Effects of Recurrent Fires on the Interactions Between Frugivorous Birds and Plants

ABSTRACT Anthropogenic fires are increasingly affecting native vegetation worldwide, with consequences not only for species occurrence but also for ecological interactions. We investigated the effects of two fire events, spaced by a 2‐year interval, on interactions between frugivorous birds and fleshy‐fruited plants. We monitored a Cerrado site—a fire‐adapted savanna ecosystem—for 5 years: 2 years before the first fire, 1 year after the first fire and 2 years after the second fire. We tested the effects of recurrent fires on weighted connectance, weighted nestedness, Shannon's index of interaction diversity, and linkage density in frugivore–plant interaction networks. We also examined how bird and plant abundance changed across fire events, and how bird body mass and degree of frugivory, as well as fruit pulp‐to‐seed mass ratio and lipid content, influenced the frequency of bird–plant interactions. Furthermore, we assessed dissimilarity between interaction networks sampled after each fire relative to pre‐fire networks by partitioning it into species turnover and interaction rewiring components. Both fruit and bird abundance declined following fires, which also reduced the total number of possible interactions (connectance) within the community. Fires decreased interaction rates per bird and per plant species, particularly those involving the most well‐connected species. Before fires, both functional traits and abundances influenced interaction frequencies, whereas after fires, species abundances became the dominant factor. Dissimilarity between pre‐ and post‐fire periods was driven more by interaction rewiring than by species turnover. We conclude that increased fire frequency alters not only species occurrence and abundances but also the structure of frugivory and seed‐dispersal networks with potential consequences for Cerrado recovery and resilience, likely depending on fire frequency and severity.