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The shortgrass steppe is a semi-arid grassland, where elevated CO2 reduces stomatal conductance and promotes soil moisture storage. Enhanced biomass growth from elevated CO2 has been attributed in part to soil moisture effects. However, the influence of this soil moisture feedback on C cycling has received little attention. We used open-top chambers to increase atmospheric CO2 concentrations to twice-ambient for four growing seasons. Soil respiration rates and stable C isotopes of soil CO2 were measured during the third and fourth seasons. Elevated CO2 increased soil respiration rates by ?25% in a moist growing season and by ?85% in a dry season. Stable C isotope partitioning of soil respiration into its components...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: 12,
13,
American Geophysical Union,
C,
C/, All tags...
Global Biogeochemical Cycles,
decomposition,
rhizosphere respiration,
shortgrass steppe,
soil C cycling,
stable isotopes, Fewer tags
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1 The ability of drought-stressed Bouteloua gracilis H.B.K. Lag. ex Steud. to respond rapidly to a small rainfall event with increases in leaf water potential and leaf conductance directed our attention to the role of the roots in these responses. Our first objective was to determine whether new root growth was required to restore the water status to that of a non-stressed plant, following a small rainfall event. The results indicated that surviving roots were able to absorb water at approximately 40% of the rate of new roots, which was sufficient to restore non-stressed leaf water potentials within one day of watering. 2 The second objective was to estimate the rate and amount of new root growth following simulated...
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