Forage Production Response of Artemisia Herba Alba to Variation in Rainfall and Changes in Soil Conditions in Arid Regions.

TThis study was conducted at four different sites in an arid region of Iran. Twenty, 1m x 1m, plots were randomly (completely randomized design) selected at each site. Rainfall was collected daily and measured at each location. The parameters measured included canopy surface area, plant height and density, bare soil surface area, numbers of the dry species, annual forage production, number of the established plants, and soil organic matter content. Although, Artemisia cover showed a poor stand in the study sites, it is an important rangeland species in dry regions and it has been overgrazed in this region. It was a sever drought during the research period and most of the rainfall occurred a few years prior to this experiment. The results showed that canopy surface area, plant height and density, number of the established plants, and annual forage production were directly related to rainfall. However, there was an inverse relationship between the number of the dry species as well as the bare soil surface area and the rainfall. The number of the dry species and the bare soil surface area significantly increased and the established plants as well as the forage production significantly decreased due to the low rainfall during the study which was characterized as dry period. Recovery of the species was curtailed when average annual rainfall was less than 40 mm during the study. The results also showed that rainfall had a major role on the soil organic matter content. Topography and soil texture have also had a major role on plants density. Precipitation significantly influenced the growth of Artemisia herba alba in the study sites. The relationships between the forage production and the rainfall for the study sites followed the regression lines of y = 0.1844x, y = 0.1554x, y = 0.0277x, and y = 0.0938x.