Abstract ID
hydrol29
Type
Oral
Theme
hydrol
Full title
Hydrologic Thresholds and the Persistence of Landscape Pattern in the Everglades
Abstract text
Many wetlands exhibit self-organized spatial patterns in which biotic feedbacks create a patchy landscape
mosaic, which in turn greatly enhances overall habitat value. The underlying feedbacks that create pattern are
scale-dependent; that is, pattern emerges from the coupled action of local positive feedbacks and distal negative
feedbacks, the spatial characteristics of which determine pattern geometry. The feedbacks that create and
maintain patterned wetlands are almost always linked to reciprocal biotic controls on hydrology (e.g., via peat
accretion or sedimentation) or nutrient redistribution (e.g., via evaporative gradients or flow convergence).
Since hydrologic changes and nutrient enrichment are most frequently the wetland attributes impacted by human
activities, and because landscapes can shift catastrophically from patterned to homogeneous states with changes
in exogenous drivers, understanding the link between hydrology and pattern persistence or loss is integral to
ecosystem management. The ridge-slough-tree island patterned peatland mosaic is among the most important
and charismatic features of the Everglades. Determining the hydrologic conditions (hydroperiod, water level
mean and variance, flow velocity) under which the feedbacks controlling landscape pattern are preserved is
critical to restoration. Ongoing work shows that catastrophic pattern loss occurs along multiple axes of
hydrologic modification, underscoring the need for a more comprehensive link between hydrology and
ecosystem condition than can be provided by simply setting minimum flow requirements. This talk will
examine the three primary mechanisms that underly pattern formation in this landscape: the presence of multiple
peat accretion equilibria, the distal effects of peat accretion on landscape discharge, and the animal-induced
redistribution of phosphorus. Further, it will explore the hydrologic thresholds (too dry, too wet, too stable)
that lead to catastophic pattern loss, and propose hydrologic targets (flows, levels, variances) for the restoration
and maintenance of landscape pattern.
Submission date
2009-10-21
Keywords
patterned landscape, Everglades, environmental flows, self-organization
Will be submitting paper?
No