WASHINGTON — A recent study by scientists with the Agriculture Research Service (ARS) of the USDA found that strategically applied livestock grazing in sagebrush communities can have an ecological benefit.

The scientific journal Ecosphere, published the findings by rangeland scientists at Burns, Ore., and Fort Collins, Colo., who challenged the previous notion that livestock grazing in the sagebrush steppe always negatively impacts these ecosystems.

The researchers found that proper grazing protocols can help limit both wildfire risk and invasive annual grasses. 

Scientists with the ARS stated they found that strategically applying livestock grazing prior to the occurrence of climate-induced wildfires can modify sagebrush steppe characteristics in ways that decrease fire probability and severity in the communities. The livestock practice can also promote biodiversity while reducing postfire annual grass invasion, fire-induced loss of native bunchgrasses, and fire damage to soil biocrusts, the collection of bacteria, fungi and mosses on the soil surface.

“There were concerns about the negative consequences of non-native livestock grazing in sagebrush communities, especially since these communities are experiencing unpreceded threats from invasive annual grasses, altered fire regimes, and climate change,” said Kirk Davies, ARS rangeland scientist. “But strategically applied grazing can spur desirable social-ecological outcomes such as reduced non-native annual grass invasion, decreased wildfire probability and spread, reduced fire suppression cost, and prevent undesirable ecological transformation post-fire.”

During its research, the ARS team compared moderately grazed and ungrazed sagebrush steppe and observed the grazing induced shorter flame lengths, slower rates of fire spread and smaller burning fronts.

The study also looked at annual grass-dominated rangelands and reduced flame length and rate of spread. Still another benefit of modified fire characteristics, the scientists reported, is a decrease in the area burned and overall mosaic of burned and unburned patches.

During the mid-to-late 1800s, ARS pointed out that non-native livestock like sheep, cattle and horses overused and degraded the grasses in these areas, which led to the loss of perennial grasses and forbs, reduced biodiversity, erosion, overabundant unpalatable species, and non-native plant invasions.

The researchers also found that grazing can modify competitive relationships by introducing bunchgrass seeding to favor native species recruitment. This can be particularly valuable for reestablishing sagebrush, a critical shrub for many native wildlife species.

“Recognizing livestock grazing as a tool that can achieve desired outcomes could improve our ability to achieve meaningful rangeland management outcomes in sagebrush and likely other rangeland communities,” Davies said.

Researchers emphasized the need for attention to the timing, duration, frequency and intensity of use needed to meet vegetation objectives. ARS said strategic grazing has the potential to reduce the detrimental impacts of invasive annual grasses, promote native species in introduced grasslands, and encourage native shrub recovery.