Bioclimatic envelope modelling of the present global distribution of Northern peatlands Angela Gallego-Sala 1 , Joanna Clark 2 , Joanna House 1 , Colin I. Prentice 1 , Pete Smith 3 , Harriet Orr 4 and Chris Freeman 2 1)QUEST Dept. of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, UK 2)School of Biological Sciences, Bangor University, ECW, Deinol Rd., Bangor, LL57 2UW, UK 3)Department of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU, Scotland, UK 4)Climate Change Team, Environment Agency, Deiniol Rd, Bangor LL57 2UW, UK 2.Experimental Approach 1. Methodology - a bioclimatic model (KLIMAT/STASH) has been adapted to delimit the spatial distribution of four different peatland ecosystems: palsa, aapa, raised and blanket mires.The programme calculates physiologically limiting variables from long-term mean monthly values of temperature, precipitation and sunshine. These bioclimatic variables are then used to decide absence/presence of species given species thresholds. 2. Previous work *Climate envelopes of mire complex types in Fennoscandia (Parvainen & Luoto, 2007) by variable partitioning *Bioclimatic models for the distribution of Shagnum dominated peatlands in North America & Canada (Gignac et al., 2000) Acknowledgements We would like to thank NERC and the Environmental Agency for their funding for this project. References CHARMAN, D. (2002) Peatlands and Environmental Change, Wiley, Chichester. GIGNAC, L. D., HALSEY, L. A. & VITT, D. H. (2000) A bioclimatic model for the distribution of Sphagnum-dominated peatlands in North America under present climatic conditions.J.Biogeog,27,1139-1151. IPCC (2007) Climate Change 2007. The Physical Science Basis. Contribution of Working Group I to the 4th Assessment Report of the IPCC (Solomons, S. et al.) Cambridge University Press, Cambridge, UK. LEEMANS, R. & CRAMER, W. (1991) The IIASA database for mean monthly values of temperature, precipitation and cloudiness of a global terrestrial grid.(IIASA). RR-91-18. LEHNER, B. & DOLL, P. (2004) Development and validation of a global database of lakes, reservoirs and wetlands. J. of Hydrol. 296(1-4):1-22 PARVIAINEN, M. & LUOTO, M. (2007) Climate envelopes of mire complex types in Fennoscandia. Geografiska Annaler Series a-Physical Geography, 89A, 137-151. SYKES, M. T., PRENTICE, I. C. & CRAMER, W. (1996) A bioclimatic model for the potential distributions of north European tree species under present and future climates. Journal of Biogeography, 23, 203-233. WIEDER, R. K. & VITT, D. H. (2006) Boreal Peatland Ecosystems, Berlin, Spring. Natural wetlands * Wetlands cover 8~10 million km 2 of the Earth’s surface (Lehner and Doll, 2004) and boreal peatlands store ~20% of the world’s carbon. * Wetlands represent 25-50% of the total methane source, i.e. 100 to 230 Tg/year of CH 4 (IPCC, 2007). Figure 2 Figure 2: Global classification of boreal : Global classification of boreal peatland (based on Wieder et al., 2006) peatland (based on Wieder et al., 2006) Research Questions: *What is the current global distribution of boreal peatlands? *Can we model the zonation of Northern peatlands at a global scale? *What are the potential changes under future climate scenarios? 1.Introduction 3.Programme Structure AET = min {Supply, Demand} Supply = Cw(Ωi-1/Ωmax) Demand = EET Rate~Energy Soil Moisture:single water KLIMAT store *Max drought index *Min Tmean *Max Tmean Peatland tresholds Peatland Survival Function Monthly mean: * Precipitation * Temperature * Cloudiness Climate 2.2 (Cramer & Leemans, 1991) Bioclimatic var: * Annual Tmean * Drought index Observed peatlands STASH Improvement by iteration Figure 3: Present day potential distribution of a) peatlands and different mire complexes b) Aapa c) Palsa d) Raised Bogs and e) Blanket Bogs simulated using STASH. 4.Preliminary Results and future work Figure 4:Global distribution of climatically suitable areas for blanket bog formation. Darker shading are areas where blanket bogs have actually been recorded (Lindsay et al (1988) in Charman, 2002). * Future work will include assessment of the model, use of TOPMODEL to evaluate % cover of wetland in each grid, and future projections using future climate change scenarios. a) b) c) d) e)