ADB Leakey, EA Ainsworth, CJ Bernacchi, X Zhu, SP Long & DR Ort (in press) Photosynthesis in a CO2 rich atmosphere. In: Photosynthesis:  A Comprehensive Treatise Physiology, Biochemistry, Biophysics and Molecular Biology. Eds: JJ Eaton-Rye and BC Tripathy. Springer.
This chapter reviews current understanding of how photosynthesis of C3 and C4 plants will respond to elevated [CO2] in the future, and the impacts this will have on ecosystem good and services.

EA Ainsworth, A Rogers, ADB Leakey, LE Heady, Y Gibon, M Stitt & U Schurr (2007) Does elevated [CO2] alter diurnal C uptake and the balance of C and N metabolites in sink and source soybean leaves? Journal of Experimental Botany 58:579-591.
Carbon and nitrogen balance was investigated in mature and growing soybean leaves exposed to elevated [CO2] in a free air CO2 enrichment facility. Elevated [CO2] alters the balance of carbon and nitrogen pools in both mature and growing soybean leaves, which could have down-stream impacts on growth and productivity.

CJ Bernacchi, ADB Leakey, LE Heady, PB Morgan, A Rogers, SP Long & DR Ort (2006) Hourly and seasonal variation in photosynthesis and stomatal conductance of soybean grown at future CO2 and ozone concentrations for three years under fully open air conditions. Plant, Cell & Environment 29:2077-2090.
In situ measurements of diurnal courses of photosynthetic gas exchange by upper canopy, mature leaves of soybean across 3 growing seasons revealed that the stimulation of photosynthesis by elevated [CO2] was positively correlated with temperature and drought stress.

ADB Leakey, CJ Bernacchi, DR Ort & SP Long (2006) Long-term growth of soybean at elevated [CO2] does not cause acclimation of stomatal conductance under fully open-air conditions. Plant, Cell & Environment 29:1794-1800.
This paper reports that there is no acclimation of stomatal function in soybean grown under elevated [CO2] and that the Ball et al (1987) model can accurately predict stomatal conductance of soybean grown under both ambient and elevated [CO2] in the field. This greatly simplifies the use of models to estimate carbon and water exchange at all scales from the leaf to the global scale, as model parameterization at each [CO2] of interest is not required.

SP Long, EA Ainsworth, ADB Leakey, J Nosberger & DR Ort (2006) Food for thought: Lower than expected crop yield stimulation with rising carbon dioxide concentrations. Science 312:1918-1921.
Model projections suggest that although increased temperature and decreased soil moisture will act to reduce global crop yields by 2050, the direct fertilization effect of rising carbon dioxide concentration ([CO2]) will offset these losses. The CO2 fertilization factors used in models to project future yields were derived from enclosure studies conducted approximately 20 years ago. Free-air concentration enrichment (FACE) technology has now facilitated large-scale trials of the major grain crops at elevated [CO2] under fully open-air field conditions. In those trials, elevated [CO2] enhanced yield by ~50% less than in enclosure studies. This casts serious doubt on projections that rising [CO2] will fully offset losses due to climate change.

ADB Leakey, M Uribelarrea, EA Ainsworth, SL Naidu, A Rogers, DR Ort & SP Long (2006) Photosynthesis, productivity and yield of Zea mays are not affected by open-air elevation of CO2 concentration in the absence of drought. Plant Physiology 140:779-790.
This paper provides unique insight into the mechanism of response of the C4 crop maize to growth at elevated [CO2]. There was no direct effect of elevated [CO2] on photosynthesis, growth or yield. However, elevated [CO2] reduced stomatal conductance and canopy evapotranspiration, which could ameliorate stress in times and places of drought.

SP Long, EA Ainsworth, CJ Bernacchi, PA Davey, GJ Hymus, ADB Leakey, PB Morgan & CP Osborne (2006) Long term responses of photosynthesis and stomata to elevated [CO2] in managed systems. In: Managed ecosystems and CO2: Case studies, processes and perspectives Ed: J N�sberger et al. Ecological Studies Series. Springer Verlag, pp. 253-270.
This synthesis of data from FACE studies concludes that stimulation of photosynthesis by elevated [CO2] is sustained in the long term (≤ 10 years) under conditions of both high and low N supply.

