An ecological study on some characteristics of Astragalus brachyodontus in rangelands of Ardabil province, Iran

In order to recognize, find and use applicable information in range management and forage production, surveying of ecological characteristics of Astragalus brachyodontus were carried out. The method of studying was as following. At the first step, we used a map of vegetation cover and surveyed range ecosystems to determine the habitats of this species in Ardebil province. Then, in every region, considering area and vegetation cover, we selected about six sites to study different ecological characteristics of the plant. In each of these areas, The factors related to total canopy cover, species frequency and amount of forage yield were measured.Also some qualitative characteristics such as root system, stem, seed quality, regeneration,preference value and chemical composition of the plant were studied. Results showed that this species is found between 1100 m to 2200 m above sea level in Ardabil province. Generally, the individuals of this species are distributed in mountain hills. Slopes of the habitats are 5 to 30 percent with south and south eastern aspects. Mid-term average of annual precipitation is 385 millimeters and average annual temperature is 17 degree centigrade. This species grows on soils with pH of about 7 and soils textures of sandy lome to clay lome. In terms of canopy cover, this species includes 5 to 15 percent of the vegetation. Depth of root system in soil vary form 30 to 80 centimeters. In habitats with 1500 meters elevation, vegetative growth starts in mid April. Completion of vegetative growth is in late May. Full flowering, seed ripening, and seed dissemination occurs in early June, early July, and late July, respectively. For this plant species, seed production and regeneration is relatively high in exclosure areas which are protected against grazing. In grazed areas, however, regeneration is low. Based on feeding minutes, preference value of this range plant species is very high. Considering forage digestibility and theamount of crude protein for this species, the best time to graze it is the time of flowering stage. The important pest of this species is a kind of small wasp from Eurytomidae family that feeds from the kernels of seeds and causes hollowness in them.