Fire effects on Atlantic Forest sites from a composition, structure and functional perspective.

Recently, some portions of the Atlantic Forest biome have been suffering an increase in forest fires, possibly changing its vegetation cover, composition, structure and functioning. Understanding these changes is critical to evaluate the present and future response of tropical forests to fire. Thus, the purpose of our study was to evaluate how diversity, structure and functioning of tree communities differed between burned and unburned sites. Two unburned and two burned forest patches were selected for floristic and phytosociological surveys. Then, we calculated species richness, Shannon diversity index, tree density and basal area, Importance Value Index for trees in each site and we assessed community weighted mean of six functional traits (maximum tree height, wood density, leaf length, leaf deciduousness, shade tolerance and dispersal mode). Diversity, species richness, tree density and basal area were similar between sites. We found changes in floristic composition, but did not verified variations in functional traits. Results indicate that recovery may be fast and that pioneer and early secondary species are occupying post burned sites (nine years old). One-time anthropogenic, superficial and low intensity fires might disrupt advanced stages of succession and start again the dynamics of species substitution.

Fire effects on Atlantic Forest sites from a composition, structure and functional perspective / Efeitos do fogo na Mata Atlântica por meio de uma abordagem de composição, estrutura e funcional

Recently, some portions of the Atlantic Forest biome have been suffering an increase in forest fires, possibly changing its vegetation cover, composition, structure and functioning. Understanding these changes is critical to evaluate the present and future response of tropical forests to fire. Thus, the purpose of our study was to evaluate how diversity, structure and functioning of tree communities differed between burned and unburned sites. Two unburned and two burned forest patches were selected for floristic and phytosociological surveys. Then, we calculated species richness, Shannon diversity index, tree density and basal area, Importance Value Index for trees in each site and we assessed community weighted mean of six functional traits (maximum tree height, wood density, leaf length, leaf deciduousness, shade tolerance and dispersal mode). Diversity, species richness, tree density and basal area were similar between sites. We found changes in floristic composition, but did not verified variations in functional traits. Results indicate that recovery may be fast and that pioneer and early secondary species are occupying post burned sites (nine years old). One-time anthropogenic, superficial and low intensity fires might disrupt advanced stages of succession and start again the dynamics of species substitution.

Recentemente, algumas regiões do bioma Mata Atlântica têm sofrido com um aumento de incêndios, possivelmente modificando sua cobertura vegetal, composição, estrutura e funcionalidade. Compreender essas mudanças é imprescindível para avaliar as respostas, no presente e futuro, das florestas tropicais ao fogo. Assim, o objetivo do nosso estudo foi avaliar como a diversidade, estrutura e funcionamento das comunidades arbóreas diferem entre áreas queimadas e não queimadas. Dois fragmentos queimados e dois fragmentos não queimados foram selecionados para os levantamentos florísticos e fitossociológicos. Depois, foram calculadas a riqueza de espécies, o Índice de diversidade de Shannon, densidade da árvore e área basal, Índice de valor de importância para as espécies em cada uma das áreas e avaliamos a média de seis características funcionais (altura máxima da árvore, densidade da madeira, comprimento da folha, deciduidade foliar, tolerância a sombra e síndrome de dispersão). Diversidade, riqueza, densidade e área basal foram similares entre as áreas analisadas. Nós encontramos mudanças na composição florística, mas não foram verificadas variações nas características funcionais. Os resultados indicam que a recuperação pode ser rápida e que espécies pioneiras e secundárias iniciais estão ocupando as áreas queimadas cerca de nove anos depois. Um único incêndio antrópico, superficial e de baixa intensidade, pode interromper estágios avançados de sucessão e iniciar a nova dinâmica de substituição de espécies.

Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil / Reprodução pós-fogo de espécies do estrato herbáceo em área de transição Cerrado-Mata de Galeria no Distrito Federal, Brasil

In Cerrado, studies of post-fire vegetation recovery show that some herbaceous species are able to flower shortly after fires. However, these were mainly short-term studies that focused on grasslands and savannas. Little is known about the effects of fire on ground layer of forests that border the savannas in Central Brazil. Thus, an accidental burning gave us the opportunity to describe the reproductive activity of the ground layer vegetation after a fire event along a savanna-forest boundary at the IBGE Ecological Reserve, Brasília, Brazil. During the 16-month of the inventory, we registered 170 herbaceous species flowering or fruiting, of which 52 species (31%) may have been influenced by fire that changed their times of reproduction. In the savanna plots reproduction peaked at the end of the rainy season. Of the total number of reproducing species, 90 species occurred only in the savanna and four in the forest. Five herbs were recorded in the forest, savanna and border environments. Late dry season fire probably lead the majority of herbaceous species to have their reproduction spread throughout the study time.(AU)

