Enterolobium Cyclocarpum Seed Passage Rate and Survival in Horses, Costa Rican Pleistocene Seed Dispersal Agents

Abstract

Costa Rican horses ranging free in deciduous forest-grassland habitats swallow about half of the seeds in the Enterolohilrnz c.xc/oc,clrputn fruits that they eat. and six such horses defecated at least 9-56% of the seeds alive. While about three-quarters of the surviving seeds appeared by the 14th d after ingestion, about a quarter of the surviving seeds emerged 15-60 d after ingestion. The horse kills Ent'rolohilr~n seeds by digestive processes shortly after the seed germinates in response to the moisture of the intestinal tract. More than 9m of the seeds that survived the trip did so as hard dormant seeds. They showed no indication that they would germinate more rapidly (break dormancy more rapidly) than seeds planted directly from the fruits. The horse-seed interaction suggests that Pleistocene horses may have contributed to both local and long-distance population recruitment by fi~terolohiunz cxc/oc.urplrnz, and contemporary horses certainly have the potential to do so.