Abstract
ABSTRACT We surveyed two savanna sites, one on flat terrain with deep soil (DS), and the other on hilly terrain with rocky outcrops and shallow soil (RS), before and after an accidental fire. We found that the fire did not cause any significant changes in the species composition or diversity of either community, and did not result in floristic homogenization. However, we did record a reduction in the density of plants and in basal area in the DS savanna in comparison with the RS savanna, as well as a higher rate of basal sprouting, which indicates a trade-off between mortality and sprouting. We conclude that, whereas post-fire changes in vegetation structure were more pronounced in the DS savanna than in the RS, the difference in the underlying substrate did not have a direct influence on the post-fire composition of woody species. The greater grass biomass found in the DS savanna in comparison with the RS savanna appears to have been the principal modulator of the severity of the fires in the two phytophysionogmies, and accounts for the distinct responses to fire we observed in the two woody communities.
Highlights
Savanna-like ecosystems are widely distributed in the tropics, where they can be found in an ample variety of habitats, ranging from flat plains to mountainous terrain, on a diversity of soil types (Collinson 1988; Young & Solbrig 1993; Mews et al 2014)
We found no evidence of any homogenization or simplification of the species composition of the two communities, nor any shift in the species diversity of either community, following the fire
A similar situation has been observed in other fire-affected areas of the cerrado (Sato & Miranda 1996; Silva et al 1996; Gomes et al 2014), as well as the present study, in which the two species excluded after the fire, Miconia albicans in the deep soil (DS) and Erythroxylum engleri in the rocky soil (RS), were each represented by only a single specimen prior to the fire
Summary
Savanna-like ecosystems are widely distributed in the tropics, where they can be found in an ample variety of habitats, ranging from flat plains to mountainous terrain, on a diversity of soil types (Collinson 1988; Young & Solbrig 1993; Mews et al 2014). Through its interaction with the climate and soil, fire can modify the basal area of woody species in savanna habitats, with profound implications for carbon storage (Lehmann et al 2014). In Brazil, most of savanna is known as the Cerrado, which originally covered an area of more than two million square kilometers. The savanna formations of the Cerrado are found primarily on deep soils (mainly Oxisols) on relatively flat terrain (Reatto et al 2008).
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