Autecology of Hyparrhenia hirta (L.) Stapf in semi steppe rangelands

In this study, the autecology of Hyparrhenia hirta was studied in rangeland ecosystems of Khuzestan province. All vegetation maps were prepared using topographic maps at a scale of 1:50000 and than all habitat characteristics including topography, climate, and soil, as well as associated species, presence, roots, phenology, regeneration, palatability, and frequency were studied. The results showed that Hyparrhenia hirta grows at altitudes of 60 to 900 meters above sea level in the steppe and semi-steppe regions. The highest density of Hyparrhenia hirta is at altitudes of 300 to 600 meters above sea level. The soil texture is sandy with gravel. The average rainfall was 320 mm annually and air temperature varied between 24.5- 26.5 ° C. Vegetative growth was observed from late September to the end of December. Seed ripening and seed dispersal occurs in the second half of May and in June, respectively. The roots of Hyparrhenia hirta are widespread in horizontal and vertical directions and vertical growth is limited under heavy grazing. This plant is not palatable; however, in the absence of palatable plants, it is used by livestock.