Introducing three forage species, Prangos latiloba, Convolvulus commutatus, and Stachys trinervis from the Northern Khorasan rangelands

Autecology of three range plant species, i.e. Prangos latiloba Korov., Convolvulus commutatus Boiss, Stachys trinervis Aitch., was studied in the Northern Khorasan province. The species provide forage for the grazing livestock in the rural rangelands, especially on the shale formations. Geographical distribution was studied, in addition to topography, soil characteristics, and climate conditions of their natural habitats. Forage quality was assessed by measuring crude protein, ADF, NDF, dry matter, and ash. S. trinervis was growing in most of the rural rangelands, on the conglomerate, sandstone and shale formations, and under the arid and semiarid climate conditions. All species started their yearly growth at early April. For P. latiloba and C. commutatus, flowering and seed ripening stages similarly occurred at the early June and early August, respectively. For S. trinervis, phenological stages were overlapped, in which flowering, seed ripening and seed shedding were simultaneously found from the early May till early September. There was a sharp reduction in crude protein and increase in ADF and NDF factors, which led to significant reduction in the forage quality of all three species. The major limiting factors on geographic distribution of C. commutatus were: its high forage palatability and quality which had led to high effect of livestock grazing. For P. latiloba the main limiting factors were seed predation by pests and herbage harvesting by farmers. On the other hand, higher distribution of S. trinervis was due to having higher essences, lower palatability, overlap of phenological stages, and probably higher adaptation to climate and soil conditions.