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

The maximum stomatal conductance (g), a major anatomical constraint on
plant productivity, is a function of the stomatal area fraction (f) and
stomatal space-use efficiency (e). However, f and g have been considered
as equivalents, with e 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 g and f was higher for arid sites, indicating greater
functional niche differentiation, whereas that for e was lower, indicating
convergence in efficiency. Besides, when other stomatal trait
distributions remained unchanged, increasing kurtosis but decreasing
skewness of g would improve ecosystem productivity, and f showed the
opposite patterns. These findings highlight how the relative importance
and equivalence of inter-related traits can differ at community scale.