ENVIRONMENTAL EFFECTS

--George Wuerthner, author and ecologist (Wuerthner 1989)

--Dave Foreman, Confessions of an Eco-warrior (Foreman 1991)

--Steve Johnson, Southwestern Representative, Defenders of Wildlife (Johnson 1985a)

Why no hue and cry to aid the range? The persistent myth of the cowboy retains its power, of course, so that to catalog his sins is to risk seeming un-American. But it's also true that the threats rangelands face seem soporifically benign at first glance. Old Bossy's dewy-eyed stare fails to stir the same measure of fear and anger as a chainsaw, a bulldozer, or John Sununu. Moved to confusion (or boredom) by a litany of rangeland ills, the general reader turns the page; the activist turns her or his energies to saving something more "majestic."

--The editors of Sierra magazine (Sierra 1990)

So, just how do "harmless" cattle and sheep harm the land? This simple question has no simple answer. Ask someone to explain Nature itself -- the virtually infinite number of complex interactions between myriad components of biologic, geologic, hydrologic, and climatic systems in ecosystems throughout the West.

Maybe a better question is: what in Nature does livestock grazing not adversely affect? Its influence is all-pervasive, as limitless as the environmental interrelationships it disrupts. As will be seen, no other land use is so destructive in so many ways.

Unfortunately, livestock's destructive influences are mostly unrecognized and thus uncorrected. Their geographic remoteness and subtle, dispersed, and insidious nature combine with our society’s blind love affair with cowboys and cows to make livestock grazing the most misunderstood and neglected major environmental problem facing the rural West.

For simplicity's sake I have assembled livestock grazing effects under 6 basic headings: Plants, Soil, Water, Animals, Fire, and Air. Please keep in mind that these headings are necessarily general and impose artificial boundaries. They merely serve as organizational aids to facilitate understanding. In the natural world there are no such delineations.

Seemeth it a small thing unto you to have eaten up the good pasture, but ye must tread down with your feet the residue of your pastures? and to have drunk of the deep waters, but ye must foul the residue with your feet? --Ezekiel: 34:18

Plants

They are taking the skin off the land.

--frorn the movie The Emerald Forest

The college textbook on zoology I am reading describes plankton as "both animals and plants which are collectively called 'oceanic meadows,' for they are the basis of food chains upon which larger organisms, such as fish, and even humans are dependent." It states that most of this planet's oxygen supply and an entire pyramid of fife, including many terrestrial plants and animals, is dependent upon marine plankton. Similarly, the ocean ecologist Jacques Cousteau and other oceanographers conclude that plankton are vital to the health of the oceans and dependent terrestrial life. They warn of the dire consequences of overharvesting, poisoning, or otherwise harming these countless trillions of tiny floating organisms.

Grass and small herbaceous plants, along with co-dependent micro-organisms and insects, are the "plankton of the land." These countless trillions of small plants and animals are the base of an extensive, complex food web -an almost infinite interdependency of life. As with ocean plankton, they are vital to the health of most terrestrial ecosystems. Like plankton, they provide oxygen to the atmosphere and, ultimately, nourishment to larger animals and necessities to humans. Additionally, they maintain soil, water, fire, and atmospheric dynamics.

Livestock grazing has destroyed the plankton of the land in the Western United States -- and around the globe -more extensively than has any other human pursuit.

Consider that on the Western range today cattle and sheep outweigh all large native herbivores combined roughly 10 times over. It takes more than 20 pounds of herbage to produce a pound of beef (Zaslowsky 1989). A cow eats for about 8 hours a day to keep its 4 stomachs full, and an average cow consumes 700-800 pounds of vegetation per month. (Again, mature cattle average 800-1000 pounds -- 1 AUM -- monthly.) An average range steer eats 12,000 pounds of range plant material and 2850 pounds of feedlot food by slaughter time (Ferguson 1983). Sheep eat roughly 115 as much as cattle, and goats eat roughly 314 as much as sheep. Generally, a stock animal will eat approximately its weight in herbage per month.

