Analysis of Succession in a Tropical Phytoplankton Community and a New Measure of Succession Rate

Abstract

Succession entails changes in the relative abundance of species in a community. The Jassby-Goldman (JG) index of succession rate is affected by any change in the relative abundance of species but weights contributions from different species unequally. There is no apparent ecological foundation for this unequal weighting. A more defensible measure of succession rate can be derived from the summed change in abundances of all species, independent of sign, expressed as a proportion of the whole community. A new index of succession rate obtained in this way is named the summed difference (SD) succession rate index. Analysis of succession in the plankton community of Lake Lanao, Philippines, shows that both the JG and SD succession rate indexes are positively correlated with three community variables: (1) absolute rate of change in autotroph abundance (numbers or biomass), (2) absolute rate of change in net primary production, (3) grazing rate. The first two variables are measures of the overall rate of change ...