So it’s quite a contrast to visit the research sites of David Wedin, an ecology professor at the University of Nebraska-Lincoln.
On a warm summer day, Wedin lead the way to one circular plot he’s put through what he calls the “death and destruction” treatment, killed once every three years.“We actually herbicide it with Roundup, glyphosate,” Wedin said.
Inside, Hanson and his students remove the outer edges of the core sample to work with the unexposed sand grains in the middle.
After sieving the sand down to the right grain size, they treat it in several different acids to concentrate the quartz.
Wedin said during the most recent mega-drought 800 years ago, “you would have been standing at this point and looking at the largest set of moving sand dunes in the western hemisphere.”UNL scientists have spent the last 15 years dating the Sandhills through a process called optically-stimulated luminescence, which measures the energy held in sand grains.
UNL Professor Paul Hanson, a geologist with the Nebraska Geological Survey, uses this technique to study how and when the sand dunes last moved.
“So we’re simulating a severe disturbance of some kind.”Wedin’s Grassland Destabilization Experiment has been going on for about a decade on university property in north-central Nebraska.
Several test plots hold only patchy vegetation and lots of bare sand.
“What happens ecologically in that process.” Dave Wedin shows how much sand has been lost on one of his test plots recently.Even with surface vegetation killed, the stressed grasslands proved far more resilient than Wedin imagined, retaining their root systems, sand and organic matter for years.He’s now trying to revegetate the plots, which he said has been even harder:“It’s a situation where the professors come out and learn something that everybody that lives out here already knew: that it’s easier to destroy the stability out here in the Sandhills than it is to restore it once it’s lost,” Wedin said.Wedin said he’s been quite surprised by the plots killed every three years, particularly given the extreme drought in 2012.Paul Hanson and David Wedin walk through a test plot being revegetated."Our goal was to get the vegetation reestablished in a couple years to study how an ecosystem with woody vegetation worked with an ecosystem with grasses.Hanson and his colleagues drill down 60-80 feet to take core samples of the dunes, then return to their lab to study them.On the UNL campus, Hanson leads the way through a rotating door of darkness to enter the lab lit by red and amber lights.Though surprised by the resilience of the grasslands, after the fourth and fifth winters, some of the patches did start to move, "and then it just went exponential on us.We went from an inch or two and before you knew it we were losing four to five inches on average, per month," Wedin said.The Plains have experienced prolonged, and in some places severe, drought during the last several years.But could drought ever make Nebraska’s Sandhills resemble the Sahara? The Sandhills are a lush and complex grassland ecosystem sitting atop the massive Ogallala aquifer, supporting many cattle ranches and species of wildlife.