Intraspecific variations in leaf traits, productivity, and resource use efficiencies in the dominant species of subalpine evergreen coniferous and deciduous broad-leaved forests along the altitudinal gradient

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. 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. On the studied mountain ran...