Agouti reintroduction recovers seed dispersal of a large-seeded tropical tree

The aim of animal reintroductions has mainly been species recovery; only
few reintroduction initiatives focus on ecosystem restoration. Therefore,
reintroduction consequences on ecological interactions are seldom
assessed. We used the interaction between a reintroduced population of
agoutis (Dasyprocta leporina) and a vulnerable tropical endemic tree
(Joannesia princeps) to examine reintroduction effects on seed dispersal
and seedling establishment. To test the outcomes of this interaction we
tracked seeds of J. princeps in two adjacent forest areas with and without
reintroduced agoutis. We also assessed if dispersal distances affected
seedling survival. To determine seed fate and dispersal distance we used
spool-and-line tracking, together with camera traps to identify
dispersers. Agoutis were the only species removing J. princeps seeds, thus
dispersal only occurred where agoutis had been reintroduced; in the area
without agoutis, all seeds remained intact on the soil, even one year
after the experiment’s beginning. At the reintroduction area, most seeds
were preyed upon by agoutis but 7% remained dispersed and 2% germinated
after ten months. Only seeds buried by agoutis were able to germinate.
Most dispersed seeds were disperse 15 m or farther and longer dispersal
distances benefited J. princeps, since seedlings farther from a
conspecific adult tree had greater survival probability. Agoutis were also
seen burying seeds of two other plant species; these mammals have the
potential to benefit dozens of large-seeded species in our study system.
Agouti reintroduction thus exemplifies the value of trophic rewilding
programs to re-establish ecological interactions and restore ecosystem
functioning.