Tree species distribution analysis for eco forest city development in Medan Belawan Subdistrict, North Sumatra, Indonesia

Medan Belawan Subdistrict, a coastal area of Medan City, faces increasing urbanization pressures that threaten the sustainability of green open spaces (GOS), particularly mangrove ecosystems. This study aims to map the composition and spatial distribution of tree species in GOS, analyze community structure using the Shannon–Wiener diversity index (H′), Simpson dominance index (D), and evenness index (1−D), and propose a contextual Eco Forest City (EFC) model for coastal urban environments. Data were gathered through a comprehensive tree census (DBH ≥ 20 cm) in terrestrial GOS and plot sampling in mangrove areas, with spatial analysis used to examine species distribution, dominance, and green–blue connectivity. The results revealed that 72.02% of the 218 GOS units were mangrove areas, with Avicennia marina dominating at 48.17% and a density of 668 ind/ha. The community indices indicated moderate diversity (H′ = 1.65), high dominance (D = 0.232), and moderate evenness (1−D = 0.72). The proposed EFC model emphasizes the protection of mangrove ecosystems, enrichment with adaptive species, diversification of terrestrial corridors, and the creation of vegetated bioswales to enhance green–blue connectivity. These strategies provide a scientific basis for sustainable, climate-adaptive coastal urban planning in Indonesia.