Abstract:

The intraspecific and interspecific variations in plant leaf traits are the core carriers for revealing the mechanisms of community species coexistence and environmental adaptability, and are of great significance for understanding the mechanisms of community species coexistence and response to environmental changes. Taking Zhangye City, in the central part of the Hexi Corridor, as the research area, this study selected two typical habitats: road area (with high human interference) and park area (with low human interference). Three ornamental plants of the Oleaceae family, Ligustrum× vicaryi, Syringa oblata, and Forsythia suspensa, were selected as the research objects. Through mathematical statistics and significance tests, the variability characteristics of leaf morphology traits (5 items such as leaf area and specific leaf area), ecological stoichiometry traits (6 items such as leaf carbon/nitrogen/phosphorus content and ratio), and physiological and biochemical traits (5 items such as soluble sugar and superoxide dismutase) were systematically analyzed. The results showed that: (1) there were significant differences in the variation of leaf traits among three plant species in two different habitats. The interspecific variation coefficient of leaf traits in the road area was 1.01%-43.90%, while in the park area it was 1.51%-29.80%. The intraspecific variation coefficient was generally 2%-40%. Moreover, the interspecific variation amplitude of leaf traits in the road area was generally larger than that in the park area, indicating that plant leaf traits are more sensitive to environmental response in high disturbance environments. (2) In terms of classification, leaf area and specific leaf area showed the most significant variation in leaf morphological traits (road area coefficient of variation 27.01%-30.84%). In terms of ecological stoichiometry, nitrogen phosphorus ratio (N/P) had the largest variation in road area (43.90%), and carbon nitrogen ratio (C/N) had the largest variation in park area (29.80%). Soluble sugar content had the highest variation in physiological and biochemical traits (road area 24.03%, park area 23.80%). (3) In terms of species specificity, the coefficient of variation of leaf area and specific leaf area of Ligustrum× vicaryi is significantly higher than that of Syringa oblata and Forsythia suspensa. Syringa oblata has the highest coefficient of variation in leaf dry matter content (4.85% in the park area), while Forsythia suspensa has the highest coefficient of variation in soluble sugar and malondialdehyde content (24.03% and 23.91% in the road area, respectively). This study clarified the variation patterns and environmental driven differences in leaf traits of ornamental plants in the Oleaceae family in Zhangye City, providing a scientific basis for habitat adaptation selection of Oleaceae plants in urban green space systems in arid areas of Northwest China, such as prioritizing the allocation of strong anti-interference Ligustrum× vicaryi in road areas.

Key words: Oleaceae, ornamental plants, leaf traits, intraspecific variation, interspecific variation, landscape and green space system, central Hexi Corridor