There is much debate in the scientific community about whether conifer “encroachment” is unnatural or due to ordinary ecological succession after massive wildfires.
Conifer removal is being promoted in the name of sage grouse recovery, though the real reason is to encourage higher forage production for livestock.
One of the myths perpetuated by the livestock industry is the notion that frequent low-severity fires occurred every 10-25 years in sagebrush ecosystems. So, the logic goes if fires were that frequent, conifers like juniper would be killed except for those growing in rocky areas where fires were limited.
There is debate about the accuracy of fire scar studies that are used to justify conifer removal. Some scientists feel the methodology of fire scar studies portray fire to be more frequent than may have occurred.
Recent research has found that wildfire in sagebrush ecosystems is far less frequent than previously assumed. Depending on the species of sagebrush, the fire rotation varies from 50-400 years.
Mountain big sage, the most common sagebrush on the Beaverhead-Deerlodge National Forest, typically burns on several-hundred-year rotations.
As a result, there are extended periods in the absence of fire when juniper or other conifers can readily colonize an area.
Furthermore, juniper burns during severe droughts on a fire rotation of 400-600 years in stand replacement blazes of high severity. Then it takes centuries for them to repopulate an area.
Many of the areas where juniper and other conifers are said to be invading are merely recolonization after massive fires that occurred during periodic warm spells and drought that happened in the past.
The justification for conifer removal is to enhance the recovery of sage grouse. However, there are worse things that can impede sage grouse recovery than conifer spread.
Indeed, one of the negative consequences of the disturbance that accompanies conifer removal is the establishment and spread of cheatgrass. Cheatgrass, an annual grass, is highly flammable. In many parts of the West, cheatgrass and the wildfire they sustain is the biggest threat to sagebrush ecosystems and sage grouse.
An inconvenient truth that the land management agencies, often fail to acknowledge is that the presence of livestock facilitates the invasion of cheatgrass. Livestock trample the biocrusts that are common in arid land grass and shrub ecosystems. These biocrusts inhibit the establishment of cheatgrass.
While it’s true that sage grouse avoid areas of dense conifers, the idea that avian predators use juniper trees for perches is also bogus. The primary bird of prey that is a threat to sage grouse is golden eagles. In all my years, I’ve never seen a golden eagle in a juniper tree. To the degree that eagles may utilize juniper for perches, it is exceedingly rare and that is also the conclusion of five sage grouse and hawk experts I consulted.
However, what is well established is avian predators use that fence posts. And why do we have fences everywhere? You guessed it. Due to livestock grazing.
Furthermore, some studies show up to 30% of sage grouse mortality is due to collisions with fences. Why are there fences all over the public land? Again livestock grazing.
The grazing of grasslands reduces the abundance and height of grass and other plants exposing sage grouse nests and birds to predators.
There is a ton of research showing that cattle compaction of soils and damage to riparian areas has damaged watersheds and is responsible for decline in stream flows. These wetlands and riparian areas are critical habitat to sage grouse chicks early in life when they feed on insects and forbs. Livestock is responsible for the degradation of the majority of all riparian areas across the West.
What is abundantly clear if you review the science on sage grouse is that livestock production poses a far greater threat to sage grouse survival than conifer “invasion.” If one wants to really help sage grouse (and other sagebrush dependent species), land management agencies would be advocating for the removal of livestock, not conifers, from our public lands.