Rare taxa in the rhizosphere primarily influence nitrogen dynamics in plantations in northeastern China, with minimal impact on carbon and phosphorus

Aims Rhizosphere effects refer to the alterations in soil properties resulting from the presence of plant roots. This study assessed the influence of rhizosphere microbial communities on the rhizosphere effects of carbon, nitrogen and phosphorus content. Methods we examined the rhizosphere effects of carbon, nitrogen and phosphorus in plantation forests of Acer saccharum (Ace), Larix gmelinii (Lar), Pinus sylvestris var. mongolica (Pin) and Populus sp. (Pin). We studied root functional traits and rhizosphere microbial communities and categorized rhizosphere microbes into two sub-communities, rare and abundant taxa, based on their relative abundance. Furthermore, we analyzed the chemical properties of rhizosphere and bulk soils and quantified the rhizosphere effects in the study areas. Results The results revealed that in Pop trees, the rhizosphere effects of total nitrogen and alkali-hydrolyzable nitrogen were significantly higher compared to other tree species. Abundant taxa assembly was dominated by deterministic processes, whereas rare taxa were more influenced by stochastic processes. The rhizosphere rare taxa exhibited a stronger correlation with root functional traits in comparison to the abundant taxa. Both the Random Forest Model and Partial Least Squares Path Model suggested that rhizosphere rare taxa played a crucial role in the rhizosphere effect of nitrogen. The rhizosphere effects of carbon and phosphorus could not be accounted for by the rhizosphere microbial community properties. Conclusion These results collectively suggest that plant roots may regulate the composition of the rhizosphere microbial sub-community to meet their nitrogen requirements, underscoring the importance of rare rhizosphere taxa in plant nutrient uptake.