Scale-related effects of grazing on native plant communities in an arid rangeland region of South Australia

摘要: Summary 1. To explore how rangeland grazing affects native plant diversity at local and regional scales, we measured the frequency of occurrence species along six transects spread across a large region arid calcareous rangelands in north-western South Australia. Four were commercial sheep-grazed paddocks two otherwise similar lands that had never been developed for pastoralism. Each transect comprised four sites area 0·5 km 2 , distances 1, 4, 7 10 from nearest stock watering point paddock, or nominal starting > water undeveloped lands. 2. Nearly 200 recorded, but distributions patchy, with 30% present < 10% sites. 3. The apparent influence pastoral development proximity to varied scale inquiry. At level, predominantly negative effect on abundance species: 16 less abundant than developed, only one was more abundant. Localized trends within positive: significantly showed increasing points associated activity. 4. study results are consistent general pattern whereby enhances richness (by providing opportunities establish) has potential decrease it removing most grazing-sensitive pool). 5. suggest there may be fundamentally different mechanisms decline under grazing. Palatable, drought-hardy, perennial likely accumulated pressure paddocks. Uncommon short-lived selectively grazed during very good seasons everywhere paddocks, regardless location points. 6. If both contribute need mix strategies protecting all any network conservation reserves.