Abstract

The Juan Fernandez Archipelago World Biosphere Reserve (33 S) contains the highest density of insular floral endemism in the world. Currently three invasive woody plant species threaten the conservation of the vegetation of Juan Fernandez, particularly on Robinson Crusoe Island. The introduced plant species, Aristotelia chilensis (maqui), Rubus ulmifolius (mora) and Ugni molinae (murta), have fleshy fruits that are dispersed primarily by a native bird, the Austral Thrush (Turdus falcklandii). We explore five key scientific questions to guide management decisions, regarding the current expansion capacity of invasive plants, the influence of the Austral Thrush on dispersal and germination of invasive plants in forest gaps, and the possible effects of Austral Thrush control on the expansion of native and invasive plants. We conclude that the interaction between the Austral Thrush and invasive weeds, in addition to the life history characteristics of the invasive species, has been a defining characteristic of the success and speed of the plant invasion, and therefore control or eradication of the Austral Thrush could be a useful tool to slow invasive plant advances. However, we recommend additional detailed studies that would guide decision-making regarding Austral Thrush control and/or eradication effectiveness on Robinson Crusoe Island, in addition to studies of invasive plant control in various life history stages. If immediate and effective control measures are not taken to prevent the expansion of maqui, mora and murta, we foresee a considerable loss of terrestrial biodiversity from Robinson Crusoe Island in the medium term.