Relationship between rainfall and annual forage production of important range species (Case study: Khoshkerood - Saveh)

Each of the range species has certain production in different months and years of grazing seasons. Without understanding the production characteristics of species during grazing season, planning and livestock management is not feasible. Therefore, understanding the annual and monthly production of different rangeland types is essential for efficient and effective management of livestock grazing. Consequently, relationships between forage production and climatic variables should be studied. For this purpose, annual forage production was measured in research exclosure of Khoshkerood-Saveh during 2007-2010 by clip and weigh method‬. Monthly rainfall in this period was calculated using Saveh synoptic station data and then the amount of cumulative rainfall in winter and spring of each year was calculated. Afterward, the relationship between production and winter and spring rainfall as well as rainfall of different months of winter and spring was studied separately. Statistical analysis was performed using Minitab software. Results showed that winter rainfall had no significant impact on the production of perennial species. However, cumulative rainfall in winter and spring showed different effects on forage production of the species. In other words, a significant relationship was observed between the production of Artemisia sieberi and Salsola laricina and rainfall while no significant relationship was recorded between the production of Stipa hohenackeriana and Poa sinaica and rainfall. Also, there was a significant relationship between cumulative rainfall in March and April and annual production of the species