Tree diversity and regeneration potentials of National Botanical Garden, Mirpur, Dhaka

Abstract

Plant diversity in botanical gardens plays a vital role in conservation, education, and research, especially in urban areas. This study assesses tree species diversity, regeneration potential and stakeholders’ perception in National Botanical Garden, Mirpur, Dhaka. A total of 220 tree species from 61 families were recorded using a stratified random quadrat method (10 × 10 m). Among these, 59% were native and 41% exotic. The most abundant and dominant species were Swietenia mahagoni (L.) Jacq., Acacia auriculiformis A. Cunn. ex Benth., Terminalia arjuna (Roxb. ex DC.) Wight & Arn., and Polyalthia longifolia (Sonn.) Thwaites. Shannon-Wiener, Simpson’s, and Margalef’s Diversity Indices were 1.97, 0.82 and 28.2, respectively, indicating moderate diversity and low evenness. Zone 1 of the garden showed the highest diversity, while Zones 1, 9, and 12 had the greatest number of exotics in their top ten dominant species. High Jaccard Similarity between zones suggested repetition in species composition. Regeneration was low, with only seven species showing seedling development. Dipterocarpus alatus Roxb. had the highest seedling density and Hopea odorata Roxb. showed the best recruitment success. Stakeholder surveys revealed strong support for increasing native species, planting more wildlife-supporting trees, and involving experts in garden management. Identified threats include poor planning, exotic dominance, and lack of awareness. Key recommendations include enhancing native diversity, lowering spatial repetition of similar species, introducing rare species, and improving expert-led management to ensure ecological sustainability.

Bangladesh J. Plant Taxon. 32(2): 177-192, 2025 (December)