Extent to which an agricultural mosaic supports endemic species-rich grasshopper assemblages in the Cape Floristic Region biodiversity hotspot

• Grasshopper diversity was compared among vineyards, orchards and natural vegetation.
• Fynbos (natural) contained the highest grasshopper diversity and endemic species.
• Vineyards had highest grasshopper abundance but few unique species.
• Agriculture does support important grasshopper assemblages.
• However, protected areas remain vital for conservation.

The impact of expansion and intensification of agriculture on biodiversity requires quantification, especially in areas of exceptionally high biodiversity like the Cape Floristic Region (CFR). In the CFR, landscape mosaics consist of agriculture alongside Mediterranean-type fynbos scrubland natural vegetation rich in endemic insect species. However, little is known about how ground-dwelling insect herbivores utilize the various elements of the mosaic. We compared species richness, abundance, species composition, diversity and evenness of grasshoppers among 46 sites in four geographical areas in the CFR. We investigated three land-use types: fynbos (the historic condition as reference), vineyards and deciduous fruit orchards, the main production types in the region. Grasshopper abundance was significantly higher in vineyards than in fynbos or orchards. Species richness, diversity, and evenness were highest in fynbos followed by vineyards and then orchards. Orchards had no unique species, vineyards two, and fynbos 14 unique species. Nevertheless, there was overall high species similarity among all three land-use types, with high species assemblage similarities between vineyards and orchards. Species that preferred fynbos were mostly flightless and endemic to the CFR. We show that agricultural areas do not support the entire species assemblage of natural vegetation, although vineyards are more diverse than orchards, probably because of the presence of often grassy ground cover and an open canopy. Vineyards provide the greatest opportunity for improved harmony between production and biodiversity conservation through continuing to improve the ground cover quality and other farming practices. Fewer opportunities are provided by orchards in view of their closed canopy and absence of grassy ground cover (for generalist species) and fynbos plants (for endemic species). However, protected areas still remain vital for maintaining the full complement of species, especially flightless endemics.

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