Foliar symptoms on Viburnum lantana reflect annual changes in summer ozone concentration in Trentino (northern Italy)

The frequency of Viburnum lantana L. plants showing visible foliar symptoms (VFS) was assessed in Trentino, north Italy in 2010, 2012, 2014 and 2015. The assessment was based on a sub-sample (n=10) of the ViburNeT observation network installed in 2010 according to a stratified random design. Depending on the year, a range of 193-232 plants were assessed during August. The frequency of symptomatic plants varied from 20.7 to 50.6%. Mean May-July hourly ozone concentration measured by conventional monitors over the same area, varied from 37.9 to 45.8 ppb. There was a consistent time pattern between ozone and VFS. Consistency is confirmed if also a pilot survey carried out in 2009 is taken into account. Results are promising and supportive of the use of V. lantana as in-situ bioindicator for monitoring ozone impact on vegetation in forest areas.