Autecology of Stipagrostis plumosa in Rangelands of Qom Province

The protection, improvement and development of renewable natural resources especially for vegetation need a comprehensive recognition of natural resources. To achieve some part of these objectives, the national project of autecology was carried out in Iran. In Qom province, autecology of Stipagrostis plumosa, an important rangeland species in desert, semi-desert and steppic regions, was studied.In this research, geographical distribution of the species in the province, morphology, phonological stages, companion species, reproduction and establishment methods were determined. Soil study, geology and climatic condition were also investigated. With regard to the wide distribution of Stipagrostis plumosa in the province and variations of climatic and ecological factors, three sites were considered. The results showed that Stipagrostis plumosa was found in silty- loam, loam- sand, loam- clay and sandy soils as a dominant species and with increase of clay percentage, canopy cover was decreased as it was not seen in soils abundant of clay. This species was also highly resistant to soil salinity and lime as tolerated the EC between 0.27 to 2.89 milmohs/cm and %13 to % 24 of lime. It was found in altitude of 900 to 1650 meters above sea level. Its height was between 12 to 35 cm and partly about 50 cm in suitable condition. It had bunch stems and scattered roots. In flowering stage, the ratio of root to shoot length was about 1.25 and ratio of root to shoot weight was about 0.47. The main activity period of this species begins generally from mid February and ends in late June with the seeds bloom and seed dispersal. Reproduction by seed is conducted appropriately while in areas with high grazing pressure asexual reproduction is done. Resistance to unfavorable environmental conditions and drought, high tolerance to different soil conditions, high resistance to grazing and suitable regeneration could be considered as the main reasons of the wide distribution of Stipagrostis plumose in Qom province.