wise use of mires and peatlands - Peatland Ecology Research Group

VALUES AND FUCTIONS OF MIRES AND PEATLANDS87“We need the tonic of wildness, - to wade sometimes in marshes where the bittern andthe meadow-hen lurk, and hear the booming of the snipe; to smell the whisperingsedge where only some wilder and more solitary fowl builds her nest, and the minkcrawls with its belly close to the ground.”Henry David Thoreau 1854cycling of material and a consequentcontinuous accumulation of organicmaterial 277 . They record their own history andthat of their wide surroundings in systematiclayers, making them particularly suited to thereconstruction of long-term human andenvironmental history 278 . The data stored inthe peat archives include macro-remains ofpeat-accumulating plants 279 , pollen andspores of plants, including those from thewider surrounding areas 280 and all sorts ofmaterials and substances that one way oranother got into the mires. Some recentdevelopments in peatland palaeo-ecology 281include the detailed reconstruction of humanlife 282 , of volcanic emissions 283 , of theatmospheric deposition of heavy metals 284and nitrogen 285 , of atmospheric CO 2concentrations 286 , and of climatic change 287and the associated role of solar forcing 288 .These recent developments illustrate that thesignificance of peatlands in this respect willincrease in future 289 .Mires and peatlands are generallycharacterised by extreme conditions, whichrequire special adaptations of the specieswhich live there. These conditions includethe scarcity of oxygen in the root layer, thepresence of toxic substances, continuouscover by peat accumulation and rising waterlevels, the immobilisation and resultingscarcity of nutrients (especially in case ofombrogenous and calcareous mires), and theazonal climatic conditions 290 .Various mire types develop sophisticated selfregulationmechanisms over time 291 andacquire an exceptional resilience againstclimatic change 292 . This means that suchmires are model examples of ecosystemswhose long-term development canfurthermore be studied with relative ease.Related features are the inherent tendency ofmires to develop complex surfacepatterning 293 and ecosystem biodiversity 294on various spatial and organisational levels(see Table 3/20). The extent to whichbiodiversity is influenced by mire size raisesquestions regarding the management andpolitical level at which decisions on mires aretaken: some types of biodiversity require(very) large areas 295 .Signalisation functions include the functionof acting as a signal or indicator 298 . Asaccumulating ecosystems, i.e. as “selfregisteringwitnesses”, mires have animportant signalisation value. The recentenvironmental impact of human activities canbe assessed by comparing the informationstored in recent peat deposits with that ofdeeper, older peat layers, where informationon the pre-human situation is stored. Aswildernesses that have been spared fromdirect human activities for a long time, miresmay offer the necessary natural “zero”references that historical cultural archivescannot provide 299 . Ombrogenous mires havea particular value in this respect, since theydepend solely on precipitation and aretherefore well suited to studies of changes in– atmospheric deposition (e.g. “acid rain”)– climatic conditions,– conditions in the cosmosphere (e.g. cosmicradiation, sun spot cycli).Special adaptations of mire plants to acquirethe necessary nutrients make these plantsuseful as environmental indicators, e.g.