Plant Ecology 149: 51–62, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. 51 Seed arrival under different genera of trees in a neotropical pasture Matthew G. Slocum ∗ & Carol C. Horvitz Department of Biology, University of Miami, P.O. Box 249118, Coral Gables, FL 33124, USA ( ∗ Current address: Department of Biological Sciences, Louisiana State University, 508 Life Sciences Building, Baton Rouge, LA 70803, USA (e-mail: mateo457@yahoo.com) Received 18 August 1998; accepted in revised form 29 December 1999 Key words: Atlantic lowlands of Costa Rica, Finca La Suerte, Recruitment foci, Seed dispersal, Tropical forest regeneration, Tropical pastures Abstract Trees in pastures attract seed dispersers, leading to increased seed arrival under their canopies and more rapid regrowth around them. The characteristics that make some trees better ‘recruitment foci’ than others, however, are poorly understood. In a neotropical pasture, we examined the arrival of seeds to open areas and underneath four genera of trees that varied in canopy architecture and type of fruit produced: Ficus trees had dense canopies and fleshy fruits, Pentaclethra trees had dense canopies and dry fruits, Cecropia trees had sparse canopies and fleshy fruits, and Cordia trees had sparse canopies and dry fruits. We found that all trees received more seeds than open pasture, probably because trees provided seed dispersers with better perches, protection from predators, nesting sites, etc. Among the tree genera, more seeds arrived under trees that produced fleshy fruits than trees that did not. This occured even during periods when trees were not fruiting (i.e., non-fruiting Ficus and Cecropia trees received more seeds than Cordia or Pentaclethra trees). Seed dispersers may periodically check Ficus and Cecropia trees for fruits, or they may become familiar with these trees while feeding and thereafter use them for other reasons. Height of trees had a slight positive effect on seed arrival, possibly because taller trees offered more protection from predators. Canopy architecture and distance to forest edge did not significantly affect seed arrival. This study demonstrates that trees in general are potentially important recruitment foci, but that different types of trees vary in the kind of recruitment that they foster in pastures. Introduction In severely disturbed sites, forest regeneration may de- pend upon seed dispersal for propagules because other sources of regeneration are lacking (Robinson & Han- del 1993; Nepstad et al. 1996). If these sites receive seeds infrequently they will return to forest slowly (Robinson & Handel 1993). Many studies have found, however, that trees and shrubs attract seed dispersers and increase the frequency of seed arrival (McDonnell & Stiles 1983; McClanahan & Wolfe 1987; Guevara & Laborde 1993). Consequently, succession in these lo- calized areas proceeds more rapidly than in open areas (Guevara et al. 1992; Robinson & Handel 1993; Vieira et al. 1994; Nepstad et al. 1996). For these reasons these woody plants have been termed ‘recruitment foci’ (McDonnell & Stiles 1983). Recruitment foci have been studied in temperate old fields (McDonnell & Stiles 1983; McClanahan & Wolfe 1987), tropical pastures (Janzen 1988; Gue- vara et al. 1992; Guevara & Laborde 1993; Vieira et al. 1994; Nepstad et al. 1996), and savannas (Kell- man 1979; Archer et al. 1988; Belsky et al. 1989). Recently, the concept of recruitment foci has been ap- plied to the problem of forest restoration (Robinson & Handel 1993). Despite these studies, the character- istics of plants that are most important for attracting seed dispersers are still poorly understood. Previous studies have concentrated on the importance of fleshy fruits, vegetative structure, tree height, and distance