Multiple Nutrient Additions Homogenize Multidimensional Plant Stoichiometry in a Meadow Steppe

Human activities are altering terrestrial ecosystem biogeochemistry globally by augmenting the availability of multiple biologically essential nutrients, thereby potentially altering plant internal concentrations (i.e., stoichiometry) across a diverse array of elements. These shifts in plant nutrient concentrations may subsequently impact crucial ecosystem processes, including litter decomposition, herbivory by insects and large animals, and ecosystem productivity. However, most work on the alteration of plant stoichiometry has focused on a few macronutrients (e.g., nitrogen or phosphorus), despite the potential importance of many other elements. In this study, we conducted a comprehensive field experiment in the Inner Mongolia Steppe, manipulating eight distinct nutrients to examine their effects on both soil and plant tissue concentrations. Our findings reveal that adding most nutrients increased their corresponding available contents in the soil. In most cases, the addition of nutrients also increased their corresponding concentrations in plant tissues at both species and community levels. Besides, multiple nutrient additions had greater effects on soil available nutrient contents than on plant internal nutrient concentrations. Notably, the concurrent addition of multiple nutrients led to a significant homogenization of plant stoichiometry among different species within the same community. This homogenization might influence interspecific interactions and coexistence within grassland ecosystems. Our findings advanced our comprehension of how anthropogenic nutrient enrichment may simplify plant nutrient profiles, thereby influencing grassland biodiversity and ecosystem functionality.