Arbuscular mycorrhizal fungi (AMF) and plant species diversity are influenced by environmental variables. But the driving factor affecting AMF in in semi-arid regions are not well recognized. Therefore, in the present study, we have investigated the effects of elevation gradient on AMF and plant diversity in the semi-arid forest of the Iran. Sampling was done using five transects along the north-facing slope, between 1400 and 2600 m a.s.l. along each transect, 7–10 sampling plots were established with 200 m a.s.l. intervals. In total 45 sampling plots (100 square meters) were established in May at six classes, including<1600, 1600–1800, 1800–2000, 2000–2200, 2200–2400, and>2400 m a.s.l. Plant and AMF species diversity indices was calculated using Shanon-wiener, Menhink, and Pielou indices, respectively. Twenty-five AMF species belonging to four families (Glomeraceae, Claroideoglomeraceae, Acaulosporaceae, and Gigasporaceae) and 144 plant species belonging to 73 genera and 31 families were identified in the studied region. The result of the General linear model (GLM) indicated that elevation significantly affects diversity, evenness, and richness of plants and AMF. The highest plant and AMF diversity values recorded in the 2200–2400 elevation class. Student t-tests indicated that plant diversity and plant richness were significantly higher compared to the AMF in the studied elevation classes. The CCA (Canonical correlation analysis) showed that plant and AMF diversity was higher at higher elevation classes and indicated a high correlation with litter thickness and nitrogen. According to the results, the lowest AMF diversities were found in low elevation gradient (<1600 m a.s.l.), where the least plant diversity and richness were recorded. In contrast, the highest AMF species were recorded in the higher elevation classes due to the higher plant richness and diversity. Moreover, litter thickness, soil nitrogen, and plant diversity are the most driving factor controlling AMF diversity in higher elevation classes. Therefore, AMF and plant diversity are gradually increased from a lower elevation to the higher elevation classes
