Ecological analyses of street trees of Indian cities to achieve United Nations sustainable development goals

The present study determined the community characteristics, structural composition, and regeneration status of street trees in two major Indian cities viz., Ranchi and Delhi. A total of 96 species of 86 genera belonging to 34 families were documented in the urban streets of Ranchi (of which 59 spp. were in the IUCN Red-list), while 64 species of 56 genera belonging to 28 families (of which 47 spp. were in the IUCN Red-list) were reported in Delhi. The study reported a very high species diversity index (H ') in both Ranchi (3.98) and Delhi (3.47), with similar species evenness (0.85). Fabaceae and Ficus were the predominant family and genus, respectively in both cities. The similarity of street trees of Ranchi and Delhi is quite low in terms of all the beta-diversity indices (SI = 38.75% and dissimilarity = 61.25%; Cj = 0.24 and dissimilarity = 0.76; BCij = 0.61 and similarity = 0.39). The total street tree density in Ranchi (217 ind. ha(-1)) and Delhi (637 ind. ha(-1)) varied significantly, while the dominance (basal area) of both cities were quite similar (20.67 m(2)ha(-1) and 21.70 m(2)ha(-1)) due to the predominance of young and adult individuals (GBH >= 30-90 cm) in the street tree community at Ranchi and pole and young individuals (GBH >= 10-60) in Delhi. The regeneration potential of street trees in both cities was quite concerning because the majority of street trees at Ranchi (62.5% of 96 spp.) and Delhi (57.38% of 64 spp.) had shown no regeneration. It is advised that re-greening, planting a variety of native tree tracts in urban niches, and tree planting in a ratio of one to three be implemented to counteract artificial urban land, maintain urban biodiversity and achieve UN SDGs.