Ecological and hydrological aspects of peat formation

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Abstract
Peat formation is dependent upon an imbalance in the energetic relations of an ecosystem such that the total energy fixation by photosynthesis exceeds the total respiration on the part of the plants, animal consumers, detritivores and microbial components of the ecosystem. The imbalance comes about through the impedence of some detritivore and microbial activity as a result of the waterlogging of the environment. A knowledge of hydrological relationships in different types of mire (any freshwater wetland ecosystem in which soil organic matter accumulates) is necessary for the understanding of the rate of formation and the nature of the peat formed. A hydrological scheme for mire classification is discussed in relation to the type of peat developed from the mire types described, particularly the proportion of inorganic material incorporated into various peatland types. Two major hydrological divisions can be distinguished—those depending entirely upon rainfall for their water intake and those receiving water both by rainfall and overland drainage. The differentiation is of profound importance in terms of the inorganic (loss on ignition; ash) content of the peat, since the rain-based (ombrotrophic) system generally has a far more limited supply of inorganic material than the flow-fed (rheotrophic) one. One must seek models for coal-forming systems among ombrogenous tropical mires. Elevated peat-forming surfaces equivalent to the temperate raised mires are recorded from tropical areas and some of these bear vegetation whose physiognomy (general form and structure) resembles that of reconstructed coal forests. In these bog forests, peats of low ash content accumulate and such mires may prove to be the closest modern analogy to coalforming systems.