Plant selection for roadside design: "the view of landscape architects"

Losses in urban green spaces due to population increase and urbanization became one of the most important problems in contemporary cities. Efforts to increase green zones require the establishment of parks and extension of planting activities in urban areas. The planting work conducted on streets, roads, avenues, and traffic islands is significant in the development of urban green spaces. Determination of the plant species that would be used in planting work and assessment of these species by experts and authorities based on scientific approaches are significant for the success of these efforts. In the present study, the issue of plant selection criteria for roadside planting was investigated with a hybrid decision-making approach based on landscape architects' perspectives. To solve the plant selection problem of decision-makers and to obtain reliable quantitative data, a set of criteria that included 5 main and 41 sub-variables was determined. Pairwise comparison technique was used by experts for evaluation of the involved criteria. The study findings revealed that the "structural criteria" were the most effective main factor in plant selection for roadside planting, followed by the "economic and ecological" criteria. Furthermore, it was determined that the growth length and diameter of the plants (10.2%), selection of indigenous species that reflect the urban identity (7.30%), and the climatic requirements of the plants (7.20%) were the sub-criteria that should be considered in selection of the plants. In conclusion, it was determined that quantitative assessment of plant selection decisions would help planting design decisions on roadside planting.