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

Frugivorous birds are key dispersal agents of many plant species and also may facilitate 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 Cordoba, Argentina: Celtis ehrenbergiana (Klotzsch) Liebm., Condalia spp. Cav., Lantana camara L., Lithraea molleoides (Vell.) Engl., Lycium cestroides Schltdl., Schinus fasciculatus (Griseb.) I. M. Johnst., and Zanthoxylum coco Gillies. We compared germination percentages and germination speed among seeds ingested by birds, manually extracted seeds, and seeds from intact fruits to understand which mechanisms are acting on bird gut-passed seeds. For six plant species, the action of frugivorous birds increased seed germination percentages and germination speed, through scarification, deinhibition, or combined mechanisms. Our results contribute to a better understanding of the mechanisms acting on seeds passed through bird gut. Also, we show the pivotal role that frugivorous birds exert on the seed germination of native woody plant species in the threatened ecosystem of the Chaco Serrano Woodland.