Iran is a mountainous country, about 50% of the country is consisted of high mountains. In many mountainous rangelands of Iran, plant are simultaneously under high pressure of livestock grazing (biotic stress) and harsh montane climate (abiotic stress). Under such conditions, nursing effects of shrubs can play a critical role on conserving the species diversity and richness. A study was conducted in northern slopes of Binalud Mountain, in northeast Iran. Facilitation effects of an allelopatic shrub (Artemisia turkestanica) and a spiny shrub (Astragalus gossipinus) were studied on other plant species. Plant sampling was conducted within 300 quadrates, taken from 5 different sites; 75 quadrates under canopy of Astragalus and 75 for Artemisia and 150 in the adjacent open areas of each shrub. Flexible plots, with the same size of shrub canopies, for both Astragalus and Artemisia and their adjacent open areas. A total of 50 plant species were identified, from which 41 were growing under canopy of Artemisia, 24 under Astragalus and 28 in open areas. Some (30) species were common between the microsites, 8 species were exclusively growing under canopy of Artemisia, 4 under Astragalus and 8 species were common under canopy of Artemisia and Astragalus. In conclusion, our results indicate importance of spiny and allelopathic shrubs for conserving species richness in the mountainous rangelands. Although these species are usually known as invasive or expansive species, but without their nursing effect, about 40% of the flora of Binalud Mountain may be vanished due to biotic and abiotic stresses.

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