Abstract: Leaf functional traits reflect plant adaptation strategies to the environment. In this study, Caragana korshinskii plantations under different planting patterns (C. korshinskii pure forest, C. korshinskii-Pinus tabuliformis mixed forest, C. korshinskii-Pinus sylvestris  var. mongolica mixed forest) in the hilly and gully region of the Loess Plateau of northern Shanxi Province, China were selected as the research objects. The main leaf functional traits of C. korshinskii and environmental factors were investigated. One-way ANOVA, simple effects analysis, and redundancy analysis were used to explore the characteristics of leaf functional traits of C. korshinskii  and their responses to environmental factors. The results showed that: (1) There were significant differences in leaf functional traits of C. korshinskii under different planting patterns. Leaf thickness and dry matter content in pure forest were significantly higher than those in mixed forests, while specific leaf area and foliar phosphorus content were significantly lower than those in mixed forests. There was no significant difference in other traits between the pure and mixed stands. (2) The coefficients of variation for leaf functional traits of C. korshinskii ranged from 1.9% to 43.7%, with varying degrees of intra-species variation for each functional trait. Overall, the degree of variation was greater for specific leaf area (40.2%) and leaf area (39.8%), and lower for leaf dry matter content (7.9%). The remaining functional traits were more stable. (3) Both environmental factors and planting patterns had significant effects on leaf functional traits of C. korshinskii. Planting patterns indirectly affected leaf functional traits by changing canopy structure. Canopy openness (15.7%) explained the highest variation in leaf functional traits, followed by soil bulk density (13.6%), total nitrogen content (10.7%), soil water content (10.7%), and total understory radiation (9.2%), which were the key environmental factors affecting leaf functional traits of C. korshinskii. The main environmental factors controlling the variation of each of leaf functional traits of C. korshinskii were different. Our results suggested that C. korshinskii could adapt to environment under different planting patterns by adjusting specific leaf area, leaf dry matter content, leaf thickness, and foliar phosphorus content. Moreover, C. korshinskii could enhance the defense and nutrient storage capability of leaves by adopting a smaller specific leaf area, increasing leaf dry matter content and leaf thickness, thus enhancing its adaptability to the barren and arid environment. Leaf functional traits were different due to the alteration of environmental factors within the community affected by planting patterns. Therefore, the influence of regional environment and planting pattern should be taken into account when selecting tree species for vegetation restoration.

Key words: Caragana korshinskii, functional trait, environmental factor, adaptation strategy.