Seeding perennial forage grass, Bromus kopetdaghensis, in open space or under the canopy of four rangeland shrubs

Kopeh-Kari is the most common method for improving mountainous rangelands in Iran. The environmental constraints, such as air dryness, high and low temperatures, wind, low soil fertility, and animal grazing can lead to high mortality of seedlings, which have been established in the Kopeh-kari small basins. Therefore, we investigated the possibility of seeding under the canopy of rangeland shrubs. Seeds of Bromus kopetdaghensis (a perennial forage grass) were sown in open areas (kopeh-kari) or under the canopy of three rangeland shrubs, i.e. Astragalus mesedensis Bunge, Acantholimon sp and Artemisia khorasanica Podl. Results indicated higher soil moisture, nutrients and organic carbon, which were coincident with the improved establishment of Bromus seedling, under the shrub canopies as compared with the open areas. However, the facilitation effect was dependent on the shrub growth form, the time of measurement, and the type of environmental factors. Lower competition for light, higher accumulation of litter and organic matter, and probably capability for fixing the atmospheric nitrogen, enhanced the facilitation effect of Astragalus on the establishment of Bromus seedlings under its canopy. On the other hand, lower light intensity and soil fertility caused to lower facilitation capabilities for Acantholimon and Artemisia, respectively. In conclusion, our results show the method of range seeding under the shrub canopies as potentially successful for improving the mountainous rangelands. However, this method is to be tested under the contrasting conditions, for knowing its strength and weakness as compared with the other restoration methods.