, 2013), a pressing need remains to quantify the consequences of elevated atmospheric CO2 (eCO2), not only for our climate, but also to account for its impact to the global spread of plant systems sequestering CO2 via photosynthesis. Elevated CO2 has been considered a possible future driver of increased productivity in some plant systems globally via a “CO2 fertilization” effect (Fisher et al., 2013). This effect provides a mechanism whereby some climatic impacts of increasing atmospheric CO2 may be buffered by plants and ecosystems. Possible evidence for a large-scale fertilization and sequestration effect comes from the striking mismatch between the rate of increase

of anthropogenic CO2 emissions and slower check details observed changes in atmospheric concentrations, suggesting that a terrestrial “carbon sink” may be buffering CO2 increases and limiting global warming (Field, 2001). Despite the importance of this phenomenon, this sink has been poorly characterized by either experimental or modeling approaches (Norby and Zak, 2011). Hence, the specific ecosystems and ecophysiological interactions responsible are largely uncertain. Identifying the underlying mechanisms remains an international, yet elusive, research priority, particularly as the capacity for such a sink to continue to sequester additional

C is unknown (Luo et al., 2006 and Luyssaert et al., 2007). The limits of terrestrial ecosystem Cediranib (AZD2171) CDK inhibitor drugs CO2 sequestration are determined by the C dynamics of individual plant communities, particularly, rates of net primary productivity (NPP) and below-ground C transfer integrating with soil characteristics. In turn, plant productivity may be constrained by nutrient dynamics and various abiotic factors that limit growth.

These include variations in soil macro-nutrients such as nitrogen (N) and phosphorous (P) (Reich et al., 2006 and Langley and Megonigal, 2010), which differ in soil availability considerably at the global scale. Considerable uncertainties exist, therefore, in quantifying the limits of ongoing eCO2 uptake via long-term increases in plant productivity from CO2 fertilization (Karnosky, 2003). The most direct basis on which to predict such responses, however, is through eCO2 experimentation (Korner, 2006). This approach also allows key factors (such as soil nutrient characteristics) to be considered, either by exploiting differences due to spatial variability, or by direct manipulation of such factors under experimental conditions. Experimental manipulation also allows research questions to be targeted at the most appropriate ecosystems. However, field experimentation examining eCO2 effects on ecosystems has declined significantly owing to funding reductions in this area of ecology, potentially leaving important gaps in our understanding of terrestrial C dynamics and how these relate to an eCO2 future.