Abstract <p>The deforestation of natural habitats due to agricultural expansion and human settlements is a major driver of global biodiversity loss. This study assessed the impact of natural habitat conversion into grasslands on ground beetle (Coleoptera: Carabidae) assemblages along two elevational gradients (~ 1900–3000&#xa0;m asl) in the southwestern tropical Andes of Colombia. Sampling was performed using pitfall traps, litter sifting, and nocturnal hand collection at six localities, each comprising a natural forest area and a deforested grassland area. Environmental variables were recorded to characterize land use. We found that these conditions differed markedly between forests and grasslands, with forests exhibiting more stable temperature and humidity, and greater leaf litter depth. Ground beetle richness and abundance were consistently higher in forests, while grasslands were dominated by a few generalist species. Assemblages in forests showed high species turnover, including a large proportion of flightless, microendemic species, whereas grassland communities were homogenized across cordilleras and elevations.</p> Implications for insect conservation <p>Our study highlights the detrimental effects of deforestation on carabid diversity and assemblage structure. The observed loss of diversity implies a high risk of extinction for flightless, endemic forest specialists restricted to small areas. These findings emphasize the importance of preserving natural forest areas at different elevations and on different slopes, highlighting the need for taxonomic studies to inform targeted conservation strategies in tropical montane ecosystems.</p>