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Abstract Shifts in stomatal trait distributions across contrasting environments and their linkage with ecosystem productivity at large spatial scales have been unclear. Here, we measured the maximum stomatal conductance (g), stomatal area fraction (f), and stomatal space-use efficiency (e, the ratio of g to f) of 800 plant species ranging from tropical to cold-temperate forests, and determined their values for community-weighted mean, variance, skewness, and kurtosis. We found that the community-weighted means of g and f were higher in drier sites, and thus, that drought ‘avoidance’ by water availability-driven growth pulses was the dominant mode of adaptation for communities at sites with low water availability. Additionally, the variance of g and f was also higher at arid sites, indicating greater functional niche differentiation, whereas that for e was lower, indicating the convergence in efficiency. When all other stomatal trait distributions were held constant, increasing kurtosis or decreasing skewness of g would improve ecosystem productivity, whereas f showed the opposite patterns, suggesting that the distributions of inter-related traits can play contrasting roles in regulating ecosystem productivity. These findings demonstrate the climatic trends of stomatal trait distributions and their significance in the prediction of ecosystem productivity. 

While nitrogen (N) amendment is known to affect the stability of ecological communities, whether this effect is scale‐dependent remains an open question. By conducting a field experiment in a temperate grassland, we found that both plant richness and temporal stability of community biomass increased with spatial scale, but N enrichment reduced richness and stability at the two scales considered. Reduced local‐scale stability under N enrichment arose from N‐induced reduction in population stability, which was partly attributable to the decline in local species richness, as well as reduction in asynchronous local population dynamics across species. Importantly, N enrichment did not alter spatial asynchrony among local communities, which provided similar spatial insurance effects at the larger scale, regardless of N enrichment levels. These results suggest that spatial variability among local communities, in addition to local diversity, may help stabilise ecosystems at larger spatial scales even in the face of anthropogenic environmental changes.

 

Nutrient allocation is an important aspect of plant resource uptake and use, which is related to life‐history strategies. Although to date considerable attention has focused on plant allocation of nitrogen and phosphorus, comparatively little information is available on the allocation of various other nutrients and their up‐scaling from the species to community level.

We measured 10 nutrient elements in the leaves, branches and fine roots of 551 plant species growing in eight forest ecosystems in China, ranging from cold temperate to subtropical forests. We estimated the scaling relationship of multiple nutrients among plant organs at the species level and scaled‐up the relationship to the community level by combining this information with that of community structure.

Nutrient allocation among plant organs was conserved in different functional groups and biomes across broad environmental gradients. Nutrient partitioning between organs with similar function tended to be isometric, whereas partitioning between organs with distinct functions tended to be allometric. The scaling relationship between above‐ and below‐ground organs remained consistent, whereas the scaling relationship within above‐ground organs changed after scaling up from the species to the community level, with the relative change in nutrients being consistently smaller in the more active organs.

Synthesis. The pattern of multiple nutrient allocation among organs showed a degree of conservatism across plant functional groups and biomes, with disproportional changes in nutrient content between functionally distinct organs and a lower relative change in more active organs. This conservative strategy implies the existence of general rules that constrain plant nutrient allocation.