Dynamic estimates of tree carbon storage and shade in Mediterranean urban areas

Abstract

To highlight the ecosystem value of trees in the urban environment an EU's funding instrument for the environment and climate action – LIFE Project – was undertaken involving four Mediterranean cities as study cases: Thessaloniki in Greece, Cascais in Portugal, and Perugia and Bologna in Italy. The methodology utilized to evaluate plant carbon storage and shade areas highlighted the usefulness of gathering data about both the current urban green asset in the Project's investigated areas and future potential performances of the same asset to evaluate its efficiency in the forthcoming decades (2030–2050). The lower future potential of some cities for CO2 storage can be attributed to having older 'green assets' in comparison to other municipalities. A projection over the next 30 years on the basis of census results in the 4 studied areas highlighted the potential of some green areas characterised by the presence of efficient carbon storage tree species (high-growing broadleaf plants) while still small in size. <br/>The main objective of this study was to present both the current urban green asset carbon storage potential in the studied areas and also its future potential efficiency. Another aim of the work was to develop tree growth curves in urban areas, not only to estimate tree volumes but also to estimate the present and future shade areas related to woody plants' presence. <br/>With regard to CO2 storage simulation, the research highlighted the potential of green areas in Perugia that present tree species particularly efficient at carbon storage yet still small in size. Conversely, the lowest value presented by the species recorded in Cascais was influenced by the predominance of Cupressus sempervirens and Pinus pinea : two species not particularly efficient and large in size with average DBH values above 50 cm.