The decline of tree diversity on newly isolated tropical islands: A test of a null hypothesis and some implications

• DOI: 10.1007/bf01237735
• Publication Date: 2005-02-27T03:44:38Z
• Authors: Egbert Giles Leigh; S. Joseph Wright; Edward Allen Herre; Francis E. Putz
• Keywords: 0301 basic medicine; 03 medical and health sciences; 0401 agriculture, forestry, and fisheries; 14. Life underwater; 04 agricultural and veterinary sciences; 15. Life on land

Six islands, each less than a hectare in area, were isolated in about 1913 from the mainland of central Panama by the rising waters of Gatun Lake. By 1980, the diversity of trees on all but one of these islands was far lower than on mainland plots of comparable size. A restricted subset of tree species has spread on these islands, notablyProtium panamense, Scheelea zonensis, Oenocarpus panamanus andSwartzia simplex. We constructed a null model to predict how chance would change tree diversity and the similarity of tree species compositions of different islands, assuming that each mature tree has equal chances of dying and/or reproducing, regardless of its species. This model cannot account for the diminished diversity of the changes in vegetation on these islands: some factors must be favoring a particular set of tree species.