NDSU Offers Recommendations on Post-Wildfire Grazing, Rangeland Management

Nov 18, 2024

By Kevin Sedivec and Miranda Meehan

North Dakota experienced a higher number of wildfires in 2024, with more than 110,000 acres being impacted. The Ray/Tioga wildfires burned almost 89,000 acres impacting rangeland, cropland and hay land.

The state has not experienced wildfires of this magnitude since 1999. The 1999 fire occurred on Halloween Day and started in Sidney, Montana, impacting more than 70,000 acres of western North Dakota, primarily range and grazing lands.

“Confounding the impacts of this year’s wildfires on range and grazing lands is the current extreme (D3) drought that western North Dakota and eastern Montana are experiencing,” says Kevin Sedivec, North Dakota State University Extension rangeland management specialist and Central Grasslands Research Extension Center director. “Drought and fire, in combination this fall, will have a negative impact on forage production the next year.”

Forage production impacts in 2025

Fire impacts different types of plants differently. Warm-season grasses usually respond by producing greater biomass after a fire. Cool-season grasses lose vigor after a burn, creating less biomass after a fire. Flowering plants are tricky, with some increasing biomass and some reducing biomass, says Sedivec.

Woody species are even more variable with suckering types, such as buckbrush, willows, sumac, and Siberian elm, having this year’s growth removed but more suckers (basal shoots and creeping roots) next year. Trees or shrubs that die from fire include most conifers (including cedars and pines), lilac, big sage and Chinese elm.

“Because North Dakota is a cool-season, grass-dominated state, ranchers should expect about a 30% to 40% decline in forage production in 2025 due to the fire if normal spring precipitation occurs,” says Miranda Meehan, NDSU Extension livestock environmental stewardship specialist.

In a study conducted by North Dakota State University following the 1999 Halloween fire, forage production was reduced 39% the following year, which had slightly below average precipitation.

“Because these areas are also in a severe drought, cool-season grasses did not develop tillers this fall,” says Meehan. “The fall drought could create another loss of 10% to 20%, even with average spring precipitation. Given these confounding impacts, ranchers should plan for 40% to 60% less forage in 2025 on areas impacted by the fire. If dry conditions persist in 2025, forage production could be further reduced.”

Wildfire impacts on the plant community

“Although wildfires can be very destructive, the impacts of fire to the plant community will be mostly positive in the long-term,” says Sedivec. “Based on research from the U.S. Department of Agriculture’s agricultural research stations in Miles City, Montana, and Mandan, North Dakota, and research conducted by NDSU, native grasses and forbs do not experience long-term negative impacts due to fire. However, introduced invasive grasses such as Kentucky bluegrass and smooth brome can be severely injured and reduced within the population. Many woody species also do not tolerate fire, with most coniferous trees, such as cedar and Rocky Mountain juniper, killed by fire.”

One negative within the grass community is the removal of all above ground plant material, leaving soils exposed to erosion until new plant growth occurs. Based on the research from North and South Dakota, litter will be significantly reduced for the first year after fire, but back to normal by year two or three.

“Honestly, there is nothing we can do to minimize this impact, especially this coming winter,” shares Sedivec. “We can hope for winter snow to blanket our rangelands to reduce erosion and provide early moisture next spring for rapid grass growth.”

Fire will impact the green ash draws differently than grasslands. Most green ash draws in western North Dakota contain green ash, box elder and American elm. All three of these trees are classified as sprouting types, meaning even when the full canopy is burned sprouts will occur from the base of the tree or from underground rhizomes. If mature trees die, new saplings will fill the draw, but it can take three to five years, or longer, to see 10 foot tall trees.

One negative within the green ash draws will be a new flush of weeds, says Sedivec. Following the 1999 fire, NDSU found Canada thistle and hounds tongue appear in the burned draws in year two. As trees re-established and grass started filling the woodland floor, both Canada thistle and hounds tongue decline significantly by year five.

Recommendations for 2025

The primary concern for ranchers impacted by the wildfires in western North Dakota and eastern Montana will be a significant decline in forage production, says Meehan. The current extreme drought conditions will exaggerate this loss. Grazing recommendations include:

  • Grazing can occur in 2025, but spring deferment from grazing will be required. Ranchers should delay turn out until mid-June if moisture conditions are above average, end of June if moisture is average, and mid-July to early August if dry.
  • Expect a loss of forage production by 30% to 50% if moisture conditions are near normal.
  • Stocking rate could be reduced by 50% to 70% if dry conditions continue into spring. 

Fires will not have any long-term negative effects on the grassland community.

  • If droughty conditions occur next year, expect a flush of annual weeds. However, these annuals will decline in time.
  • Although litter will be reduced, it will return to normal levels unless overgrazing occurs.
  • Native grass and wildflower populations will either not change or increase in population.
  • Invasive cool-season grasses will decline, at least temporarily.
  • Nutritional value of the grass, flowers and shrubs will be greater, providing a higher quality diet through late summer.
  • Do not reseed native rangelands or perennial grass pastures.

These fires will alter the woody (trees and shrubs) plant community. Some impacts may include:

  • Conifer trees will die. This is a positive for rangelands as trees should not be found on our upland grasslands. Herbage production will increase with tree mortality.
  • Deciduous trees in green ash draws may die if fully burned; however, trees should survive fast fires that only burned the bottom trucks (and did not damage the cambium layer – first section of the tree under the bark). However, they may be more susceptible to disease and pests.
  • Most deciduous trees and many shrubs burned by these fires will re-sprout, creating new saplings even in year one. The fire may actually promote more deciduous trees and shrubs in the draw.

“Wildfire will negatively impact forage production in 2025,” concludes Sedivec. “However, with proper grazing management these sites will quickly recover forage production. Additionally, fires will likely have positive benefits to the plant community that will improve diversity and the long-term resilience of rangelands to future droughts and wildfires.”

Source : ndsu.edu
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