CDR LTER’s BioCON experiment

In CDR LTER’s BioCON experiment we grew 296 field plots (each 2m x 2m) containing different numbers and combinations of perennial grassland species under ambient and elevated atmospheric CO₂ and with either ambient or enriched soil N supply. In three elevated-CO₂ rings, a free-air CO₂ enrichment system was used during each growing season to maintain the CO₂ concentration at an average of 560 μmol mol-1, a concentration likely to be reached this century. Our results are consistent with the idea that although some models indicate a considerable capacity of land ecosystems to sequester large amounts of C in the coming century, this C accumulation is likely to be constrained over time by N availability.