Plant C:N ratio predicts community composition changes under N addition in an alpine meadow

Plant functional traits play important roles in determining plant responses to environmental change and further shaping community composition, but the role of plant stoichiometry remains poorly understood in regulating community responses to continually increased nitrogen (N) deposition. Here, we used a five-year manipulative experiment with six N addition rates (N_rate) to explore how the N response of different plant functional groups links to aboveground plant carbon-to-N ratio in an alpine meadow. We found that functional groups with higher C:N tended to grow better and have greater abundance over increasing N_rate, yet those with lower C:N were at risk of loss, subsequently mitigating the N-caused decline in community-level plant C:N. This was mainly due to that functional groups with higher C:N not only possessed higher N use efficiency but also had greater competitiveness for aboveground light due to higher plant height. Our results show that the N responses of different herbaceous plants can be well explained by plant C:N. Thus, we suggest the prediction of plant community composition changes under N deposition would be greatly improved by considering this easily measured stoichiometric trait. Here we share our dataset related to our manuscript.