Abstract Detail



Pacific Biogeography

Stuessy, Tod [1].

Historical ecology of the Juan Fernandez (Robinson Crusoe) Archipelago, Chile.

The interpretation of evolutionary patterns and processes depends upon understanding changes to landscape over geological and historical time.  The geographical and ecological context seen now may be very different from what it was when diversity within a particular landscape originated. This is true for any terrestrial area of the world, but particularly so for relatively youthful oceanic islands. The Juan Fernández (Robinson Crusoe) Archipelago provides an instructive example of the importance of understanding landscape changes.  The archipelago consists of two major islands: Robinson Crusoe Island, 687 km W of continental Chile, and Alejandro Selkirk Island, 181 kms further westward into the Pacific Ocean.  Both islands are approximately 50 kms sq., but they differ in geological age at 4 million and 1 million years, respectively.  Oceanic islands change rapidly through subsidence and erosion, and this can be seen in the older Robinson Crusoe Island, which may have lost up to 95% of its surface area during its ontogeny.  The younger Alejandro Selkirk Island may have lost only 28% of its area during the past 1 million years of its existence.  These changes have had a particularly severe impact on the older island, and the endemic flora now exists as a compacted refugium at higher elevations, very likely not reflecting original geographic or ecological patterns when the islands were larger and more ecologically diverse. On top of these natural alterations, human impacts have been substantial, especially on the older island, which contains the only well-protected bay and associated village. No people lived in this archipelago until discovery by the Spanish navigator Juan Fernández in 1574, and from that point onward, numerous visitors arrived. Many historical documents exist that chronicle over more than 400 years the human impacts on the vegetation, which include cutting of forests, introduction of domesticated animals and invasive plants, and fire. Taking into account geological modifications plus human activities allows a realistic assessment of the forces that have shaped the natural vegetation seen today on both islands.


1 - The Ohio State University, Evolution, Ecology, and Organismal Biology, Herbarium and Museum of Biological Diversity, 1315 Kinnear Road, Columbus, OH, 43212, USA

Keywords:
islands
biogeography
ecology.

Presentation Type: Colloquium Presentations
Number:
Abstract ID:113
Candidate for Awards:None


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