Study Highlights the Effects of Historic Land Use and Future Drought on Playa Wetlands

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New research funded by the Northwest CASC explores how drought may reduce the availability of playas and their role in providing climate refugia to diverse species, such as migratory birds, in the northern Great Basin region. 

clay surface of playa

Lithium-clay surface of the Clayton Valley playa, Nevada. View is looking east.

(Credit: Lisa Stillings, U.S. Geological Survey. Public domain.)

Playas are seasonal wetlands that typically remain dry throughout much of the year but provide critical wildlife habitat with food and water for both aquatic and terrestrial species. Only a small amount of precipitation is needed to flood a playa, and in the northern Great Basin (southern Oregon, southern Idaho, northern Nevada and northern Utah), that can take the form of snowmelt, rain, or surface runoff from summer thunderstorms. Hundreds of nutrient rich playas in the northern Great Basin serve as crucial resting and foraging habitat for migrating shorebirds while moist playa soils support vegetation for wildlife including pronghorn, mule deer and the federally listed species of concern greater sage grouse. However, playas altered by previous land management practices, such as livestock grazing and dredging, are now facing intensifying drought under a changing climate, conditions under which playas can only provide a fraction of the services that allow for native species to flourish.  

In a recently published study in Applied Wetland Science funded by the Northwest CASC, researchers studied 153 playas in the northern Great Basin over a 30-year period using remotely sensed surface-water data to better understand playa inundation, or flooding, trends in the region. By studying the inundation patterns of playas as climate conditions change, researchers sought to identify areas that may be altered more gradually and/or have more consistent and persistent wet periods, to provide local wildlife with drought refugia, localized drought-resistant areas that are able to sustain wildlife populations under escalating drought conditions.     

The researchers found that as droughts in the northern Great Basin become longer, more frequent and/or more severe, the less likely playas are able to hold water and that only about 6 of the 153 playas studied have the potential to serve as drought refugia. Playas identified as drought refugia based on dry-year analysis were also likely to be wet in non-drought years. However, the reverse was not necessarily true: playas that were consistently inundated during non-drought years were not necessarily found to serve as drought refugia during dry-years. Northern Great Basin playas that were larger in size, had been historically modified, and could functionally hold water, were the most likely to serve as drought refugia. These findings can help wetland managers identify playas that may serve as drought refugia for the abundance of wildlife found in the northern Great Basin as climate and land use change continues to impact this region.   

This project was funded by the Northwest CASC project “Identifying and Evaluating Refugia from Drought and Climate Change in the Pacific Northwest.” 

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