In order to reveal the response of leaves of Crataegus songarica to altitude changes, the functional traits and anatomical structure of Crataegus songarica in different altitudes (1100~1700 m) in Yili Guozigou, Xinjiang were used to determine the functional traits and anatomical structure of the leaves, clarify the functional traits and anatomical structure differences of different altitude gradient sheets, and explore the adaptation strategies of Crataegus songarica to environmental changes. The results showed that: (1) The leaf length, leaf width, leaf area, specific leaf area and chlorophyll content of Crataegus songarica decreased with the increase of altitude, while the leaf length-to-width ratio, specific leaf weight and leaf dry matter quality increased with the increase of altitude. The analysis of leaf functional trait plasticity showed that the plasticity index was the largest than leaf weight, followed by leaf dry matter content, and the plasticity index of chlorophyll content was the smallest. (2) The leaf thickness, fence tissue thickness, upper epidermis thickness, sponge tissue thickness and cuticle thickness of Crataegus songarica increased significantly with the increase of altitude (P<0.05), and the thickness of the main vein and the protrusion of the main vein decreased significantly with the increase of altitude (P<0.05), the tightness of tissue structure and the looseness of tissue structure showed a trend of first increasing and then decreasing with the increase of altitude, while the grid-sea ratio showed a trend of first decreasing and then rising and then decreasing with the increase of altitude. The analysis of leaf anatomical plasticity showed that the plasticity index of main vein protrusion was the largest, followed by the thickness of the stratum corneum, and the plasticity index of fence tissue was the smallest. (3) Through the correlation analysis between the leaf traits of Crataegus songarica, it was found that the leaf area was positively correlated with leaf length, leaf length-to-width ratio and specific leaf area, negatively correlated with leaf width and specific leaf weight, and leaf thickness was positively correlated with upper epidermal thickness, main vein protrusion, fence tissue thickness, cuticle thickness and sponge tissue thickness, and negatively correlated with main vein thickness, tissue structure tightness and tissue structure looseness. The results show that the adaptation strategies of Crataegus songarica at different altitudes are different, and the main manifestations in high altitude areas are to increase leaf thickness and leaf dry matter content, fence tissue, sponge tissue thickness to improve stress resistance, reduce leaf area, chlorophyll content, main vein thickness to reduce the damage caused by excessive light to leaves, and in low altitude areas Crataegus songarica mainly increases the accumulation of organic matter by increasing leaf area and chlorophyll content. The research results can provide some basic information for the conservation of the resources of Crataegus songarica.
Words: Crataegus songarica; Elevation gradient; Leaf anatomy; Functional traits; Environmental adaptability