conductance of species occurring at our sites but not yet available in the literature. FO3X is a last generation, 3D O3-FACE, with O3 diffusion through microholes, pre-mixing of air and O3, an O3 generator system with integral oxygen generator. FO3X is one of the few O3-FACEs at present available in the world, the only one in Mediterranean climate, one of the two 3D ozone-FACEs, and one of the very few O3-FACEs investigating more than one stressor at a time.
The parameterization of some species is missing, specific free-air exposure experiments have been designed and carried out by CNR-IPSP at the FO3X facility, where all environmental parameters are continuously recorded and availability of O3 in the air and water in the soil can be adjusted.