Changes in plant multidimensional chemical diversity along a local soil chemical gradient in temperate forest swamps

Multiple elements are critical for plant growth and survival, community structure, and vegetation function. Chemical diversity, defined as the ranges in element concentrations of plant species within communities, could provide essential insights into plant nutrient strategies and community assembly rules. However, little is known about the chemical diversity of multi-elements besides N and P, and current understanding of chemical diversity is largely based on aboveground plant traits. We investigated understory plant communities in forest swamps along a local soil chemical gradient and determined 11 major and trace elements in leaves and roots of dominant and subordinate plants. Using n-dimensional hypervolume, we examined the changes in leaf and root chemical diversity and their linkages with soil properties. Plant chemical diversity decreased significantly with soil Al, Mn, Mg, and Zn concentrations, but showed no relationships with soil N, P, K, Na, and Fe concentrations, soil pH and C:N. These patterns also held after controlling for species richness and soil moisture. Furthermore, leaf and root chemical diversity were positively correlated and showed similar relationships with soil factors. Root chemical diversity was not significantly higher than leaf chemical diversity. Our results emphasized the important role of soil trace elements for plant chemical diversity along the local soil chemical gradient. Similar patterns and extent of leaf and root chemical diversity may indicate similar local-scale environmental constraint on above- and belowground plant chemical diversity. These findings have important implications for plant community assembly and ecosystem functioning influenced by soil nutrient changes.