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Previous issue date: 2015-09-28 === Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq === Disturbances affect plant populations in different ways, and their understanding is extremely important to define management strategies and biodiversity conservation. Such disturbances may be natural, as in the case of fire initiated by lightning, or can be anthropogenic, as the extraction of natural products. In both cases, populations of plants under interference from disturbances may increase or decrease, being necessary to understand its effects on populations in the long run. A key plant for conservation is Vellozia aff. sincorana L.B.Sm. & Ayensu (Velloziaceae), is an important species for the conservation of rupestrian fields of the western portion of the Serra do Sincor?, which is endemic. The largest area of distribution of this species, popularly know as candomba, is within the limits of the Chapada Diamantina National Park (CDNP), Bahia, Brazil, where it has a elevated cover. Candomb? branches are target of extraction in the region, which are destined to ignite wood stoves. In addition to this anthropic disturbance, V. aff. sincorana is also frequently affected by fires, which despite being a natural phenomenon are largely generated by human activity in CDNP. The fire has a marked effect on V. aff. sincorana, as it stimulates their mass flowering and synchronic, with no registration of flowering in this species in the absence of fire. This study evaluated the effects of fire in individuals of V. aff. sincorana in space and stages structure and the population dynamics of this species. In addition, simulations were performed with different frequencies fire, harvest intensities, and the association of fire and harvesting in order to assess the possibilities of using fire as management tool of harvest to this species. For analyzes involving harvest, the two techniques used by candomb? collectors in the region (removal of whole adult plants or branches) were simulated. For this study, individuals of V. aff. sincorana were marked, measured and monitored on 16m? plots over two censuses (2012 and 2013) in six populations, three unaffected by fire since 2008, and three affected by recent fires (2011 or 2012), approximately 40 days before the first census. In total, we monitored 1,617 individuals in 56 plots. The results showed that the recent fire affects individuals of V. aff. sincorana stimulating flowering and increases in canopy area, plant height and number of rosettes. Populations had lower rates of mortality and recruitment, however, in areas without recent fire, both the recruitment by seeds and mortality of juveniles were higher. The distribution of individuals was aggregate in all populations, averaging two individuals per m?. The recent fire caused changes in distribution of individuals in class of life stages. In general, populations tended to have higher concentration of adults. The reproduction stimulus by fire increases fertility and causes growth of recent fire populations, so the recent fire encourages population increase of V. aff. sincorana, while in absence of fire populations tended to decrease. The simulation results showed that populations of V. aff. sincorana tend to decrease with increasing the gap between the fire events. In harvest simulations, the growth of population was negatively affected by the decrease in harvest intervals and no fire. The results showed that the harvesting technique of whole adult is not sustainable and that the maintenance of the populations of V. aff. sincorana depends on the survival of individuals, mostly adults. In general, we find evidence that the conservation of V. aff. sincorana and its management for extractive purposes depend on periodic fire occurrence. === Os dist?rbios afetam as popula??es vegetais de diversos modos, sendo sua compreens?o de extrema import?ncia para defini??o de estrat?gias de manejo e conserva??o da biodiversidade. Tais dist?rbios podem ter origem antr?pica ou n?o, a exemplo do fogo iniciado por raio e da extra??o de produtos naturais. Em ambos os casos, as popula??es de plantas sob interfer?ncia podem crescer ou diminuir demasiadamente, sendo necess?ria a compreen??o dos efeitos em longo prazo dos dist?rbios nas popula??es. Vellozia aff. sincorana L.B.Sm. & Ayensu (Velloziaceae) ? uma esp?cie importante para a conserva??o dos campos rupestres da por??o ocidental da Serra do Sincor?, da qual ? end?mica. A maior ?rea de distribui??o dessa esp?cie, popularmente conhecida como candomb?, encontra-se dentro dos limites do Parque Nacional da Chapada Diamantina (PNCD), Bahia, Brasil, onde apresenta uma elevada cobertura. Os ramos do candomb? s?o alvo de extrativismo na regi?o, os quais s?o destinados a acender fog?es a lenha. Al?m desse dist?rbio antr?pico, V. aff. sincorana tamb?m ? frequentemente afetada por inc?ndios, que apesar de serem um fen?meno natural, s?o majoritariamente originados pela a??o humana no PNCD. O fogo tem um efeito marcante sobre V. aff. sincorana, j? que estimula sua flora??o em massa e sincr?nica, n?o havendo registros de flora??o da esp?cie na aus?ncia de fogo. O presente estudo avaliou os efeitos do fogo nos indiv?duos de V. aff. sincorana, na estrutura espacial e de est?dios, bem como na din?mica populacional dessa esp?cie. Al?m disso, foram realizadas simula??es com diferentes frequ?ncias de fogo, intensidades de colheita, e da associa??o entre fogo e colheita, a fim de avaliar as possibilidades do uso do fogo como ferramenta do manejo extrativista dessa esp?cie. Para as an?lises envolvendo colheita, foram simuladas as duas t?cnicas utilizadas pelos coletores de candomb? na regi?o (retirada de plantas adultas inteiras ou a de ramos). Para esse estudo, os indiv?duos de V. aff. sincorana foram marcados, medidos e acompanhados em parcelas de 16m? durante dois censos (2012 e 2013) em seis popula??es, tr?s n?o afetadas por fogo desde 2008, e tr?s afetadas por inc?ndios recentes (2011 ou 2012), aproximadamente 40 dias antes do primeiro censo. No total, foram acompanhados 1.617 indiv?duos distribu?dos em 56 parcelas. Os resultados evidenciaram que o fogo recente afeta os indiv?duos de V. aff. sincorana estimulando ? flora??o e aos incrementos em ?rea da copa, altura da planta e produ??o de rosetas. As popula??es apresentaram baixas taxas de mortalidade e recrutamento, por?m, nas ?reas sem fogo recente, tanto o recrutamento via sementes quanto a mortalidade de juvenis foram maiores. A distribui??o dos indiv?duos foi agregada em todas as popula??es, com m?dia de dois indiv?duos/m?. O fogo recente provocou mudan?as na distribui??o dos indiv?duos entre as classes de est?dios de vida. Em geral, as popula??es tenderam ? maior concentra??o de adultos. A reprodu??o estimulada por fogo aumenta a fertilidade e ocasiona crescimento das popula??es rec?m-incendiadas, de modo que o inc?ndio recente favoreceu o aumento populacional de V. aff. sincorana, enquanto na sua aus?ncia as popula??es tenderam ? diminui??o. Os resultados das simula??es evidenciaram que as popula??es de V. aff. sincorana tendem ? diminui??o com o aumento do intervalo entre os eventos de fogo. Nas simula??es de colheita, o crescimento das popula??es foi afetado negativamente pela diminui??o dos intervalos de colheita e aus?ncia de fogo. Os resultados evidenciaram que a t?cnica de colheita de adultos inteiros n?o ? sustent?vel e que a manuten??o das popula??es de V. aff. sincorana depende da sobreviv?ncia dos indiv?duos, principalmente os adultos. De modo geral, encontramos ind?cios de que a conserva??o de V. aff. sincorana e seu manejo para fins extrativistas dependem da ocorr?ncia peri?dica do fogo.
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