Effects of elevated CO2 and N fertilization on plant and soil carbon pools of managed grasslands: a meta-analysis

[摘要] Elevated atmospheric CO₂ levels and increasing nitrogen deposition bothstimulate plant production in terrestrial ecosystems. Moreover, nitrogendeposition could alleviate an increasing nitrogen limitation experienced byplants exposed to elevated CO₂ concentrations. However, an increasedrate of C flux through the soil compartment as a consequence of elevatedCO₂ concentrations has been suggested to limit C sequestration interrestrial ecosystems, questioning the potential for terrestrial C uptaketo mitigate increasing atmospheric CO₂ concentrations. Our study useddata from 77 published studies applying elevated CO₂ and/or Nfertilization treatment to monitor carbon storage potential in grasslands,and considered the influence of management practices involving biomassremoval or irrigation on the elevated CO₂ effects. Our resultsconfirmed a positive effect of elevated CO₂ levels and nitrogenfertilization on plant growth, but revealed that N availability is essentialfor the increased C influx under elevated CO₂ to propagate intobelowground C pools. However, moderate nutrient additions also promoteddecomposition processes in elevated CO₂, reducing the potential forincreased soil C storage. An important role was attributed to the CO₂response of root biomass in soil carbon responses to elevated CO₂,since there was a lower potential for increases in soil C content when rootbiomass increased. Future elevated CO₂ concentrations and increasing Ndeposition might thus increase C storage in plant biomass, but the potentialfor increased soil C storage is limited.

[学科分类] 地球化学与岩石