Elevated atmospheric [CO2] from a natural soda spring affects the initial mineralization rates of naturally senesced C3 and C4 leaf litter
2000
Sowerby, A. | Ball, A.S. | Gray, T.R.G. | Newton, P.C.D. | Clark, H.
Naturally senesced leaves from the grasses Holcus lanatus (Yorkshire fog; C3 photosynthetic pathway) and Pennisetum clandestirum (Kikuyu; C4 photosynthetic pathway), grown in elevated atmospheric [CO2] surrounding a natural soda spring, were decomposed within respiratory chambers and the initial mineralization (0-30 days) of the litter measured. Significantly greater rates of initial mineralization of the C3 litters previously grown in elevated atmospheric [CO2] were detected compared to the C3 litters grown in ambient [CO2]. For example, within the first 15 days the rate of CO2 production from the litters grown in the elevated atmospheric [CO2] was two to five times greater than that seen from the litters grown in the ambient concentrations of CO2. The effect of elevated atmospheric [CO2] on the mineralization of the C4 litter was less pronounced, however rates of mineralization were still significantly greater from litters grown originally in elevated [CO2]. A significant decline in the C:N ratios and nitrogen content of the leaves of both the C3 and C4 grasses was observed, although analysing the relationship between the carbon and nitrogen content, or the C:N ratio, with the initial mineralization rate indicated that these litter quality parameters were not good indicators of the rate of mineralization of the litter from these grasses.
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