Post-fire flowering and fruiting in Vellozia sincorana, a caulescent rosette plant endemic to Northeast Brazil

Vellozia sincorana L.B. Sm. & Ayensu, an endemic of campos rupestres, is an endangered species collected by local people to start cooking fires due to the flammability of its resinous stems. A massive flowering of V. sincorana following a wildfire in October 1999 raised some questions: Does fire affect flowering and fruiting of V. sincorana? Is the height of individuals correlated with flowering and fruit production? A wildfire event on 8 November 2008 provided an opportunity to explore these questions. Two populations of V. sincorana in two campos rupestres sites (12º31'S - 41º29'W; 12º36'S - 41º28'W) on ridgetops in the Chapada Diamantina National Park (Brazil) were monitored, one burned in the November 2008 fire and the other unburned since the 1999 fire. In both sites, 25 individuals were randomly labeled and monitored. Nine plant samplings were conducted between 2008 and 2010, during which the number of flowers and fruits were tallied and the heights measured. Spearman's rank correlation coefficient and linear regression were used to evaluate the relationship between the height of individuals and phenology. Flowering and fruiting occurred only in the recently burnt population, about 40 days after the fire, in 24 of the 25 individuals monitored (96%). The quantity of flower and/or fruit was positively and significantly correlated with plant height. The abundant flowering after fire suggests that fire triggers this phenological phase. Estimates of age of the taller individuals and the periods of flowering can be used to estimate fire frequency in the V. sincorana population sites, which contributes to the knowledge of fire ecology and is useful for conservation biology and fire management of campos rupestres

Campo rupestre recém-queimado na Chapada Diamantina, Bahia, Brasil: plantas de rebrota e sementes, com espécies endêmicas na rocha Recently burnt 'campo rupestre' in the Chapada Diamantina, Bahia, Brazil: resprouters and seeders, with endemic rock species

O fogo é um distúrbio recorrente em muitas áreas da Chapada Diamantina, geralmente originado por ação antrópica e que ocasiona rápidas mudanças nas comunidades. Este trabalho objetiva conhecer a composição e estrutura da vegetação de uma área de campo rupestre recém-queimada no Parque Nacional da Chapada Diamantina, Bahia, Brasil, situada entre 700 e 800 m acima do nível do mar, visando discussão das estratégias de regeneração das espécies mais conspícuas e das similaridades florísticas entre áreas com e sem distúrbio recente de fogo. Foi realizado um censo das espécies de plantas vasculares ocorrentes em 16 parcelas de 10x10 m, sendo as coberturas estimadas em cinco subparcelas de 2x2 m de cada parcela. Foram encontradas 85 espécies de 34 famílias, sendo 11 de monocotiledôneas, 22 de eudicotiledôneas e uma de monilófita. A espécie mais abundante foi Panicum trinii Kunth (Poaceae) e a mais frequente Periandra mediterranea (Vell.) Taub. (Fabaceae). O índice de Shannon foi 3,4. A área estudada agrupou-se com a área de afloramento rochoso em altitude menos elevada (38% de similaridade). É possível que o fogo seja mais frequente nessas áreas menos isoladas, em relação às dos topos de morros. As espécies dominantes se restabeleceram principalmente a partir de gemas de sistemas subterrâneos e aéreos. Uma das espécies mais frequentes, Dactylaena microphylla Eichler, estabeceu-se de sementes. Espécies endêmicas sensíveis à ação do fogo sobrevivem em ilhas de vegetação nos afloramentos rochosos.<br>Fire is a recurrent disturbance in many areas of Chapada Diamantina, generally set by human activity that drives rapid changes in communities. This study aims to investigate the composition and structure of 'campo rupestre' vegetation in a recently burned area, between 700 and 800 m above sea level, at Chapada Diamantina National Park, Bahia, Brazil, and to discuss the strategies of regeneration for the most conspicuous species and floristic similarities among sites with and without recent fire disturbance. A species census of all vascular plants in 16 plots (10x10 m) was performed, and species cover was estimated in five subplots (2x2 m). 85 species were found, distributed among 34 families, including 11 monocotyledons, 22 eudicotyledons and one monilophyte. The most abundant specie was Panicum trinii Kunth (Poaceae) and the most frequent was Periandra mediterranea (Vell.) Taub (Fabaceae). The Shannon index was 3.4. The study area grouped with a rocky area at lower altitudes (38% similarity). Probably, fire is more frequent in these areas than on hill summits. The main dominant species resprouted from underground buds and from aerial organs. One of the most frequent species, Dactylaena microphylla Eichler, was established from seed. Fire-sensitive endemic species survive on vegetation islands on rocky outcrops