Effectiveness of Dispersal of an Ornithocorous Cactus Myrtillocactus geometrizans (Cactaceae) in a Patchy Environment

摘要

Effectiveness of seed dispersal by different species that feed on the fruits of Myrtillocactus geometrizans wasevaluated, considering both quantity and quality of dispersal, in a patch of tropical deciduous forest in Zapotitlán de lasSalinas. Effectiveness was estimated to be strongly influenced by the post-foraging movements of the frugivores, leadingus to suggest that the quality component of seed dispersal occupies a central role in the assessment of dispersereffectiveness and to expect that dispersers that stay in the tropical deciduous forest patch after foraging would havehighest effectiveness. Birds were the principal dispersers of M. geometrizans. This was particularly true of Phainopeplanitens, since this species showed a high fidelity within the tropical deciduous forest. These observations emphasize that itis important to determine the post-foraging habits of seed dispersers that may move across vegetation patches over thelandscape in order to obtain a complete assessment of their role in Neotropical environments.