Eastern redcedar trees may look innocuous but they could potentially become a widespread threat to Nebraska's water resources.
This is particularly true in the Nebraska Sandhills, where eastern redcedars have spread more rapidly throughout the region in the past 20 years. The Sandhills is a crucial area of recharge to the Ogallala Aquifer and discharge to the Elkhorn, Loup, Niobrara and Platte rivers. In addition to threatening water resources, redcedars also threaten the Sandhills grasslands where more than half a million cattle graze, said Aaron Mittelstet, watershed hydrologist in the Department of Biological Systems Engineering at the University of Nebraska–Lincoln.
While redcedars are native to Nebraska, conservation plantings and lack of wildfires have led to the species' expansion. “Due to its drought resistance, the expansion could continue unhindered,” he added.
“There is a clear and critical need to quantify the cumulative hydrological effects of future encroachment of the redcedar on groundwater recharge and levels, on streamflows and on the cattle industry,” Mittelstet said. He and his research team are conducting a study that will assess the impact of redcedar encroachment on recharge and streamflow in the Sandhills and ultimately on the water quantity and quality in the Platte River.
“The only method to understand the complexities of the hydrological cycle in the Sandhills is to use a hydrological model to demonstrate the interaction between surface and groundwater,” said Mittelstet, a fellow in the Daugherty Water for Food Global Institute at the University of Nebraska.
A hydrologic model is a conceptual representation of a part of the water cycle. It is used for hydrologic prediction and for understanding hydrologic processes. Mittelstet and his team are using satellite and airborne imagery to quantify the current location and magnitude of redcedars in the Sandhills. The model will be created using the measurements of evapotranspiration, groundwater levels, streamflows and soil moisture.
“We will create a hydrological model to simulate multiple scenarios of future redcedar encroachment and its impact on water resources,” Mittelstet said.
Predicting the future encroachment of redcedar and its effects on the hydrologic cycle of the Sandhills will be essential to development of water policy decisions in Nebraska, he said. “This information will encourage state agencies and agricultural producers to be proactive in eliminating redcedar encroachment into the Nebraska Sandhills.”
Other research team members are Christopher Neale, Daugherty Water for Food Global Institute; Dirac Twidwell, Agronomy and Horticulture; Troy Gilmore, School of Natural Resources; and graduate students Yaser Kishawi, Biological Systems Engineering, and Nawaraj Shrestha, School of Natural Resources.
The Water Sustainability Fund and the Daugherty Water for Food Global Institute fund this research.