Seedling Mortality and Herbivory Damage in Subtropical and Temperate Populations: Testing the Hypothesis of Higher Herbivore Pressure Toward the Tropics

• Published in: Biotropica Vol. 42; no. 2; pp. 174 - 179
• Main Authors: del-Val, Ek, Armesto, Juan J
• Format: Journal Article
• Language: English
• Published: Malden, USA Malden, USA : Blackwell Publishing Inc 01.03.2010; Blackwell Publishing Inc; Wiley Subscription Services; Wiley
• Subjects: Aextoxicon punctatum; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; broad-latitudinal range; Chiloé Island; Conservation, protection and management of environment and wildlife; Forest canopy; Forests; Fray Jorge National Park; Fundamental and applied biological sciences. Psychology; General aspects; Herbivores; Herbivory; herbivory gradient; invertebrate herbivory; Invertebrates; Islands; latitude; mammal herbivory; Mammalia; Mammals; Mortality; National parks; Phytophagous insects; planting; Plants; seedling growth; Seedlings; small mammals; Survival; Temperate forests; Temperate rain forests; tree growth; Trees; Tropical Biology; Tropical environments; tropics; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; I, Pacific; ISE, Chile; PSW, Chile, Los Lagos, Chiloe I; Herbivorous; Mortality; Plant juvenile growth stage; Tropical zone; herbivory gradient; Latitude; Island; Chiloé Island; mammal herbivory; National park; Hypothesis test; Vertebrata; Mammalia; Fray Jorge National Park; broad-latitudinal range; Damage; Invertebrata; invertebrate herbivory
• ISSN: 0006-3606; 1744-7429
• DOI: 10.1111/j.1744-7429.2009.00554.x

Herbivory rates are generally thought to be higher in tropical than in temperate forests. Nevertheless, tests of this biogeographic prediction by comparing a single plant species across a tropical-temperate range are scarce. Here, we compare herbivore damage between subtropical and temperate populations of the evergreen tree Aextoxicon punctatum (Olivillo), distributed between 30° and 43° S along the Pacific margin of Chile. To assess the impact of herbivory on Olivillo seedlings, we set up 29 experimental plots, 1.5 x 3 m: 16 in forests of Fray Jorge National Park (subtropical latitude), and 13 in Guabún, Chiloé Island (temperate latitude). Half of each plot was fenced around with chicken wire, to exclude small mammals, and the other half was left unfenced. In each half of the plots we planted 16 seedlings of Olivillo in December 2003, with a total of 928 plants. Seedling survival, leaf production and herbivory by invertebrates were monitored over the next 16 mo. Small mammal herbivores killed ca 30 percent of seedlings in both sites. Nevertheless, invertebrate herbivory was greater in the temperate forest, thus contradicting the expected trend of increasing herbivore impact toward the tropics. Seedling growth was greater in subtropical forest suggesting better conditions for tree growth or that higher invertebrate herbivory depressed seedling growth in the temperate forest. Invertebrate herbivory increased toward temperate latitudes while small mammal herbivory was similar in both sites. We suggest that comparison of single species can be useful to test generalizations about latitudinal patterns and allow disentangling factors controlling herbivory patterns across communities. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp