Why Targeted Grazing Cannot Stop Large Rangefires and Recover Sage Grouse

The Department of Interior recently released its Integrated Rangeland Fire Management Strategy whose goal is to reduce range fires in sagebrush ecosystems critical to sage grouse. The plan correctly identifies that cheatgrass is a major threat to the bird, as well as the sagebrush ecosystems.  Cheatgrass is an exotic annual plant that greens up early, but dries quickly and provides fuel for range fires.

LIVESTOCK GRAZING CANNOT PRECLUDE LARGE RANGE FIRE

However, the report does a disservice by suggesting that targeted grazing by livestock can preclude large range fires. Ranchers naturally hailed the report as a vindication of their assertions that livestock grazing is beneficial to sage grouse recovery. Nothing could be further from the truth, and the DOI report misleads the public by looking at grazing of cheatgrass by livestock in isolation.

The problem is that livestock grazing is the major factor facilitating the spread of cheatgrass and targeted grazing as a fire prevention solution is a delusion for reasons I’ll discuss below.

Even if livestock grazing were effective, there is collateral damage to sagebrush ecosystems that is typically ignored. Worse, livestock grazing has multiple other impacts on sage grouse at all stages of life cycle that are virtually impossible to eliminate.

Often targeted livestock grazing is implemented well after cheatgrass has started to dry up and dropped its seeds.  Then livestock trample the dried grass pushing seed into the soil, improving the seed germination of cheatgrass.

HOW LIVESTOCK GRAZING FACILITATES SPREAD OF CHEATGRASS

The reason cheatgrass poses a threat is that it can sustain repeated burns. Cheatgrass, as an annual, whose seeds can remain viable in the soil for years, can burn repeatedly, even every summer, and maintain itself on the site.

Native perennial grasses and sagebrush, by contrast, historically burned at long fire rotations, often up to hundreds of years.  For instance, many perennial grasses may only produce a good seed crop once in ten years, but that is fine for plants that may live up to a hundred years or more.  And sagebrush requires decades to fully recover from a fire.

On rangelands in good condition, the annual cheatgrass typically cannot outcompete the native grasses. One of the factors that protects native grasses are soil crusts. These crusts cover the soil surface in the spaces between the native bunchgrasses.  They make it difficult for cheatgrass seeds to become established (Deines, L., Rosentreter, R., Eldridge, D.J. et al. Plant Soil (2007) 295: 23)

However, when the soil crust is broken and disturbed by livestock (or other activities like ATVS) across the landscape, it provides an empty niche for cheatgrass to become established. Because cows don’t fly, there is no way to avoid breaking up the soil crusts, and aiding cheatgrass seeding. Cows weigh 4x the native antelope.  Often livestock trampling is worse than the herbivory of the desirable plants.

In addition to facilitating the seeding and establishment of cheatgrass, livestock preferentially graze native grasses before they consume cheatgrass. Thus, the native grasses are suffering losses. This increases the gaps between plants, opening up the soil surface to colonization by cheatgrass.

Grazing can also reduce the seed crop of native plants by close cropping of the plants as would occur under targeted grazing. If it happens to be one of the few years when conditions are right for native grass establishment, then grazing can inhibit new grass recruitment. This is exactly what happens on far too many public lands and why many of our rangelands slowly degrade over time.

To quote from one paper by Reisner et al. 2013:” If the goal is to conserve and restore resistance of these (sagebrush ecosystem) systems, managers should consider maintaining or restoring: (i) high bunchgrass cover and structure characterized by spatially dispersed bunchgrasses and small gaps between them; (ii) a diverse assemblage of bunchgrass species to maximize competitive interactions with B. tectorum (cheatgrass) in time and space; and (iii) biological soil crusts to limit B. tectorum establishment. Passive restoration by reducing cumulative cattle grazing may be one of the most effective means of achieving these three goals.”

WHY TARGETED GRAZING IS A DELUSION

There are a number of scientific studies that purport to show that targeted grazing can reduce fire intensity and preclude rangeland fires. There are many inconsistency in these reports. The problem with these studies is that they don’t work on a landscape scale, nor under extreme fire weather conditions, which are the only times when you have large range fires.

Finally, to be effective targeted grazing requires highly concentrated animals in small areas which ensures that native grasses and sagebrush will be trampled and the soil crusts destroyed, thus aiding even more cheatgrass establishment.

The first problem with all these studies is that they only work to any degree at very small scales. Nearly all the studies purporting to show that livestock can reduce fuels are done under very controlled conditions in small acreage with electric fencing and/or tightly herded concentrated animals. The idea is to prevent the livestock from being choosy, and forcing them to consume cheatgrass.

