Element Pool Changes within a Scrub-Oak Ecosystem after 11 Years of Exposure to Elevated CO(2)

The effects of elevated CO(2) on ecosystem element stocks are equivocal, in part because cumulative effects of CO(2) on element pools are difficult to detect. We conducted a complete above and belowground inventory of non-nitrogen macro- and micronutrient stocks in a subtropical woodland exposed to twice-ambient CO(2) concentrations for 11 years. We analyzed a suite of nutrient elements and metals important for nutrient cycling in soils to a depth of ∼2 m, in leaves and stems of the dominant oaks, in fine and coarse roots, and in litter. In conjunction with large biomass stimulation, elevated CO(2) increased oak stem stocks of Na, Mg, P, K, V, Zn and Mo, and the aboveground pool of K and S. Elevated CO(2) increased root pools of most elements, except Zn. CO(2)-stimulation of plant Ca was larger than the decline in the extractable Ca pool in soils, whereas for other elements, increased plant uptake matched the decline in the extractable pool in soil. We conclude that elevated CO(2) caused a net transfer of a subset of nutrients from soil to plants, suggesting that ecosystems with a positive plant growth response under high CO(2) will likely cause mobilization of elements from soil pools to plant biomass.