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

CAMPOS, C. M.; VELEZ, S.; MIGUEL, M. F.; PAPÚ, S.; CONA, M. I.

Ecology and Evolution

Wiley-Blackwell

Año: 2018 vol. 8 p. 5470 - 5479

2045-7758

1. The quantity component of effectiveness of seed dispersal by animals is determined by two events: fruit removal (intensity of the interaction) and animal visitation to the plant (frequency of interactions). Enclosure experiments and camera trapping are methods used for studying seed dispersal.2. Considering dispersal of Prosopis flexuosa seeds as case study, this work aimed at investigating the strengths and weaknesses of the two methods for assessing the quantity component of seed dispersal effectiveness. Prosopis fruits were offered during 2 days. Enclosure treatments were performed using two types of wire-screen cages, allowing access to ants (?closed enclosure?) and to small mammals up to 100 g (?open to small mammals?), and a treatment without enclosure (?open to all removers?). The camera trapping experiment was carried out using vertically-oriented cameras placed at 1.80 m height and focused on the fruits. The cameras were set in ?motion detect mode?, taking series of three consecutive photos.3. The enclosures allowed estimating fruit removal by animals according to their body size, without giving information about the identity of species. Some of the assumptions of this method are not fulfilled, for example mammals larger than 100 g are able to enter enclosures only in the ?open to small mammals? treatment. Camera trapping allowed identifying species and discriminating among small mammals playing different roles, without underestimating fruit removal by scatter-hoarding species.4. The quality of estimation of the quantity component of seed dispersal is remarkably better when the camera trapping method is applied, because it allows determining the number of fruits removed and the number of visits to trees by animal species. Additional information obtained, such as discrimination between animal visits with or without fruit removal, and activity patterns of species, can contribute to a better understanding of the seed dispersal process.