The majority of alpine plants are of small stature. Through their small size alpine plants are decoupled from the free atmospheric circulation and accumulate solar heat. However, a few alpine species do not follow that “rule” and protrude with their aboveground structures from the microclimatic shelter of the main canopy boundary layer. We aim at explaining the phenomenon of being tall by exploring the biomass production and carbon relations of four pairs of small and tall phylogenetically related taxa in alpine grassland. We compared species and stature-specific biomass allocation, shifts in non-structural carbohydrate (NSC) concentrations in different tissues throughout the season, and we used ¹³C labels to track carbon transfer from leaves to belowground structures. Small and tall herbs did not differ in their above- to belowground biomass allocation. The NSC composition (starch, fructan, simple sugars) and allocation did not show a stature-specific pattern, except for higher concentrations of simple sugars in tall species during their extended shoot growth. In relative terms, tall species had higher NSC pools in rhizomes, whereas small species had higher NSC pools in roots. Our findings do not place tall alpine forbs in an exceptional category in terms of biomass allocation and carbohydrate storage. The tall versus small stature of the examined herbs does not seem to be associated with specific adjustments in carbon relations. ¹³C pulse labelling revealed early C autonomy in young, unfolding leaves of the tall species, which are thus independent of the carbon reserves in the massive belowground organs.

大多数高山植物体型较小。通过它们的小尺寸高山植物与自由大气循环脱钩并积累太阳热量。然而，一些高山物种不遵循这个“规则”，它们的地上结构从主冠层边界层的小气候庇护所中突出。我们旨在通过探索高寒草原四对小型和高大系统发育相关类群的生物量生产和碳关系来解释高大现象。我们比较了物种和身高特定的生物量分配，整个季节不同组织中非结构性碳水化合物 (NSC) 浓度的变化，我们使用了¹³C 标签跟踪从树叶到地下结构的碳转移。小型和高大的草本植物的地上到地下生物量分配没有差异。NSC 组成（淀粉、果聚糖、单糖）和分配没有显示出特定于身高的模式，除了高大物种在延长枝条生长期间单糖浓度较高。相对而言，高大的物种在根茎中具有较高的 NSC 库，而小型物种在根中具有较高的 NSC 库。就生物量分配和碳水化合物储存而言，我们的研究结果并未将高大的高山草本植物置于特殊类别中。被检查的草药的高矮身材似乎与碳关系的具体调整无关。¹³C 脉冲标记揭示了高大物种的年轻、展开的叶子的早期 C 自主性，因此它们与大量地下器官中的碳储量无关。