Technical and economic aspects of Stone Pine ( Pinus pinea L.) maintenance in urban environments

The Italian Stone Pine (Pinus pinea L.) is one of the most employed ornamental trees in towns with Mediterranean climates. For example, in the city of Rome, Pinus is the most common genus, with more than 51,000 trees. Due to numerous reasons, the maintenance of this species may constitute a serious issue for the owners. Pruning and felling are the most frequent management operations of trees in towns and this study analyzes the technical and economic features of these operations carried out in 14 work sites (with a total of 25 observed trees). The operations were carried out either with aerial platforms (19 trees) or ascending the crown by tree-climbing (six trees). The operations were sampled with time studies (12 trees for pruning and 13 for felling). Work time was measured from the beginning of operations to the transport of the residual biomass to the collection and loading point, using centesimal stopwatches and video recording. The total residual biomass was weighed or assessed. Total observation time amounted to 63.1 h. The evaluation of the costs of each work site considered the fixed and the variable costs and the costs for the labor force. A multiple linear regression modeling was adopted to predict the gross time of the operations. This paper can contribute to optimize tree maintenance methods in urban sites and to assess the potential residual wood biomass attainable from urban forestry maintenance.