PROJECT DESCRIPTION
BACKGROUND
Climate change and air pollution are interlinked, representing a challenge for the management of European forests, with ozone (O3) being the most phytotoxic air pollutant for trees. European standards for the protection of ecosystems, including forests, have been defined through experiments carried out under controlled conditions. Yet, research has highlighted the need to also conduct open-air experiments and epidemiological investigations based on observations with high temporal resolution (e.g. one-hour intervals). Another shortcoming concerns the monitoring of O3 concentrations, which at remote forest sites is a particularly challenging task due to a lack of electricity, making the use of passive samplers unavoidable. Unfortunately, such monitoring systems suffer from low temporal resolution (e.g. two weeks to one month), making it impossible to correlate O3 data with epidemiological observations. Most European countries carry out forest monitoring, but the different approaches used by the countries make comparisons at the European level problematic. This is particularly the case for O3 injury, where obsolete measurement tools (passive samplers) are still used in the European monitoring network (ICP-Forests), which generate errors when calculating recent stomatal uptake based indices. Therefore, there is a need for a harmonised and up-to-date European forest monitoring scheme for ozone.
OBJECTIVES
The LIFE MOTTLES project aimed to define scientifically-based thresholds and critical levels for the protection of forests from ozone (O3) in the changing climate scenario. To do this, an innovative integrated monitoring station system for the continuous measurement of parameters affecting European forest ecosystems sustainability was to be set up and tested across three European countries. This will support management strategies for sustainable forest management and stimulate the development of usable legislative standards for protecting forests against O3. The project aimed to address the 2020 Biodiversity Strategy and 2013 Forest Strategy, by anticipating the adverse effects of climate change and taking appropriate measures to prevent associated damage. Furthermore, as there is a demand for tools supporting the assessment of impacts of policies both at EU and national level, LIFE MOTTLES will facilitate the development of science-based strategies for policy-makers and managers to enable the protection of forests against O3 and climate change.
RESULTS
The LIFE MOTTLES project developed a novel ozone (O3) monitoring strategy that has established new scientifically-sound critical levels for protecting forests against ozone pollution, to set new legislative standards in Europe. The project’s approach is a significant advance for ozone monitoring because European standards to protect vegetation from this air pollutant are currently based on O3 concentration in the atmosphere, not on stomatal ozone fluxes (i.e. how much ozone is effectively taken up by trees).
The project established a MOTTLES network in three European countries at medium and high risk for ozone levels, through projects partners ACRI-HE (now ARGANS) and Groupe International d’Etudes des Forêts Sud-européennes (GIEFS) in France; Consiglio Nazionale delle Ricerche (CNR) and Agricultural Research and Economics - Forestry and Wood (CREA-FL) in Italy; and Institutul Național de Cercetare Dezvoltare în Silviculturã ”Marin Drãcea” (INCDS) in Romania. This long-term monitoring network allows the combination of real-time ozone concentrations, meteorological parameters, and plant response indicators for ozone on vegetation (i.e. visible ozone injury, crown defoliation and hourly radial growth), to estimate stomatal fluxes and critical levels for O3. To this end, the project partners equipped 17 sites, selected from existing European networks (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests, and European Monitoring and Evaluation Programme), with new instrumentation to obtain, for the first time, reliable data for the in-field quantification of the Phytotoxic Ozone Dose (PODY). PODY is a new and more effective metric proposed as a legislative standard rather than the Accumulated Ozone over Threshold of 40 ppb (AOT40), which is based on an estimation of O3 entering stomata during a given time period.
Plant response indicators of forest health and vitality were assessed and related to a range of different Y thresholds of PODY. The project team also evaluated the health and vitality of trees using dendrometers (e.g. to estimate seasonal stem growth increment) to provide best practice lessons for large-scale implementation of forest monitoring networks. LIFE MOTTLES recommended critical levels of ozone for protecting broadleaved species and conifers (POD1-based critical levels of 12 and 5 mmol m-², respectively) from visible foliar ozone injury; as well as AOT40-based critical levels for crown defoliation.
The project partners produced an atlas of visible foliar injury (https://mottles-project.wixsite.com/life). They also developed a validation system for visible foliar O3 injury, by making use of an O3 free-air controlled exposure (FACE) facility (https://www.iret.cnr.it/images/infrastrutture/ozoneface_en.pdf).
The project team explained their best practices in a publication ‘Integrated tool box of practices summarising the new knowledge for evaluating expected risks and benefits of adaptation and mitigation options’ (https://f47aab25-e449-45a6-bc34-8468465ee6e4.filesusr.com/ugd/da6a6d_ddae51cf108d484298cb763800fa2695.pdf) and produced guidelines for assessing the effectiveness of air pollution control strategies for ecosystem protection (https://f47aab25-e449-45a6-bc34-8468465ee6e4.filesusr.com/ugd/da6a6d_21d7896972a94c52b30cf47ea545b148.pdf). The results were also widely disseminated through diverse activities, and transferred to International Co-operative Programmes (ICPs) and national stakeholders to encourage the adoption of the new monitoring approach at pan-European scale and beyond.
The project team demonstrated that the new monitoring system is sustainable from an environmental and economic point of view, even after 5 years, leading to savings for the whole network of deciduous forests (102 tons of CO2-equiv) and conifers (194 tons of CO2-equiv). LIFE MOTTLES sites in Italy and Romania have been included in the national lists of NEC sites (under the EU National Emission Ceilings Directive). The project contributes to the EU 2020 Biodiversity Strategy, the Forest Strategy, and EU policy on air pollution and climate change.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
