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

Experimental site
Experimental site

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.