Drought beginning to take hold on area rangelands; June was 2nd driest June on record in Neb.
July 20, 2017
While hot, dry, and windy weather has helped the recent winter wheat harvest across the High Plains, area pasture and range conditions have lately taken a turn for the worse.
This is especially true across much of Nebraska, eastern Wyoming, and the far northeastern plains of Colorado. According to the most recent National Agricultural Statistics Service report, only 35 percent of the Cornhusker State's pastures and rangelands were in good-to-excellent condition.
Recent data released by the University of Nebraska–Lincoln's National Drought Mitigation Center (http://droughtmonitor.unl.edu/) supports this. Last week, the percentage of moderate drought (D1) in Nebraska rose to 15.8 percent of the state (7.8 million acres), up from 8.7 percent of the state (4.3 million acres) the previous week. Most D1–affected rangelands are in the southwestern part of the state (Cheyenne, Garden, Deuel, Keith, Perkins, Chase and Dundy counties). However, abnormally dry (D0) conditions are occurring across most of Nebraska, covering 75.8 percent of the state (37.5 million acres).
On the climatological side, there is also unsettling data from UNL's High Plains Regional Climate Center (https://hprcc.unl.edu/). Thirty- and 60-day Standardized Precipitation Index values across the larger region are almost entirely negative. This means that recent standardized precipitation (i.e. independent of local amount) has been significantly below average. Longer-term data also shows warming trends. In addition to a five-to-25 day increase in the frost-free season, UNL reports that statewide temperatures have risen over 1 degree Fahrenheit since 1895. When warmer temperatures are combined with dry conditions, drought can occur.
Early-warning drought models are producing similar results. Quick Drought Response Index (QuickDRI) (http://quickdri.unl.edu/) is a public weekly, satellite-based drought modeling product developed by the U.S. Geological Service. This tool is already showing widespread areas of more significant drought stress developing across much of Nebraska, as well as much of eastern Wyoming and Colorado.
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According to USGS Geographer Jesslyn Brown, based in Sioux Falls, S.D., QuickDRI serves as a sort of "drought alarm." "Instead of analyzing one drought indicator like other monitoring systems, QuickDRI looks at four … it analyzes evaporation stress, vegetation health, soil moisture and precipitation weekly," she said. Brown explained that QuickDRI is designed to allow rapid action by farmers and ranchers. "It allows people to make decisions differently, if they find out sooner," she said.
Julie Elliott, range management specialist for the Natural Resources Conservation Service, based in Holyoke, Colo., confirmed the conditions on the ground. She also recently traveled across the affected areas in Nebraska. "Things are definitely trending downward," she reported. "It's too early to know specifics; some folks have gotten spotty rains, but a general (precipitation) decrease will impact forage production."
Rangelands with sandy soils, such as the Nebraska Sandhills, as well as localized sandy sites across the greater area, are especially affected by recent conditions. This is because of a complex interaction between soil type, timing of precipitation, and vegetation type. Mitchell Stephenson, range and forage specialist at the University of Nebraska Panhandle Research and Extension Center in Scottsbluff, Neb., explained further.
According to Stephenson, it all comes down to warm- and cool-season grasses. High-quality, native sandy ecological sites are usually dominated by warm-season (C4) bunch grasses, such as little bluestem, sand dropseed, switchgrass, prairie sandreed, Indian ricegrass and Indiangrass. Cool-season (C3) grasses, such as western wheatgrass and needle-and-thread, are also present in these communities, but in smaller proportions. The C3 and C4 designations refer to the different initial molecules formed during their respective photosynthetic processes. Grasses of each photosynthetic type occupy different niches in the rangeland ecosystem.
While April and May provided some moisture, "June was extremely dry," Stephenson said. "Some areas of the Sandhills received less than 25 percent of normal precipitation in June." Reports from the National Weather Service confirmed that June 2017 was the second driest June on record in Nebraska. This had a significant effect on warm-season grasses, as they complete much of their vegetative growth in June. "June is the month for warm-season grasses to get up and going," Stephenson said. He continued, "From here on out, I don't know if those warm-season grasses will be able to compensate."
These conditions will have a negative effect on forage production. In 2012, according to UNL Panhandle Research and Extension Center station data, forage production decreased by 60 to 65 percent from normal levels because of that drought. When asked about forage reductions for 2017, Stephenson generally described future forage production as, "Definitely (there will be) a reduction, I don't know if it will be quite as bad as 2012, because this year we still got decent growth on our cool seasons, but the warm seasons will be stunted." ❖
— Schoderbek, Sterling, Colo., covers ranching, resource and agricultural issues across the grasslands of the High Plains. He is also a private range consultant at Range Horizons LLC, a firm that specializes in precision ranching, mapping and UAS operations. Reach him at email@example.com, or on his cell at (970) 520-9294.