Journal Article 7440-44-0 Carbon Soil 142M471B3J Carbon Dioxide Comment N762921K75 Nitrogen PhotoCent model Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Review below-ground plant ecology competition decomposition dynamic global vegetation model elevated CO2 fine roots game theory nitrogen over-proliferation plant roots plant-microbe interactions root biomass root growth rooting depth roots soil organic matter (SOM) terrestrial biosphere model