Roper Gates: Contingency plans for forage after fire, grasshoppers or hail
February 25, 2011
March 1 marks the beginning of meteorological spring. A glance out the window reminds us that winter is holding fast. Nonetheless, the growing season will arrive shortly and now is an appropriate time to project grazing plans for the upcoming year.
An inclusive plan will anticipate the possibility of shortages that might occur. Most are breathing a sigh of relief that widespread drought has moved out of the Northern Great Plains. However, there is always a risk of more localized “defoliation events” that complicate man’s “best laid plans.” Fall 2010 adult grasshopper surveys indicated that 2011 holds the risk of elevated grasshopper populations once again. Anticipating that probability and building contingency plans for grasshopper damage and considerations for control would be a wise addition to this year’s grazing plans. Another event that is impossible to predict is wildfire. Depending on the time of year and location, fires can eliminate vegetation from substantial areas. Again, including a contingency plan for grazing lost because of fire would be prudent.
Consideration of fire often includes questions about post-fire management. It is often suggested that grazing should be deferred, sometimes as much as an entire growing season, to allow vegetation to recover. Two recent research reports address the response of rangeland vegetation following fire.
Research conducted in northeast Colorado compared the response of shortgrass steppe vegetation when it was burned, grazed or ungrazed. Burns were conducted in March, before the start of the growing season. David Augustine and his co-authors reported that during the growing season immediately following the spring burn, production of vegetation, dominated by warm-season shortgrasses, was similar on burned and unburned sites. Vegetation sampled in late May actually had higher digestibility on burned sites, at least in part due to the removal of standing dead vegetation by the fire. During that first growing season, burned sites were either grazed or protected from grazing.
Vegetation production during the second growing season was similar on burned sites whether they had been grazed or remained ungrazed following the burn. Researchers concluded that, as long as stocking rates are moderate, vegetation dominated by warm-season shortgrasses did not seem to benefit from grazing deferment following the burn.
Another study, in Montana, examined the response of mixed grass vegetation to late summer fires. Summer fires may be most typical in the Northern Great Plains. Burns were conducted in August and repeated the second year. The post-burn growing season was described as dry following the first burn and wet following the second. Lance Vermeire and his fellow researchers found that in both situations, vegetation production and root biomass were not decreased during the growing season immediately following the fire.
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Grass species responded differentially to the burn. Annual grasses were decreased. Warm-season perennial grasses were not affected by the burn. Perennial cool-season grasses, notably western wheatgrass, increased following the fire. While needleandthread decreased in the year immediately following burning, it recovered rapidly thereafter.
In both sets of experiments, responses to fire were neutral or positive. Montana researchers concluded that precipitation had a much greater influence on vegetation production than the occurrence of a fire. In indicting how well adapted native grassland species are to the occurrence of fire, they suggested that the exclusion of fire may represent a greater disturbance than occurrence of a summer fire.
Wildfires represent a major risk and can be devastating to life and property. Careful preparation to manage wildfire and protect property and livestock are essential to ranching in the Northern Great Plains.
While loss of vegetation can be substantial, adaptation of native species to the occurrence of fire means they will recover rapidly with reasonable growing conditions. A grass stand that is vigorous before a fire occurs should not require a full grazing season to recover.
In looking forward to the coming season, contingency plans for forage shortage resulting from fire, grasshoppers or hail should prepare you for “worst case” situations. Fortunately, research indicates that losses resulting from wildfire are relatively short term.