Effect of simulated grazing on the regenerative and vegetative attribute of two foraging species Astragalus effusus and Astragalus cyclophyllon

The balanced grazing is a critical managing factor regarding to resource conservation and quantitative and qualitative increase of plants production at the rangeland ecosystems. In addition, understanding the effects of different grazing intensity on the dominant plants can be used as a valuable tool in order to resource management. The current study aimed to determine vulnerability and tolerance as well as amount of re-growth of Astragalus cyclophyllon and Astragalus effuses in the two growth season (2010-2011) in the semi-steppe rangeland in the research station of Zayanderod dam, Charmahal va Bakhtiari. Simulation of animal grazing was carried out by cutting treatment of 0, 30, 50 and 80 percent of total plant on the 240 individuals plant across three time with 20-day time interval according to the growing season. Before applying each treatment, number of flower and seed, height and production were measured. In order to statistical analysis, the GLM and one-way-ANOVA were employed. The results showed that two years cutting treatment in both studied species had a significant effect on the number of flower and seed, height and production. According to the results, the production of A. effuses was decreased about 2.5 and 5 times under cutting of 30-50 and 80 percent, respectively while, treatment of 30, 50 and 80 percent of cutting in the A. cyclophyllon resulted in decreasing of production about 2.2, 3.3 and 6.6 times. Based on the results, by increase the cutting intensity A. effuses was less sensitive than A. cyclophyllon. Therefore, A. effuses could be suitable species regarding to the improve and developing for sustainable utilization in the semi-steppe rangeland.