Interspecific association and species composition of plants affected by erosion winds in the south west of Iran

Abstract

Species interactions are considered important in the process of understanding the structure and composition of natural plant communities. This study evaluated a field survey to investigate species composition and interspecific associations in natural vegetation of an arid area in Hanitie rangeland, Khuzestan Province, Southwest of Iran. The interspecific associations of major species were quantitatively analyzed using a 2 - 2 contingency table, χ2 test, and interspecific association coefficients. Eighty quadrates were located along four 800m transverse transects, two of which were located in the general direction of dominant winds while others were perpendicular to the dominant wind. This vegetation type's quadrate size was determined using the minimal area method (3 3m). Thirty-eight species belonging to 10 families were recorded on this site. The highest number of species belonged to the Graminea, followed by Chenopodiacea. This study shows that Holocnemum strobilaceum and Aeluropus littoralis have identical interspecific association patterns and share a positive interspecific association. But the distribution of Tamarix leptopetala was significantly different (P<0.05) within Aeluropus littoralis and Agropyron elangatum, which indicates a negative association. Also, the results show that when Holocnemum strobilaceum and Aeluropus littoralis co-occurred in the general direction of dominant winds, the mean frequency was significantly higher than when they co-occurred perpendicular to the dominant wind. This research may support the view that facilitation is more prominent in a severely disturbed habitat than the competition

Keywords

• species interaction
• facilitation
• inhibition
• interspecific association