Does fire determine distinct floristic composition of two Cerrado savanna communities on different substrates?

Abstract

We surveyed two savanna sites, one on fl at terrain with deep soil (DS), and the other on hilly terrain with rocky outcrops and shallow soil (RS), before and after an accidental fi re. We found that the fi re did not cause any signifi cant changes in the species composition or diversity of either community, and did not result in fl oristic 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-fi re changes in vegetation structure were more pronounced in the DS savanna than in the RS, the diff erence in the underlying substrate did not have a direct infl uence on the post-fi re composition of woody species. Th e 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 fi res in the two phytophysionogmies, and accounts for the distinct responses to fi re we observed in the two woody communities.

The Role of Vegetation on the Dynamics of Water and Fire in the Cerrado Ecosystems: Implications for Management and Conservation

“…Nevertheless, despite those increments, there is no evidence that fire changes one phyto-physiognomy into another entirely, since edaphic limitations play an important role in determining Cerrado physiognomies [ 142 ]. Only when the vegetation before fires was already a more closed physiognomy can the increment of woody plants and tree species, after a long time of fire suppression (over 20 years), change phyto-physiognomies [ 143 , 144 , 145 ].…”

Together yet separate: variation in soil chemistry determines differences in the arboreal-shrub structure of two contiguous rupestrian environments

“…The rupestrian cerrado island encompasses only 8000 m 2 , and thus no more than 10 plots were set to assure sampling independence since both sampling areas were contiguous. Despite the fact that fire is a strong environmental filter in rupestrian environments (Figueira et al 2016), some studies have reported no floristic differences after fires (Lenza et al 2017), and so we disregard the effect of fire on the mosaic formation since no fires had been recorded for at least ten years in the study area.…”

The type of substrate does not influence the intraspecific population structure of shrub‐tree species in the Brazilian savanna

“…We assume as a premise that the distribution pattern of the Cerrado sensu stricto shrub‐tree species is strongly associated with edaphic characteristics (Furley & Ratter, 1988; Lehmann et al, 2014; Oliveira‐Filho & Ratter, 2002; Reatto et al, 2008), as in the rupestrian environment, the physical–chemical conditions of soils are restrictive (Almeida et al, 2018; Benites et al, 2007; Fernandes et al, 2018, 2020; Moura et al, 2011; Negreiros et al, 2014; Oliveira et al, 2015; Schaefer et al, 2016). However, wildfires (depending on the frequency and intensity of fires) can modify the floristic composition and vegetation structure in the Cerrado sensu stricto (Coutinho, 1982; Gomes et al, 2016; Gomes et al, 2020; Henriques & Hay, 2002; Lenza et al, 2017; Miranda & Sato, 2005; Ribeiro et al, 2012), although the fire intensity is lower in the Rupestrian Savanna (Gomes et al, 2016; Kolbek & Alves, 2008; Lenza et al, 2017). Thus, our hypothesis is that the relief and limiting soil conditions in the Rupestrian Savanna have an influence at the intraspecific level, as a negative effect on the horizontal and vertical structure of the populations, as well as on the contribution of the species to the phytosociological structure of the community.…”