Tingey, David T., Donald L. Phillips, Mark G. Johnson, Marjorie J. Storm, and J. Timothy Ball. 1997. Effects of elevated CO2 on fine root dynamics and fungal growth in seedling Pinus ponderosa. Environmental and Experimental Botany 37:73-83.
The effects of elevated CO2 and N fertilization on fine root growth of Pinus ponderosa Dougl.ex P.Laws.C.Laws., grown in native soil in open-top field-exposure chambers at Placerville, CA, were monitored for a 2-year period using minirhizotrons. The experimental design was a replicated 3 x 3 factorial with a treatment missing; plants were exposed to ambient ( ~365 Ámol mol-1) air or ambient air plus either 175 or 350 Ámol mol-1 CO2 and three levels of N addition (0, 100 and 200 kg ha-1 year-1). By the second year, elevated CO2 increased fine root occurrence and root length while N fertilization had no effect. The CO2 x N interactions were not significant. Neither elevated CO2 nor N fertilization altered fine root diameter. Fine root mortality was increased by increasing soil N but was reduced in elevated CO2. Highest fine root mortality occurred during summer and lowest during winter. Elevated CO2 increased mycorrhizal and fungal occurrence earlier than N fertilization.