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Extensive variables will be collected using four field crews. Each crew will consist of a crew leader and two technicians. We will have a vegetation crew, soils crew, mapping crew, and a linkage variable crew. The vegetation, soils, and mapping crews, will focus on collecting extensive variables listed in Table 1 (Study Plan 168.01, Objective 2); whereas the linkage variable crew will focus on collecting "special linkage" variables requested by collaborators (Study Plan 168.01, Objective 3).

The survey will focus on collecting information on 12 replicate seasonal and 12 replicate semipermanent wetlands in ground moraine (Glaciated Plains) and combined terminal/dead ice moraine (Missouri and Prairie Coteau) land forms in five wetland categories (n=240; a summary of total replication is shown in Table 2):

1. Restored wetlands 1-5 years old

   Wetlands in Conservation Reserve Program (CRP) habitats or similar grasslands restored for 1-5 years. CRP type habitats are defined as once farmed lands that have been planted back to grassland cover. Hence, study sties may or may not be enrolled in CRP contracts.

2. Restored wetlands >5-10 years old

   Wetlands in CRP or similar grasslands restored for >5-10 years.

3. Drained wetland analogue

   Drained wetland analogues are drained wetlands in CRP habitats or similar grasslands and will be similar to restored wetlands with respect to land-use history, wetland area, catchment area, and soils.

4. Nondrained wetland analogue

   Nondrained wetland analogues are nondrained wetlands (i.e., natural wetland) in CRP habitats or similar grasslands and are similar to restored wetlands with respect to land-use history, wetland area, catchment area, and soils.

5. Pristine wetland

   This wetland category was added as a special linkage variable for the U.S. Army Corps of Engineer's Waterways Experiment Station, and the Department of Agriculture's Natural Resources Conservation Service (NRCS). Pristine wetlands are defined as nondrained wetlands (i.e., natural wetland) in non-tilled (i.e., never tilled) grasslands. This may include grazed, hayland, and native prairie habitats. Hence, land-use history of pristine wetlands will differ from the other 4 categories, but will be similar with respect to wetland area, catchment area, and soils.

Study sites will be representative of wetlands restored by conservation agencies and organizations throughout the United States Prairie Pothole Region (PPR). The study area thus includes portions of Montana, North Dakota, South Dakota, Minnesota, and Iowa. We used a random-systematic sampling plan to define a representative geographic sample of wetlands along specific longitudinal and latitudinal gradients within the PPR. We used a georeferenced map stratified by three physiographic regions: Missouri Coteau, Prairie Coteau, and Glaciated Plains (Figure 1). A line was drawn through the medial portion of each physiographic region along the long axis/natural orientation of these regions (Figure 1). Along those axes, we random-systematically placed 9 sampling points in the Missouri Coteau, 3 in the Prairie Coteau, and 12 in the Glaciated Plains (Figure 1). The number of sampling points in the Coteau physiographic region's (i.e., Missouri and Prairie) were allocated proportionately based on the linear length (km) of each physiographic region. We selected one seasonal and one semipermanent wetland in each wetland treatment group nearest each random point that met the following criteria:

1. Similar size (Based on NWI data for each physiographic region):
   1. Missouri Coteau: seasonal wetlands within 0.4-0.8 ha, and semipermanent wetlands within 2-4 ha.

   2. Prairie Coteau: seasonal wetlands within 0.4 - 0.6 ha, and semipermanent wetlands within 2.5 - 5.5 ha.

   3. Glaciated Plains: seasonal wetlands within 0.5-0.8 ha, and semipermanent within 2.5 - 5 ha.

2. Land form:
   1. Wetlands in the Missouri and Prairie Coteau must be in ground moraine or dead ice moraine geologic land forms.

   2. Wetlands in the Glaciated Plains must be in ground moraine land forms.