Variação espacial nas interações entre o palmito Euterpe edulis e as aves frugívoras: implicações para a dispersão de sementes
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Data
2006-05-30
Autores
Côrtes, Marina Corrêa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A investigação da identidade dos frugívoros e da remoção de sementes pelos dispersores é o primeiro passo para se compreender os processos envolvidos na estrutura populacional de uma planta. Porém, a assembléia de aves assim como os padrões de interação planta-dispersores podem variar em múltiplas escalas. Assim, objetivou-se responder às seguintes questões gerais: (i) Como varia a frugivoria ao longo de um gradiente espacial? e (ii) Como os fatores estruturais do micro-ambiente e intrínsecos da planta influenciam a frugivoria em diferentes ambientes? Para isso o estudo foi desenvolvido em três tipos florestais localizados ao longo de um gradiente altitudinal de Mata Atlântica, na Ilha do Cardoso, Cananéia, SP. A planta estudada foi a abundante palmeira Euterpe edulis, cujos frutos são intensivamente consumidos por uma grande gama de vertebrados, principalmente aves. Foram realizadas observações árvore-focal em 102 palmitos distribuídos na vegetação de Restinga, floresta de Planície e floresta de Encosta. Além disso, foram mensurados 9 fatores, incluindo características individuais das árvores observadas e aspectos estruturais do micro-ambiente. A frugivoria variou significativamente entre os tipos florestais de modo que ambientes contíguos apresentaram-se mais similares, principalmente quando localizados no mesmo nível altitudinal. Somando todas as observações, foram vistas 22 aves consumindo frutos de palmito, sendo que apenas 13 foram registradas nos focais. As aves da família Muscicapidae, Cotingidae e Ramphastidae foram os dispersores mais importantes, sendo que os componentes quantitativos variaram entre espécies e entre ambientes. Poucos fatores influenciaram a atividade dos dispersores. Quando separados em dois grupos, Muscicapidae e grandes frugívoros, alguns fatores foram especialmente importantes para os últimos de acordo com a área...
The investigation of the seed dispersers identity and their relative importance on fruit removal is the first step to understand the processes involved in the structure of a species population. However, avian assemblage as well as plantdisperser interactions patterns might show high variability in multiples scales. The general goals of this study are to answer to the following questions: (i) To what extent does frugivory vary along a spatial gradient? and (ii) How structural factors of microhabitat and intrinsic plant attributes affect frugivory in different sites? To answer these questions, the investigation was developed in three Atlantic Forest types located along an elevational gradient in Cardoso Island, Cananéia, SP. The plant chosen was the abundant palm Euterpe edulis, which fruits are intensively consumed by several vertebrates, mainly birds. Focal-tree observations were carried out in 102 palm-hearts distributed in Restinga vegetation, Lowland forest and Sub-montane forest. Moreover, 9 factors were measured, including individual attributes of the observed palms and structural traits of the microhabitat. Among 22 species observed consuming E. edulis fruits for all sites pooled, only 13 birds were recorded in the focal observations. Frugivory by avian dispersers varied greatly between sites. Continuous areas showed more similarities when located in the same elevational level. The birds belonging to Muscicapidae, Cotingidae and Ramphastidae families were the most important seed disperses and the values of their quantitative component varied between species and sites. Few factors affected the avian disperser activities. When separated in two groups, Muscicapidae and large-bodied frugivores, some factors were especially important to large frugivores group but relationships were inconsistent among sites... (Complete abstract, click electronic access below)
The investigation of the seed dispersers identity and their relative importance on fruit removal is the first step to understand the processes involved in the structure of a species population. However, avian assemblage as well as plantdisperser interactions patterns might show high variability in multiples scales. The general goals of this study are to answer to the following questions: (i) To what extent does frugivory vary along a spatial gradient? and (ii) How structural factors of microhabitat and intrinsic plant attributes affect frugivory in different sites? To answer these questions, the investigation was developed in three Atlantic Forest types located along an elevational gradient in Cardoso Island, Cananéia, SP. The plant chosen was the abundant palm Euterpe edulis, which fruits are intensively consumed by several vertebrates, mainly birds. Focal-tree observations were carried out in 102 palm-hearts distributed in Restinga vegetation, Lowland forest and Sub-montane forest. Moreover, 9 factors were measured, including individual attributes of the observed palms and structural traits of the microhabitat. Among 22 species observed consuming E. edulis fruits for all sites pooled, only 13 birds were recorded in the focal observations. Frugivory by avian dispersers varied greatly between sites. Continuous areas showed more similarities when located in the same elevational level. The birds belonging to Muscicapidae, Cotingidae and Ramphastidae families were the most important seed disperses and the values of their quantitative component varied between species and sites. Few factors affected the avian disperser activities. When separated in two groups, Muscicapidae and large-bodied frugivores, some factors were especially important to large frugivores group but relationships were inconsistent among sites... (Complete abstract, click electronic access below)
Descrição
Palavras-chave
Ecologia vegetal, Dispersão de sementes, Frugivoria, Mata Atlântica
Como citar
CÔRTES, Marina Corrêa. Variação espacial nas interações entre o palmito Euterpe edulis e as aves frugívoras: implicações para a dispersão de sementes. 2006. vi, 95 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, 2006.