The effects of a catastrophic forest fire on the biomass of submerged stream macrophytes

•Catastrophic forest fire disturbed streams dominated by submerged macrophytes.•Monsoonal floods and a large regional flood reduced standing mean plant biomass.•Post-fire flooding created a fertilization effect that increased macrophyte biomass.•Total mean plant biomass ranged from 42 to 234 g AFDM m−2 over the study period.•Macrophyte species responses to floods and fertilization events varied between taxa.