Abstract: Identifying the relationship between leaf traits and environmental factors in arid areas will provide scientific guidance for revealing plant survival strategies and optimizing vegetation management practices in water-limited areas. Based on large-scale field investigations in arid regions of Northwest China, we quantitatively identified the variability of leaf traits of typical shrub and herb species, and explored the responses and adaptation mechanisms of leaf traits to variability of climate factors. The results showed that: (1) The average leaf area, leaf thickness, and specific leaf area of shrub species were 136.77 mm², 0.41 mm, and 55.36 cm²·g^-1, respectively, while the values for herb species were 351.45 mm², 0.31 mm, and 111.45 cm²·g^-1, respectively. There were significant differences in leaf traits between shrub and herb species, with leaf size and specific leaf area being more sensitive than other parameters. (2) Similar responses of leaf traits to the variability of climate factors were found in shrub and herb species. Leaf length, leaf width, leaf area, and specific leaf area decreased with increasing drought intensity, while leaf thickness showed an increasing trend. (3) The sensitivity of shrubs to climate variability was higher than that of herbs. Results of redundancy analysis showed that climatic factors accounted for 52% and 12% of the variation of leaf traits of shrub and herb species, respectively. Annual mean precipitation had higher effect on variability of plant leaf traits than annual mean potential evapotranspiration, while the latter had higher effect than annual mean temperature. Our results can help understand plant responses to environmental stress in arid areas.

Key words: dryland plant, leaf trait, adaptation, climate-driven, redundancy analysis.