Dispersão de sementes e processos de limitação demográfica de plantas em ambientes com e sem bambus na Floresta Pluvial Atlântica
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Data
2010-11-30
Autores
Rother, Débora Cristina [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Em florestas tropicais, ainda são incipientes os estudos que tratam da influência dos bambus na dinâmica da vegetação. Pela grande capacidade de se expandir rapidamente no ambiente seja por crescimento vegetativo ou por produção massiva de sementes, os bambus promovem alterações significativas na estrutura das comunidades vegetais. Desta forma, esse estudo teve como objetivo avaliar o ciclo de vida das plantas em ambientes com (B) e sem bambus (SB) em uma área de floresta Atlântica densamente ocupada pelo bambu nativo Guadua tagoara. Os objetivos específicos deste estudo foram separados em capítulos. Para o capítulo 1, conhecer a composição de aves associadas aos ambientes com e sem bambus, identificar as aves que compõem a guilda de dispersores de sementes de Euterpe edulis, Sloanea guianensis e Virola bicuhyba e avaliar o potencial de dispersão das aves registradas em censos. Para o capítulo 2, avaliar o padrão espacial dos estágios iniciais da regeneração da comunidade de plantas nos ambientes B e SB. Finalmente para o capítulo 3, quantificar as perdas de propágulos e as probabilidades de transição entre cada etapa demográfica das três espécies de plantas selecionadas, e identificar os gargalos demográficos do recrutamento que podem colapsar a regeneração natural das três espécies de plantas nos ambientes B e SB. Verificamos que nos ambientes B foi registrado maior número de espécies de aves do que em ambientes SB. A maioria das aves registradas em censos nos dois ambientes foi insetívora, seguida por espécies frugívoras. A efetividade da dispersão de Euterpe, Sloanea e Virola, esteve restrita a um pequeno grupo de dispersores efetivos. As aves que mais contribuíram para a dispersão de Virola ocorreram mais freqüentemente em B. Este padrão foi similar para Sloanea, enquanto Euterpe apresentou um padrão misto, com algumas espécies de aves...
Studies about the bamboo influence in the plant dynamic process are still incipient. Given that bamboos are able to quickly expand in environment by either vegetative growth or massive seed production, bamboos promote significant changes in plant community structure. Thus, this work aimed at assessing the plant life cycles in bamboo (B) and non bamboo stands (NB) in an Atlantic forest area where the native bamboo Guadua tagoara occurs at high densities. The specific goals of this study were showed in chapters. For chapter 1, to know bird species associated with bamboo and non bamboo stands, identify the birds which belong to seed dispersers guild of Euterpe edulis, Sloanea guianensis and Virola bicuhyba and evaluate dispersal effectiveness and potential contribution to seed dispersal for the three plant species. For chapter 2, assess the spatial pattern of early regeneration stages of plant communities in B and NB stands. Finally, for chapter 3, quantify propagule losses as well as the probabilities of transition between each stage for all three plant species, and identify the demographic bottlenecks in recruitment that could collapse natural regeneration of the three plant species in B and NB stands. We verified that a higher number of bird species was registered in B stands than in NB. Most of registered birds in both B and NB stands were insectivorous followed by frugivorous species. The dispersal effectiveness of Euterpe, Sloanea and Virola depended on a restricted subset of effective bird dispersers. Birds which mostly contributed to the seed dispersal of Virola occurred more frequently in B. This pattern was similar for Sloanea while Euterpe exhibited a mixed pattern with some bird species contributing to the dispersal in the B stands and other species contributing in NB stands. We conclude that a substantial number of frugivorous bird species can favor borders of bamboo patches... (Complete abstract click electronic access below)
Studies about the bamboo influence in the plant dynamic process are still incipient. Given that bamboos are able to quickly expand in environment by either vegetative growth or massive seed production, bamboos promote significant changes in plant community structure. Thus, this work aimed at assessing the plant life cycles in bamboo (B) and non bamboo stands (NB) in an Atlantic forest area where the native bamboo Guadua tagoara occurs at high densities. The specific goals of this study were showed in chapters. For chapter 1, to know bird species associated with bamboo and non bamboo stands, identify the birds which belong to seed dispersers guild of Euterpe edulis, Sloanea guianensis and Virola bicuhyba and evaluate dispersal effectiveness and potential contribution to seed dispersal for the three plant species. For chapter 2, assess the spatial pattern of early regeneration stages of plant communities in B and NB stands. Finally, for chapter 3, quantify propagule losses as well as the probabilities of transition between each stage for all three plant species, and identify the demographic bottlenecks in recruitment that could collapse natural regeneration of the three plant species in B and NB stands. We verified that a higher number of bird species was registered in B stands than in NB. Most of registered birds in both B and NB stands were insectivorous followed by frugivorous species. The dispersal effectiveness of Euterpe, Sloanea and Virola depended on a restricted subset of effective bird dispersers. Birds which mostly contributed to the seed dispersal of Virola occurred more frequently in B. This pattern was similar for Sloanea while Euterpe exhibited a mixed pattern with some bird species contributing to the dispersal in the B stands and other species contributing in NB stands. We conclude that a substantial number of frugivorous bird species can favor borders of bamboo patches... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Sementes, Regeneração (Biologia), Frugivoria, Chuva de sementes, Estabelecimento de plântulas, Gargalos demográficos, Frugivory, Heterogeneity, Demographic limitation, Seed rain, Bamboos
Como citar
ROTHER, Débora Cristina. Dispersão de sementes e processos de limitação demográfica de plantas em ambientes com e sem bambus na Floresta Pluvial Atlântica. 2010. 131 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2010.