DR Ort, EA Ainsworth, M Aldea, DJ Allen, CJ Bernacchi, MR Berenbaum, GA Bollero, G Cornic, PA Davey, O Dermody, FG Dohleman, JG Hamilton, EA Heaton, ADB Leakey,  J Mahoney, TA Mies, PB Morgan, RL Nelson, A Rogers, AR Zangerl, X-G Zhu, EH DeLucia & SP Long (2006) SoyFACE: The effects and interactions of elevated [CO2] and [O3] on soybean. In: Managed ecosystems and CO2: Case studies, processes and perspectives Ed: J N�sberger et al. Ecological Studies Series. Springer Verlag, pp. 71-86.
This review summarizes the early results from the SoyFACE project.

SP Long, EA Ainsworth, ADB Leakey & PB Morgan (2005) Global food insecurity. Treatment of major food crops with elevated carbon dioxide and ozone under large-scale fully open-air conditions suggests models may seriously overestimate future yields. Philosophical Transactions of the Royal Society 360:2011-2020.
Free-Air Concentration Enrichment (FACE) technology now allows investigation of the effects of rising [CO2] and ozone on field crops under fully open-air conditions at an agronomic scale. Experiments with rice, wheat, maize and soybean show smaller increases in yield than anticipated from studies in chambers. Experiments with increased ozone show large yield losses (20%), which are not accounted for in projections of global food security.

ADB Leakey, JD Scholes & MC Press (2005). Physiological and ecological significance of sunflecks for dipterocarp seedlings. Journal of Experimental Botany 56:469-482.
In this synthesis I discuss evidence that for the model species Shorea leprosula seedling photosynthesis and growth may be more responsive to interactions with abiotic factors, including future changes in climate, than previously estimated. The sensitivity of seedling growth to varying patterns of dynamic irradiance, and the increased likelihood of species-specific responses through interactions with environmental factors, indicates the potential for sunflecks to influence regeneration processes, and hence forest structure and composition.

ADB Leakey, CJ Bernacchi, FG Dohleman, DR Ort & SP Long (2004) Will photosynthesis of maize (Zea mays) in the U.S. Corn Belt increase in future [CO2] rich atmospheres?  An analysis of diurnal courses of CO�2 uptake under Free-Air Concentration Enrichment (FACE). Global Change Biology 10:951-962.
This paper demonstrates that C4 photosynthesis can be stimulated by growth at elevated [CO2], but that the effect is indirect and episodic, as it is mediated by reduced stomatal conductance which lowers the demand for water and ameliorates stress during periods of drought.

ADB Leakey, JD Scholes & MC Press (2003) High temperature inhibition of photosynthesis is greater under sunflecks than uniform irradiance in a tropical rain forest tree seedling. Plant, Cell & Environment 26:1681-1690.
Greater inhibition of photosynthesis by high temperature during a shade/fleck sequence, when compared with uniform irradiance, was driven by lower efficiency of dynamic photosynthesis combined with lower steady-state rates of photosynthesis. This suggests that, contrary to current dogma, sunfleck activity may not always result in significant carbon gain.

ADB Leakey, MC Press & JD Scholes (2003) Patterns of dynamic irradiance affect the photosynthetic capacity and growth of dipterocarp tree seedlings. Oecologia 135:184-193.
This study used a manipulation of the understorey light environment in a Bornean rainforest to uniquely demonstrate that sunflecks are a heterogeneous resource affecting seedling photosynthesis and growth.

ADB Leakey, MC Press, JD Scholes & JR Watling (2002) Relative enhancement of photosynthesis and growth at elevated CO2 is greater under sunflecks than uniform irradiance in a tropical rain forest tree seedling. Plant, Cell & Environment 25:1701-1714.
Relatively greater enhancement of growth and photosynthesis at elevated CO2
under sunflecks has important potential consequences for seedling regeneration
processes and hence forest structure and composition.