HAYS, Kan. - Rising temperatures, faster evaporation rates, and more sustained drought brought on by climate change will bring stress to water resources and particularly our wetlands. Climate change is likely to affect native plant and animal species by altering key habitats such as the wetland ecosystems known as prairie potholes or playa lakes.
The new research shows that the prairies will be much more sensitive to climate warming and drying than previously thought.
Kansas wetlands supply water for humans, help with flood control, and serve as purifying filters for larger bodies of water. Often near sources of drinkable water, wetlands trap silt, sediments, pesticides, pollutants, and toxins that would otherwise flow into streams, rivers, and lakes. Our wetlands are life sustaining for hundreds of species of birds. Some use these as rest stops and stopovers during migration, while other species depend upon them as home and primary breeding sites.
Prairie potholes are important habitats for migratory waterfowl and other wildlife, supporting more than 50% of North America's migratory waterfowl. Up to 90% of the original natural potholes have been drained in the last 100 years and converted to agriculture.
The loss of wetlands in the prairie of central North America due to a warmer and drier climate will negatively affect millions of waterfowl that depend on the region for food, shelter and raising young, according to research published in the journal BioScience.
"The impact to the millions of wetlands that attract countless ducks to these breeding grounds in spring makes it difficult to imagine how to maintain today's level of waterfowl populations in altered climate conditions," said Dr. Glenn Guntenspergen, a U.S. Geological Survey researcher and one of the report authors.
"Parents may not have time to raise their young to where they can fly because of wetlands drying up too quickly in the warming climate of the future," he added.
For example, according to the Kansas Department of Wildlife and Parks (KDWP), 27 species of ducks have been known to stop in Kansas and 14 duck species are known to nest here. The ducks are in decline now. KDWP reports that duck numbers declined from levels experienced during the 1970's, when an all time high of 10,015,000 ducks were reported during waterfowl surveys in 1972, and the average number observed each year (1970-79) was 5,820,000. In the years since, we've had as few as 1,194,000 individual ducks in Kansas.
Kansas is located in a migratory area called the Central Flyway, which is composed of ten states including Montana and North Dakota to the north, extending south through Texas and New Mexico. The decline in Kansas duck numbers is due to loss of breeding habitat in Canada and states north of Kansas, aging of our own Kansas reservoirs, and changing agricultural practices in our state. Poor habitat conditions in Kansas will continue to lower bird populations.
Though the new wetland model was developed by the authors to understand the impacts of climate change on wetlands in the "prairie pothole region," 800,000-square kilometer region in the United States (North and South Dakota, Montana, Minnesota and Iowa) and Canada, its findings can also be used to consider changes that may impact wildlife in the Central Great Plains and in Kansas too.
The Great Plains region consists of the states of North Dakota, South Dakota, Wyoming, Nebraska, Kansas, Oklahoma, and parts of Texas, Montana, Colorado and New Mexico. This is an area of strong seasonal climate variations. Over the past few decades average temperatures have risen throughout the region.
The prairie pothole region of the northern Great Plains is comprised of midgrass and tallgrass prairies containing thousands of shallow wetlands. These "potholes" were created over 10,000 years ago by glacier activity in the Wisconsin glaciation. The decaying ice sheet left behind depressions formed by the uneven deposition of till in ground moraines. The melting ice blocks which created kettle lakes - depressions filled with water, now called potholes.
Wetlands in Kansas may be even more susceptible to dry spells than the more northern wetlands. The northern states have many more lakes, ponds and undrained depressions than Kansas. Also unlike the states in the study, summers are longer and hotter in Kansas. Temperatures are projected to continue to increase over this century, with summer changes being larger than those in winter. Precipitation is also projected to change. Conditions are expected to become wetter in the north and drier in the south.
Not only is Kansas drier than states to the north, Western Kansas is much drier than Eastern Kansas. Western Kansas experiences a water deficit most years because there are few large rivers or perennial streams and less precipitation than in the east.
Many wetland species, such as waterfowl and amphibians, require a minimum time in water to complete their life cycles. For example, most dabbling ducks, such as mallards and teal, require at least 80 to 110 days of surface water for their young to grow to where they can fly and for breeding adults to complete molting, the time when birds are flightless while growing new feathers.
In addition, an abundance of wetlands are needed because breeding waterfowl typically isolate themselves from others of the same species.
"Unfortunately, the model simulations show that under forecasted climate-change scenarios for this region (an increase of 4-degrees Celsius), the western prairie potholes will be too dry and the eastern ones will have too few functional wetlands and nesting habitat to support historical levels of waterfowl and other wetland-dependent species," said Dr. W. Carter Johnson, another study author and a researcher at South Dakota State University.
The authors noted that their model allowed a more comprehensive analysis of climate change impacts across the northern prairies because it simultaneously examined the hydrology and vegetation dynamics of the wetland complex, which are both important for the wildlife that depend on the prairie potholes for part or all of their life cycles.
"Our results indicate that the prairie wetlands are highly vulnerable to climate warming, and are less resilient than we previously believed," said Guntenspergen. "All but the very wettest of the historic boom years for waterfowl production in the more arid parts of the prairie pothole region may be bust years in a 4-degrees Celsius warmer climate."
The model shows projected major reductions in water volume, shortening of the time water remains in wetlands and changes to wetland vegetation dynamics.
These findings may serve as a foundation for managers and policy makers to develop management plans to prepare for and adapt to climate change in the Great Plains.
The long term degradation and loss of wetlands and native prairie is a serious problem for both wildlife and human life.