Spatiotemporal land use changes shaping biodiversity dynamics in southeastern regions of Bangladesh: a multi-scale geospatial and ecological analysis

Land-use and land-cover (LULC) change is a major driver of biodiversity loss in tropical regions, yet comprehensive assessments linking landscape changes to ecological impacts remain limited in South Asia. This study develops a multi-method framework to assess biodiversity vulnerability in the Chittagong Hill Tracts (CHT) and neighboring districts of southeastern Bangladesh, a vital part of the Indo-Burma Biodiversity Hotspot. We integrate multi-temporal Landsat images (2000–2020), MOLUSCE-based cellular-automata projections to 2050, landscape metrics from FRAGSTATS, InVEST habitat-quality models, and species-richness data for amphibians, birds, and mammals. Results show rapid forest conversion to farmland and urban areas, with forest cover expected to decrease 170.77 km2 by 2050. ANOVA and Tukey HSD tests indicate that grassland has significantly higher fragmentation (p < 0.001) than other land-cover types, with patch density rising from 9.80 to 15.69 patches per 100 hectares. Habitat quality varies greatly across regions: upland districts (Bandarban, Rangamati) maintain over 82% high-quality habitat, while urbanizing districts (Chittagong, Cox’s Bazar) experience low-quality habitat expansion, with low-quality habitat exceeding 5% by 2050. Forest areas support the highest species richness, including 51.69% of mammals and 27.32% of amphibians, highlighting the disproportionate biodiversity risk due to even small forest losses. These spatially explicit findings underscore the need to prioritize forest-corridor restoration, enforce land-use zoning, and promote community-based conservation in one of South Asia’s most ecologically important yet threatened landscapes.