Abstract: Aim Physiological responses at the leaf level are limited by the underlying anatomical structure, which has a deeper interpretation of plant physiological mechanisms. Quantitative analysis of the response of plant anatomy to human disturbance such as grazing in desert steppe is of great theoretical value to reveal the ecological adaptation mechanism of fragile ecosystem to harsh environment. Methods Beta In this study, the leaves of C. songorica, the dominant species in desert steppe under different grazing intensities (CK, LG, MG, HG) were used as experimental materials to make paraffin sections, and 13 anatomical indexes including protective tissue, vascular tissue and Kranz structure area related to photosynthesis were measured. Comparative analysis was made between different grazing intensities. Important findings The results showed that: (1) the cuticle thickness, as well as the ratio of cuticle thickness to leaf thickness first decreased and then increased with the increase of grazing intensity; (2) In terms of vascular tissue, the area of vascular bundle, vessel area and phloem area were firstly increased and then decreased with the increase of grazing intensity. The thickness of motor cells and xylem area first decreased and then increased with the increase of grazing intensity. Compared with control and moderately heavy grazing areas, the thickness of motor cells in lightly grazing areas decreased significantly (P<0.05). In terms of vascular tissue proportion, the ratio of xylem to vascular bundle area increased with the increase of grazing intensity, while the dominant vessel to vascular bundle area ratio decreased with the increase of grazing intensity. The phloem area increased first and then decreased with the increase of grazing intensity. Compared with the control area, the phloem area in the three grazing areas decreased significantly (P<0.05); (3) The area of Kranz structure increased with the increase of grazing intensity. Compared with the control area, the area of Kranz structure in the three grazing areas was significantly increased (P<0.05);

Key words: desert steppe, long-term grazing, grazing intensity, leaf anatomical structure, Cleistogenes songorica