Urban trees for biomonitoring atmospheric particulate matter. An integrated approach combining plant functional traits, magnetic and chemical properties

Increased attention has been given to particulate matter (PM) that, as well as worsening air quality, is responsible for chronic and acute respiratory or cardiovascular diseases. Currently, most of the studies are focused on the capacity of plants and other biological media to adsorb PM, whereas few works explore the functional damage due to PM on urban vegetation. The present study, considering Quercus ilex L. as target species for its wide distribution in the Mediterranean urban and natural areas, pointed out that PM accumulation, inferred from magnetic and chemical properties, has almost no effects on structural morpho-functional traits as Relative Water Content or Specific Leaf Area but can impair processes related to the first photochemical reactions suggesting shading effect on leaves. PSI functionality and thus, carbon assimilation related processes, are impaired to a lesser extent by the oxidative potential of PM. Our results showed that, although several oxidative stressors can simultaneously affect morpho-functional traits, the interdisciplinary approach tested here can be a key tool to enlarge the spatial scale of biomonitoring activities as much as possible, and highlight a functional indicator of PM injury. This is needed to enhance the knowledge about the complex processes that are implied in the dynamic relationship between air quality, vegetation functionality and ecosystem services provisioning in urban areas.