Effect of drought on Phenological stages of two shrub species in the steppe rangelands (Case study: Rangelands of Nodoushan, Ashkzar)

Phonological knowledge of species are important in rangeland management. The aim of this study was to determine the phenological stages of two species of Artemisia sieberiand Eurotia ceratoides in Nodoushan steppe rangelands of Yazd during the period of 4 years (2007-2010). First، for each species، 10 plants were identified within the enclosure and these plants were inventoried in the study process. Phenological characteristics of vegetative and reproductive stages at intervals of 15 days and 7 days، respectively، were measured. Based on results، the growth of sagebrush could be started in second decade of February. Flowering occurs during first to second decade of October. The milky seed continues until mid-November. Seeding of this species in the study area will be in December. Maximum canopy height was 50 cm، which is owned by the wet year، 2007، and at least it was 36 cm، which is related to the very dry year، 2008، and this difference is significant. Maximum and minimum canopy diameter، respectively 67 cm (2007) and 56 cm (2008) and did not differ significantly (P ≤ 0. 05). Growth of Eurotia ceratoides started in the first decade of February. Therefore، This species appears in about 10 days earlier than Artemisia sieberi in the field and the lower the temperature needed for germination. Flowering occurs from the first to third decade of May. This seeding is the second decade of June to first decade of July. Maximum canopy diameter and height are respectively 56 and 42 cm in 2007. Minimum values ​​of 57 and 37 cm has emerged، in the dry year of 2008،that there is no significant difference between them (P ≤ 0. 05).