CENTA Studentship: Temperate forest nitrogen availability, carbon uptake and future climate change

More than a quarter of recent anthropogenic CO2 emissions are absorbed by the forests. This is primarily attributed to enhanced plant growth as a result of elevated atmospheric carbon dioxide concentration (eCO2). Without forest carbon uptake, atmospheric CO2 concentration would be much higher now.

However, there is emerging evidence from 1st generation Free-air carbon dioxide enrichment (FACE) experiments (on immature trees) showed that nitrogen availability limit carbon uptake in forests. Whether nitrogen availability will limit carbon uptake in a mature forest remains unknown. But if confirmed, C uptake by terrestrial ecosystems in the future may be much less than we expected, adding tens of ppmv (15 – 150 ppmv) to the predicted 21st-century atmospheric CO2 concentration. If so, a major reduction in allowable emissions of CO2 would be required to achieve the challenging < 2oC target agreed at the UN COP21, which has profound policy and social implications.

The Birmingham Forest Research Institute’s FACE is the only 2nd-generation FACE in a temperate forest in the world. It offers a unmatchable opportunity to examine whether the availability of nitrogen may limit temperate forest carbon uptake or whether the temperate forest ecosystems are resilient to nitrogen shortage by exchanging carbon with microbiomes for N.

Aim and objectives: The aim of this project is to determine the role of nitrogen availability in carbon cycle in a temperate forest under elevated CO2. The specific objectives are:

• To determine whether BIFoR-FACE woodland is nitrogen limited
• To determine the nitrogen availability in soils and N2O emissions from the control and fumigated rings at BIFoR-FACE site.
• To examine how nitrogen availability affects the soil respiration and carbon storage at BIFoR-FACE woodland.
• Atmospheric deposition, soil and soil water, soil availble nutrients (using memberances), leaves, and roots will be collected regularly from BIFoR-FACE site. Samples will be analysed for N species and soil N2O flux will be measured continously to understand the N cycling processes in the control and fumigated rings.
• Instruments: Picarro N2O analyser for automatic N2O flux measurements; Shimadzu TOC and TON analyser; Skalar nutrient auto-analyser.
• On-going work within the research group: soil respiration is routinely monitored using Li-Cor 8100; Atmospheric deposition and soil available nutrient samples are being taken on a monthly basis.

Funding Notes

In addition to completing an online application form, you will also need to complete and submit the CENTA studentship application form available from www.centa.org.uk
CENTA studentships are for 3.5 years and are funded by the Natural Environment Research Council (NERC). In addition to the full payment of their tuition fees, successful candidates will received the following financial support.

Annual stipend, set as £14,553 for 2017/18
Research training support grant (RTSG) of £8,000
CENTA students are required to undertake 45 days training throughout their PhD including a 10 day placement.


 

References

Bernhardt E et al., 2006. Long-term effects of free air CO2 enrichment (FACE) on soil respiration. Biogeochem, 77, 91-116

Fernandez-Martinez M et al., 2014. Nutrient availability as the key regulator of global forest carbon balance. Nat Clim Change, 4, 471-476.

Hartley IP, 2014. Soil carbon: Resisting climate change. Nat Climate Change, 4, 760-761.

Hartley I et al., 2013. A potential loss of carbon associated with greater plant growth in the European Arctic. Nat Climate Change, 2, 875-879.

Jackon RB et al., 2009. Increased belowground biomass and soil CO2 fluxes after a decade of carbon dioxide enrichment in a warm-temperate forest. Ecology, 90, 3352-3366.

Medlyn B et al., 2015. Using ecosystem experiments to improve vegetation models. Nat Clim Change 5, 528-534.

Mildner, M. et al., 2015. Respiratory fluxes and fine root responses in mature Picea abies trees exposed to elevated atmospheric CO2 concentrations. Biogeochem, 124, 95-111.

Norby R et al., 2016. Model-data synthesis for the next generation of forest free-air CO2 enrichment (FACE) experiments. New Phytol 209, 1728.

Siemens J et al., 2012. Elevated air carbon dioxide concentrations increase dissolved carbon leaching from a cropland soil. Biogeochem,108, 135-148.

Van Groenigen KJ et al. 2014. Faster decomposition under increased atmospheric CO2 limits soil carbon storage. Science, 344, 508-509.