How to choose a species for planting?

As far as urban greening is concerned, there is an array of species available for planting.  Basically, designers would make a choice among the species in the light of the concept of the design, environmental factors (such as the micro-climate, quality of soil, visual impact, traffic flow, landscape features within the planting area and can help protecting the slope from soil erosion) or the aim of redeveloping the eco-environment, or tying in with education or other theme factors, etc.  Consideration must also be given to the estimated construction cost and views on maintenance of departments concerned.