wise use of mires and peatlands - Peatland Ecology Research Group

MIRES AND PEATLANDS41differs in this respect from organic sediments likegyttjas and folisols (Blattmudde, “Waldtorf”),which originate from organic matter “falling” fromabove (planktonic material, resp. leaves andbranches) (cf. Pakarinen 1984). Peat may have asedimentary component (e.g. derived from algaein hollows, seeds and leaves, or in case of springand flood mires consisting of mineral material),but a strict sedentary component derived fromnon-aquatic plants should always be present (cf.Succow & Stegmann 2001a).10Varying with country and scientific discipline, peathas been defined as requiring a minimal content of5, 15, 30, 50, 65% or more (dry mass) of organicmaterial (cf. Andrejko et al. 1983, AgricultureCanada 1987, Driessen & Dudal 1991, Succow &Stegmann 2001b). The organic matter content isof importance for the use of peats. The differentapproaches, however, probably do not lead tostrongly different global volumes of “peat”(Joosten 1999a). The definition used here isproposed so as to provide this document with aconsistent term. The 30% is a value oftenencountered in definitions of peats and organicsoils in international literature.11Peat may contain living organisms and (livingand dead) biomass, even in deep layers, includingmicro-organisms, spores, and living roots (Cf.Belanger et al. 1988), but these do not dominate(Joosten & Couwenberg 1998).12By “organic” is meant that the material resultsfrom carbon chemical biosynthesis. Organicmaterials belong to the larger group “organogenic”materials, which include all substances that haveoriginated from organisms. For example, coralsare organogenic, but not organic, sedentates(Joosten & Couwenberg 1998).13Varying with country and scientific discipline,peatlands have been defined as having a minimumthickness of 20, 30, 45, 50 or 70 cm of peat. Thisquestion is discussed in detail in work on soilclassification – for example in Agriculture Canada1987. See also Joosten & Couwenberg 1998. Thedefinition used here is proposed so as to providethis document with a consistent definition. Itshould be noted that – to provide a uniformstandard – the inventories in §2.4 and Appendix 1use a minimum peat depth of 30 cm to which allavailable data were recalculated.14Cf. Sjörs 1948. It is difficult to test in practicewhether or not peat is accumulating. Thedominance in the vegetation of species, whoseremains are also found in peat, can together withthe incidence of almost permanent waterloggedconditions, be taken as good indicators of peatformation.15Some concepts of “mires” (e.g. the Finnish “suo”,the Russian “áîëîòî” (boloto), and the miredefinition of Löfroth 1994) in fact refer to whatwe here call “suo”.16Mires are wetlands, as peat is largely formed underwaterlogged conditions. Approximately half ofthe world‘s wetlands are peatlands (Mitsch et al.1994, Lappalainen 1996). Peatlands where peataccumulation has stopped, e.g. following drainage,are no longer mires. When drainage has beensevere, they are no longer wetlands.17Clymo 1983, Koppisch 2001.18Koppisch 2001.19Cf. Succow & Stegmann 2001a. Peat types arefurthermore distinguished on the basis of theirdegree of decomposition (cf. black peat, grey/white peat - Von Post scale), nutrient content,acidity, ash content/content of organic material(cf. Halbtorf, Volltorf, Reintorf), pedogenicalteration (cf. the German Ried, Fen, Mulm), fibrecontent (fibric, hemic, sapric), and othercharacteristics (cf. Fuchsman 1980, Andriesse1988, Succow & Stegmann 2001b).20Ball 2000.21Denny, M.W. 1993.22Moore 1993, Freeman et al. 2001.23Demchuk et al. 1995, Lyons & Alpern 1989,Cobb & Cecil 1993.24Lappalainen 199625Cf. Turunen et al. 2000a, UNESCO 1978.26Classification comprises the sorting and groupingof things into classes (“classi”-fication) on thebasis of their similarities and dissimilarities. Theclassification procedure results in a typology: asystem of categories (“types”, cf. “typ”-ology)on the basis of logical principles and functionalinterests. Classification is the process, typologyis the result. Cf. Joosten 1998.27Cf. Overbeck 1975, Gore 1983a, b, Moore 1984a,Eurola & Huttunen 1985, National WetlandsWorking Group 1988, Brinson 1993, Finlayson& Van der Valk 1995, Wheeler & Proctor 2000,Succow & Joosten 2001, http://www.imcg.net/docum/greifswa/greifs00.htm.28Dau (1823) was the first to acknowledge that bogsare fed “by merely rain and dew of heaven.”29Based on the origin of water, geogenous mireshave been further subdivided into topogenous andsoligenous mires. According to the originaldefinitions (Von Post 1926) topogenous miresdepend on topographic conditions and arerelatively independent of climate, because they“develop in terrestrialising lakes or river valleys,or at springs”. In soligenous mires, peat formationis not only induced and continued by directprecipitation, but “also by meteoric water runningoff from the surrounding terrain” (Von Post &Granlund 1926). See Table 2/2 below. In laterpublications the term “soligenous” has often beenused differently to mean “originated underinfluence of streaming groundwater” (cf. Sjörs1948) which a.o. leads to a typological switch ofspring-fed mires from “topogenous” to“soligenous”. To make the confusion even larger(cf. footnote 2), the term “soligenous” has alsobeen used to describe solely spring mires (cf.Masing 1975, Wolejko 2000).30Cf. Sjörs 1948.31Weber 1900, Gams & Ruoff 1929. Kulczyñski1949 contributed to the development of ahydrological mire typology by pointing out theimportance of water movement (Cf. Bellamy1972, Moore & Bellamy 1974, Ivanov 1981).32Succow 1981, 1983, 1999; Succow & Lange 1984,