NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
Issue link: http://mag.outdoornebraska.gov/i/604047
DECEMBER 2015 • NEBRASKAland 55 moisture, which is primarily driven by humidity and in summer also by soil moisture content as plants are actively taking up water. If the humidity is over 85 percent, prairie grass generally does not burn well. What is nice about the late summer daytime humidity is that it generally stays above 40 percent. Below this point, prairie fires can burn hot and fast. The air temperature doesn't matter all that much as long as the humidity stays high; we once did a grassland burn when it was over 100° F and it went well." Under the right conditions, Pfeiffer believes summer prescribed burns could be used nearly statewide. In large prairie landscapes, such as the Sandhills, where wildfires can burn from horizon to horizon, slow burning summer fires may be an effective and safe way to control cedars. "If a fire did escape, it would be easy to catch," said Pfeiffer. Getting southeastern Nebraska landowners to conduct summer prairie burns, however, has been a hard sell. "For many people, summer fires just seem too strange. Whoever thinks about burning in August? And cattlemen hate to give up green grass," said Pfeiffer. "If it rains or there is good soil moisture, the pastures will green up a few weeks after a burn and provide excellent forage through the fall and into early winter, a time when good forage is hard to come by." Summer fires have other advantages. High summer air temperatures increase the overall heat of fires, thus having a greater impact on woody plants than burns in other seasons. Also summer flowering and fruiting expends energy reserves reducing the post-fire sprouting ability of deciduous shrubs and trees. The tender, late-season sprouts are also susceptible to winter freeze off. Summer burns are also patchy, leaving plenty of un-burned habitat for wildlife. And because they temporarily stress the dominant warm- season grasses, seedlings of prairie wildflowers have a better chance to establish the following summer, providing long-term benefits to pollinators and other wildlife. For those Nebraska landowners tied to spring burning, it might be time to break tradition and burn out of season. ■ The Green Glacier V olatile oils in the leaves of eastern red cedar and their inability to sprout after being top-killed make them highly susceptible to fire. Prior to Euroamerican settlement of the Plains, prairie fires, set mostly by Native Americans, limited cedars to steep, fire- protected stream bluffs and islands, and in the west, rocky outcrops. Nebraska settlers acknowledged their presence with place names such as Cedar River, Cedar Rapids and Cedar Bluffs. With settlement came the control of wildfires, and cedars began creeping out from their refuges onto adjacent grasslands. After the Dust Bowl, the widespread planting of cedar windbreaks provided an abundant source of the bird- dispersed seeds and a green glacier of cedars began its spread in earnest across our state. The Nebraska Forest Service estimated that between 2005 and 2010, 25,000 acres of Nebraska grasslands were converted annually to cedar woodlands and 13,000 acres of other woodlands types, such as oak woods, were overtaken by cedars. In the Loess Hills grasslands of central Nebraska, cedar coverage can balloon from five to 90 percent in as little as 25 years. More dire, there are an estimated 300 million cedar seedlings in the state to feed the green glacier in coming years. Cedar encroachment has severe consequences for both our state's ecology and economy. "Cedars displace native prairie plants, and as little as three to 10 percent tree coverage in grasslands can cause declines in prairie chickens and other grassland bird populations," said Dr. Dirac Twidwell, a rangeland ecologist with the University of Nebraska-Lincoln. When dense, cedars can cut livestock production by as much as 75 percent and become a wildfire threat. Eastern red cedar- and Ashe juniper-fueled wildfires in Oklahoma and Texas, for example, now burn with the catastrophic intensity of California chaparral fires. Cedar control can be expensive. Mechanical cutting or shredding can cost $50 to $1,000 per acre depending on tree density and topography, whereas herbicide control is also expensive and not always effective. A complicating factor, a few years after mechanical and herbicide control, young cedars often reestablish from seed. Periodic prescribed fire is the only practical way of controlling cedars and is most effective in the early stages of infestation. When stands become tall and dense with little grass fuel remaining below, prescribed fires often lacks the intensity to kill cedars. In the Edwards Plateau of Texas, Twidwell has successfully experimented using prescribed fire under extreme burn conditions to restore cedar- and juniper- choked grasslands. "The Edwards Plateau is constant cedars. The future of the Sandhills and other Nebraska grasslands will be the same unless we band together and develop strategies for their control," said Twidwell. "No other state has effectively acted in time. Nebraska has a chance to be the first."