Sustained impact of drought on wet shrublands mediated by soil physical changes
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Projected climate warming may substantially increase carbon emissions from wet organic soils, contributing to a positive feedback between the terrestrial carbon cycle and climate change. Evidence suggests that in these soils the stimulation of soil respiration by warming can be sustained over long periods of time due to the large availability of C substrates. However, the long-term response of wet organic soils to drought remains uncertain. Organo-mineral soils might be particularly vulnerable, because of their limited soil moisture pool to buffer drought events. Using a whole-ecosystem climate-change experiment in North Wales (UK) we show that soil respiration in podzolic (organo-mineral) soils from wet shrublands is more vulnerable to recurrent drought than to warming, and that the drought impact does not attenuate at decadal time scales. Stimulation of soil respiration by drought was linked to major changes in soil structure that led to a 54 % reduction in water holding capacity compared to control. Bryophyte abundance was found to buffer soil moisture losses, moderating soil CO2 efflux under warming. As there was no evidence of change in plant productivity to offset the increased soil C emissions under drought, this response may result in a positive climate feedback. The results indicate the potentially critical role that changes in sub-dominant vegetation and in soil physical properties may have in determining climate change impacts on soil C dynamics.
KeywordsSoil respiration Acclimation Water retention Warming Bryophyte Calluna vulgaris Soil structure
We thank all the CEH staff members who have contributed to the experiment establishment and maintenance over the years, in particular David Williams. This research was funded by the EU projects CLIMOOR, VULCAN and INCREASE FP7-INFRASTRUCTURE-2008-1 (Grant Agreement no. 227628)—the INCREASE project. M.T.D was supported by two postdoctoral fellowships awarded by the Spanish National Science and Technology Foundation.
- Bol R, Blackwell M, Emmett BA, Reynolds B, Hall JA, Bhogal A, Ritz K ( 2011) Assessment of the response of organo-mineral soils to change in management practices. Sub-project ii of Project SP1106. UK Department of Environment and Rural Affair, London. http://sciencesearch.defra.gov.uk/. Accessed 23 June 2014
- Christensen JH, Hewitson B, Busuioc A, Chen A, Gao X, Held I, Jones R, Kolli RK, Kwon WT, Laprise R, Magaña-Rueda V, Mearns L, Menéndez CG, Räisänen J, Rinke A, Sarr A, Whetton P (2007) Regional climate projections. In: Solomon S, Qin D, Manning M, Chen MZ, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate change 2007: the physical science basis. Contribution of working group I to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Cranfield University (2014) The Soils Guide. www.landis.org.uk. Cranfield University, UK (http://www.landis.org.uk/services/soilsguide/series.cfm?serno=755). Accessed 18 Nov 2014
- Denman KL, Brasseur G, Chidthaisong A, Ciais P, Cox PM, Dickinson RE, Hauglustaine D, Heinze C, Holland E, Jacob D, Lohmann U, Ramachandran S, da Silva Dias PL, Wofsy SC, Zhang X (2007) Couplings between changes in the climate system and biogeochemistry. In: Solomon S, Qin D, Manning M, Chen MZ, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate change 2007: the physical science basis contribution of working group I to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, pp 500–587Google Scholar
- Friedlingstein P, Cox P, Betts R, Bopp L, von Bloh W, Brovkin V, Cadule P, Doney S, Eby M, Fung I, Bala G, John J, Jones C, Joos F, Kato T, Kawamiya M, Knorr W, Lindsay K, Matthews HD, Raddatz T, Rayner P, Reick C, Roeckner E, Schnitzler KG, Schnur R, Strassmann K, Weaver AJ, Yoshikawa C, Zeng N (2006) Climate–carbon cycle feedback analysis: results from the C4MIP model intercomparison. J Climate 19(14):3337–3353CrossRefGoogle Scholar
- Hall J, Curti C, Dore T, Smith R (2014) Methods for the calculation of critical loads and their exceedances in the UK, draft report to UK Department of Environment and Rural Affairs-DEFRA. http://nora.nerc.ac.uk/505595/. Accessed 25 June 2014
- Reynolds B, Chamberlain PM, Poskitt J, Woods C, Scott WA, Rowe EC, Robinson DA, Frogbrook ZL, Keith AM, Henrys PA, Black HIJ, Emmett BA (2013) Countryside Survey: national “soil change” 1978–2007 for topsoils in Great Britain—acidity, carbon, and total nitrogen status. Vadose Zone J 12(2)Google Scholar
- Sowerby A, Emmett B, Beier C, Tietema A, Peñuelas J, Estiarte M, Van Meeteren MJM, Hughes S, Freeman C (2005) Microbial community changes in heathland soil communities along a geographical gradient: interaction with climate change manipulations. Soil Biol Biochem 37(10):1805–1813CrossRefGoogle Scholar
- van Oldenborgh GJ, Collins M, Arblaster J, Christensen JH, Marotzke J, Power SB, Rummukainen M (2013) Annex I: atlas of global and regional climate projections. In: Stocker TF, Qin D, Plattner GK, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar