Stipa tenacissima L. (S. tenacissima), may be subject to various constraints that cause increasing degradation of Algerian steppes colonized by these important pastoral species. Understanding its responses to abiotic conditions can be useful for steppes sustainable development. At Laghouat Province in two sites under two bioclimates, semi-arid and arid, and during autumn and spring, we analyzed biometric and physiological parameters of S.tenacissima. We measured S.tenacissima clumps volume, and on its fresh leaves measurements of water content, total chlorophyll, soluble sugars and proline were performed. For both sites we carried out a climatic synthesis and physicochemical soil analysis.\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\r\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\nSoils are light textured sands> 63%, alkaline pH>7,8, moderately calcareous CaCO3<8%, non saline Electrical Conductivity<0,6 dS/m, and have organic matter content of <0,35%. Depending on bioclimate type, Aridity Index are 0,26 and 0,06. S.tenacissima clump volumes are >1,38m3. In the leaves of the plant, water contents are <17,5%.Contents of total chlorophyll, soluble sugars and proline are variable depending on bioclimate and season, their respective intervals are:1,1- 2,1mg/g FM; 14,58- 80,6mg/g FM; and 10-6- 2,10-3mmol/g FM. The findings show that S.tenacissima develops osmoregulatory mechanism by seasonal fluctuations of stress parameters that allow it resist to variations of environmental conditions. Relatively, high content of proline with low content of water are observed in autumn under the arid bioclimate. Responses to variations in abiotic conditions, suggest, that S.tenacissima better tolerates conditions under the semi arid bioclimate, and is constrained in autumn under the arid bioclimate. S.tenacissima is not promising with increase of aridity and drought.

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