Ning Zhao, Huming Liu, Qiufeng Wang, Ruili Wang, Zhiwei Xu, Cuicui Jiao, Jianxing Zhu, Guirui Yu, Nianpeng He
How can many plant species co-occur at a given place to form a community? Are there general rules for how plant species are assembled into communities? Ecologists have suggested that the environment and competition between species act like nested sieves in this assembly process. The environment sieves selected species that possess a set of similar traits suitable for a given habit, while competition sieves species with dissimilar traits to avoid competitive elimination.
Root elemental composition, which is associated with plant nutrient acquisition and utilization, is an important chemical property of plant species. However, all plants use the same nutrients and acquire them in similar ways. It has never been tested how the environment and competition sieves act on root elemental composition at different scales during the community assembly process.
We analyzed the concentrations of 15 elements in roots of 281 species across five forests along a North–South transect in China. Our study showed that root elemental composition of the forests changed along the transect. At the large spatial scale, the environmental sieve was a strong driver of root elemental composition of communities. Root phosphorus and calcium were the most important nutrients in distinguishing different forests, driven by soil acidity or alkalinity, the concentrations of phosphorus and calcium in soil, temperature and precipitation. At the site scale, co-occurring species showed a characteristic root elemental composition, which could be a consequence of reducing competition for nutrients, especially for nitrogen.
The analysis of root elemental composition could help us to understand community assembly processes from the local to the large spatial scale. Further information about root morphological and structural properties is needed to achieve a comprehensive understanding of nutrient utilization by roots.
This paper is part of a special on Functional Traits Along a Transect.