Global biodiversity is at high risk of rapid loss due to anthropogenic pressure, which may jeopardize ecosystem functions that provide fundamental services to human society. The relationship between biodiversity and ecosystem functioning is critical for understanding the consequences of biodiversity loss and hence represents a central question of ecology. Although many local-scale experiments have provided support for the positive effects of biodiversity on ecosystem functioning, evidence from observational data across large spatial scales remains controversial. The accumulation of macroecological data provides an important opportunity to explore the effects of plant diversity on ecosystem functioning. By integrating newly compiled large databases of functional traits (leaf size and shape, leaf element concentrations and mature height) and distributions of ca. 12500 species of woody seed plants with environmental data across eastern Asia, we compared the effects of community mean functional traits with effects of climate and soil on primary productivity at the scale of 50 x 50 km grid cells.
Results/Conclusions
We show that at the given scale spatial variations in mean leaf size and mean plant height are strongly correlated with variation in primary productivity, independent of plant life form. In comparison, correlations of climate and soil variables with primary productivity are weaker but also correlated with mean plant functional traits. This suggests that the effects of leaf size on ecosystem primary productivity reflect how natural selection modified leaf size across varying climates in conjunction with how climate influences canopy total leaf area. We show that the mean leaf size‒primary productivity function based on the dataset from east Asia can be used to predict productivity from mean leaf size in North America and vice-versa. In addition to advancing our understanding of the relationship between a climate-driven trait and ecosystem functioning, our findings suggest that the mean size of collections of fossil leaves can also be a used to reconstruct paleo-primary productivity of woody ecosystems.