Restoring Montana’s Pothole Wetlands: Demonstration Sites and Adaptive Management

Geologic processes from the last ice age have generated extensive areas of pothole wetlands in several Montana landscapes. The Laurentide ice sheet, originating in the Northwest Territories, provided the dominant force in eastern Montana. Similar landscapes developed in the broad valleys of western Montana through the actions of the Cordilleran ice sheet, originating in the mountains of British Columbia. Wetlands in these landforms have evolved in response to biotic and abiotic processes that continue to the present, providing the wetland systems we see today and that are still evolving. Pothole wetlands are some of the most valuable, yet most vulnerable, of Montana’s wetlands. Federal, state, and private programs are designed to conserve these wetlands through protection, restoration, and management. Our research collaboration is intended to provide the science needed for an increasingly important and complex wetland conservation effort.

This project will examine land use practices in relation to sedimentation, groundwater hydrology, wetland vegetation, and greenhouse gas emissions in wetlands. We are establishing a network of sites in Sheridan County, MT randomly selected from NWI maps, DOQQs, soils maps, other digital sources, and field inspection. All sites represent the same basic glacial landscapes originating 10-15,000 years before present, and we will be attempting to hold abiotic factors (such as soils, topography, geomorphology, etc.) constant. We expect that most PEMC wetlands in the area have Dimmick, McKenzie, Nishon, and similar soils. However, the immediately surrounding uplands for these soils are slightly different in their soils, slopes, etc. Stagnation moraine of the Missouri Coteau is typical in the vicinity of Comertown, MT and of particular interest to the natural resource management agencies with which we work. This is due to the thousands of wetlands, there, as well as its agricultural importance.

The management questions of scientific interest important to our modeldevelopment include:

• Can we predict whether a wetland (natural, restored, and un-restored) functions as a groundwater recharge, discharge, or flow through site based on abiotic parameters (e.g., soils, water quality, geomorphology, watershed size, topographic position, surrounding land practices, etc.) and biotic parameters (e.g., wetland plants)? Groundwater/surface water interchange is particularly important because it influences soil genesis in the long term, and marsh plant and bird community development in the short term.
• Is there a difference in sediment and recently buried A horizons in seasonal wetlands between areas in native prairie, CRP, and those in areas having been tilled (dry land wheat) for at least 25 years? Can we estimate sedimentation trajectories?
• Is deposition a function of landscape position, land use, climate, or a combination of these?
• Does removal of sediment from seasonal wetlands to restore the basin’s original morphology result in restoration of wetland hydrology and plant communities?

Prairie Pothole Repeat Photography Project
This page features repeat photography of twelve prairie wetland sites in Sheridan County, Montana. The purpose of this project is to show the seasonal variation and progression of prairie pothole vegetation under three different land use practices: Cultivated Cropland (CL), Conservation Reserve Program (CRP), and Native Prairie (NP).

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