Livestock operations are typically located in areas of highly variable weather or unfavorable soil conditions that preclude farming. In areas with highly variable climate, livestock managers can benefit from local and regional estimates of forage production. USGS researchers are quantifying livestock forage amounts, including the predicted impacts of drought, to help land managers (Federal, State, and private) make informed drought mitigation strategies. Spatial maps of expected summer forage at a resolution of 250 meters provide managers with local estimates of livestock forage for each pasture. The maps also provide regional information, which allows for regional solutions such as buying hay from areas with above normal forage, or trucking livestock to more productive areas.
A protype study was done on the Nebraska Sandhills where livestock production is a major part of the economy. Maps of expected summer livestock forage driven exclusively by weather and site conditions were produced from 2000 to the present using regression-tree modeling. Because the resultant models reflect only weather and site conditions, effects of management and disturbance are captured as the error term in model predictions. The annual modeled time series of expected annual forage production and the difference from the long-term median quantify the impacts of drought on the livestock forage availability in pounds per acre. Measures of available forage are then readily converted to animal unit months of grazing.
Near-real-time mapping of predicted summer livestock forage in late spring, with models driven by operational drought products from winter and spring, have proven highly accurate – predicting 90% of the variation in observed forage. Future efforts include extending this modeling to non-irrigated western grasslands. Current work is in conjunction with the National Drought Mitigation Center, which is seeking to include this product as an operational drought product.
Annual biomass deviation maps developed for the Sandhills Major Land Resource Area (MLRA) from 2000 to 2016. Sandhills MLRA was masked to include only desired grassland areas. Green colors represent statistically significant positive deviation from the long-term median, while red colors represent significant negative deviation.