Influência de agrupamentos de bambu na dinâmica pós-fogo da vegetação lenhosa de um cerrado típico, Mato Grosso, Brasil

Abstract

Neste estudo foram avaliadas as mudanças na composição florística e na estrutura da vegetação lenhosa logo após incêndio acidental ocorrido em sítios de cerrado típico sem (SB, controle) e com (CB) agrupamentos do bambu Actinocladum verticillatum em Nova Xavantina/MT. Foram amostrados todos os indivíduos com diâmetro de base (Db30) ≥ 3 cm antes e após o fogo em ambos os sítios. A amostragem foi realizada em 30 parcelas de 10 × 10 m, sendo 15 parcelas em cada sítio. A ocorrência de fogo ocasionou mudanças na composição florística e reduções na riqueza e diversidade de espécies lenhosas mais evidentes no sítio CB (perda de 61% das espécies) em relação ao SB (perda de 20% das espécies). Entretanto, o incêndio ocasionou perda relativa de indivíduos (67,4% e 73,5%) e de área basal (75,6% e 55,2%) semelhante entre os sítios SB e CB, respectivamente, com exceção dos indivíduos de pequeno porte, os quais foram mais acentuadamente reduzidos no sítio CB. Queimadas em áreas de cerrado com agrupamentos de A. verticillatum podem criar condições de retroalimentação positiva e resultar na redução da densidade de indivíduos e na exclusão local de espécies menos tolerantes ao fogo.

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

“…41% in Hoffmann et al (2009), 67.4 % in Mews et al (2013, and 13-16 % in , or shallow ones, i.e., 43.6 % in Gomes et al (2014). These mortality rates caused a significant reduction in the abundance of trees and shrubs in the Cerrado, in contrast with the pattern observed in the present study Fiedler et al 2004;Lima et al 2009;Mews et al 2013). We believe that the low mortality rates recorded in the present study are related to the relatively high frequency of fires in the two studied savannas.…”

“…However, fires may also cause considerable impacts on species richness and composition, Does fire determine distinct floristic composition of two Cerrado savanna communities on different substrates? as recorded by Mews et al (2013). These inconsistencies are probably the result of the distinct history of wildfires in each community.…”

“…These inconsistencies are probably the result of the distinct history of wildfires in each community. The Cerrado studied by Mews et al (2013) was protected from fire for more than a decade, while the two savannas studied here had been burned off every other year over the past 10 years. This may have determined the accumulation of fine-stemmed and inflammable biomass in the savanna studied by Mews et al (2013), resulting in more intense fires (Pivello & Norton 1996;Pivello 2006;França et al 2007;Higgins et al 2007), which had a greater impact on the flora.…”

“…The Cerrado studied by Mews et al (2013) was protected from fire for more than a decade, while the two savannas studied here had been burned off every other year over the past 10 years. This may have determined the accumulation of fine-stemmed and inflammable biomass in the savanna studied by Mews et al (2013), resulting in more intense fires (Pivello & Norton 1996;Pivello 2006;França et al 2007;Higgins et al 2007), which had a greater impact on the flora. In areas with a prolonged absence of fire, the establishment of more fire-sensitive plant species will tend to be more likely (Moreira 2000), making these habitats more vulnerable to fire-induced changes in composition.…”

Surface fire drives short-term changes in the vegetative phenology of woody species in a Brazilian savanna

“…On September 2008, this plot was burned accidentally. As no fires were recorded in the park during the preceding five years, a great deal of flammable material had accumulated, resulting in flames that attained a height of 5 m, reaching the canopy (Mews et al 2013). No precipitation had been recorded during the four months prior to the fire.…”