Biological processes controlling the development of modern peat-forming ecosystems

摘要: Abstract Although no precise modern analogue exists for the peat-forming ecosystems (mires) of Tertiary times, it is argued that principles underlying peat formation are essentially unchanged in sense a ecosystem has an incomplete decomposition process (normally because waterlogging), leaving residue organic material its overall energy-flow budget. The study modem mires therefore relevance to coal geologists. classification best achieved by reference their hydrological characteristics, particularly source water entering system. Flow-fed (rheotrophic) often relatively rich nutrients and clastic, while rainfed (ombrotrophic) poor. transition from one state other can occur during mire development involves physical elevation surface growth peat. Such have two-layered (diplotelmic) structure which layer (acrotelm) periodically aerobic, loose high hydraulic conductivity, lower (catotelm) compacted, anaerobic low conductivity. outcome precipitation landing upon raised, ombrotrophic drains elevated laterally through acrotelm. retention table dependent on poor conductivity catotelm. condition accompanied higher rates accumulation increasing acidity. It begins with isolated colonization hummock-forming plants later converge into extended cupola. This ecological may be consequence external changes, such as climatic alteration (increased precipitation: evaporation ratio) or autogenic, internal successional developments. Basin subsidence, however, eustatic sea-level rise case coastal systems, operate reverse direction prevent permanent establishment ultimately limited depth microbial respiration within As catotelm extends accumulation, total respiratory activity profile will equilibrate primary productivity slows down eventual standstill. On assumption peatland hydrology operated similar way former deep peats (and eventually coals) times explained, therefore, terms stacks sequential rather than single, continuously forming ecosystems.