"Fruiting phenology as a "triggering attribute" of invasion process: Do invasive species take advantage of seed dispersal service provided by native birds?

DAVID L. VERGARA-TABARES; BADINI JULIETA.; PELUC, SUSANA INES

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2015

1387-3547

Mechanisms underlying biological invasion of highly disturbed ecosystemsare well known, yet mechanisms responsible for biological invasion ofundisturbed or weakly disturbed ecosystems are less understood. Thetriggering attribute (TA) approach, proposed as a mechanism that explainsplant invasion success in undisturbed or weakly disturbed systems,considers that the spread of alien species depends on specific vegetative orregenerative traits in invasive species, discontinuously distributed incomparison to the resident community. In mountain Chaco woodland,fruiting phenology of ornithocorous invasive plants has been proposed as aTA, because it would allow invasive species to benefit from seed dispersalservice, which is unused by native plants during a specific period of theyear (winter). Under the seed dispersal ecology framework, we evaluated iffruiting phenology (fructification largely uncoupled with native species) ofthe fleshy­fruited invasive Pyracantha angustifolia affects bird fruitconsumption, and allows the invasive to take advantage of the unused seeddispersal service during winter. If uncoupled fructification phenologyrepresents a TA, seed disperser, seed predator, and pulp consumerdiversity, abundance, and fruit consumption on P. angustifolia (whichfructifies in winter), will be higher than on its exotic congeneric P.coccinea during summer, when fructification overlaps with native Celtisehrenbergiana and many other native species. We found that: (1) disperserbird abundance and fruit consumption did not differ between P.angustifolia and P. coccinea; (2) the most diverse frugivorous assemblagewas observed on C. ehrenbergiana, yet it had the lowest proportion of seeddispersers and the highest fruit consumption by seed predators and, (3) wealso observed higher proportion of seed predators on P. angustifolia(uncoupled fructification scenario) than on P. coccinea (coupledfructification scenario). Our results suggest that ­invasive uncoupledfructification phenology does not represent a true TA which facilitatesplant invasion processes in undisturbed or weakly disturbed ecosystems