In terrestrial ecosystems, nitrogen (N) and phosphorus (P) are major nutrients limiting the increase in primary productivity, and the N:P ratio is especially essential for plant growth and development and furthermore the maintenance of ecosystem functions. The imbalance of nitrogen and phosphorus input may result in a series of ecological results. 

The N:P stoichiometry (or N:P ratio) may indicate nutrient imbalance status of specific plants. However, how stoichiometric characteristics (e.g. stoichiometric plasticity or flexibility) of different plant species affect the imbalance of nitrogen and phosphorus at the community level has not been well studied. 

In an attempt to answer this scientific question, Dr. LV Xiaotao from the Ecological Stoichiometry Research Team of the Institute of Applied Ecology (IAE), Chinese Academy of Sciences (CAS), together with researchers from the Institute of Botany of CAS and the University of Sydney in Australia, led a long-term nitrogen manipulation experiment study in an Inner Mongolia grassland ecosystem.

The researchers found that nitrogen addition led to a significant increase in N:P ratio of the plant community as a whole, and the community nitrogen and phosphorus imbalance could be attributed to the variation in plant species composition. 

The N:P ratio of Leymus chinensis and Chenopodium glaucum increased significantly with the increase of soil N:P ratio, showing a high stoichiometric plasticity/flexibility. In addition, according to the researchers, the increase in relative dominance/biomass of both plants further exacerbated the imbalance of nitrogen and phosphorus at the community level.

This study confirms the importance of stoichiometric plasticity of certain plant species in driving the community-level nutrient balance status, and provides in-depth understanding of plant community dynamics in the context of increasing nutrient availability.

This study, funded by the National Key Research and Development Program of China and the National Natural Science Foundation of China, has been published in Biogeochemistry entitled "Increases in the dominance of species with higher N:P flexibility exacerbate community N–P imbalances following N inputs".