(6,500 – 10,000) – Early Warning of Rangelands Forage Productivity
Mountain ranges are higher elevation, and dominated by grasses that grow best below 75 degrees F. If moisture is available from monsoons, high altitude grazing areas can continue to produce forage into the summer due to generally lower temperatures. However, we know that even at high elevations, spring moisture/ slow snowmelt is absolutely critical for the total amount of forage produced. Using satellite data, we know the rate of growth of grasses slows by early July at the highest elevations ( > 10,000 ft). Even though grass continues to grow into July and may retain high nutritional quality, the rate declines after the early part of the month. This means that if you don’t get good early growth, you are unlikely to make it up even with monsoons.
At lower elevations 6,500-8,500, the rate of growth slows by late June, again pointing to the importance of cool, wet springs and a slow runoff for forage production.
From a planning perspective, the summer forecasts will provide little information on if monsoons will come. Some people rely on assessing the timing and amount of the runoff, observing fall moisture the year before a grazing season, and/or looking at soil moisture early season. Since there is considerable uncertainty and many microclimates, the key is to rely on what is meaningful to you and you past observations.