Distribution and abundance of rodents, millipedes and trees in coastal dune forests in northern KwaZulu-Natal

Abstract

A widely observed pattern in nature is a positive relationship between local abundance and spatial distribution. This study investigates this relationship amongst three taxa namely rodents, millipedes and trees on regenerating and unmined coastal dune forests at Richards Bay, KwaZulu-Natal. No sensible analyses were possible on the rodent data. Both millipedes and trees had a positive relationship between local abundance and distribution (measured as species incidence). Millipedes showed no changes in the relationship with changes in habitat regeneration time. For trees, the regression slope decreased with time due to changes in abundance and incidence of Acacia karroo. Lack of bimodality in incidence frequency distributions ruled the core-satellite metapopulation hypothesis out as a mechanism producing the positive abundance-incidence relationship. The resource availability hypothesis was a most likely mechanism. This study confirmed that rare species tend to be restricted in both abundance and incidence.