LB 9-85 - Spatiotemporal patterns of leaf morphological traits and ecological implications

Leaves as the important functional organs of plants are diverse in morphological characteristics. In past decades, botanists tried to explore the biological significance of particular leaf functional traits and their correlations with environmental factors. However, studies of variation in leaf traits across large geographic scales in China, with its particularly large diversity of plants, have rarely been carried out due to limits in the quality of available data. Based on online databases, herbarium specimens, published floras and further literature, we collected and cleaned leaf morphological traits for all Chinese woody plants (11,405 species in total) and >6000 leaf sampling of 7 species in China spanning about 100 years. We mapped the spatial patterns of leaf traits with distribution, explored their environmental drivers along with the influence of plant life-forms and evolutionary history, and evaluated their potential to predict ecosystem productivity and response to climate change. We found that regional mean leaf size of woody dicots decreased from southeast China to northwest. Spatial variation of leaf size closely correlated with climate and responded more tightly to precipitation than to temperature. Spatial variation in satellite-derived ecosystem primary productivity was found strongly linked to the variation in leaf size, and the predictive power of leaf size for scaling up to ecosystem primary productivity was not influenced by plant life-form or evolutionary history. Moreover, the leaf size‒primary productivity functions calibrated on Chinese data similarly predict the primary productivity in North America and vice versa, suggesting that the functional relationship may be general. Our results suggest that leaf size provides a useful surrogate for the reconstruction of paleo-primary productivity based on well-preserved leaf fossils, and could be a useful tool to scale up from leaf trait measures at community level to ecosystem functioning. We also found that intra-specific average leaf size showed a trend of increasing with time. The temporal variation of leaf size was significantly positively correlated with precipitation, while that of leaf shape mainly response to temperature. Our study revealed the spatiotemporal variation of leaf size and shape in response to climate change, and suggested the importance of specimens in herbariums in studying how plant response to climate change.