Appendix A. Description of the study areas.
Inverewe (Ross and Cromarty, Scotland)Inverewe (57˚ 46' N, 5˚ 34' W) lies 3 km from the coast of Loch Ewe, which flows into the Atlantic Ocean, about 30 km southwest of Ullapool (see Fig. 1A of the main text). Current climate is maritime, with a mean annual temperature of about 9˚C (Belyea, 2007). Compared with the other study areas, the precipitation excess is large: annual precipitation is 1700 mm, whereas the annual ET (from hollows) is 380 mm (Belyea, 2007). Across the study area several sites of surface patterning occur within generally non-patterned blanket bog (Belyea, 2007) The ombrotrophic character of the study area is reflected by low values for pH and alkalinity, but the Ca:Mg ratio (on a mass basis, mg/mg) of the peatland water may indicate some influence of minerogenic water or weathering of the rock outcrops that are present in the study area (Table A1; Bragazza and Gerdol, 1999). Proximity to the Atlantic Ocean is reflected in high values of chloride (Cl) and sodium (Na) concentrations in the peatland water (Table A1). We sampled two types of pattern in this study area. The first pattern occurs on relatively flat terrain, and comprises a three-phase mosaic of hummocks, lawns and hollows, irregularly arranged in space (Fig. 1B). The second pattern occurs on peatland slopes and comprises ridges alternating with wet hollows, both features orientated along contours (Fig. 1C) Vegetation on the ridges and hummocks is characterized by Rhynchospora alba, Racomitrium lanuginosum, Calluna vulgaris, Erica tetralix, Molinia caerulea, Droserarotundifolia, D. anglica, and Sphagnum capillifolium. Vegetation in the lawns and hollows is dominated by R. alba, Carex lasiocarpa, C. limosai, C. pulicaris, Eriophorum, angustifolium, Narthecium ossifragum, Menyanthes trifoliata, and Utricularia intermedia; R. alba occurred on all ridges, hummocks, lawns, and hollows. The measurement period in this study site was from 9 August to 15 August 2007.
Degerö Stormyr (Västerbotten, Sweden)
Degerö Stormyr (64˚ 11' N, 19˚ 33' E) is on a highland between the rivers Umeälven and Vindelälven, approximately 70 km west of the Gulf of Bothnia and 300 km east of the Atlantic Ocean (Fig. 1A). The study area can be characterized as a mixed peatland system with low pH and no alkalinity in the peatland water (Table A1). However, there is also minerogenic groundwater input (Malmström 1923), which is reflected by relatively high values of the Ca: Mg ratio in the peatland water (Table A1). The influence of the Atlantic Ocean is reflected in intermediate values of Cl and Na concentrations in the peatland water (Table A1). Degerö Stormyr has a temperate cold humid climate (Nilsson et al. 2008), with a mean monthly temperature ranging between about -12˚C and +15˚C (Granberg et al. 2001). Long-term annual precipitation is 523 mm (Granberg et al. 2001). Between 2000 and 2005, annual ET in the study area ranged between 227–337 mm (in these years, precipitation ranged between 546 mm and 936 mm; Sagerfors 2007). We sampled two types of pattern in this study area. The first pattern occurs on relatively flat terrain, and comprises individual hummocks within a matrix of peatland lawn (Fig. 1D). The second pattern occurs on slopes and comprises ridges set in lawns, both features oriented along contours (Fig. 1E). Vegetation on the ridges is characterized by Pinus sylvestris, Andromeda polifolia, Betula nana, Empetrum nigrum, Eriophorum vaginatum, Vaccinium oxycoccos, Calluna vulgaris, Sphagnum balticum, S. rubellum, and S. fuscum. Trees very rarely occur on the hummocks within the pattern on flat ground. Vegetation on these hummocks is characterized by E. vaginatum, Sphagnum fuscum, and S. rubellum. For both patterns on flat ground and slopes, vegetation in the lawns is dominated by E. vaginatum, V. oxycoccos, A. polifolia, Scheuchzeria palustris, Carex limosa, Sphagnum balticum, S. majus, and S. lindbergii; E. vaginatum occurred on all ridges, hummocks and lawns. The measurement period in this study area was from 22 August to 26 August 2007.
