Hydrologic Modification and the Loss of Self-organized Patterning in the Ridge–Slough Mosaic of the Everglades
- 360 Downloads
The ridge–slough landscape of the Everglades (Florida, USA), is characterized by elevated ridges dominated by sawgrass (Cladium jamaicense) interspersed among deeper sloughs dominated by floating, submerged and emergent macrophytes and calcareous periphyton. Interactions among hydrologic conditions (water depth, hydroperiod), plant composition and production, and respiration are hypothesized to create alternative peat accretion equilibria at the point scale, while spatial interactions among patches create regular pattern at the landscape scale. Despite significant research on these interactions, few studies have examined the hypothesis that the ridge–slough landscape consists of spatially coupled alternative stable patch states, and none has used diagnostic indicators thereof to assess landscape resilience to hydrologic change. Dense random sampling of water depths (a proxy for soil elevation) along a gradient of hydrologic impairment of drained to relatively natural to impounded conditions was used to evaluate four predictions related to this hypothesis: (1) bimodal soil elevation distributions show strong fidelity to community type; (2) positive autocorrelation at short distances with negative values at longer distances; (3) strong anisotropy (diagnostic of flow orientation), and spatial structure (diagnostic of the strength of landscape self-organization); and (4) loss of these features with hydrologic modification. Our results support the hypothesis that soil elevations are strongly bimodal and anisotropic in areas with minimal hydrologic impact, and spatial autocorrelation patterns indicate the operation of scale-dependent feedbacks. These metrics change markedly with hydrologic modification, although with differences between drainage and impoundment. Moreover, changes in landform precede associated changes in vegetation, suggesting their utility as diagnostic indicators of landscape degradation and recovery.
Keywordsbiogeomorphology bi-modality scale-dependent feedbacks alternative stable states peat accretion patterned landscape
We are indebted to Elizabeth Deimeke, Jason Evans, Dina Liebowitz, Tae-goo Oh, Laura Schreeg, Lauren Long, Justin Vogel, and Adam Watts for field support, and to Sanjay Lamsal for advice on spatial analyses. This manuscript benefited greatly from comments by Maarten Eppinga, Donald DeAngelis, and Laurel Larsen. We acknowledge the support of MAP-RECOVER and the US Army Corps of Engineers through grants to the University of Florida.
- Baldwin M, Hawker HW. 1915. Soil survey of the Fort Lauderdale area, Florida. In: Field operations of the Bureau of Soils, 1915. U.S. Department of Agriculture. pp 751–98.Google Scholar
- Cohen MJ, Osborne TZ, Lamsal SJ, Clark, M. 2009a. Regional distribution of soil nutrients—hierarchical soil nutrient mapping for improved ecosystem change detection. SFWMD Report. 91 p.Google Scholar
- Cohen MJ, Watts DL, Heffernan JB, Osborne TZ. 2010. Reciprocal biotic control of hydrology, nutrient gradients and landform in the Greater Everglades. Crit Rev Environ Sci Technol (in press).Google Scholar
- Conrads PA, Roehl EA, Jr. 2007. Hydrologic record extension of water-level data in the Everglades Depth Estimation Network (EDEN) using artificial neural network models, 2000–2006. U.S. Geological Survey Open-File Report 2007-1350. 56 p (only online at http://pubs.water.usgs.gove/ofr2007-1350).
- Eppinga M, Rietkerk M, Belyea L, Nilsson M, de Ruiter P, Wassen M. 2009b. Resource contrast in patterned peatlands increases along a climatic gradient. Ecology. doi: 10.1890/09-1313.
- Givnish TJ, Volin JC, Owen D, Volin VC, Muss JD, Glaser PH. 2007. Vegetation differentiation in the patterned landscape of the central Everglades: importance of local and landscape drivers. Glob Ecol Biogeogr 17:1–19.Google Scholar
- Goovaerts P, Ed. 1997. Geostatistics for natural resources evaluation. New York: Oxford University Press. p 483.Google Scholar
- Jorczak E. 2006. Influence of hydrology on Everglades ridge and slough soil topography. Soil and Water Science. M.S. Thesis, University of Florida, Gainesville (FL), USA. 63 p.Google Scholar
- Larsen LG, Aumen C, Bernhardt V, Engel T, Givnish S, Hagerhey J, Harvey L, Leonard P, McCormick C, McVoy G, Noe M, Nungesser M, Rutchey K, Sklar F, Troxler T, Volin J, Willard D. 2010. Recent and historic drivers of landscape change in the Everglades ridge, slough, and tree island mosaic. Crit Rev Environ Sci Technol (in press).Google Scholar
- Leeds JA, Smith SM, Garrett PB. 2002. Seedbanks and their potential rold in the vegetation dynamics of a northern Everglades marsh. Florida Scientist 65:16–34.Google Scholar
- Lewis CG. 2005. Linkages among vegetative substrate quality, biomass production, and decomposition in maintaining Everglades ridge and slough vegetative communities. Soil and Water Science. M.S. Thesis, University of Florida, Gainesville (FL), USA. 58 p.Google Scholar
- Light SS, Dineen JW. 1997. Water control in the Everglades: a historical perspective. In: Davis SM, Ogden JC, Eds. Everglades: the ecosystem and its restoration. Boca Raton (FL): St. Lucie Press. pp 47–84.Google Scholar
- McVoy CW, Said WP, Obeysekeran J, Arman JV, Dreschel TW. 2010. Landscapes and hydrology of the pre-drainage Everglades. Gainesville, FL: University Press of Florida (in press).Google Scholar
- SCT. 2003. The role of flow in the Everglades ridge and slough landscape. Science Coordinating Team, Miami (FL): South Florida Ecosystem Restoration Working Group.Google Scholar
- SFWMD. 1992. Surface water improvement and management plan for the Everglades: supporting information document. West Palm Beach (FL): South Florida Water Management District.Google Scholar
- Sklar FH, Coronado-Molina CA, Gras A, Rutchey K, Gawlik DE, Crozier G, Bauman L, Hagerthy S, Shuford R, Leeds JA, Wu Y, Madden CJ, Garrett PB, Nungesser M, Korvela M, McVoy C. 2004. Ecological effects of hydrology. Everglades Consolidated Report. West Palm Beach (FL): South Florida Water Management District. pp 6–58.Google Scholar
- Zafke M. 1983. Plant communities of water conservation area 3A; baseline documentation prior to the operation of S-339 and S-340. Technical Memorandum DRE-164. West Palm Beach (FL): South Florida Water Management District. pp 1–31.Google Scholar