The Level I network: forests and beyond – the Ozone EFFORT study in Trentino (Italy)

Traditionally, Level I forest monitoring network has been used for assessing status and trends of forest condition. Here, we demonstrate its potential in providing a framework for cause-effect relationships and risk analysis, even at local level and beyond the forest community. We considered ozone as a key environmental factor. The 15 Level I plots in the Trento province (Northern Italy) were equipped with passive samplers for ozone, and data were used for three main studies: (i) evaluation and mapping of potential risk for forests; (ii) cause-effect investigation in terms of ozone impacts on defoliation and growth; (iii) evaluation and mapping of ozone risk for human population. All the three studies were based on five years of measurements. As for study (i), passive sampling data were used for geo-statistical modelling. Results show that ozone critical levels were exceeded over wide areas with approximately 71 % of forests in Trentino exposed at AOT40 values higher than two times the UNECE Critical Level. Despite these results, the study (ii), based on Linear Mixed Models and Multiple Regression, suggested that ozone has a limited (if any) impact on defoliation and growth, in terms of relative Basal Area Increment (BAI) as measured on Level I plots. These results were confirmed by a time series analysis carried out on one Level II plot, and also when considering the flux approach. Finally (iii), data originated from Level I passive sampling, integrated with other available measurements (ozone concentrations from automatic analysers, population census) allowed for mapping the risk of potentially dangerous ozone exposure for human population. All together the results provide evidence that the Level I network can be useful much beyond its traditional, intended aim, and – with a few integration initiatives - can be a suitable framework to address a wide range of environmental concerns, even at local level.