Exploring the Role of Secondary Metabolites in Post-Fire Ecological Memory

Fire is a significant cause of ecosystem disturbance with many direct and indirect effects on the structure and functioning of plant communities. The effects of fire disturbance and post-fire acclimation have been well-documented through changes in plant community composition and structure and the triggering of multiple adaptive responses. However, the role of plant secondary metabolites (SM) in the post-fire acclimation process is underestimated. These compounds have mostly been recognized as determinants of plant flammability, while their post-fire dynamics and ecological consequences remain largely unknown. This literature review synthesizes evidence from 43 studies on changes in plant SM following wildfires and prescribed burns and their potential ecological roles. Literature searches were conducted in Web of Science and Scopus, and a bipartite co-occurrence network analysis was performed to examine associations among vegetation types, post-fire timelines, and secondary metabolite classes, including the direction and frequency of reported responses. Phenolic compounds and volatile organic compounds (VOCs) were the main SM groups identified, with substantial variation in the direction and magnitude of responses depending on species and time since fire. Karrikins and their potential role in post-fire environments were considered separately as fire-derived signaling compounds. Key knowledge gaps include uneven representation of ecological zones, limited compound-specific analyses, insufficient integration of fire-induced metabolite responses with subsequent ecological effects, and limited translation of biochemical findings into ecosystem management and restoration.