مرتضی اکبرزاده
تقی میرحاجی

The phenological stages of some important rangeland plants were assessed from ] 994 to ] 997. The study was conducted in six stations in central A]borz region in Tehran province that their elevations differed from 1100 to 2600 meters. The main object of this study was to detennine the phenological stages of 34 rangeland plants and to recommend their use in range management planning, including the grazing management. In this study ten plants of each selected species was marked in each station. Regular recording was made fi.om the beginning of plant growth, for phenological stages with seven days intervals in vegetative and fifteen days in donnancy periods. The phenological stages were: growth initiation, vegetative growth, heads out or floral bud present, flowering, seed ripening and dissemination, domlancy and fall regrowth. Observations interpreted with regarding the climatic data. Results indicated that phenological phases have the logical relations with environmental temperature. Temperature variations in different years influenced the dates of phenological stages. Flowering dates of species changed in different sites. Flowering delayed when site elevation increased. In genera] the flowering date of many species in Polour, higher Sirachal and Dizin, lower Sirachal and Homand, Ghazal park and rudshoor were in July, eady July, June, early June and May respectively. The flowering period in grasses lasted two weeks on the average, that varied from to to 20 days in different species. Flowering period in forbs and shrubs was more. Growth initiation affected by slope direction, and on sOl1them sides it was a little earlier than nothem's one. An increase in site elevation will cause a delay on phenological stages. For per lOa meters increase in elevation, this delay, approximately, will be 2 to 3 days. It may be affected by slope directions. Many grasses, will grow again in the fall if it rains enough. However, this growth is very little in height and teaf density, relative to spring growth. Precipitation reduction in some years influenced the plants growth, and its effect was higher in steppic regions, due to their sensitiveness.

فنولوژی گیاهان مرتعی,البرز مرکزی,تخریب مراتع,فنولوژی,مدیریت منابع طبیعی,ایستگاه سیراچال,منطقه پلور - رینه,ایستگاه همند آب سرد,پارک غزال,ایستگاه رودشور,دیزین,ارتفاع از سطح دریا,گونه های علف گندمی,رشد رویشی,گل دهی,ریزش بذر,رسیدن بذر,رشد پاییزه,خواب موقت,خواب زمستانه