Maintaining vegetation diversity on reserves: the relationship between persistence and species richness

Abstract

Botanical records collected over a period of almost 90 years are analysed in order to interpret the distribution and temporal occurrence of plant species on Blakeney Point, a complex near-natural coastal nature reserve in eastern England. A unimodal relationship is found between the number of plant species that are characteristic of each biotope and the persistence of rare plants. This pattern can best be explained in terms of two types of disturbance: (1) the relatively predictable, small-scale, often biotic disturbances that may promote diversity by generating local heterogeneity; and (2) large-scale disturbances which may reduce plant diversity in the harsher biotopes. Both types of disturbance are vital for the maintenance of the overall natural diversity of sites and should be recognised and preserved by managers who may wish to prevent the loss of plant species.