Studying the quantity component of seed dispersal effectiveness from exclosure treatments and camera trapping

CAMPOS, CLAUDIA M.; VELEZ, SILVINA; MIGUEL, MARÍA FLORENCIA; PAPÚ, SOFÍA; CONA, MÓNICA I.

Ecology and Evolution

Wiley

Año: 2018

The quantity component of effectiveness of seed dispersal by animals is determinedby two events: fruit removal (intensity of the interaction) and animal visitation to theplant (frequency of interactions). Considering dispersal of Prosopis flexuosa seeds ascase study, this work aimed at investigating the strengths and weaknesses of the twomethods for assessing the quantity component of seed dispersal effectiveness: exclosuresand camera traps. Prosopis fruits were offered for 48 hr. Exclosure treatmentswere performed using two types of wire-screencages, allowing access to ants(?closed exclosure?) and to small mammals up to 100 g (?open to small mammals?), anda treatment without exclosure (?open to all removers?). The camera trapping experimentwas carried out using vertically oriented cameras placed at approximately1.80 m height and focused on the fruits. The cameras were set in ?motion detectmode,? taking series of three consecutive photographs. The exclosures largely allowedestimation of fruit removal by size-basedgroups of animals, but did not provideinformation on species identity. In contrast, camera traps were able to identifyall visitors to species level and could not only determine the number of visits by eachspecies but also the proportion of visits, which resulted in removal of fruits. Cameratrapping allowed discriminating among small mammals playing different roles, withoutunderestimating fruit removal by scatter-hoardingspecies. The quality of estimationof the quantity component of seed dispersal is remarkably better when thecamera trapping method is applied. Additional information obtained, such as activitypatterns of visitors, can contribute to a better understanding of the seed dispersalprocess.