Can the scaling of plant nitrogen to phosphorus be altered by global change? An empirical test

Aims Global change may cause unparalleled supplies of soil nutrients and further lead to stoichiometric imbalance of nitrogen (N) and phosphorus (P) in terrestrial plants. While previous studies had reported the effects of global change factors on plant N, P contents and their ratios, few had examined whether or how these factors may influence the scaling of these two elements. Methods Taking advantage of a manipulative experiment with altered precipitation, warming and N addition, and using the general scaling function N = beta P-a, we examined how the scaling of plant N to P may respond to global change factors in a Loess grassland in northwestern China. Important Findings We found that precipitation reduction (PR) and warming decreased plant P concentrations, while N addition increased plant N concentrations, resulting in increased N:P ratios. The slopes of the linear regressions between plant N and P (i.e. log-transformed N versus P) did not change significantly, whereas the intercepts increased significantly under PR, warming and N addition. These results indicate that global change factors may not affect the synergistic variation of plant N and P, showing a closely coupled relationship between them. Our findings may help to better understand plant nutrient dynamics and element balance in a changing world.