Post-fire dynamics of the woody vegetation of a savanna forest (Cerradão) in the Cerrado-Amazon transition zone

ABSTRACT

Fire can change the species composition, diversity, and structure of savanna vegetation, thus altering growth and mortality rates. Such changes in the woody vegetation of burned savanna forest were evaluated over four years in comparison to unburned savanna forest. All woody plants with a diameter at breast height > 10 cm were measured in 100 permanent plots. Six months later, 38 of these plots were burned. Three and a half years later, all surviving individuals were re-sampled. Species richness, diversity, and the number of individuals did not change in the burned plots, although they had significantly higher (p < 0.05) increases in basal area and mortality rates (5.1% year^-1) than the unburned plots (3.0% year^-1).Tachigali vulgaris had the greatest post-fire increase in basal area (53%). The results indicate that fire alters the dynamics and structure of the savanna forest, excluding the less fire-tolerant species and smaller individuals (? 15cm). Tachigali vulgaris is a key species for the recovery of savanna forest biomass due to its considerable post-fire gains in basal area, at least over the short term due to its short life cycle. It follows that frequent burning of savanna forest would result in a marked change in the species composition and structure of its woody vegetation.

Keywords:
conservation; land-use change; mortality; structural and floristic changes; wildfire