FACE Underground - University of Birmingham

The FACE Underground project aims to explore if mature temperate forests can absorb more soil nutrients under higher levels of carbon dioxide (eCO2). This could indicate a significant, enduring carbon sink within these ecosystems, which is a critical unknown in current carbon models. Should our findings reveal that forests may face nutrient shortages in the future, it would signal a need for drastic reductions in greenhouse gas emissions to prevent severe climate change impacts.

Land ecosystems including forests capture about 30% of the carbon dioxide (CO₂) released by human activities. This uptake is mainly attributed to the beneficial effects of increasing atmospheric CO₂ concentrations (eCO₂) on rates of photosynthesis (the "CO₂ fertilisation effect"). Based on current CO₂ uptake rates and the predicted increases in atmospheric CO₂ concentrations, an attempt has been made to predict future Carbon (C) uptake by forests using different large-scale models. However, the model estimates are highly uncertain because we lack a clear understanding of how the limited availability of soil nutrients, particularly nitrogen (N) and phosphorus (P), regulate the CO₂ fertilisation effect. For example, incorporating nitrogen availability into models reduced predicted uptake rates of CO₂ by ~50%, which shows that previous estimates may have been optimistic. Furthermore, previous experiments have focused on young forests and to date there are no large-scale CO₂ enrichment experiments in mature temperate forests. This is important because: 1) mature forests in northern temperate regions are currently responsible for almost half (~40%) of the global net C uptake and 2) young forests may be able to increase access to nutrients by increasing root growth under eCO₂ to explore more of the soil space, whereas mature forests already have well-developed root systems, so greater carbon allocation to roots and their associated fungal partners (mycorrhizas) may have less potential to increase access to nutrients. Therefore, a realistic assessment of the role of nutrient availability in controlling the responses of mature temperate forests to eCO₂ is essential.

Given the global significance of temperate forests, the Birmingham Institute of Forest Research (BIFoR), established a CO₂ fertilization experiment (>£15 million investment) in a >160 year old deciduous forest stand in Staffordshire in 2017. This is the first such experiment in a mature temperate forests and thus provides a unique opportunity to test a key question: can mature trees gain greater access to limiting nutrients under eCO₂ and, if so, which strategies do they employ to do so? Thus, we aim to test the broad hypothesis that under eCO₂ a mature, deciduous temperate forest will transfer additional carbon below-ground to increase nitrogen and phosphorus availability and subsequent uptake by trees.

Objectives

Determine the effects of eCO₂ on below ground C allocation to different nutrient acquisition strategies including fine root production, rates and types of root exudation, and association with mycorrhizal fungi
Assess the role of these mechanisms in controlling rates of decomposition, soil microbial community function, and N and P availability.
Evaluate how N uptake capacities and preferences of tree roots change under eCO₂ and whether these changes are related to the effects of eCO₂ on N transformation rates.

The research was undertaken in three plots under eCO₂ and three control plots. We measured root and mycorrhizal hyphal production, and the release of substrates (exudates) from roots throughout the year. We also carried out a series of experiments to determine the relative roles of roots versus mycorrhizal fungi in controlling rates of decomposition and nutrient cycling, and the extent to which these are affected by eCO₂. These decomposition experiments involved root and/or mycorrhizal fungi exclusion, as well as a novel approach for simulating root exudation.

The results will enable us to determine whether, and through which mechanisms, trees can stimulate decomposition and nutrient mobilization under eCO₂. Finally, we will be able to determine if the types of nitrogen containing compounds that roots take up changes under eCO2 and how this relates to their availability in the soil.

People

Dr Sami Ullah, Principal Investigator at FACE Underground Project
Dr Michaela Reay, Research Fellow at FACE Underground Project
Dr Hannah Martin, (née Tedds), Research Technician at FACE Underground Project
Professor Iain Hartley, Professor at the University of Exeter, Co-investigator in the FACE Underground project
Dr Liz Hamilton, lecturer at the university of Birmingham, Co-investigator on the FACE Underground project
Dr Emma J. Sayer, Reader in Ecosystem Ecology at Lancaster University, Co-Investigator on the FACE Underground project
Professor Rob MacKenzie, Director at the Birmingham Institute of Forest Research, Co-investigator on the FACE Underground project

Publications

Seasonal variability of sediment controls of nitrogen cycling in an agricultural stream. Comer-Warner, SA, Gooddy, DC, Ullah S, Glover, L, Kettridge, N, Wexler, SK, Kaiser, J & Krause, S 2020, Biogeochemistry, vol. 148, no. 1, pp. 31-48.

Reply to ‘Pseudoreplication and greenhouse-gas emissions from rivers'' Comer-Warner, SA, Romeijn, P, Gooddy, DC, Ullah S, Kettridge, N, Marchant, B, Hannah, DM & Krause, S 2019, Nature Communications.

Seasonal variability of sediment controls of carbon cycling in an agricultural stream. Comer-Warner, SA, Gooddy, DC, Ullah S, Glover, L, Percival, A, Kettridge, N & Krause, S 2019, Science of the Total Environment, vol. 688, pp. 732-741.

¹⁵N-amino sugar stable isotope probing (¹⁵N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities. Michaela K. Reay., Alice F. Charteris., Davey L. Jones., and Richard P. Evershed. (2019) Soil Biology and Biochemistry. vol.138.

