The Conservation of Juniper: The Fauna of Food-Plant Island Sites in Southern England

Abstract

Sites with native Juniperus communis L. in southern England were compared to islands and the relationship between the specific phytophagous fauna and the characteristics of the sampled sites investigated in the light of biogeographic theories. Fifteen native species were recorded on the sampled sites out of a possible 19 known to occur in southern England. The species were sequentially and not randomly represented on the site sizes. As site size was reduced the 3 fruit-feeding species were the first to be lost. Multiple regression analysis showed that the number of bushes was the most important site variable, accounting for 79% and 87% of the variation in species numbers on the North Downs and Chilterns sites, respectively. The age of the oldest bush accounted for a further 9% of the variation on the North Downs, but was not significant for the Chilterns. Variables reflecting the site isolation did not have a significant effect in the analyses for the 2 sample areas. However, in the analysis of the pooled data the effects of one of the isolation variables reached significance. Prediction equations derived from the analysis were used to estimate the resources of the fauna still remaining on all known sites with > 50 bushes in southern England. There are 86 of these, and it is predicted that there are still 19 sites with .gtoreq. 13 species, and that a further 17 sites have 12 spp. Applications of the results to nature conservation are discussed.