Explaining the pattern of plant selection in urban landscape of arid areas using fuzzy multi-criteria models (a case study of Birjand)

Choosing appropriate species to use in urban green space to improve the urban landscapes is vital to avoid the financial and environmental potential losses if the selection of effective parameters are not taken into account. The main goal of this study was to introduce a list of the best plant species for planting in the urban green space of Birjand. For this purpose, 6 criteria and 24 sub-criteria which were obtained by examining the researches conducted in the field of effective criteria in the selection of plants for urban environments were defined so that the 63 proposed plant species (26 trees, 12 shrubs and 25 groundcovers) were evaluated and weighed according to these criteria and with the help of 15 faculty members and experts who were specialized in Landscape Architecture, Environmental Design and horticulture. The method used in this research was a combination of the techniques of FAHP, to obtain the weight of each criteria and sub-criteria for plant selection, and FTOPSIS, to rank plant species such as trees, shrubs and groundcovers according to the criteria and sub-criteria effective in selecting plants. The findings show that the criteria of compatibility with the environmental conditions of the region and compatibility with the urban environment are both, as compared to the other 4 criteria, are equally of greater importance and weight and are more effective in selecting the plants to be used in the urban landscape. Also, in the prioritization of the tree species, Cupressus arizonica with a proximity coefficient of 0.775, Tamarix aphylla with 0.6961, Phoenix dactylifera with 0.6959, and Prosopis cineraria with 0.6918, in the shrub species, Spartium junceum with a proximity coefficient of 0.6426, Amygdalus scoparia with 0.637, Berberis vulgaris with 0.6352 and Atriplex canescens with 0.6276, and in the groundcover species, Opuntia ficus-indica with a proximity coefficient of 0.7019, Aloe vera with 0.6852, Rosmarinus officinalis with 0.6489, and Lavandula angustifolia with 0.6489, are considered as the top four priority in each category to be used in the green space of Birjand. Finally, suggestions and strategies for the use of plant species to improve the landscape and the urban environment are presented.