SAVING THE PLAYAS
There's plenty of reason for keeping these shallow lakes healthy.
Written by Jeff Stoughton
There's plenty of reason for keeping these shallow lakes healthy.
Birdwatchers in the Arctic and Mexico are probably unaware of small, shallow lakes scattered across the Great Plains. But these playas (Spanish for beaches) play an important role for migratory birds and other wildlife.
Playas are so important, in fact, that patterns of birds migrating in the Central Flyway form an hourglass shape, narrowing in the Southern High Plains where most playas can be found. The Central Flyway is one of four main north-south corridors used by migrating birds in the U.S. But birds aren’t the only wildlife playas serve here.
Texas Tech researchers are finding ways to help stop the damage done to these lakes by sediment that runs off plowed fields. Sediment fills in the lakes and decreases the amount of time they hold water.
Loren Smith, Kleberg professor of wildlife ecology, says sedimentation is among the biggest threats to playa lakes today. He and other researchers are working on several projects to study the effect of erosion on the playas and, in turn, on the animals and plants that need them.
Among these projects is an Environmental Protection Agency study of climate and humans and their effect on playas. There’s also a National Science Foundation project to study amphibian diseases and how they are related to stress caused when the playas are filled with sediment.
The researchers spend many hours weekly at each playa they study, noting details about the flora and fauna there. Birds are counted using a spotting scope from several points around the lake. Amphibian larvae and adults are collected.
Researchers from the departments of Agricultural Economics; Math and Statistics; Range, Wildlife and Fisheries; Biological Sciences; and The Institute of Environmental and Human Health are among those working to digest the data collected from the field expeditions.
A fragile system
Plowing the land leaves bare soil exposed and causes erosion. Irrigation and precipitation wash the soil into the playas since they are the lowest points in the landscape. The sediment fills them in over time, speeding up evaporation and decreasing their hydroperiod, or amount of time they hold water.
Even though most playas are shallow—not much deeper than a desk —they can have a profound effect on the surrounding area. Even a small change in depth can dramatically affect the amount of time they hold water, changing which kinds of wildlife use them. A playa that stops functioning properly has negative effects on the diversity of life using it. 
Scott McMurry, associate professor of ecotoxicology at The Institute of Environmental and Human Health, says various life forms can appear in a snap when a playa that has been dry for several years finally fills with water.
“Within 24 hours of being filled up, you’ll hear several species of frogs calling,” he says.
Smith says decreased hydroperiod affects all of the wildlife associated with a particular playa. More exotic weeds sprout. Amphibians—especially salamanders, which take longer to reproduce than frogs—have a shorter time to breed and thus decline in number. Waterfowl can no longer use the lakes as rest stops during their long migratory voyage.
Rest and Recharge
Smith began his research on playa lakes as an assistant professor at Texas Tech in 1984. He wanted to determine the significance of playas to migratory birds, especially ducks.
He found that playas are a key part of the migration path for ducks, geese and cranes, and the birds fared better here in wet years than when rain was scarce.
Smith and colleagues wanted to find what factors besides rainfall were affecting the amount of time a playa holds water. He found sedimentation is a key player. The erosion caused by crop runoff changes which plants can grow in and around the lake and, in turn, the birds that are attracted there. He found perennial plant species are declining in these lakes and non-native weeds and other annuals are taking their place.
Smith and his colleagues at the U.S. Department of Agriculture’s Ag Research Service and TTU’s Department of Plant and Soil Science and Center for Water Resources are also researching playas’ effects on the Ogallala Aquifer. He believes the lakes are important recharge points for the aquifer. Researchers are using underground probes to determine the amount of water that flows from the playas into the Ogallala.
Solution
Smith says the easiest way to keep sediment out of the playas is to leave 30 to 50 yards of buffer strips —uncultivated land—around each lake. The buffer strips trap sediment and prevent it from filling the lakes. Government assistance is available for landowners who wish to plant these strips.
Removing the sediment is costly but it works. Landowners in Nebraska are focusing on dredging out the sediment because there are fewer playa lakes there than farther south. Smith says after the sediment is removed, the playas function much better than they did beforehand.
“It’s easier to prevent the damage from occurring than fix it once it’s happened, though,” he says.
Story by Jeff Stoughton; Photography by Wyman Meinzer
Researchers from the departments of Agricultural Economics (D. Willis); Math and Statistics (L. Allen, E. Allen); Range, Wildlife and Fisheries (L. Smith); Biological Sciences (M. San Francisco); The Institute of Environmental and Human Health (S. McMurry, Phil Smith),Plant and Soil Sciences (R. Zartman, W. Hudnall); Center for Water Resources (K. Rainwater) and USDA's Agricultural Research Services (D. Gitz) are among those working to digest the data collected from the field expeditions.
Related
For more information, go to: www.rw.ttu.edu/smith/playa.htm or visit the CASNR Water Center Web site.
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Photos by Wyman Meinzer
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