Mud-bottom hollows are depressions on the bog surface where Sphagnum mosses have died and peat accumulation is retarded or even replaced with loss by oxidation. Results of measurements carried out at Männikjärve Bog, central Estonia, con” rmed that peat accumulation has stopped and that in 1999–2001 the uppermost 2–3 cm thick surface layer of mud-bottom hollows became thinner by 1.95 6 0.75 mm yr21 (n = 188). Different methods revealed the corresponding carbon loss from the mud-bottom hollows 25 mm thick surface layer as 50–60 g C m22 yr21. As a result, the surface of mud-bottom hollows becomes lower as compared to surroundings with peat accumulation c. 1.5 mm yr21, and they are likely to have an important role in the differentiation of bog microtopography. Owing to the combination of a cessation in peat accumu lation, carbon loss by oxidation and increased emission of decomposition gases, mud-bottom hollows could have an important in‘ uence on the carbon budget of bogs.
Anderson, P.1997: Fire damage on blanket mires. In Tallis, J.H. , Meade, R. and Hulme, P.D. , editors, Blanket mire degradation. Causes, consequences and challenges, Proceedings, University of Manchester 9–11 April, British Ecological Society , 16–28.
2.
Bridgham, S.D. , Johnston, C.A. , Pastor, J. and Updegraff, K.1995: Potential feedbacks of northern wetlands on climate change . Bio-Science45, 262–274 .
3.
Caroll, P. and Crill, P.1997: Carbon balance of a temperate poor fen . Global Biogeochemical Cycles11, 349–356 .
4.
Charman, D.J. , Aravena, R. , Bryant, C.D. and Harkness, D.D.1999: Carbon isotope in peat, DOC, CO2, and CH4 in a Holocene peatland on Dartmoor, southwest England . Geology27, 539–542 .
5.
Clymo, R.S.1996: Assessing the accumulation of carbon in peatlands. In Laiho, R. , Laine, J. and Vasander, H. , editors, Northern peatlands in global climate change, Helsinki: The Academy of Finland , 207–212.
6.
Crill, P. , Bartlett, K. and Roulet, N. 1992: Methane flux from boreal peatlands . In Vasander, H. and Starr, M. , editors, Suo 43(4–5), Proceedings of the InternationalWorkshop on Carbon Cycling in Boreal Peatlands and Climate Change, Helsinki: Finnish Peat Society, 173–182 .
7.
Franzén, L.G.1994: Are wetlands the key to ice-age cycle enigma?Ambio23, 300–308 .
8.
Frenzel, P. and Karofeld, E.2000: CH4 emission from a hollow-ridge complex in a raised bog: the role of CH4 production and oxidation . Biogeo-chemistry51, 91–112 .
9.
Gorham, E.1991: Northern peatlands: role in the global carbon cycle and probable responses to climate warming . Ecological Applications1, 182–195 .
10.
Henrichs, S.M. and Farrington, J.W.1987: Early diagnesis of amino acids and organic matter in two coastal marine sediments . Cosmochimica Acta51, 1–15 .
11.
Ilomets, M.1996: Temporal changes of Estonian peatlands and carbon balance. In Punning, J.-M. , editor, Estonia in the system of global climate change, Tallin: Institute of Ecology , Publication 4, 65–74.
12.
Ilomets, M., Animägi, J. and Kallas, R. 1995: Estonian peatlands: a brief review of their development, state, conservation, peat resources and management. Published for the Peat Industry and Environment Conference, Pärnu, EStonia, 12–15 September. Tallinn: Ministry of Environment, Republic of Estonia, 48 pp.
13.
Karofeld, E. 1999: Formation and development of microtopography on Estonian raised bogs. Tallinn Pedagogical University, Dissertations on Natural Sciences.
14.
Karofeld, E. 2001: Transplantation experiment to study the development of mudbottoms . Proceedings of the Estonian Academy of Sciences Biology/Ecology 50, 256–268 .
15.
Karofeld, E. and Toom. M. 1999: Mud-bottoms in Männjärveve Bog, Central Estonia . Proceedings of the Estonian Academy of Sciences Biology/Ecology 48, 216–236 .
16.
Large, A.R.G. and Hamilton A.C.1991: The distribution, extent and causes of peat loss in central and northwest Ireland . Applied Geography11, 309–326 .
17.
Malmer, N. and Holm, E.1984: Variation in the C/N-quotient of peat in relation to decomposition rate and age determination with 210 Pb . Oikos43, 171–182 .
18.
Masing, V. 1958: Ida-Eesti rabade taimekooslused ja nende dnaamika. PhD thesis, University of Tartu.
19.
Masing, V.1982: On structural analysis of plant cover. In Masing, V. , editor, Peatland ecosystems, Tallinn: Valgus , 3–11.
20.
Moore, T.R. , Roulet, N.T. and Waddington, J.M.1998: Uncertainty in predicting the effect of climatic change on the carbon cycling of Canadian peatlands . Climatic Change40, 229–245 .
21.
Paasio, I. 1934: Über die Lebermoore der Hochmoore Finnlands. Annales botanici societatis zoologicae-botanicae Fennicae ‘Vanamo’ (Botanical Proceedings of the Finnish Zoological-botanical Society ‘Vanamo’) 5(10), 20–30.
22.
Post, W.M. , Emanuel, W.R. , Zinke, P.L. and Stangenberger, A.G.1982: Soil carbon pools and world life zones . Nature298, 156–159 .
23.
Tallis, J.H.1997: The Southern Pennine experience: an overview of blanket mire degradation. In Tallis, J.H. , Meade, R. and Hulme, P.D. , editors, Blanket mire Degradation. Causes, consequences and challenges. Manchester: University of Manchester , 7–15.
24.
Thomson, P.1924: Der Einfluss der Gaseruptionen auf die Oberflächenformen der Hochmoore . Botanisches Archive8, 1–2 .
25.
Tomlinson, R.W.1982: The erosion of peat in the uplands of Northern Ireland . Irish Geography14, 15–64 .
26.
Tolonen, K. and Turunen, J.1996: Accumulation rates of carbon in mires in Finland and implications for climate change . The Holocene6, 171–178 .
27.
Tyuremnov, S.N.1976: Peatlands. Moscow: Nedra .
28.
Vitt, D.H. , Halsey, L.A. , Bauer, I.E. and Campbell, C.2000: Spatial and temporal trends of carbon sequestration in peatlands of continental western Canada through the Holocene . Canadian Journal of Earth Sciences37, 683–693 .
29.
Vourlitis, G.L. and Oechel, W.C.1997: Landscape-scale CO2, H2O vapour and energy flux of moist-wet coastal tundra ecosystems over two growing seasons . Journal of Ecology85, 575–590 .
30.
Waddington, J.M. and Roulet, N.T.1996: Atmosphere-wetland carbon exchanges: scale dependency of carbon dioxide and methane exchange on the developmental topography of peatland . Global Biogeochemical Cycles10, 233–245 .
31.
Weltzin, J.F. , Harth, C. , Bridgham, S.D. , Pastor, J. and Vonderharr, M.2001: Production and microtopography of bog bryophytes: response to warming and water-table manipulations . Oecologia128, 557–565 .
32.
Yu, Z. , Campbell, I.D. , Vitt, D.H. and Apps, M.J.2001: Modelling long-term peatland dynamics. I. Concepts, review, and proposed design . Ecological Modelling145, 197–210 .