No Cerrado, estudos de recuperação da vegetação pós-fogo mostram que algumas espécies herbáceas são capazes de florescer logo após queimadas. No entanto, esses foram principalmente estudos de curto prazo, que se concentraram em áreas campestres e savânicas. Pouco se sabe sobre os efeitos do fogo no sub-bosque de matas que margeiam as savanas do Brasil Central. Assim, uma queima acidental nos deu a oportunidade de descrever a atividade reprodutiva pós-fogo do estrato herbáceo ao longo de ecótono cerrado-mata na Reserva Ecológica do IBGE, Brasília, Brasil. Durante os 16 meses do inventário, foram registrados 170 espécies herbáceas com flores ou frutos, das quais 52 espécies (31%) podem ter sido influenciadas pelo fogo, que alterou suas épocas reprodutivas. Nas parcelas de cerrado, a reprodução teve seu pico ao final da estação chuvosa. Do número total de espécies, 90 ocorreram exclusivamente no cerrado e quatro na floresta. Cinco espécies herbáceas foram registradas na floresta, cerrado e borda. O fogo ao final da estação seca pode ter levado a maioria das plantas a se reproduzir através do período de estudo.(AU)

Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil / Reprodução pós-fogo de espécies do estrato herbáceo em área de transição Cerrado-Mata de Galeria no Distrito Federal, Brasil

Abstract In Cerrado, studies of post-fire vegetation recovery show that some herbaceous species are able to flower shortly after fires. However, these were mainly short-term studies that focused on grasslands and savannas. Little is known about the effects of fire on ground layer of forests that border the savannas in Central Brazil. Thus, an accidental burning gave us the opportunity to describe the reproductive activity of the ground layer vegetation after a fire event along a savanna-forest boundary at the IBGE Ecological Reserve, Brasília, Brazil. During the 16-month of the inventory, we registered 170 herbaceous species flowering or fruiting, of which 52 species (31%) may have been influenced by fire that changed their times of reproduction. In the savanna plots reproduction peaked at the end of the rainy season. Of the total number of reproducing species, 90 species occurred only in the savanna and four in the forest. Five herbs were recorded in the forest, savanna and border environments. Late dry season fire probably lead the majority of herbaceous species to have their reproduction spread throughout the study time.

Resumo No Cerrado, estudos de recuperação da vegetação pós-fogo mostram que algumas espécies herbáceas são capazes de florescer logo após queimadas. No entanto, esses foram principalmente estudos de curto prazo, que se concentraram em áreas campestres e savânicas. Pouco se sabe sobre os efeitos do fogo no sub-bosque de matas que margeiam as savanas do Brasil Central. Assim, uma queima acidental nos deu a oportunidade de descrever a atividade reprodutiva pós-fogo do estrato herbáceo ao longo de ecótono cerrado-mata na Reserva Ecológica do IBGE, Brasília, Brasil. Durante os 16 meses do inventário, foram registrados 170 espécies herbáceas com flores ou frutos, das quais 52 espécies (31%) podem ter sido influenciadas pelo fogo, que alterou suas épocas reprodutivas. Nas parcelas de cerrado, a reprodução teve seu pico ao final da estação chuvosa. Do número total de espécies, 90 ocorreram exclusivamente no cerrado e quatro na floresta. Cinco espécies herbáceas foram registradas na floresta, cerrado e borda. O fogo ao final da estação seca pode ter levado a maioria das plantas a se reproduzir através do período de estudo.

Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil.

In Cerrado, studies of post-fire vegetation recovery show that some herbaceous species are able to flower shortly after fires. However, these were mainly short-term studies that focused on grasslands and savannas. Little is known about the effects of fire on ground layer of forests that border the savannas in Central Brazil. Thus, an accidental burning gave us the opportunity to describe the reproductive activity of the ground layer vegetation after a fire event along a savanna-forest boundary at the IBGE Ecological Reserve, Brasília, Brazil. During the 16-month of the inventory, we registered 170 herbaceous species flowering or fruiting, of which 52 species (31%) may have been influenced by fire that changed their times of reproduction. In the savanna plots reproduction peaked at the end of the rainy season. Of the total number of reproducing species, 90 species occurred only in the savanna and four in the forest. Five herbs were recorded in the forest, savanna and border environments. Late dry season fire probably lead the majority of herbaceous species to have their reproduction spread throughout the study time.