Unveiling the composition, diversity, and structure of the urban forests in Chattogram City, Bangladesh

Urban forests deliver critical ecosystem services, but harnessing their full potential for these benefits requires a clear understanding of their composition, diversity, and structure. Therefore, this study offers a benchmark that effectively maximises the potential of the urban forests in Chattogram City, Bangladesh. A total of 208 sample circular plots (8.4032 ha), each covering 0.0404 hectares, were classified into three zones (Trees, Built-up with trees, and Others) of urban forests. Therefore, the Google Earth Engine platform and i-Tree Eco model were used to generate plots and organise outputs. The results revealed that the urban forests of Chattogram City comprised approximately 2.99 million trees, with 23.3% tree cover, and a density of 194 trees ha−1. Besides, the forest contained a basal area of 6.48 m² ha−1 with mean tree height of 4.71 m and mean DBH of 12.44 cm. Moreover, a total of 136 species belonging to 107 genera and 53 plant families were identified, with the three most common species being Mangifera indica (15.8%), Artocarpus heterophyllus (6.2%), and Tectona grandis (5.4%). The Shannon diversity index of 3.82 represents a moderate to good level of diversity in the study area. In addition, residential areas nested within the existing zones were reported to contain highest percentage of trees (41%). These areas had the maximum number of fruit trees compared to other land uses like hills, institutions, near water bodies, agricultural land, commercial areas, and others. Therefore, sustainable management of Chattogram’s urban forest is essential for enhancing biodiversity, supporting ecosystem services, and guiding resilient urban development through policy-backed planning.