فهرست مطالب s. zarekia

In this study, phenology of Salsola laricina as an important range species was studied for period of four years. The phonological stages were recorded at vegetative stage every two weeks and at the reproductive stage once a week. Temperature and precipitation data of the study years were used to interpret the phenology of the species. Results showed that the phenological period of Salsola laricina varied each year due to climate change. Generally, this type of vegetative growth begins in mid-March and continues until mid-July and temporary sleep begins. Flowering occurs in first decade of September and seed ripening stage begin in early November. Generally, the best time to collect seeds is November 10-30, depending on rainfall. Start growing was earlier in the dry year of 2008 (47% lower than long-term) and vegetative period was about 15 to 20 days shorter than in 2009 (16% higher than long-term). Increasing rainfall also increases the vegetative period and delay flowering and seeding about a week. Understanding the phenology of Salsola laricina is important for regulating plant utilization plans, determining the time of entry and exit of livestock, collection of seeds, prevention of untimely harvesting in the steppic rangelands.

Forage production of rangelands differs during different times of grazing season and in the same month of different years. In range management projects, grazing capacity calculated once during the grazing season, which coincides with the maximum production of rangeland species. This may cause more livestock entry into the rangeland during the grazing season, leading to more degradation. Therefore, it is necessary to measure forage production during the months of grazing season over a few years, based on which the long-term grazing capacity of key range species could be estimated. Production variations of the key species, namely Artemisia sieberi, Salsola laricina, and Stipa hohenackeriana were investigated in Khoshkerood-e-Saveh site in growth and grazing season over the course of three years. For this purpose, the production of each species measured in a one-hectare exclosure with one month intervals until the growth dormancy. After air-drying, forage production was analyzed by SAS software. Based on the results, due to the high variability of monthly and annual precipitation in the region, forage production of key range species had significant differences at P ≤5% level. The maximum and minimum mean production (543 and 388 kg/ha) belonged to 2009 and 2008, respectively. According to the production fluctuation in different years, it is recommended that range management plans account for the long-term average of good production.