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Ecohydrological feedbacks in peatland development: a theoretical modelling study
Author(s) -
Morris Paul J.,
Belyea Lisa R.,
Baird Andrew J.
Publication year - 2011
Publication title -
journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.452
H-Index - 181
eISSN - 1365-2745
pISSN - 0022-0477
DOI - 10.1111/j.1365-2745.2011.01842.x
Subject(s) - peat , ecohydrology , environmental science , anoxic waters , bog , litter , soil science , hydrology (agriculture) , atmospheric sciences , geology , ecology , ecosystem , oceanography , geotechnical engineering , biology
Summary 1. Peatlands are complex ecohydrological systems. In a theoretical modelling study we identify three ecohydrological links – commonly omitted from existing models – as potentially important to long‐term peatland development, namely those between: I oxic‐zone thickness and the rates of litter addition and depth‐integrated decay; II time‐integrated decay and hydraulic conductivity; and III drainage and peatland lateral expansion via paludification. 2. In a simple model that includes none of these links, total peat thickness increases monotonically with annual rainfall, while oxic‐zone thickness is controlled by the rates of litter addition and depth‐integrated decay. 3. In an intermediate model that includes Link I, bi‐stable behaviour occurs, with both ‘dry’ and ‘wet’ peatland forms possible at low rainfall, but only ‘wet’ peatland forms possible above a threshold value of rainfall. This finding agrees with those from a similar published model. 4. In a more complicated model that includes both Link I and Link II, the bi‐stability of the intermediate model is lost. Increases in net rainfall lead to little change in oxic‐zone thickness because the model’s feedbacks confer self‐dampening (stabilizing) behaviour. Bog height after 5000 years is maximal at an intermediate anoxic decay rate, an initially counter‐intuitive finding that reflects complex behaviour arising from the interacting feedbacks represented within the model. 5. In a final model that includes Links I, II and a partial representation of Link III, the mode of peatland lateral expansion (i.e. linear, logarithmic or step‐wise expansion) has a strong effect on patterns and rates of peat accumulation. 6. Synthesis . Understanding long‐term peatland development requires consideration of ecohydrological feedbacks; models without such feedbacks are likely to misrepresent peatland behaviour. Down‐profile changes in peat properties, commonly taken to indicate external (climatic) influences in palaeoclimatic studies, may in some cases be consequences of internal peatland dynamics under a steady climate.