Long-term effects of CO2 enrichment and temperature increase on a temperate grass sward

摘要: Perennial ryegrass swards were grown in large containers on a soil and exposed during two years to elevated (700 μL L-1) or ambient atmospheric CO2 concentration at outdoor temperature 3 °C increase air CO2. The nitrogen nutrition of the grass sward was studied sub-optimal (160 530 kg N ha-1 y-1) one non-limiting (1000 fertilizer supplies. At cutting date, reduced by 25 33%, average, leaf per unit mass. Due an blade weight area CO2, this decline did not translate for all cuts lower area. With supply, (% N) declined with shoot dry-matter (DM) according highly significant power models N=4.9 DM-0.38) (%N=5.3 DM-0.52) difference between both regressions indicated critical than high, but low values biomass. supplies, index sward, calculated as ratio actual concentration, significantly lowered This inorganic availability plants which also apparent from declines annual yield nitrate leaching winter. For most cuts, harvested fraction plant decreased due, 45–52% root phytomass. In same way, smaller share total cutting, 25–41% content roots. means DM harvest indices correlated index. Changes positively correlated. possible implication changes introgen cycle limitation growth potential elevated. is discussed.