Intraspecific trait variability (ITV) is an important component of functional ecology studies. While functional biogeography requires us to understand broad-scale patterns of trait distribution, ITV remains inadequately studied. Due to isolation of ranges, habitat fragmentation and sharp topoclimatic gradients over short distances, temperate mountains offer opportunities to study the ITV in widespread species. In this study, we explored ITV in geographically separated populations of matgrass (Nardus stricta), a clonal dominant plant species of mountain pastures. We measured plant height and leaf traits in 55 populations distributed across six European mountain ranges (from the Pyrenees to the Carpathians) to examine the structure of ITV. We hypothesised that the leaf economics spectrum (LES) and plant size exhibit a strong convergence across a prevailing gradient of growing season length (GSL). We then partitioned the ITV into between ranges, between populations nested in ranges and between individuals nested in populations, and examined the role of climate and local variables on the spatial variation and covariation of traits. Traits showed large ITV and higher between- than within-population variability. Leaf traits displayed a high dependency on height reflecting the growing phase climate and other local factors, while range identity alone (differentiation between ranges) explained a low to moderate amount of the variability in the traits. The strength of coordination between several of the LES traits was higher under shorter GSL due to late snowmelt, suggesting higher phenotypic integration. In the context of functional biogeography of mountain ecosystems, allometric effects and growing phase climate are both key to understanding ITV. We discuss the implications of these findings as they relate to future comparative studies of ITV in seasonal environments.

种内性状变异性（ITV）是功能生态学研究的重要组成部分。尽管功能性生物地理学要求我们了解性状分布的广泛模式，但ITV仍未得到足够的研究。由于范围的隔离，生境的破碎和短距离的急剧的地形气候梯度，温带山脉为研究广泛物种中的ITV提供了机会。在这项研究中，我们在地理上分开的马草（Nardus stricta）种群中探索了ITV），是山区牧场的克隆优势植物。我们测量了分布在六个欧洲山脉（从比利牛斯山到喀尔巴阡山脉）的55个种群中的植物高度和叶片特征，以研究ITV的结构。我们假设叶片经济谱（LES）和植物大小在生长季节长度（GSL）的主要梯度上表现出强烈的趋同性。然后，我们将ITV划分为范围之间，嵌套在范围中的种群之间以及嵌套在种群中的个体之间，并研究了气候和局部变量对性状的空间变异和协变的作用。性状表现出较大的ITV，且种群间变异性高于种群内变异性。叶片性状显示出高度依赖高度，反映了生长期气候和其他局部因素，而单独的范围同一性（范围之间的差异）解释了性状的低至中等程度的变异性。由于融雪较晚，GSL较短时，几个LES性状之间的协调强度较高，表明表型整合较高。在山区生态系统的功能性生物地理环境中，异速生长效应和生长期气候都是理解ITV的关键。我们讨论这些发现的含义，因为它们与ITV在季节性环境中的未来比较研究有关。在山区生态系统的功能性生物地理环境中，异速生长效应和生长期气候都是理解ITV的关键。我们讨论这些发现的含义，因为它们与ITV在季节性环境中的未来比较研究有关。在山区生态系统的功能性生物地理环境中，异速生长效应和生长期气候都是理解ITV的关键。我们讨论这些发现的含义，因为它们与ITV在季节性环境中的未来比较研究有关。