The Effects of Long-Term Grazing Exdosures on Range Plants in the Central Anatolian Region of Turkey

摘要

Over the last fifty years, almost half of the steppe rangeland in the Central Anatolian Region of Turkey (CAR) has been converted to cropland without an equivalent reduction in grazing animals. This shift has led to heavy grazing pressure on rangeland vegetation. A study was initiated in June 2003 using 6 multiscale Modified-Whittaker plots to determine differences in plant composition between areas that have not been grazed in 27 years with neighboring grazed plant communities. A total of 113 plant species were identified in the study area with the ungrazed plots containing 32 plants more than the grazed plots. The major species were Astragalus acicularis, Bromus tomentellus, Festuca valesiaca, Genista albida, Globu-laria orientalis, Poa bulbosa, and Thymus spyleus ssp rosulans. Grazing impacts on forbs were more pronounced than for grasses and shrubs. Based on Jaccard's index, there was only a 37% similarity of plant species between the two treatments. Our study led to four generalizations about the current grazing regime and long-term exclosures in the steppe range-land around the study area: (1) exclosures will increase species richness, (2) heavy grazing may have removed some plant species, (3) complete protection from grazing for a prolonged period of time after a long history of grazing disturbance may not lead to an increase in desirable plant species with a concomitant improvement in range condition, and (4) research needs to be conducted to determine how these rangelands can be improved.