Urban and peri-urban forests in the metropolitan area of Rome: Ecophysiological response of Quercus ilex L. in two green infrastructures in an ecosystem services perspective

Green infrastructures (GI), such as urban forests, deliver ecosystem services (ESs) and benefits. Among ESs the amelioration of urban air quality through the removal of air pollutants deserves large attention owing to the positive impact on human well-being. Experimental data, as detailed descriptions of functional parameters, are needed for reliable quantification of ESs. The present study was carried out in the metropolitan area of Rome, considering an urban and a periurban forest. Both forests are dominated by Quercus ilex L., which has been chosen as target species for its wide natural distribution in the Mediterranean Basin, as well as for its widespread use in urban contexts. The two studied sites were characterized by different environmental stressor and forest management practices, resulting in different trends of leaf gas exchanges, photosystems functionality and plant water status. During spring, gas exchanges were lower in the urban than in the periurban forest, due to higher air temperature and vapor pressure deficit in the latter site. During summer, instead, in the periurban area the functionality of Q. ilex was affected by drought, which did not occur in the urban forest due to higher summer rainfalls as well as periodic irrigations. The water use efficiency was basically lower in the urban park, as well as the photosystems functionality. Differences in the intensity of the main phenological phases were also highlighted. Our results point out that the two GIs fulfill a complementary role in the ESs provision in the metropolitan area of Rome, in relation to the ozone removal and the resulting air quality improvement and climate regulation.