Invasion of Rubus praecox (Rosaceae) is promoted by the native tree Aristotelia chilensis (Elaeocarpaceae) due to seed dispersal facilitation

Abstract

Seed dispersal facilitation among plant neighbours can be defined as an increase in the number, distances, and/or places reached by
a plant’s seeds that is due to the presence of co-fruiting plant neighbours with which it shares seed dispersers. Many cases of this
phenomenon have been described among native species and some also among introduced invasive species. Moreover, facilitation
of native species recruitment by non-native fleshy-fruiting trees has been reported. Surprisingly, seed dispersal facilitation of exotic
species by native species is either less common or has not been properly documented so far. Casual observation of secondary
vegetation in La Araucanía Region, Chile, suggests that more individuals of exotic fleshy-fruiting bird-dispersed Rubus praecox
(Rosaceae) are established under the native fleshy fruiting bird-dispersed subdioecious tree Aristotelia chilensis (Elaeocarpaceae)
than under other native dry-fruiting tree species in the same areas. To assess whether these observation-suggested differences are
statistically significant, two plots were sampled for interspecific associations between Rubus and Aristotelia and between Rubus and
the most common dry-fruiting monoecious tree –Lomatia hirsuta (Proteaceae). The first important conclusion from this study is that
invasive Rubus is substantially more common under both focal tree species than in open grasslands. Second, Rubus is associated
more strongly with fleshy-fruiting Aristotelia than with dry-fruiting Lomatia in this landscape. Additionally, the frequency of Rubus
is higher under Aristotelia fruiting (female or hermaphroditic) trees. Management implications are discussed.