The effects of opening trails on exotic plant invasion in protected areas on La Reunion Island (Mascarene Archipelago, Indian Ocean)

Exotic species have become a major problem in protected areas. A better knowledge of ecosystem functioning is necessary to improve management practice that facilitates habitat conservation. We suggest that small-scale disturbances such as trail opening and the effects on exotic plants invasions are underestimated. We have, therefore, quantitatively measured the effect of forest trail building on invasive plant colonization, a phenomenon in constant progression but never studied before. Our study shows that Rubus alceifolius, the widespread exotic invasive plant on La Reunion, is able to germinate on both narrow and wide trails, but persists only on the wider ones. Our results show moreover that wide forest trails favored establishment of exotics and significantly decreases species richness. We suggest to forest managers that building narrow forest trails is preferable as it will stop the persistence and propagation of R. alceifolius and other non-indigenous plants.