The vegetation of three localities of the threatened butterfly species Chrysoritis aureus (Lepidoptera: Lycaenidae)

Abstract

The vegetation and habitat characteristics of three localities of Chrysoritis aureus at the Alice Glockner Nature Reserve, Suikerbosrand Nature Reserve and Malanskraal farm near Heidelberg in South Africa, were compared. A numerical classification technique, TWINSPAN, was used and refined by using Braun Blanquet procedures to classify the vegetation at the different localities. A DCA ordination was applied to confirm the results of the classification. Although the general vegetation structure at the three habitats of Chrysoritis aureus were found to be similar, marked differences in the floristic composition were evidenced. A different sub-community, compared to the vegetation at Suikerbosrand and Alice Glockner Nature Reserve, was recorded at the Malanskraal habitat of Chrysoritis aureus. These differences in floristic composition, but with similarities in vegetation structure, indicate the possible importance of fire for the ultimate survival of these butterflies in the Rocky Highveld Grassland. The host plant of Chrysoritis aureus, Clutia pulchella, collected at Malanskraal differed markedly and consistently in their morphology, compared to the individuals from the habitats at Suikerbosrand and Alice Glockner Nature Reserve. These differences in the floristic composition of one of the habitats compared to the others, raise research questions concerning the butterfly metapopulation structure, since the subpopulations seem to be adapted to slightly different habitat conditions. The variation in the habitat suggests that the "last remaining locality scenario" for other localised butterflies in South Africa, such as Orachrysops niobe, needs to be redressed. Management strategies are addressed while the importance of conserving rare, localised ecosystems are highlighted by the phytosociological study.