The influence of fire on the demography of a dominant grass species of West African savannas, Hyparrhenia diplandra

Citation
Lkm. Garnier et I. Dajoz, The influence of fire on the demography of a dominant grass species of West African savannas, Hyparrhenia diplandra, J ECOLOGY, 89(2), 2001, pp. 200-208
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ECOLOGY
ISSN journal
0022-0477 → ACNP
Volume
89
Issue
2
Year of publication
2001
Pages
200 - 208
Database
ISI
SICI code
0022-0477(200104)89:2<200:TIOFOT>2.0.ZU;2-4
Abstract
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 ronments. 3 Size-structured matrix models were constructed separately for each fire t reatment, incorporating demographic and fire parameters estimated from fiel d data. 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.