Leaf venation topology modulates climate-soil-productivity pathways driving trait variation across China's vascular...

Leaf venation networks are central to leaf water and nutrient transport, and differences in venation topology may impose long-term structural constraints on functional traits and resource-use strategies. Using a nationwide dataset of 30,047 vascular plant species in China, we compared trait differentiation between open- and closed-venation plants and quantified how climate, soil properties and ecosystem productivity (net primary productivity, NPP) contribute to trait spatial variation and its underlying pathways.

We used Bayesian regression and piecewise structural equation modelling to compare climate-soil-NPP pathways underlying trait variation between open- and closed-venation plants, and applied generalized additive models to project future trait shifts under CMIP6 SSP scenarios.

Closed-venation plants exhibited significantly larger values for all four traits than open-venation plants (P < 0.001) and showed more consistent and direct trait-environment responses, consistent with a high-investment strategy in both growth and reproductive construction. In contrast, open-venation plants tended to 23 have smaller traits and exhibited response pathways primarily mediated through indirect upstream effects, reflecting weak direct climate-trait coupling, indicative of a low-investment strategy. Climate emerged as the dominant driver of trait spatial variation, soil effects were intermediate, and NPP primarily acted as an indirect mediator. Projections under future climate scenarios suggested an overall increase in all four traits for closed-venation plants, whereas open-venation plants were predicted to increase vegetative traits but decrease reproductive traits.

Venation topology shapes broad-scale trait strategies, plausibly through variation in hydraulic capacity and venation network redundancy, and helps explain contrasting trait-environment relationships and projected responses to future climate change.