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n African Entomology - Dung beetle diversity in South Africa : influential factors, conservation status, data inadequacies and survey design

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Abstract

Dung beetles are useful as indicators in conservation and global warming studies owing to their specialized regional and local distribution patterns. However, existing South African data are inadequate for indication at the necessary degree of spatial resolution. To improve the database, survey methods need to be designed according to the spatial and temporal factors that influence dung beetle diversity. Across four major climatic regions, there are seven principal species distribution centres for dung beetles in which activity is influenced primarily by differences in rainfall seasonality and temperature. Across these regions, generic endemism is largely concentrated around the coastline and in montane areas. The conservation status of endemic genera is discussed. At a local scale, spatial diversity is influenced primarily by soil, vegetation and dung type. Maximum local diversity of dung beetles is observed after rainfall and decreases as surface conditions become warmer and drier. After workshop discussions, a coarse-grained, asymmetrical gradsect survey grid has been designed according to vegetative, climatic and land-usage gradients across South Africa. It is suggested that each survey point across these regional gradients should comprise a quarter-degree square in which local ecological gradients should be surveyed for invertebrates. Baited pitfall trapping is an easy method to provide quantitative data for dung beetles across such environmental gradients. Lining up each catch on a tray provides a relatively quick way to compare the specimens, identify the species present, and provide a quantitative assessment of species abundance. Data collection may be conducted on one or more occasions to accommodate seasonal and daily variation in species occurrence. This exercise could identify localities suitable for ecotourism reserves representative of the variation in ecotypes across the country, particularly in coastal, natural grass and wooded regions, where many invertebrate taxa are endangered by habitat fragmentation including some rare dung beetle species.

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/content/ento/10/1/EJC31894
2002-03-01
2016-12-05
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