Abstract:

Artemisia gansuensis， Lespedeza bicolor， and Stipa capillata are three typical native plant species in the Ningxia desert steppe， playing significant ecological roles. However， their physiological response mechanisms under environmental stressors such as intensified drought and nitrogen deposition remain unclear. This study conducted field-controlled experiments to investigate the physiological responses and adaptive strategies of these desert steppe plants by analyzing their photosynthetic and transpiration characteristics under varying water and nitrogen conditions. The results indicate that： （1） Artemisia gansuensis exhibits high sensitivity to changes in water availability， while Lespedeza bicolor demonstrates relatively higher adaptability to water stress. All three species adapt to water variability through distinct stomatal regulation strategies； （2） Appropriate nitrogen addition optimizes the photosynthetic system of Artemisia gansuensis， enhancing its photosynthetic efficiency； （3） Nitrogen deposition significantly affects Lespedeza bicolor， with excessive nitrogen addition reducing its competitive ability within the plant community； （4） Stipa capillata shows minimal response to changes in nitrogen availability， adopting a highly conservative nitrogen utilization strategy. This study provides insights into the physiological responses and adaptation mechanisms of Artemisia gansuensis， Lespedeza bicolor， and Stipa capillata under water and nitrogen gradients， offering a scientific basis for further research on desert steppe plants and their conservation and restoration.

Key words: physiological response, nitrogen addition, photosynthesis, desert plants, graded water treatment