Discharge competence and pattern formation in peatlands: a meta-ecosystem model of the Everglades ridge-slough landscape.
Abstract
Regular landscape patterning arises from spatially-dependent feedbacks, and can undergo
catastrophic loss in response to changing landscape drivers. The central Everglades
(Florida, USA) historically exhibited regular, linear, flow-parallel orientation of
high-elevation sawgrass ridges and low-elevation sloughs that has degraded due to
hydrologic modification. In this study, we use a meta-ecosystem approach to model
a mechanism for the establishment, persistence, and loss of this landscape. The discharge
competence (or self-organizing canal) hypothesis assumes non-linear relationships
between peat accretion and water depth, and describes flow-dependent feedbacks of
microtopography on water depth. Closed-form model solutions demonstrate that 1) this
mechanism can produce spontaneous divergence of local elevation; 2) divergent and
homogenous states can exhibit global bi-stability; and 3) feedbacks that produce divergence
act anisotropically. Thus, discharge competence and non-linear peat accretion dynamics
may explain the establishment, persistence, and loss of landscape pattern, even in
the absence of other spatial feedbacks. Our model provides specific, testable predictions
that may allow discrimination between the self-organizing canal hypotheses and competing
explanations. The potential for global bi-stability suggested by our model suggests
that hydrologic restoration may not re-initiate spontaneous pattern establishment,
particularly where distinct soil elevation modes have been lost. As a result, we recommend
that management efforts should prioritize maintenance of historic hydroperiods in
areas of conserved pattern over restoration of hydrologic regimes in degraded regions.
This study illustrates the value of simple meta-ecosystem models for investigation
of spatial processes.
Type
Journal articleSubject
AlgorithmsConservation of Natural Resources
Ecosystem
Environmental Monitoring
Florida
Models, Theoretical
Water Movements
Wetlands
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https://hdl.handle.net/10161/8321Published Version (Please cite this version)
10.1371/journal.pone.0064174Publication Info
Heffernan, James B; Watts, Danielle L; & Cohen, Matthew J (2013). Discharge competence and pattern formation in peatlands: a meta-ecosystem model of
the Everglades ridge-slough landscape. PLoS One, 8(5). pp. e64174. 10.1371/journal.pone.0064174. Retrieved from https://hdl.handle.net/10161/8321.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
James Brendan Heffernan
Associate Professor of Ecosystem Ecology and Ecohydrology
I am interested in major changes in ecosystem structure, particularly in streams,
rivers and wetlands. My work focuses on feedbacks among ecological, physical, and
biogeochemical processes, and uses a wide range of tools and approaches. I am particularly
interested in projects that address both basic ecological theory and pressing environmental
problems. Increasingly, we are applying tools and theories developed for local ecosystems
to better understand ecological patterns and mechanisms at regi

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