The ecological condition of geographically isolated wetlands in the southeastern United States: The relationship between landscape level assessments and macrophyte assemblages

•Isolated wetland condition assessment varied with resolution of land cover data.•Incongruence of vegetation composition and LDI scores occurs in forested landscapes.•LDI assessments may be biased toward an overestimation of reference conditions.•Remote assessments do not include important regional...

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Bibliographic Details
Published in:Ecological indicators 2016-03, Vol.62, p.191-200
Main Authors: Stuber, O. Stribling, Kirkman, L. Katherine, Hepinstall-Cymerman, Jeffrey, Martin, Glenn I.
Format: Article
Language:English
Subjects:
agricultural land
Assessments
botanical composition
Dougherty Plain
Ecological monitoring
Farmlands
Floristic quality index
Geographically isolated wetland
habitats
humans
irrigation
land cover
Land use
Landscape Development Intensity Index
Landscapes
macrophytes
plant communities
Plants (organisms)
prescribed burning
Prescribed fire
remote sensing
Vegetation
Wetland condition assessment
Wetland plant community
wetland plants
Wetlands
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Summary:•Isolated wetland condition assessment varied with resolution of land cover data.•Incongruence of vegetation composition and LDI scores occurs in forested landscapes.•LDI assessments may be biased toward an overestimation of reference conditions.•Remote assessments do not include important regional drivers such as fire history.•Conservation of ecologically intact GIWs should be a regional conservation goal. Geographically isolated wetlands (GIWs) are common features of the Dougherty Plain physiographic region in southwestern Georgia. Due to lack of protection at the state and federal levels, these wetlands are threatened by intensive agricultural and silvicultural land uses common in the region. Recently, the ecological condition of such GIWs was assessed for the southeastern United States using the Landscape Development Intensity Index (LDI), a practical assessment tool that relies on remotely sensed land use and land cover (LULC) data surrounding isolated wetlands to rapidly predict wetland condition. However, no assessments have been attempted for GIWs in the Dougherty Plain specifically. Our goal was to develop a framework to guide and refine remote assessment of wetland condition within this agriculturally intense region of the southeastern USA. In this study, we characterized human disturbances associated with isolated wetlands in the Dougherty Plain, and paired the rapid assessment of GIWs using LDI with an intensive assessment of wetland plant communities. Specifically, we: (1) examined how macrophyte assemblages and vegetation metrics vary across a human disturbance gradient in the Dougherty Plain; (2) compared multiple condition assessment outcomes using variations of the LDI method that differed in spatial extent and resolution of LULC categories; and (3) determined the predicted condition of GIWs in the Dougherty Plain as indexed by LDI and compared with region-wide assessments of GIWs of the southeastern USA. Generally, the relationship between wetland plant communities and surrounding land use supported the assumptions of the LDI index in that wetlands surrounded by agricultural land use classes featured distinct plant communities relative to those surrounded by forested land use classes. Our results indicated that finer spatial resolution of LULC data improved the predictive ability of LDI. However, based on incongruence between wetland vegetation composition and LDI scores in some forested landscapes, this study identified limitations of th
ISSN:1470-160X
1872-7034
DOI:10.1016/j.ecolind.2015.11.037