Spatial patterns and coexistence of the native forb, Psathyrostachys fragilis (Asteracea) and the native invader, Gundelia tournefortii (Poaceae) in a semi-arid rangeland of Iran

In this study, we investigated the interactions between the dominant native invader, Gundelia tournefortii, and the dominant forage species, Psathyrostachys fragilis in rangelands of Taleghan (Iran). Four transects of 150 meters were considered as sampling unit. Using randomly-systematic method, 15 plots (1 x 1m) were placed along each transect with a distance of 10 m. List of species, the canopy cover and the numbers of plant species were determined in each plot. The spatial association of the two dominant species was assessed by studying association, covariation, and distribution pattern (using the Hopkins’ index) of plants. We found a clumped distribution pattern in both two dominant species. Results of this study revealed a strong competitive interaction between the dominant plant species in studied area with P. fragilis was more frequent and had more canopy cover than the native invader G. tournefortii. So, according to our findings, P. fragilis may present a suitable candidate for artificial re-vegetating and protecting against invaders to restore the biodiversity and ecological health of endangered rangelands.