Decoupling of plant nitrogen and phosphorus under global change over the last two decades

It has long been assumed that nitrogen and phosphorus cycles are closely coupled. However, this assumption has not been rigorously examined under global change, limiting the predictive power of nitrogen and phosphorus cycling. We conducted a meta-analysis of 1341 data points from 107 published articles on the response of leaf nitrogen and phosphorus resorption efficiency to major global change factors (i.e. warming, drought, increased rainfall, elevated CO₂, nitrogen fertilization and phosphorus fertilization) over the last two decades. We showed contrast responses of plant nitrogen and phosphorus resorption to these global change factors, indicating a decoupling of plant nitrogen and phosphorus cycles in the face of global change. These divergent responses were primarily driven by the shifts in nitrogen and phosphorus limitations induced by global change, suggesting that the decoupling of nitrogen and phosphorus cycles may be a plant adaptation strategy in response to nutrient limitation. Furthermore, multiple global change factors exerted additive effects on nitrogen and phosphorus resorption, with nitrogen fertilization being the most influential among them. Synthesis. Our results highlight that the decoupling of plant nitrogen and phosphorus cycles should be incorporated into ecological models to accurately predict ecosystem responses to global change.