Plant species persistence and turnover on small Bahamian islands

Abstract

I conducted surveys of the plant species occupying 136 small islands in the Exuma Cays and 58 small islands near Andros, Bahamas. Most species occurred on relatively few islands, and most islands contained relatively few species. Identities of the most common species differed between the two archipelagos. Comparisons with earlier surveys revealed species extinctions and immigrations. Turnover was relatively low on both a per island and a per species basis on both archipelagos, although significant spatial variation in turnover rates between archipelagos was found. Most islands experienced no turnover; islands on which turnover did occur were larger and had higher species richness. Likewise, most species did not turnover, although much variation existed in turnover rates among those that did. Experimental introductions of two species to very small islands naturally devoid of vegetation revealed that these islands could support plant life. One species survived on eight of ten islands for >9 years, including the effects of a moderate (class 2) hurricane. This hurricane caused substantial damage and loss of plant biomass, but resulted in no species extinctions on 30 small islands. Data for the small islands in this region, now spanning almost a decade, reveal that most populations are persistent over periods of years to decades, rarely going extinct or immigrating. Even moderate hurricanes seem to have little impact on species compositions.

Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover

“…Initial richness has been shown to be higher in systems with a richer and more connected species pool (e.g., interactive systems) wherein good dispersers reach sites first, but do not necessarily become long-term residents (Morrison 2003, Starzomski et al 2008. Although average species richness in the control plots along the turbulent reaches was 12.8 6 0.97 species, species richness in treatments in both the turbulent and tranquil reaches reached a maximum at a value near the average richness of the tranquil control plots in the reach (8.2 6 0.95 species; Fig.…”

Beyond Island Biogeography Theory

“…Demonstration of such relationships is a litmus test for IBT (Gilbert 1980, Abbott 1983) because other biogeographic phenomena, such as the species-area relationship, can arise for reasons aside from those hypothesized by IBT (for example, higher habitat diversity, rather than lower extinction rates, can cause species richness to increase on larger islands; Boecklen andGotelli 1984, Ricklefs andLovette 1999). Given its central importance, it is perhaps surprising that only a modest subset of all IBT studies has demonstrated elevated turnover (e.g., Diamond 1969, Wright 1985, Honer and Greuter 1988, Schmigelow et al 1997-and even these have often been controversial (Simberloff 1976, Diamond and May 1977, Morrison 2003reviewed in Schoener, this volume). As discussed below, population and community dynamics are often greatly amplifi ed in habitat fragments relative to natural conditions , but a number of factors aside from those hypothesized by IBT can be responsible.…”

Theory meets reality: How habitat fragmentation research has transcended island biogeographic theory

“…Given its central importance to the theory, it is perhaps surprising that relatively few IBT studies have demonstrated elevated turnover (e.g. Diamond, 1969;Wright, 1985;Honer and Greuter, 1988;Schmigelow et al, 1997;Sodhi et al, 2005a)-and even these have often been controversial (Simberloff, 1976;Diamond and May, 1977;Morrison, 2003). As discussed below, population and community dynamics are often greatly amplified in habitat fragments relative to natural conditions (Laurance, 2002), but a variety of factors aside from those hypothesized by IBT can be responsible.…”