The Western Association of Fish & Wildlife Agencies released a report declaring that invasive plants, especially cheatgrass, is an enormous threat to the sagebrush ecosystem and sage grouse. Ironically the report emphasized that invasive weeds are a threat to the livestock industry as well.
The reason it is ironic is that across the West livestock production is the primary cause of invasive plant establishment and spread as well as the demise of the sage grouse.
However, we in the western United States live behind a “Bovine Curtain” that filters out all negative news about ranching. There are many scientists funded by the government or from range departments who will extoll the benefits of livestock for sage-grouse and sagebrush ecosystems, but they fail to take a holistic ecological perspective.
Livestock production has a significant negative impact on sage grouse and sagebrush ecosystems. For instance, livestock consume the forbs which SG chicks feed upon. Cattle trampling and soil compaction is one of the causes of wetlands loss and damaged riparian areas utilized by grouse chicks. Livestock fencing has been shown to be a major cause of sage grouse mortality due to collisions. The presence of livestock has caused an increase in avian predators like ravens.
However, perhaps the biggest role that livestock plays in the extinction of sage grouse has to do with its role in the establishment and spread of cheatgrass and other annuals which increases wildfires that are consuming sagebrush landscapes.
Cheatgrass as an annual can experience a fire every year and remain viable on the site.
On the other hand, most dominant sagebrush ecosystem plants like sagebrush and many native perennial grasses historically burned infrequently, often many decades to hundreds of years between blazes. They cannot tolerate frequent blazes. With more fires, you get more acres of cheatgrass which in turn favors more fires.
Here’s what the government agencies (controlled by the livestock industry just as the tobacco industry controlled the government health agencies for years) fails to tell the public.
First, a basic tenant of “invasive” plants is that they thrive on disturbance, particularly unnatural disturbance. In the case of livestock, much of the arid West never had large herds of grazing animals such as bison which were abundant on the plains, but rare west of the Continental Divide.
As a result, the native grasses and shrubs are intolerant of livestock trampling, heavy grazing, and soil compaction.
Throughout much of this region which includes the Great Basin and Southwest deserts, the soil is typically encrusted with bacteria, algae, lichens, and mosses collectively called “biocrusts”.
Biocrusts live on the surface of the soil between the native bunchgrasses. Not only do they preclude wind and water erosion, but they also fix nitrogen from the air and release it into the soil to enrich the growth of other plants. Biocrusts also act as a soil cover that is largely impenetrable to the seeds of invasive plants like cheatgrass, thus hinder the establishment and germination of invasives.
Biocrusts are fragile and very susceptible to tramping and soil compaction. Cattle and large herds of domestic sheep can break up and destroy these crusts.
In addition to the destruction of soil crusts, domestic livestock consume native perennial grasses. Since most of the sagebrush ecosystem evolve without heavy grazing pressure, the native grasses are easily weakened by repeated cropping from domestic animals. This can eliminate them from a site, or at the least reduce their vigor so they are less competitive against invasive plants.
An honest appraisal of the real threats to our sagebrush ecosystems and sage grouse would articulate the multiple ways that livestock and ranching contribute to the degradation of this landscape. In particular, we would hear about the livestock-biocrust-cheatgrass-wildfire linkage. But until we can tear down the Bovine Curtain, there may only be an occasional radio-free West broadcast or editorial like this that makes it through the censorship of the livestock oligarchy.