THE OVERRIDING INFLUENCE OF FLASH FLOODS ON SPECIES-AREA CURVES IN EPHEMERAL NEGEV DESERT POOLS - A CONSIDERATION OF THE VALUE OF ISLAND BIOGEOGRAPHY THEORY

We examined the relationship between species richness of the arthropod fauna in temporary Negev desert pools and key environmental variables. Treating these pools as habitat islands, we found that three of the five predictions of island biogeography theory were upheld. However, the crucial claim of island biogeography theory that there is turnover of species while species richness remains constant was not supported. Although there was turnover, species richness increased steadily throughout the study. The slope of the species richness v. pool area regression decreased with time, while the coefficient of determination for this relationship steadily increased. We found that the percentage cover of terrestrial plant species in the pools explained more of the variance in species richness than pool size over most of the study. Flash floods may be of overriding importance in these pools, because a single flood can flush all species out of the pools, forcing colonization to be repeated.