Fire promotes growth and reproduction of Saccharum spontaneum (L.) in Panama

Abstract

Fire can be an important mechanism by which invasive grasses maintain their dominance in introduced habitats. In April 2009 a dense stand of Saccharum spontaneum in the Panama Canal Watershed burned as a result of an anthropogenic fire. Regrowth was monitored throughout the 2009 growing season and compared to a nearby unburned stand with a similar management history. Six months after the fire, live aboveground biomass and stem density were similar but flowering shoot densities were significantly higher in the burned stand. Aboveground dead biomass was significantly higher in the unburned stand, and bare soil remained below much of the burned stand. Viability of seeds produced in the burned stand was comparable to surrounding unburned populations. Germinants were also observed in the burned stand in October and November whereas no seedlings were found in the unburned stand. These results suggest that fire promotes the growth of Saccharum and may enhance its spread by stimulating new shoot growth, increasing flowering shoot density and thereby seed production, and creating available habitat for recruitment of new populations by removing litter. It also may delay flowering thus extending the reproductive period of the species in Panama. Appropriate measures, including increased funding for fire control and public education, to reduce the frequency of dry-season fires would likely help to manage the spread of this very aggressive invader in Panama.