title: Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity.
abstract: It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause-effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets (n = 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30-100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010-2011 and 2011-2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.
authors.affiliation: Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Col. Ex-Hacienda de San José de la Huerta, Morelia, MICH 58190, Mexico.
authors.forename: Angela A
authors.initials: AA
authors.lastname: Camargo-Sanabria
authors.affiliation: Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, Avenida San Juanito Itzicuaro s/n, Col. Nueva Esperanza, Morelia, MICH 58337, Mexico mendoza.mere@gmail.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mendoza
authors.affiliation: Red de Biología Evolutiva, Instituto de Ecología, A.C., Carretera Antigua a Coatepec 351, Col. El Haya, Xalapa, VER 91070, Mexico.
authors.forename: Roger
authors.initials: R
authors.lastname: Guevara
authors.affiliation: Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Col. Ex-Hacienda de San José de la Huerta, Morelia, MICH 58190, Mexico.
authors.forename: Miguel
authors.initials: M
authors.lastname: Martínez-Ramos
authors.affiliation: Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Dirzo
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D060434:Herbivory; D008322:Mammals / Q000502:physiology*; D008800:Mexico; D011157:Population Dynamics; D065947:Rainforest; D036226:Seedlings / Q000502:physiology; D014197:Trees / Q000502:physiology*; D014329:Tropical Climate
keywords: anthropogenic impact; plant–mammal interactions; tropical diversity; tropical rainforest mammals