However, not only is this expensive to implement, translating such a model of concentrated grazing across the vast grazing allotments that are typical of public and private lands in the arid West is impossible.

In addition, forcing cattle/sheep to consume forage to a sufficient amount to affect fire behavior—basically cropping to golf course putting green height—results in tremendous collateral damage. It compacts soils, increases drying of soils, reduces carbon storage, reduces forage for other native herbivores from grasshoppers to elk, and reduces hiding/security cover for many ground nesting animals. This includes the sage grouse. Many studies have documented that heavy grazing of sage grouse habitat and reduce of grass height increases predation losses.

Good range management always avoided heavy grazing (greater than 50% utilization) since weed species find empty niches after reducing the plant cover and disturbing the soil surface.  So one can reduce cheatgrass for a single year with targeted grazing, but one is gambling with establishing an ever worse perennial weed problem in the long run.

CONDITIONS THAT PROMOTE LARGE FIRES THWARTS TARGETED GRAZING

The second problem is a failure to understand or acknowledge the conditions that create large rangelands fires. All large fires are driven by extreme fire weather/climate conditions. You need extended drought, high temperatures, low humidity and most importantly high winds. If you do not have these ingredients with an ignition source, you simply don’t get a large uncontrollable fire.

However, anecdotal evidence from large range fires, as well as many studies have documented that under extreme weather conditions, you cannot stop range fire. High winds blow embers miles ahead of any flame front. Even presuming targeted grazing had sufficiently reduced fuels to affect fire behavior, it simply cannot preclude large wind-driven fires which are the only blazes that pose a threat to the sagebrush ecosystem.

Indeed, one scientific paper by Bruegger et.al  (2015)  and widely cited by livestock advocates in support of targeted grazing admitted its final conclusions: “Although it is a promising tool for altering fire behavior, targeted grazing will be most effective in grass communities under moderate weather conditions.”

Furthermore, since one cannot predict where a fire will occur, most targeted grazing will be imposed on lands that will not burn during the short period when fuels are reduced. However, these same lands will suffer many of the negatives associated with heavy livestock grazing including soil compaction, loss of hiding cover and forage for other native wildlife, among others.

SPREAD OF WEEDS

Another problem frequently ignored by livestock supporters is the problem of new weed establishment. Most livestock are moved around from place to place, and in the process, pick up seeds of other exotic non-native plants.

Most alien plants do best in disturbed habitat, the kind created by the trampling of soil crusts and nutrient enrichment from livestock manure (Belsky and Gelbard 2000).

One study (Silkes and Muir 2009) in Oregon found after an experimental fuel control program was initiated, some 25 new alien species were established on the site. While this study was done in fuel treatments in chaparral, it does make that case that soil disturbance contributes to increased weed invasion.

HOW LIVESTOCK GRAZING HARMS SAGE GROUSE

Finally, what the DOI report ignores is all the collateral damage that livestock production has on sage grouse ecology.

As mentioned previously, livestock grazing is the major disturbance factor that is facilitating the spread of cheatgrass, thus contributing to the flammability of rangelands. Suggesting that livestock grazing can be used as a major deterrent to cheatgrass spread is irresponsible.

In addition, heavy grazing that occurs with “targeted grazing” it exposes sage grouse nests, chicks, and adults to greater predation from everything from ravens to coyotes.

Riparian areas and wet meadows are critical habitats for sage grouse chicks who spend the first month or six weeks of their lives feeding on insects and forbs. Livestock grazing is undisputed as the major factor that has damaged riparian habitat throughout the West, and is also the major factor that is precluding riparian habitat recovery.

It’s nearly impossible to graze livestock in the West without fences, and indeed, targeted grazing usually increases fencing mileage. Sage grouse are weak fliers and suffer high mortality from collision with fences.

Plus, the ubiquitous fence posts that exist throughout the West also provide perching posts for the grouse’s avian predators like golden eagles and ravens. Some studies have documented that sage grouse will preferentially avoid up to a half mile on either side of the fence line, potentially eliminating millions of acres of otherwise prime sage grouse habitat from use.

In some areas, West Nile Virus is decimating sage grouse populations. Livestock watering troughs are a major breeding ground for the mosquitos that carry the diseases.

SUMMARY: In the end, the DOI is happy talk to placate the livestock industry’s unease about sage grouse recovery efforts by advocating targeted grazing as a potential solution to rangelands fires. It’s delusional and ignores the multiple ways that livestock grazing negatively impacts the recovery of sage grouse populations.

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