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Wetland habitat persistence and transition in the southeastern United States

Status: 
Complete
Dates: 
March, 2007 to May, 2011
Wetlands habitat near Jacksonville, Florida
Development pressure on wetland habitats near Jacksonville, Florida
Wetlands are generally very productive ecosystems and provide valuable ecosystem services in the form of flood control, aquifer recharge, water-quality improvement, and carbon sequestration. These ecosystem services have become all the more important nationally given the reduction in wetland habitats that has occurred since European settlement. Of the 89.4 million ha of wetland that were present in the conterminous United States during Colonial America, less than 50% remain. 

 

Despite a diverse collection of laws, regulations, executive orders, and administrative rulings directed at wetland protection, wetland conversion continues to occur as a consequence of permitting systems, exemptions, mitigation, and enforcement problems. Between 1992 and 1997, just over 204,000 ha of palustrine and estuarine wetlands were lost in the United States with the greatest losses occurring in the South (59% of the national losses). If land-use policy and planning are to be efficient in conserving wetland habitats, it is important to identify, in a geographically explicit fashion, those areas where the risks of future wetland habitat conversion are highest. The scientists’ objective was to predict the probability of wetland loss based on local characteristics of the wetland itself (e.g., type of wetland) as well as the wetland’s landscape context (e.g., surrounding land uses).

Maps of Florida showing predicted wetland habitat loss risk
Maps of Florida showing predicted wetland habitat loss risk

Approach

Because the South is home to nearly half the wetlands occurring in the coterminous U.S., and the region where the majority of wetlands were converted during the 1990s, the scientists focused their analysis of wetland conversion risk across the South. They used data from the National Resources Inventory (NRI) to identify inventory points that were classified as wetland habitat in 1992 and that, by 1997, either remained wetland or were converted to a non-wetland status. Wetland fate (retained or converted) was thought to be influenced by both local and landscape-level processes. For this reason, they defined two sets of predictors; local predictors that were derived directly from the NRI point inventory; and landscape predictors derived from the 1992 National Land Cover Data that was based on remotely sensed imagery to characterized land use and land cover in the vicinity of wetland points. A flexible and innovative statistical modeling approach (multivariate adaptive regression splines) was used to relate wetland fate to local features of the wetland and characteristics of the surrounding landscape.

Key Findings

  • Predicted risks of wetland habitat loss were generally greater for highlands (Appalachian region and western parts of the study area) than they were for lowlands (Coastal Plains, Piedmont, Mississippi Basin). Because of their topographic and edaphic characteristics, highlands are likely to be better drained than are lowlands. Wetlands situated in highlands may therefore be less extensive and more isolated than wetlands situated in lowlands. 
  • Although, the Coastal Plain and Piedmont region was characterized by generally lower probabilities of wetland conversion relative to the highlands, there are notable areas of high risk interspersed throughout the region. 
  • Throughout the South, higher predicted risks of wetland habitat loss occurred in and near large urban areas, as illustrated by specific sites in Florida (see images associated with this project).

Implications

Because conservation resources are scarce, it is essential to focus conservation efforts where the risks for further wetland habitat loss are greatest. The scientists’ model of conversion risk can be used to inform protection efforts by helping to prioritize wetland areas for conservation. Wetland habitats with high conservation value, high conversion risk, and low prediction errors would receive the highest priority for acquisition or other forms of long-term protection.

Publications

Other

Documents and Media

Presentations

  • Land use, landscape pattern, and wildlife: implications to biodiversity conservation.  2010 RPA Assessment Findings. Invited seminar.  21-23 February 2012.  Washington, D.C.
  • A predictive model for wetland loss on private lands in the southeastern United States: implications for land-use decision making. Presentations made to the Society for Conservation Biology (13-17 July 2008); Ecological Society of American (3-8 August 2008); and the American Ornithologists’ Union (4-9 August 2008).

News articles



Project Contact: 

Principal Investigators:
Kevin J. Gutzwiller - Baylor University

Research Staff: