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EFFECTS OF ELEVATED CO-2 AND N FERTILIZATION ON FINE ROOT DYNAMICS AND FUNGAL GROWTH IN SEEDLING PINUS PONDEROSA
Citation:
Tingey, D., D. Phillips, M. Johnson, M. J. Storm, AND J. T. Ball. EFFECTS OF ELEVATED CO-2 AND N FERTILIZATION ON FINE ROOT DYNAMICS AND FUNGAL GROWTH IN SEEDLING PINUS PONDEROSA. Environmental and Experimental Botany 37(2-3):73-83, (1997).
Description:
The effects of elevated CO-2 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 times 3 factorial with a treatment missing; plants were exposed to ambient (apprxeq 365 mu-mol mol-1) air or ambient air plus either 175 or 350 mu-mol mol-1 CO-2 and three levels of N addition (0, 100 and 200 kg ha-l year-1). By the second year, elevated CO-2 increased fine root occurrence and root length while N fertilization had no effect. The CO-2 times N interactions were not significant. Neither elevated CO-2 nor N fertilization altered fine root diameter. Fine root morality was increased by increasing soil N but was reduced in elevated CO-2. Highest fine root mortality occurred during summer and was lowest during winter. Elevated CO-2 increased mycorrhizal and fungal occurrence earlier than N fertilization.