Revista Chilena de Historia Natural 77 (3): 523-538, 2004
RESEARCH ARTICLE
New additions to the introduced flora of the Juan Fernández Islands: origin, distribution, life
history traits, and potential of invasion
Oceanic islands, such as Juan Fernández in Chile, are the home for particular biotas that
have evolved in isolation over a long period. The anthropogenic introduction of allochtonous plants is one of many problems for the
conservation of endemic elements. In this paper, we present the new additions to the introduced flora of the Juan Fernández Islands,
adding some comments about their life form, origin, morphological characteristics, ecology, distribution, abundance, and their potential
of invasion. We cited 27 new species, 12 new genera, and three new families for the Juan Fernández flora (Amaryllidaceae,
Commelinaceae and Violaceae). Most genera belonged to Asteraceae (seven species). Fifty-nine percent of taxa were perennial herbs,
followed by annual or biennial herbs. Wind was the main vector of propagule dispersal (42 %), followed by vegetative dispersal (23 %).
Fifty-two percent of the species were weeds and 44 % were plants with dual behaviour: garden-weed plant. Eurasia was the most
frequent area of plant origin (70 %). Ninetyfour percent of the taxa with known geographic range are in the V Region of mainland Chile,
which is the main region of export of plants and materials to the archipelago, suggesting that this may have been the immediate origin
of these introductions. Sixty-three percent of the species were only found in the San Juan Bautista urban area, while the remaining taxa
were also (22 %) or exclusively (15 %) found in other places of the main island (Robinson Crusoe). Sixteen species (59 %) are
considered as noxious weeds in Juan Fernández or elsewhere, and they should be a focus of attention and, eventually, control.
Summing our findings to previous lists of introduced taxa, we obtained 260 non-native taxa in Juan Fernández. This number is greater
than the native taxa (211), which demonstrate how the human intentional and non-intentional action can dramatically change the
floristic composition of an oceanic archipelago. We strongly recommend the installation of a sanitary control in Robinson Crusoe Island
or in Valparaíso, in association with quarantine procedures with the food vegetables, and biological products in
general.
Key words:
biological invasions,
garden plants, oceanic islands, plant introductions, weeds
