1. Many studies have reported intraspecific variations in leaf functional traits, but their contribution to plant performance and ecosystem function are poorly understood. We studied altitudinal gradients of intraspecific variations in leaf traits, productivity and resource use efficiency in the dominant species of subalpine evergreen coniferous and deciduous broad‐leaved forests in Japan.
2. We addressed three hypotheses, which are exclusive to each other. (1) Leaf traits vary along the leaf economics spectrum (LES). Plants that grow at lower and higher altitudes have fast‐ and slow‐return strategies, respectively, which improve productivity or resource use efficiency in the respective habitat. (2) Leaf trait variations are not consistent with the LES, but they contribute to improving productivity or resource use efficiency in the respective habitat. (3) Leaf trait variations do not contribute to improving productivity or resource use efficiency at higher altitudes.
3. On the studied mountain range, Fagus crenata, a deciduous broad‐leaved tree, and Abies mariesii, an evergreen conifer, are the dominant species at lower and higher altitudes respectively. In F. crenata, leaf mass per area (LMA) and nitrogen concentrations were higher at higher altitudes. The net assimilation rate and light use efficiency during the growing season were greater at higher altitudes, which compensated for the shorter growing season in terms of annual productivity. In A. mariesii, the LMA was lower and the leaf life span was unchanged at higher altitudes. Productivity and resource use efficiency decreased with altitude.
4. Synthesis. We conclude that F. crenata improves its productivity and resource use efficiency at higher altitudes by altering its leaf functional traits (Hypothesis 2), whereas alterations to leaf traits in A. mariesii are not associated with any improvement at higher altitudes (Hypothesis 3), which may result from the negative impact of environmental stress. Hence, the ecological significance of altitudinal variations in leaf traits depends on species and environment.

中文翻译：

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亚高山常绿针叶和落叶阔叶林的优势物种沿海拔梯度的叶片性状，生产力和资源利用效率的种内变化

1. 许多研究报告了叶片功能性状的种内变异，但对它们对植物性能和生态系统功能的贡献知之甚少。我们研究了日本亚高山常绿针叶和落叶阔叶林的优势种中叶片性状，生产力和资源利用效率的种内变异的垂直梯度。
2. 我们提出了三个互斥的假设。（1）叶片性状随叶片经济学谱（LES）的变化而变化。在低海拔和高海拔地区生长的植物分别具有快退和慢退策略，可以提高各自生境的生产力或资源利用效率。（2）叶片性状的变化与LES不一致，但是它们有助于提高各自生境的生产力或资源利用效率。（3）叶片性状的变化并不能帮助提高高原地区的生产力或资源利用效率。
3. 在所研究的山脉上，落叶阔叶树Fagus crenata和常绿针叶树Abies mariesii分别是低海拔和高海拔的优势种。在高海拔地区，樱桃葡萄的单位面积叶片质量（LMA）和氮浓度更高。在较高的海拔高度，生长期的净同化率和光利用效率更高，这可以弥补年生产率较短的生长期。在滨海曲霉中，LMA较低，而海拔较高时叶片寿命没有变化。生产力和资源利用效率随着海拔的升高而下降。
4. 综合。我们得出的结论是，褐变镰刀菌通过改变其叶片的功能性状来提高其生产力和资源利用效率（假设2），而滨海曲霉的叶片性状的改变与更高海拔上的任何改善都不相关（假设3），这可能是由于环境压力带来的负面影响。因此，叶片性状的垂直变化的生态学意义取决于物种和环境。