Recently Nevada Bureau of Land Management (BLM) State Director Jon Raby suggested that the agency will try “targeted grazing” among other methods to reduce wildfires in the sagebrush ecosystem. Raby says the BLM is implementing this action “because of the threat of annual invasive grasses, specifically cheatgrass, play in altering fire regime conditions that intensify wildland fire frequency, duration, and size.”
The BLM’s response to cheatgrass has an analogy in the Hans Christian Anderson story about the Emperor new clothes. Only a small child is willing to say the obvious—the Emperor is naked.
We have a similar situation with regards to cheatgrass spread and livestock grazing. No one in the BLM is willing to admit the obvious– that livestock grazing is largely responsible for the spread of cheatgrass.
The reason the BLM is closed mouth about the relationship between cheatgrass spread and livestock is political, not due a lack of scientific information.
Throughout the arid West, biological soil crusts (BSC) consisting of moss, algae, lichens, and cyanobacteria cover the soil between native bunchgrasses. These crusts are very fragile and easily broken up by trampling from livestock hooves. As livestock destroy soil crusts, cheatgrass seeds can establish on the bare soil.
A second way that livestock promotes cheatgrass is by selectively grazing native bunchgrasses. Native bunchgrasses in the Great Basin evolved without large herds of grazing animals like bison. Therefore, they have few adaptations for resisting grazing pressure and are slow to recover from grazing. By selectively and preferentially grazing the native grasses, livestock gives cheatgrass a competitive advantage.
A study published in the Journal of Applied Ecology looked at 75 Great Basin sites invaded by cheatgrass found that greater grazing intensity promoted the alien’s spread. As the researchers concluded: “Evidence suggests abundant bunchgrasses limit invasions by limiting the size and connectivity of gaps between vegetation, and BSCs (biological soil crusts) appear to limit invasions within gaps.”
The study goes on to conclude: “Results also suggest that cattle grazing reduces invasion resistance by decreasing bunchgrass abundance, shifting bunchgrass composition, and thereby increasing connectivity of gaps between perennial plants while trampling further reduces resistance by reducing BSC.”
However, you won’t hear anything about this and other studies from the BLM. Just as the EPA is not allowed to mention climate change, the BLM is not permitted to say anything that could be conceived as negative about ranching.
Another ruse used by the BLM is “targeted grazing” is the idea that eliminating grasses, can reduce the spread of wildfires.
Again, the BLM’s Emperor has no clothes. What is never mentioned is that climate/weather conditions primarily drive large wildfires. Extreme fire weather with low humidity, high temperatures, extended drought, and most importantly, high winds are the primary driver of large blazes. Under such conditions, windblown embers easily cross any “fuel break” created by targeted grazing.
In a widely cited paper, Targeted Grazing in Southern Arizona: Using Cattle to Reduce Fine Fuel Loads, the researchers noted in the next to last paragraph: Although it (targeted grazing) is a promising tool for altering fire behavior, targeted grazing will be most effective in grass communities under moderate weather conditions.” In other words, livestock grazing doesn’t work under extreme fire weather conditions.
Why is this important? Because all the large fires that we seek to control or suppress only occur under extreme fire weather conditions. In other words, the very fires that all this manipulation, livestock grazing, and so forth are supposed to control are ineffective under extreme fire weather conditions.
This conclusion was recently reiterated in a recent paper on fuel breaks with the title: “The ecological uncertainty of wildfire fuel breaks: examples from the sagebrush steppe.” In that paper, the authors warn that fuel breaks are of unproven effectiveness in the face of extreme fire weather.
The BLM is hamstrung by livestock interests when it comes to protecting our natural resources. The Emperor has no clothes, but you won’t hear it from the agency.