Plant crown traits and carbon sequestration capability by Platanus hybrida Brot. in Rome

Measurements of carbon dioxide (CO2) concentration carried out in the city of Rome in the period January-December 2005 showed a mean yearly CO2 concentration of 414 +/- 45 ppm; polluted sites (P sites) had 21% higher CO2 concentration than control sites (C sites). The significant (p < 0.01) correlation analysis between CO2 concentration and traffic density measured during the study period at P sites showed that traffic density explained 51% of the CO2 variation. The CO2 trend during the traffic limitation days (provision imposed by ordinance of the City Council) did not show significant differences as regards regular traffic days, suggesting the ineffectiveness of this provision. Leaf area index (LAI) of Platanus hybrida Brot. was on an average 11% lower at P sites than at C ones associated with a lower total photosynthetic leaf surface area (SPT, 34% lower at P sites than at C ones). P. hybrida had a total carbon sequestration of 117 +/- 13 kg year(-1) (mean value of P and C sites) playing an important role in sequestering CO2. Thus, the choice of plant species for urban areas may be set out taking into account their own air amelioration capability. Plant traits of each species may be used for urban tree planting programs to ameliorate urban air pollution. (c) 2007 Elsevier B.V. All rights reserved.