1. Evaluating Viking eco-cultural niche variability between the Medieval Climate Optimum and the Little Ice Age Antunes Nicolas 1, William Banks 1, Francesco D’Errico 1 1 Univ. Bordeaux, PACEA, UMR 5199, F-33400 Talence, France. DEBATING SPATIAL ARCHAEOLOGY International Workshop on Landscape and Spatial Analysis in Archaeology Santander, June 8 th - 9 th, 2012

2. Ecological Niche (Hutchinson 1957) : a region in a multi-dimensional space of environmental factors that allow species survival (n-dimensional = hypervolume). => Predictive Algorithms

3. Predictive Algorithms GARP : Genetic Algorithm Rule-set Prediction ( Stockwell and Petersr, 1999) Maxent : Maximum Entropy ( Phillips et al., 2004, 2006)

4.  Obtaining a niche prediction

5. 1 – Observed presence – geographic coords. - Presence / absence or pseudo-absence - Presence only

6. 1 – Observed presence – geographic coords. - Presence / absence or pseudo-absence - Presence only  Obtaining a niche prediction

7. 1 – Observed presence – geographic coords. - Presence / absence or pseudo-absence - Presence only 2 – Environmental layers  Obtaining a niche prediction

8. 1 – Observed presence – geographic coords. - Presence / absence or pseudo-absence - Presence only 2 – Environmental layers  Obtaining a niche prediction 3 – Algorithm Run => Hypervolume calculation => Applied to each pixel.

9. Ecological Niche Estimation 3 – Algorithm Run => Hypervolume calculation => Applied to each pixel. 1 – Observed presence – geographic coords. - Presence / absence or pseudo-absence - Presence only 2 – Environmental layers  Obtaining a niche prediction

10. Predictive Algorithm Environnemental layers Culture locations Ecocultural Niche Eco-cultural Niche Modelling ( ECNM)  Replacement of Species by Culture

11. Norse Settlement

12. Collapse hypothesis

13. Isolated

14. Iron Timber Fresh water Hay Isolated Wind & Summer Drought Collapse hypothesis

15. Isolated Wind & Summer Drought Disease & Famine Iron Timber Fresh water Hay

16. Isolated Wind & Summer Drought Disease & Famine Farming Impact Collapse hypothesis Iron Timber Fresh water Hay

17. Collapse hypothesis Isolated Wind & Summer Drought Disease & Famine Farming Impact Conflict with indigenous Piracy Iron Timber Fresh water Hay

18. Collapse hypothesis Little Ice Age Isolated Wind & Summer Drought Disease & Famine Farming Impact Conflict with indigenous Piracy Iron Timber Fresh water Hay

19. first to disappear (Abandoned Sites before 1350 AD) Sites occupied during MCO and the LIA

20. MCO Settlement LIA Settlement Settlement location

21. Example: January, 801 DCE, Global simulation (Jungclaus 2010) Surface Solar RadiationSurface Temperature PrecipitationMean Barometric Pressure

22. Time Focus 1: IX / X Centuries Spatial Focus : Northern Regions Time Focus 2: XV /XVI Centuries Mean by year Mean by January Monthes Mean by April Monthes Mean by July Monthes Mean by October Monthes Mean by year Mean by January Monthes Mean by April Monthes Mean by July Monthes Mean by October Monthes 20 Climatic Variables

23. Interpolation of each 2x20 layers Var LDVar HD =>future = Statistical DownScaling

24. DEM future experiments => more topographic variables Environemental Layers 20 Climatic Variables

25. MaxentGARP MCO LIA MCO Presence probability

26. Environmental Layers (x21) ECNM Prediction => Principal Component Analysis (PCA) presence Quantifying the environmental parameters that define the predicted niche

27. MCO

28. October Precipitation July Solar Radiation January Barometric Pressure October Temperature Densities of predicted area as a function of climatic variables MCO Settlement LIA Settlement

29. October Precipitation July Solar Radiation January Mean Sea Level Pressure at the Surface October Temperature Densities of predicted area as a function of climatic variables Left offset of Niche MCO Settlement LIA Settlement

30. Perspectives Add additional variables Apply Downscaling method Compare Niche Breadth Evaluate possible niche shift

31. Gracias por su atención.