Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland

Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland

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Rising atmospheric CO2 concentrations may alter the nitrogen (N) content of ecosystems by changing N inputs and N losses, but responses vary in field experiments, possibly because multiple mechanisms are at play.We measured N fixation and N losses in a subtropical oak woodland exposed to 11 a&d ej-123 years of elevated atmospheric CO2 concentrations.We also explored the role of herbivory, carbon limitation, and competition for light or nutrients in shaping the response of N fixation to elevated CO2.

Elevated CO2 did not significantly alter gaseous N losses, but lower recovery and deeper distribution in the soil of a long-term 15N tracer indicated that elevated CO2 increased leaching losses.Elevated baseball scoreboards for sale CO2 had no effect on nonsymbiotic N fixation, and had a transient effect on symbiotic N fixation by the dominant legume.Elevated CO2 tended to reduce soil and plant concentrations of iron, molybdenum, phosphorus, and vanadium, nutrients essential for N fixation.

Competition for nutrients and herbivory likely contributed to the declining response of N fixation to elevated CO2.These results indicate that positive responses of N fixation to elevated CO2 may be transient and that chronic exposure to elevated CO2 can increase N leaching.Models that assume increased fixation or reduced N losses with elevated CO2 may overestimate future N accumulation in the biosphere.