Abstract:

The geographical patterns of plant functional traits and their environmental drivers remain central questions in plant population ecology. Leaf functional traits can directly affect the physiological and biochemical processes of plants, reflecting resource acquisition strategies and adaptation mechanisms. In this paper, we measured 17 functional traits of 18 populations of the national key protected wild plant Davidia involucrata Baillon across its natural distribution range in China, and analyzed the geographical patterns of leaf functional traits and their adaptation mechanisms to heterogeneous environments. At the local scale, the coefficients of variation of leaf traits ranged from 1.48% to 24.81%. The variation degree in the leaf carbon phosphorus ratio was the largest, while the variation degree of leaf organic carbon content was the smallest. With increasing longitude and latitude, leaf area, thickness, and serration number decreased significantly. With increasing altitude, leaf thickness, dry matter content, area, and phosphorus content increased significantly, while leaf shape became wider and rounder. Leaf serration enhanced the adaptability of D. involucrata leaves to cold. Significant leaf trait-geography correlations were mediated by climatic and/or soil factors. Environmental factors explained 79.90% of the variation in D. involucrata leaf traits, with variation of leaf traits mainly driven by geographical variables, climatic factors, and soil factors. Annual precipitation and soil nitrogen content were the strongest explanatory factors for leaf trait variation, with increasing precipitation or decreasing soil nitrogen leading to smaller and thinner leaves. In general, the functional traits of D. involucrata leaves showed a clear pattern at the species distribution scale, with precipitation and soil nitrogen content playing an important role in the formation of geographical patterns.

摘要：

以国家重点保护植物珙桐（Davidia involucrata Baillon）为研究对象，对其分布区内18个种群的17项叶片功能性状进行测量，探究叶功能性状的地理格局与对异质环境的适应机制。结果显示，在局域尺度上，珙桐叶片功能性状变异系数介于1.48%~24.81%，其中，叶碳磷比变异程度最大，叶有机质含量变异最小。随着经度或纬度的增加，珙桐叶片叶锯齿数、叶面积、叶厚度显著降低。随着海拔的增加，珙桐叶片叶磷含量、叶面积、叶厚度、叶干物质含量显著增加，珙桐叶片形状变得更宽且更近于圆形。叶片边缘锯齿增强了珙桐叶片对于寒冷的适应性。环境因子解释了79.90%的珙桐叶片性状变异，该变异主要由地理变量与气候因子驱动，同时受到土壤因子的影响。年降水和土壤氮元素是叶片性状变异的最强解释因子，随着降水增加或者土壤氮元素减少，叶片变得小且薄。研究结果说明，珙桐叶片功能性状在物种分布区尺度上呈现出明显的地理格局，其中降水、土壤氮元素含量在地理格局的形成中发挥了重要的作用。