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Accessing the effectivness of wetland restoration on cattle ranches

PIs: Betsey Boughton, Patrick Bohlen, and Hilary Swain

 

Background

USDA Wetland Reserve Program. The US Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Wetland Reserve Program (WRP) is a voluntary program offering landowners the opportunity to protect, restore, and enhance wetlands on their property. The USDA provides technical and financial support to help landowners with their wetland restoration efforts. The NRCS goal is to achieve the greatest wetland functions and values, along with optimum wildlife habitat.

 

Permanent Conservation Easements and Restoration Plans for WRP Sites at MAERC.. In a regionally competitive ranking process, two sites on Buck Island Ranch, one in the East Marsh and one in the South Marsh, encompassing a total of approximately 750 acres, were approved for the WRP under the permanent easement option.

 

The MacArthur Foundation entered into negotiations with USDA and established permanent conservation easements on these sites in 2002. Construction was completed in early 2008.

 

Evaluation of the restoration. One limitation of USDA-NRCS conservation easement programs is lack of adequate resources to monitor the success or conservation or restoration programs. Our interest in establishing WRP sites at MAERC was two fold: 1) initiate a research and monitoring program to evaluate the effectiveness of the restoration in terms of the explicitly stated goals of the WRP program, and 2) demonstrate the viability of such easements to other ranchers in the region and provide them with information of the land management and economic consequences of such an easement. Seed funded to start the research and monitoring program was obtained through a generous gift from the John D. and Catherine T. MacArthur Foundation to Archbold Biological Station.

 

Objectives

Our goal is to assess the effectiveness of ecological restoration of ~750 acres of degraded wetlands at two sites at MAERC by measuring responses to the main policy objectives of the USDA Wetland Reserve Program:

  1. Restore and protect aquatic and associated upland habitats
  2. Enhance biological diversity
  3. Increase carbon storage
  4. Improve water quality
  5. Assess impacts on sustainable economic performance of the Ranch

 

Research and Monitoring Approach

 

Restoration Sites

The WRP sites are on two locations at Buck Island Ranch: one in the East Marsh North, and one in the West 770 pasture. The East Marsh site consists of a mosaic of native and semi-native communities including: depressional sawgrass and other herbaceous marshes, wet prairies, upland savanna, hardwood hammock, calcareous wetland ecotones, and a willow swamp. The West 770 site consists of a mixture of wet prairie and bahia grass communities with a few scattered swamp trees. This site was historically mostly a bayhead swamp community, but the swamp trees were removed at various stages during the period from 1940-1980.

 

Hydrologic Conditions

In the spring of 2003 we installed 19 instrumented ground water wells at various locations inside and adjacent to the two WRP sites to collect baseline data on hydrologic conditions prior to and after implementation of the hydrologic restoration. The wells are 10 feet deep and are instrumented with small data logging pressure transducers for monitoring ground water levels as 6 hour intervals.

 

Well Locations

 

Well Locations West

 

Wetland Plant Communities

We have created a detailed plant community level digital vegetation map of the current wetland community types and their boundaries in each of the two wetland reserve sites, to enable us to test the effect of restoration on plant communities, particularly in transition zones occurring along hydrologic gradients.  Community boundaries are entered in ArcView as polygon shapefiles.  The resulting combined map serves as baseline qualitative spatially explicit data, as well as providing the basis for designing a vegetation sampling system stratified to more intensively sample the plant communities most likely to show change as a result of hydrologic restoration.

East Marsh North transect locations

 

West Marsh Transect locations

 

 

Plant communities were sampled in fall 2004 with a stratified sampling design based on sampling units of one square meter plots spaced along permanent linear transects of from 50 to 100 meters in length with sample plots at equally spaced distances (5 to 10 meters apart) along each transect. A total of 300 such plots were established along 32 transects, and sampling of these plots resulted in the identification of 156 plant taxa within 9 plant community types. Four of these are communities impacted by drainage, past soil disturbance, and altered vegetation. Five more natural communities representing less disturbed condition were identified in the East Marsh WRP site. A calcareous wet prairie was the most species rich community type, encompassing 143 identified plant taxa. The transects were sampled again in 2012 to examine vegetation change after hydrological restoration.

 

Evaluating Impacts of Cattle grazing on Restored Sites

Land managers and state agency personnel are eager for more information on using grazing as a management tool in restored wetland plant communities. Cattle is viewed as an agricultural use with potentially negative impact on restored wetland sites, but proper prescribed grazing may actually help control invasion of woody and shrub species and may also enhance plant species diversity. More information is need on the effects of cattle on these systems. We are evaluating the effects of cattle removal by placing grazing exclosures around sampling points on the permanent transects established to monitor changes in the plant community at the sites. Small grazing exclosures of 10m x 10m will be established around two randomly selected sampling plot along 20 of the transects to evaluate the effects of grazing on representative plant communities in the WRP sites. Evaluating the effects of cattle removal on wetland restoration is only a first step in evaluating grazing impacts. Further studies are needed on intensity and seasonality to develop prescribed grazing management.

Click here to download a copy of the WRP report written by Edwin