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The present work aims to study the effect of deferring grazing on the floristic diversity of Stipa tenacissima Loefl. ex L. rangelands in the central Algerian steppe in two different bioclimatic stages, namely semi‐arid and arid. This work is part of a perspective to know the floristic characteristics of an area excluded from grazing and an unrestricted rangeland, in two different environments in order to highlight the factors that are conceivably responsible for the diversification of flora in the steppe ecosystems. In the present study, a number of 96 floristic surveys were performed during the spring season of the years 2014, 2015 and 2016. The methodology adopted is a subjective sampling. The minimum area retained is 100 m2 defined by the method of Braun Blanquet and de Bolos (1957, Annales Estacion Experimental de Aula Dei, 5, 266). This method has been used to study the floristic diversity represented by the floristic richness, Shannon index, the equitability, the biological and the phytochoric type. The climatic correction according to the altitudinal gradient was applied to determine the bioclimatic stage. The results from the surveys indicate that the rangelands at the studied sites contain 109 species, 27 families and 63 genera out of which 79 species and 22 families are in the semi‐arid bioclimatic stage. A two‐way analysis of variance was employed to examine the effect of the bioclimatic stage and the pasture land put at rest. Variance analysis of the diversity indices showed that the bioclimatic stage has a significant impact on the floristic richness and flora diversity of the S. tenacissima steppe (p ≤ 0.01) with a 5% threshold; on the other hand, the protection of these ecosystems does not have a remarkable influence on the floristic diversity (p > 0.05). In recent years, climatic disturbances have resulted in changes in vegetation, even in rested areas located between the study localities. [ABSTRACT FROM AUTHOR]