Does avian gut passage favour seed germination of woody species of the Chaco Serrano Woodland in Argentina?

Abstract

Frugivorous birds are key dispersal agents of many plant species and also mayfacilitate seed germination after gut-passage. However, the general effects of gut-passage on seed germination are still not clear, with positive, negative and neutral effects reported on seed germination. We evaluated seed germination of seven bird-dispersed plant species of the Chaco Serrano Woodland in Córdoba, Argentina: Celtis ehrenbergiana, Condalia spp., Lantana camara, Lithraea molleoides, Lycium cestroides, Schinus fasciculatus and Zanthoxylum coco. We compared germination percentages and germination speed among seeds ingested by birds, manually extracted seeds, and seeds from intact fruits in order to understand which mechanisms are acting on bird gut-passed seeds. For six plantspecies, the action of frugivorous birds increased seed germination percentages and provides faster germination, either through scarification, deinhibition, or through combined mechanisms. Our results contribute to better understand the mechanisms acting on bird gutpassed seeds. Also, we show the pivotal role that frugivorous birds exert on the seed germination of native woody plant species in the threatened ecosystem of Chaco Serrano Woodland.