Global emissions of atmospheric CO2 and tropospheric O3 are rising and expected to impact large areas of the Earth’s forests. While CO2 stimulates net primary production, O3 reduces photosynthesis, altering plant C allocation and reducing ecosystem C storage. The effects of multiple air pollutants can alter belowground C allocation, leading to changes in the partial pressure of CO2 (pCO2) in th...

The projected rise in atmospheric CO2 concentration is expected to increase growth and yield of many agricultural crops. The magnitude of this stimulus will partly depend on interactions with other components of the atmosphere such as tropospheric O3. Elevated CO2 concentrations often lessen the deleterious effects of O3, but the mechanisms responsible for this response have received little dir...

Several recent studies have indicated that an enriched atmosphere of carbon dioxide (CO2) could exacerbate the intensity of plant invasions within natural ecosystems, but little is known of how rising CO2 impacts the belowground characteristics of these invaded systems. In this study, we examined the effects of elevated CO2 and nitrogen (N) inputs on plant and soil microbial community character...

The stimulation of plant growth by elevated CO2 concentration has been widely observed. Such fertilization, and associated carbon storage, could dampen future increases in atmospheric CO2 levels and associated climate warming1. However, the CO2 fertilization of plant biomass may be sensitive to nitrogen supply2–4. Herein we show that in the latest decade of a long-term perennial grassland exper...

We report changes in nitrogen cycling in Florida scrub oak in response to elevated atmospheric CO2 during the ®rst 14 months of experimental treatment. Elevated CO2 stimulated above-ground growth, nitrogen mass, and root nodule production of the nitrogen-®xing vine, Galactia elliottii Nuttall. During this period, elevated CO2 reduced rates of gross nitrogen mineralization in soil, and resulted ...

The ammonia compensation point ( ) controls the direction and magnitude of NH3 exchange between plant leaves and the atmosphere. Very limited information is currently available on how responds to anticipated climate changes. Young barley plants were grown for 2 weeks at ambient (400 μmol mol(-1)) or elevated (800 μmol mol(-1)) CO2 concentration with or NH4NO3 as the nitrogen source. The concent...

were exposed to two concentrations of atmospheric CO2 (365 or 720 μmol mol) in combination with two N treatments (40 or 400 kg N ha year) and two irrigation treatments (target values of −0.5 or −1.5 MPa xylem pressure potential) in opentop chambers from March 1993 through November 1994. Irrigation treatments were imposed after seedling establishment (i.e., 19 weeks after planting). Seedlings we...