Studying the Effect of Index Species Astragalus ammodendron on Associated Plants Agropyron tauri and Bromus tomentellus from Different Aspects (Case Study: Arak Province-Shazand, Iran)

Document Type : Research and Full Length Article


1 Natural Resource Faculty, University of Tehran

2 Natural Recourse Faculty, University of Tehran

3 Natural Resource Faculty, Islamic Azad University, Tehran Branch


The aim of this research was to investigate the effect of index species, Astragalus
ammodendron on the associated plants of Agropyron tauri and Bromus tomentellus from
different aspects in Shazand rangeland in southwest of Markazi province. The effects of
species density and distribution pattern and then index species on the soil properties were
studied. Based on the randomized – systematic method, 4 transects with a length of 50 m were
established. To find the relationships between index and associated plants, 30 points were
randomly chosen along the transects and the number of species was counted from these points
to a 50 cm distance in different aspects. Along the transects, the distribution pattern of index
plants and their presence and absence were determined. To find the effects of index species on
soil properties, soil samples were taken and soil properties were determined in laboratory.
Data were analyzed using SPSS software. The results showed that Astragalus ammodendron
density with Agropyron tauri and Bromus tomentellus were similar to the east and west
aspects and near distances. Astragalus ammodendron distribution pattern was randomized
with a tendency toward the clumped pattern. The effect of Astragalus ammodendron on the
soil characteristics was not significant except for the north aspect. Generally, it is concluded
that the effect of Astragalus ammodendron (index species) on Agropyron tauri and Bromus
tomentellus densities was not significant.