Phenology Study of Four Rangeland Species at Dehbid Site of Fars ,

This research was conducted to study the phenological stages of four important range species in the Dehbid enclosure during three years from 1998 to 2001.
Factors of seasonal variations , morphological differences and plant development stages were
studied. The aim of the research was to determine the proper grazing time in rangelands based upon range readiness and to recommend the best grazing systems.
The studies were conducted on three perennial grasses (Stipa barbata, Bromus tomentellus and
Oryzopsis molinioides ) as well as one perennial forb (Onobrychis melanotricha). Nine individual
plants of each species were selected. Growth development stages during a three years period (once every week at active growth stages and an extra time'every month) were recorded. The climatic data, including daily air moisture and temperature, were also recorded. On the basis of phenological stages and ombero-thermique curves, the best grazing time for longevity as well as optimum seed harvesting time were determined.
The results indicated that the growth period of Stipa barbata, Bromus tomentellus and Oryzopsis
molinioides is longer than that of Onobrychis melanotricha. All four species have autumnal regrowth, if the environmental conditions such as moisture and temperature are favorable.