1 Effects of fire on the demography of a population of a long-lived perenni
al tussock grass, Hyparrhenia diplandra, were investigated in a West Africa
n savanna that normally burns annually. Seedling growth, survival and fecun
dity were recorded in burned and unburned plots during 3 years for a first
cohort and during 1 year for a second cohort initiated 1 year later.
2 Seedling growth and survival rates were significantly higher in unburned
plots, with larger seedlings surviving burning better. Regardless of treatm
ent/fire regime, seedlings grew faster when located further from the neares
t tuft, but differences between clones showed that growth rate also had a g
enetic basis in this apomictic species. Adult survival was always high, but
exclusion of fire increased size, and therefore age, at maturity. Fire the
refore affects life-history traits in this grass species of fire-prone envi
3 Size-structured matrix models were constructed separately for each fire t
reatment, incorporating demographic and fire parameters estimated from fiel
4 The asymptotic population growth rate was higher in the unburned model (l
ambda = 1.23) than in the burned one (lambda = 1.07), indicating that the p
opulation of H. diplandra expanded quickly in the absence of fire.
5 Overall, results indicate that annual burning limits population growth ra
te. Less frequent, but still regular fires may allow establishment while pr
eventing the accumulation of litter and accelerating nutrient recycling; th
us lead to more stable populations than in the total absence of fire.