Fire Constrains Orchid Occurrence in Chapada Diamantina, Brazil

ABSTRACT Fires are key ecological disturbances in tropical ecosystems and are shifting in response to human activities, underscoring the need to understand species‐specific responses. Their impacts on orchids remain poorly understood, particularly in biodiverse tropical mosaics such as the Chapada Diamantina region in Brazil. Here, we investigate the relationship between the occurrence of endemic orchids and the time since the last fire (TSLF), testing whether responses are positive, negative, or mixed. We applied a Bayesian hierarchical model within a use–availability framework to analyse records of endemic orchids sampled across a 38‐year fire chronosequence, both for orchids at a group level and for individual species. As a group, orchids showed a positive association with TSLF, indicating that orchids are generally suppressed following fire. Individual species exhibited little variation in their responses, with no significant species‐specific effects detected. Nevertheless, our results suggest that orchids are generally sensitive to fire, likely because of ecological mechanisms that warrant further investigation. These findings highlight that fire represents a significant threat to endemic orchids in the Chapada Diamantina, with important implications for their conservation and for fire management in this Brazilian biodiversity hotspot.