High resolution HPLC-MS confirms overestimation of urea in soil by the diacetyl monoxime (DAM) colorimetric method. Michaela K. Reay., Chris A. Yates., Penny J. Johnes., Christopher J. Arthur., Davey L. Jones., and Richard P. Evershed (2019) Soil Biology and Biochemistry vol.135. pp.127-133

Development of Alditol Acetate Derivatives for the Determination of ¹⁵N-Enriched Amino Sugars by Gas Chromatography–Combustion–Isotope Ratio Mass Spectrometry. Michaela K.Reay., Timothy D.J. Knowles., Davey L.Jones., and Richard P.Evershed. (2019) Analytical Chemistry, 91 (5). pp. 3397-4304.

The PRT6 N-degron pathway restricts VERNALIZATION2 to endogenous hypoxic niches to regulate plant development. Labandera, Anne-Marie., Tedds, Hannah M., Bailey, Mark., White, Mark., Sprigg, Colleen., Etherington, Ross., Akintewe, Olunwatunmise., Kalleenchurn, Geetika., Holdsworth. Michael J., and Gibbs, Daniel J. (2019) New Phytologist

The N-end rule pathway couples polycomb repressive complex 2 to environment sensing in angiosperms. Gibbs, Daniel J., Tedds, Hannah M., Labandera, Anne-Marie., Bailey, Mark., White, Mark., Hartman, Sjon., Sprigg, Colleen., Mogg, Sophie L., Osborne, Rory., Dambire, Charlene., Boeckx, Tinne., Paling, Zachary., Voesenel, Laurentius A.C.J., Flashman, Emily., and Holdsworth, Michael J. (2018) Nature Communications, 9 (1). pp. 5438.

From start to finish: amino-terminal protein modifications as degradation signals in plants. Gibbs, Daniel J., Bailey, Mark., Tedds, Hannah M., and Holdsworth, Michael J. (2016) New Phytologist, 211 (4). pp. 1188- 1194.

Persistence of soil microbial function at the rock-soil interface in degraded karst topsoils.

Wang Y, Dungait JAJ, Xing K, Green SM, Hartley IP, Tu C, Quine TA, Tian J, Kuzyakov Y (2020). LAND DEGRADATION & DEVELOPMENT, 31(2), 251-265.

Rapid root assimilation of added phosphorus in a lowland tropical rainforest of French Guiana. Van Langenhove L, Janssens IA, Verryckt L, Brechet L, Hartley IP, Stahl C, Courtois E, Urbina I, Grau O, Sardans J, et al (2020). Soil Biology and Biochemistry, 140, 107646-107646.

Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.

Parker TC, Clemmensen KE, Friggens NL, Hartley IP, Johnson D, Lindahl BD, Olofsson J, Siewert MB, Street LE, Subke J-A, et al (2020). New Phytologist.

Revisiting nutrient cycling by litterfall—Insights from 15 years of litter manipulation in old-growth lowland tropical forest. Sayer, E.J., Rodtassana, C., Sheldrake, M., Bréchet, L. M., Ashford, O. S., Lopez-Sangil, L., Kerdraon-Byrne, D., Castro, B., Turner, B. L., Wright, S. J. & Tanner, E. V. J., 1/03/2020, Tropical Ecosystems in the 21st Century. Dumbrell, A. J., Turner, E. C. & Fayle, T. M. (eds.). Academic Press, p. 173-223 51 p. (Advances in Ecological Research).

Deepened winter snow cover enhances net ecosystem exchange and stabilizes plant community composition and productivity in a temperate grassland. Li, P.,Sayer, E.J., Jia, Z., Liu, W., Wu, Y., Yang, S., Wang, C., Yang, L., Chen, D., Bai, Y. & Liu, L., 27/02/2020, (Accepted/In press) In : Global Change Biology.

Litter Inputs, but Not Litter Diversity, Maintain Soil Processes in Degraded Tropical Forests—A Cross-Continental Comparison. Kerdraon-Byrne, D., Drewer, J., Chung, A. Y. C., Majalap-Lee, N., Slade, E., Brechet, L., Wallwork, A., Castro-Trujillo, B. & Sayer, E.J., 14/01/2020, In : Frontiers in Forests and Global Change. 2, 14 p., 90.

Using green infrastructure to improve urban air quality (GI4AQ). Hewitt, CN, Ashworth, K & MacKenzie, AR 2020), Ambio, vol. 49, no. 1, pp. 62-73.

Traffic-induced multicomponent ultrafine particle microphysics in the WRF v3.6.1 large eddy simulation model: general behaviour from idealised scenarios at the neighbourhood-scale. Zhong, J, Nikolova, I, Cai, X, MacKenzie, AR, Alam, S, Xu, R, Singh, A & Harrison, R (2019), Atmospheric Environment.

Experimental vapour pressures of eight n-Alkanes (C_17, C₁₈, C₂₀, C₂₂, C₂₄, C₂₆, C₂₈ and C₃₁) at ambient temperatures. Alam, S, Nikolova, I, Singh, A, MacKenzie, AR & Harrison, R (2019), Atmospheric Environment, vol. 213, pp. 739-745.

Characteristics of free air carbon dioxide enrichment of a northern temperate mature forest. Hart, KM, Curioni, G, Blaen, P, Harper, NJ, Miles, P, Lewin, KF, Nagy, J, Bannister, EJ, Cai, XM, Thomas, RM, Krause, S, Tausz, M & MacKenzie, AR (2019), Global Change Biology.