关键词: 石质生境, 岩石裂隙网络结构, 土壤理化性, 叶片功能性状

Abstract:

【Objective】This study aims to investigate the characteristics of leaf functional traits in Tirpitzia sinensis across different Karst fissure networks, and provide a theoretical basis for understanding plant growth adaptability mechanisms in Karst areas.【Method】In this study, we selected typical dominant shrub habitats of T. sinensis with various rock fissure characteristics: high dip angle, short track length, fewer turns, multiple connections, high density, and aggregation type (type Ⅰ); moderate dip angle, moderate track length, multiple turns, moderate connections, moderate density, and uniform type (type Ⅱ); and low dip angle, long track length, moderate turns, fewer connections, low density, and random type (type Ⅲ). We investigated the response of leaf functional traits to different rock fissure networks and soil physicochemical properties using One-way analysis of variance and correlation analysis. 【Result】The nutrient and water contents of fissure soil were the highest in type Ⅰ rocky habitats, followed by type Ⅱ, and the lowest in type Ⅲ, while soil pH showed an opposite trend. Soil nutrients in type Ⅲ were significantly lower than in type Ⅰ (P < 0.05), but there were no significant differences in soil pH or water content. Significant differences were found in leaf chemical traits among different rocky habitats (P < 0.05), but not in structural traits. Leaf nutrient concentration and specific leaf area were highest in type Ⅰ, followed by type Ⅱ and the lowest in type Ⅲ, with leaf dry matter content showing the opposite trend. Leaf N/P mass ratios and leaf thickness were the highest in type Ⅱ, followed by type Ⅲ, and the lowest in type Ⅰ. The dip angle and connectivity of rock fissures were the main factors affecting soil physicochemical properties. Soil organic carbon, total nitrogen, available nitrogen, and available phosphorus content were the primary factors influencing leaf chemical traits and leaf area, which were significantly affected by the connectivity of the rock fissure network. The leaf nitrogen/phosphorus mass ratio was higher than 16 across the three rocky habitats, which indicated that T. sinensis growth was phosphorus-limited. Compared with other Karst shrubs in the same area, the growth rates of T. sinensis in the three rocky habitats were slower, reflecting a more conservative nutritional investment strategy. 【Conclusion】The rock fissure network indirectly affects leaf functional traits primarily by altering soil physicochemical properties, with leaf chemical traits showing greater plasticity than structural traits. In type Ⅲ rocky habitats, T. sinensis is most susceptible to nutrient stress, demonstrating pronounced tolerance to nutrient-poor conditions in its leaf functional traits.

Key words: rocky habitat, rock fracture network structure, soil physicochemical property, leaf functional trait