Effects of elevated atmospheric CO2 concentrations, clipping regimen and differential day/night atmospheric warming on tissue nitrogen concentrations of a perennial pasture grass

Forecasting the effects of climate change on nitrogen (N) cycling in pastures requires an understanding of changes in tissue N. A new study published in AoB PLANTS by Volder et al. shows that elevated CO₂, climate warming, and management impact shoot and root nitrogen concentrations in different ways in managed pastures. Management (clipping frequency) had the strongest impact on aboveground tissue N concentrations, while the impact of the climate change drivers on shoot N concentration was interactive and varied seasonally. Green leaf N concentrations were decreased by elevated CO₂ and increased by more frequent clipping. Both warming treatments increased leaf N concentrations under ambient CO₂ concentrations, but did not significantly alter leaf N concentrations under elevated CO₂ concentrations. Fine root N concentrations were mostly unaffected by the treatments, although elevated CO₂ decreased root N concentration in deeper soil layers. The interactive nature of the climate change drivers through time, as well as the fact that root N concentration response to the treatments was entirely different from aboveground responses, highlights the complexity in predicting plant N nutrition responses to projected climate change.