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This article is part of the Spring 2021 issue of the Earth Science Matters Newsletter.

Aerial photo of the prairie pothole region of North American
Wetlands in the prairie pothole region of North American, while often appearing as being isolated from each other, are interconnect to each through a variety of ways including temporary surface-water flows, long-term groundwater flows, and biotic movements.

Tens of millions of dollars are invested annually into the management of wetlands and grasslands in the Prairie Pothole Region (PPR). These managed ecosystems provide critical breeding habitat for migratory waterbirds in North America. Yet, how these important managed lands will respond to and be affected by climate change is not fully understood. To better understand the Prairie Pothole wetlands USGS scientists studied:

  • how grazing and burning can affect snow accumulation in grasslands adjacent to prairie-pothole wetlands,
  • how sensitive prairie-pothole wetland water levels are to changes in precipitation, temperature, and nearby grassland management, and
  • how changes in upland management strategy could alter the impacts of climate change on prairie-pothole wetland hydrology.

The overall objective of the recent work was to estimate the effects of climate change on prairie-pothole wetland hydrology, and to explore grassland management strategies that increase surface-water inputs to wetlands to mitigate potential impacts of atmospheric warming.

map of Prairie Pothole Region
Figure 1. The Woodworth Study Area (WSA; 47º8’N, 99º14’W) lies within the Central Grasslands biome and Prairie Pothole Region (PPR) of eastern North Dakota and along the eastern edge of the Missouri Coteau physiographic region. (From USGS Open-File Report 2014-1188)

The methodological approach combined both field and modeling experiments in a portion of the Prairie Pothole Region in North Dakota, USA. First, the scientists measured the effect of grazing and burning on snow accumulation through a multiyear, multi-catchment, field experiment and incorporated observed effects of upland management on snow into a mechanistic systems-model to simulate ponded-water depth through time in a typical prairie-pothole wetland. They used this modeling approach to analyze the sensitivity of wetland ponding to changes in precipitation, temperature, and land-management strategies separately. Finally, the model was upscaled to a sub-section of the PPR with a high density of wetland basins to estimate the effect of different climate-change and land-management scenarios on the number of wetland basins that hold ponded water and subsequently provide viable waterfowl habitat during Spring breeding season.

The results showed that local wetland pond duration, and the number of wetland basins that are ponded during waterfowl breeding season in a wetland-dense section of North Dakota, are highly sensitive to changes in temperature, precipitation, and land management. Under wet-hot and dry-hot climate-change scenarios our modeling results suggested that grazing was the most effective land-management strategy to increase snowmelt and partially offset the potential pond-drying effects of climate change. However, neither the additional water inputs derived from grazing or burning could completely negate the deleterious impacts of the hot dry scenario on wetland water levels. Understanding how management actions such as grazing and burning of grasslands can impact the hydrology of adjacent wetlands is important for helping managers develop strategies for enhancing wetland water levels in the future under climate warming.

The paper, “Upland burning and grazing as strategies to offset climate-change effects on wetlands” was published in Wetlands Ecology and Management.


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