(< 6,500) – Early Warning of Rangelands Forage Productivity

From a range management perspective, lower elevations [below 6,500] on the western slope are some of the most challenging to manage well, and drought management is critical to protect resources. Grasses on the western slope are exposed to hotter conditions compared to those at higher elevations. They have a shorter window for growth when soils are wet enough for them to grow, and temperatures are cool enough. Even at lower elevations, the bulk of forage species on the western slope are cool-season grasses, meaning their growth stops when temperatures exceed 75 degrees.

Studies done near Canyonland National Park and Moab, Utah showed that cool, wet springs, predicted the bulk of forage growth in these lower-elevation grasses, and also that very, hot and dry summers could result in grass mortality. In these areas, previous year’s fall moisture, combined with spring conditions are key indicators (Schwinning et al.[1] 2005). The rate of growth in lower elevations (estimated below 6,000 ft) slows by late May, meaning April/ May moisture is absolutely critical for forage production.

[1] Schwinning, S, Starr, B.I, Ehleringer. (2005) Summer and winter drought in a cold desert ecosystem (Colorado Plateau) part I: effects on soil water and plant water uptake. https://www.sciencedirect.com/science/article/abs/pii/S0140196304001417