DispersÃo e predaÃÃo de grandes sementes por Sciurus aestuans L. em fragmentos de floresta AtlÃntica montana no Estado do EspÃrito Santo, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The plantâdispersor interactions influence the adaptive values of plants and animals, acting directly on the reproductive characters of plant species and life histories of animal species. The fruvigory pattern influences the seed shadow patterns of plants, the predation rates by invertebrates and consequently the germination, seedling survival and adult recruitment. Considering that the demographic characters of plant species are affected by adult recruitment, it follows that foraging patterns of animal dispersal agents are partially responsible for the maintenance of community organization. In relation to the seed dispersal mediated by sactterhoarder rodents, it is expected that plant species adapt to plantâdispersor systems, investing in a high production of large, edible seeds with synchronized maturation to attract predators. In return, the rodent species would scatterhoard, decreasing competition and providing a great seed distribution. The seeds would be cached in low densities and distant from parental trees, which would protect them from predator attacks. This study aimed to describe the frugivory pattern of the scatterhoarder rodent, Sciurus aestuans, to establish parameters related to frugivory activities and to evaluate their effects on population characteristics of tree species. This research project was conducted at Atlantic forest fragments located at Santa Teresa county, EspÃrito Santo state, Southeastern Brazil. The studied forest fragments present some defaunation, being influenced by anthropogenic activities. The plant species investigated here show fruits whose morfological characters fit well to a seed dispersal syndrome by rodents. The following plant species were studied: (1) Attalea oleifera, Syagrus pseudococos, S. ruschiana, Polyandrococos caudescens, Bactris setosa and Euterpe edulis (Arecaceae); (2) Licania kunthiana and L. leptostachia (Chrisobalanaceae); (3) Caryocar edule (Cariocaraceae); (4) Hymenea aurea (Caesalpinaceae); and (5) Vantanea obovata (Humiriaceae). Different fruit species from the same seed dispersal syndrome were differently manipulated and cosumed by S. aestuans, which indicates the existence of a selective behavior in this animal species. The squirrel preferred plant species with a high productivity, with large fruits containing few seeds covered by a rigid endocarp and that are not utilized by other arborean seed predators. S. aestuans spend more time and showed a more complex fruit manipulation pattern in plant species characterized by higher productivity and larger, harder fruits, when comparing different species within the range of characters present in the typical seed dispersal syndrome. In addition, lower predation rates and higher caching rates were observed for plant species with larger fruits.There are few works dealing with the foraging patterns of seed predators from the Atlantic forest and their influence on the reproductive characters in the associated plant species. This study is relevant for showing inedited or not fully quantified behavioral patterns, providing a basis to more profound investigations of the mutualistic interactions involving S. aestuans at Atlantic forest

ASSUNTO(S)

sciurus aestuans anatomia vegetal mata atlÃntica - espirito santo dipersÃo e predaÃÃo

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