Leaf stomatal density is known to covary with leaf vein density. However, the functional underpinning of this relation, and how it scales to whole-plant water transport anatomy, is still unresolved. We hypothesized that the balance of water exchange between the vapour phase (in stomata) and liquid phase (in vessels) depends on the consistent scaling between the summed stomatal areas and xylem cross-sectional areas, both at the whole-plant and single-leaf level. This predicted size-covariation should be driven by the covariation of numbers of stomata and terminal vessels. We examined the relationships of stomatal traits and xylem anatomical traits from the entire plant to individual leaves across seedlings of 53 European woody angiosperm species. There was strong and convergent scaling between total stomatal area and stem xylem area per plant and between leaf total stomatal area and midvein xylem area per leaf across all the species, irrespective of variation in leaf habit, growth-form or relative growth rate (RGR). Moreover, strong scaling was found between stomatal number and terminal vessel number while not in their respective average areas. Our findings have broad implications for integrating xylem architecture and stomatal distribution, and deepen our understanding of the design rules of plants’ water transport network.

Community assembly theory proposed a hierarchy by which local composition is determined by both regional processes, e.g. dispersal and migration, and local processes, e.g. local filtering by environmental conditions and competition. How these factors interact and combined govern local species assembly and trait composition is poorly known. Thereto, we propose a conceptual model in which strong dispersal ability (linked to low environmental tolerance) is fitness-dependent, promoting species to track environmental changes; weak dispersal (linked to high tolerance) should be fitness-independent, enhancing the influence of competition. Conquently, local trait dissimilarity should have a positive humpback shape, while regional trait dissimilarity should have an upturned-humpback relationship with a dispersal trait gradient. We found strong empirical support for this concept in trait distribution patterns of stream macroinvertebrates from five basins across China. These findings are discussed in terms of metacommunity theory and merit further testing of our concept across ecosystems and organism worldwide.

Biodiversity losses may impact ecosystem processes via food-webs. We hypothesized that time can modulate feedbacks among plant functional diversity, resource quality, prey and predator populations and litter turnover. Thereto we incubated coarse deadwood of 34 woody species, with and without (wood-feeding) termite access, in Chinese subtropical forests with and without (termite-feeding) pangolins. The results supported our hypothesis: in the first 12 months, termites amplified the positive linear relationship between % wood mass loss and initial wood quality (along a wood economics spectrum, WES). In contrast, between 12 and 18 months, termite-mediated consumption, and associated wood mass loss, showed a humpback relation with the initial WES. This shift in termite preference of deadwood species along the WES indicated complementary food availability to termites through time, thereby promoting both termites and endangered pangolins. Thus, plant functional diversity through time can help to sustain keystone consumers, predators and their effects on carbon turnover.