Study of the Suitable Time of Entry and Exit (Range Readiness) of Livestock in key ranges of 5 bioclimatic zones of Iran (Fars _ sepidan)

Range species consist of different plant species, each with different vegetative and reproductive stages. Thus, each species has a particular time period for growing readiness and grazing at a particular time must also stop. Moreover, rangeland soil is ready only in certain times to sever livestock. Without understanding these characteristics, determining the grazing season and livestock management and grazing is not possible. With this study, the revising of grazing rangeland management programs in similar areas with similar vegetation will be possible. So in order to determine the timing of entry and exit of livestock to and from rangeland this study was carried out in a semi-steppe rangeland in Barme-khoshk of Fars, 125 km North West of Shiraz for five years from 2006 to 2010. Data such as the stages of plant phenology, total height of six range species and soil moisture conditions were recorded since the beginning of growing season to plant drying for of 20 weeks and 4 years to determine the appropriate time for livestock exit from rangeland utilization percentage evaluation method was employed to compare their level of exploitation with the main range species. The results showed that there were significant differences among six species of rangeland in terms of phenology stages in the years studied. Plant growth in wet years starts two or three weeks earlier, and in dry years the same period also begins later in terms of vegetative and reproductive activity of different plants. The result of allowance forage of range plants rate of 25 to 50 percent for most species were estimated that time is different in dry and wet, recommended in dry year early September and wet year, late September is considered the right time to exit the trap in which the executive calendar and out of the trap on the plan, the difference is between 2 to 3 weeks.