The Great Vasyugan Bog (Siberia, Russia)
The Great Vasyugan Bog (55–59˚ N, 76–83˚ E) is the largest undisturbed peat complex in the world, covering an area of more than 5 × 104 km2 (Lapshina et al. 2001). The area is situated at the water divide between the rivers Ob and Irtish, about 200 km northeast of Novosibirsk(Fig. 1A). The study area is about 10 km from the water divide, and the relatively high values of pH, alkalinity, and Ca: Mg ratio of the peatland water (Table A1) suggest that the area is receiving water from the peatland areas closer to the water divide. The absence of marine influence is reflected in low Cl and Na concentrations in the peatland water (Table A1). Current climate is typically humid continental, with a mean monthly temperature ranging between about -20˚C and about +18˚C (Semenova and Lapshina 2001). Contrary to most regions in the boreal zone, the precipitation excess is small: annual precipitation is 500 mm, whereas the annual ET is 300–500 mm (Semenova and Lapshina 2001). We sampled only one type of pattern in this study area, on relatively flat terrain. Patterning in the Siberian study area (56˚ 18 N, 81˚ 28 E) can be characterized as a maze of ridges set in a matrix of waterlogged hollows (Fig.1F, 1G; Eppinga et al. 2008). Vegetation on the ridges is characterized by Pinus sylvestris, Chamaedaphne calyculata, Ledum palustre, and Sphagnum fuscum. The vegetation in the hollows is dominated by Carex lasiocarpa. In the study area, C. lasiocarpa occurred on all ridges and in all hollows. The measurement period in this study area was from 28 July to 31 July 2005.
Belyea, L. R. 2007. Climatic and topographic limits to the abundance of bog pools. Hydrological Processes 21:675–687.
Bragazza, L., and R. Gerdol. 1999. Hydrology, groundwater chemistry and peat chemistry in relation to habitat conditions in a peatland on the south-eastern Alps of Italy. Plant Ecology 144:243–256.
Eppinga, M. B., M. Rietkerk, W. Borren, E. D. Lapshina, W. Bleuten, and M. J. Wassen. 2008. Regular surface patterning of peatlands: confronting theory with field data. Ecosystems 11:520–536.
Granberg, G., I. Sundh, B. H. Svensson, and M. Nilsson. 2001. Effects of temperature, and nitrogen and sulfur deposition, on methane emission from a boreal peatland. Ecology 82:1982–1998.
Lapshina, E. D., E. Y. Mouldiyarov, and S. V. Vasiliev. 2001. Analyses of key area studies. Pages 23–37 in W. Bleuten and E. D. Lapshina, editors. Carbon storage and atmospheric exchange by West Siberian peatlands. Department of Physical Geography Utrecht University, Utrecht, The Netherlands.
Malmström, C. 1923. Degerö Stormyr. En botanisk, hydrologisk och utvecklingshistorisk undersökning över ett nordsvenskt myrkomplex (In Swedish with German summary). Doctoral dissertation. Department of Plant Ecology, Uppsala University, Uppsala, Sweden.
Nilsson, M. B., J. Sagerfors, I. Buffam, H. Laudon, T. Eriksson, A. Grelle, L. Klemedtsson, P. Weslien, and A. Lindroth. 2008. Contemporary carbon accumulation in an oligotrophic minerogenic peatland – a significant sink after accounting for all C-fluxes. Global Change Biology 14:2317–2332.
Sagerfors, J. 2007. Land–atmosphere exchange of CO2, water and energy at a boreal minerotrophic peatland. Doctoral dissertation. Department of Forest Ecology and Management, SLU, Acta Universitatis agriculturae Sueciae, vol. 2007, 4, Umeå, Sweden.
Semenova, N. M., and E. D. Lapshina. 2001. Pages 10–22 in W. Bleuten and E. D. Lapshina, editors. Description of the West Siberian plain. Carbon storage and atmospheric exchange by West Siberian peatlands. Department of Physical Geography, Utrecht University, Utrecht, The Netherlands.
|TABLE A1. Measured average values of water-related variables on hummocks and hollows in five pattern-localities in Scotland (on flat ground and slopes), Sweden (on flat ground and slopes) and Siberia (on flat ground only). Standard errors are given in parentheses. b.d. means that all measurements were below the detection limit.|
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