干旱区生态环境知识资源中心

Impact of grazing on the floristic diversity of arid rangelands in South Tunisia. If the effects of grazing on plant diversity have been extensively studied in a wide range of ecosystems, effects of controlled grazing are still largely unknown. Species diversity indices are useful indicators of the sustainability of collective rangelands in southern Tunisia. In order to determine an optimal management method of arid rangelands with high heritage value, we examined the respective effects of continuous grazing, moderate grazing and rest on the plant community’s diversity. We compared diversity indices of the vegetation for three levels of grazing pressure (null, moderate and heavy) in the collective rangelands dominated by Gymnocarpos decander, Hammada schmittiana, Stipagrostis pungens and Anthyllis sericea of Dhahars in the south-eastern region of Tataouine (Tunisia). Species richness and Simpson’s diversity tended to decrease with increased grazing pressure, but the difference was not significant between ungrazed and moderately grazed rangelands. By contrast, species evenness tended to increase with grazing pressure. Diversity and vegetation biological spectrum were only slightly affected by controlled grazing. This study demonstrates the value of this management practice for biodiversity conservation.