Untangling the influence of abiotic and biotic factors on leaf C, N, and P stoichiometry along a desert-grassland transition zone in northern China

Plant elemental composition and stoichiometry are useful tools for understanding plant nutrient strategy and biogeochemical cycling in terrestrial ecosystems. However, no studies have examined how plant leaf carbon (C), nitrogen (N), and phosphorus (P) stoichiometry responds to abiotic and biotic factors in the fragile desert-grassland ecological transition zone in northern China. Then a systematically designed 400 km transect was established to investigate the C, N, and P stoichiometry of 870 leaf samples of 61 species from 47 plant communities in the desert-grassland transition zone. At the individual level, plant taxonomic groups and life forms rather than climate or soil factors determined the leaf C, N, and P stoichiometry. In addition, leaf C, N, and P stoichiometry (except leaf C) was significantly influenced by soil moisture content in the desert-grassland transition zone. At the community level, leaf C content showed a considerable interspecific variation (73.41 %); however, the variation in leaf N and P content, as well as C:N and C:P ratios, was mainly due to intraspecific variation, which was in turn driven by soil moisture. We suggested that intraspecific trait variation played a key role in regulating community structure and function to enhance the resistance and resilience of plant communities to climate change in the desert-grassland transition zone. Our results highlighted the role of soil moisture content as a critical parameter for modeling the biogeochemical cycling in dryland plant-soil systems.