Coleopteran assemblages in afromontane grasslands reflect fine-scale variation in vegetation

The endemic-rich Afromontane grassland on the Drakensberg in Southern Africa is subjected to intensive afforestation. We describe fine-scale variation in the assemblages of the Coleoptera within the context of a grassland fragmentation experiment. The study site supports a speciose coleopteran fauna of >131 morphospecies. Variation in beetle assemblage corresponds to fine-scale variation within the plant community of which the 10 most dominant plant species are shared across all plant associations. Because these variants of the grassland community are localized, this suggests a high degree of endemicity for the grassland Coleoptera. The correlation between ordinations of beetle assemblages and those reflecting botanical composition is remarkable. Spatial auto-correlation analysis reveals that several species have geographically clumped distributions among sites. There was a correlation between, on the one hand, seasonal differences between beetle assemblages within each treatment (due to the fact that some insects are closely associated with particular plant assemblages), and, on the other hand, seasons in which correlations in beetle-habitat ordinations were high. However, within the context of the fragmentation experiment, the grassland fragments and control sites are statistically comparable because similar plant-beetle associations existed in both treatments. Thirteen beetle taxa are identified which collectively comprise an efficient tool for monitoring the effects of habitat fragmentation on the montane grassland.