Stomatal density, size and space-use efficiency at the community level in China

<p>The maximum stomatal conductance (<em>g</em>), a major anatomical constraint on plant productivity, is a function of the stomatal area fraction (<em>f</em>) and stomatal space-use efficiency (<em>e</em>). However, <em>f</em> and <em>g</em> have been considered as equivalents, with <em>e</em> rarely considered, and their adaptation to the environment and their regulation of ecosystem productivity are unclear. Here, we analyzed the community-weighted mean, variance, skewness, and kurtosis of stomatal traits from tropical to cold-temperature forests. The variance of <em>g</em> and <em>f</em> was higher for arid sites, indicating greater functional niche differentiation, whereas that for <em>e</em> was lower, indicating convergence in efficiency. Besides, when other stomatal trait distributions remained unchanged, increasing kurtosis but decreasing skewness of <em>g</em> would improve ecosystem productivity<em>, </em>and <em>f</em> showed the opposite patterns. These findings highlight how the relative importance and equivalence of inter-related traits can differ at community scale.</p>