Thus, on most Western rangeland domestic livestock eat most of the forage (grass, herbs, and other non-woody plants) and much of the browse (leaves and twigs on shrubs and trees). Indeed, they eat not only preferred grasses, but willow shoots, wild celery, young agave stalks, rosehips, lupine, honeysuckle, miner's lettuce, cottonwood saplings, wild tobacco, desert marigolds, clover, watercress, saltbush, mesquite pods, wild oats, mountain mahogany leaves, morning glories, reeds, wild strawberries, monkey flowers, vetch, mulberry leaves, bracken ferns, sunflowers, small aspens, dandelions, marijuana, apple leaves, cacti, acorns, peppermint, maple stems, ad infinitum. Government grazing management plans specifically call for heavy "utilization" of many of these and scores of other species.

If preferred vegetation is not available, as is often the case in the overgrazed West, cattle, sheep, and goats resort to eating decreasingly palatable species, such as sagebrush, scrub oak, bear grass, manzanita, yucca, tumbleweed, and cheatgrass, eventually eating nearly anything organic, including tree bark and, according to one eyewitness, old newspapers. This plasticity of diet allows ranchers to "mine" the public's range vegetation with their livestock year after year, eventually right down to the bare dirt, and is a key to range degradation.

Cattle-eaten yucca.

Cattle eating mesquite.

Cattle even eat cattails.

This stripping of the vegetation cover is livestock's most obvious impact. Many plants are simply ripped out of the ground roots and all and swallowed; sheep are especially destructive in this respect. However, most plants are damaged by being heavily cropped or browsed. ("Cropped!" refers to the refers to the leaves and stems of non-woody vegetation being eaten off-, "browsed" refers to the leaves and twigs of woody plants being eaten off.) When too much of a plant is removed or taken at the wrong time of year, its future growth is retarded. In fact, livestock usually remove more than half of the above-ground portions of most nonwoody plants in their grazing areas and often graze during the weeks most critical to plant growth and development. When a plant is, cropped or browsed too often in a single season or too heavily year after year, it dies. With the extreme grazing prevalent throughout the West, livestock stunt or kill most rangeland plants in these ways.

Cropping and browsing also destroy vegetation by preventing plants from seeding properly. Many plants are eaten before they are able to flower or produce seedheads or seed pods. As reserves in roots are depleted, other plants are so stunted in growth that they produce infertile or reduced numbers of seeds. The seeds that are produced may be eaten by livestock and rendered useless for reproduction (although seeds of several species pass through unharmed and may be spread through livestock feces). Due to reduced ground cover and other factors, many of the seeds that do fall to the ground are rendered sterile or caused to sprout at the wrong time of year by increased cold, heat, light or unfavorable moisture levels. On some soils, seeds of certain species may even be physically damaged by livestock hooves.

Indeed, perhaps even more destructive to vegetation than the actual grazing and browsing is the trampling that accompanies them. Most Western native plants -- those of the and to semi-arid regions (most of the West) especially -- are ill-equipped to survive frequent, intense pounding from the cloven hooves of unnaturally managed, heavy, non-native ungulates. Small plants and seedlings are easily killed, and larger plants suffer physical disruption, injuries to root systems, exposure, and other damages. Vegetation has regularly been broken, beaten down, cut off, and crushed for over 100 years on hundreds of millions of Western acres.

Thus, livestock have transformed much of the West's relatively lush natural vegetation to wasteland. This biotic change is manifested in 4 basic ways:

1. Decreasers:

Most vegetation communities are a combination of many different plant species living together in competitive, yet mutually supportive, generally stable relationships. Though livestock are for the most part less selective than native herbivores, they nonetheless generally feed upon their favorite plants first -- the most palatable, succulent, and nutritious species, sometimes called "ice cream" species. On Western rangeland these include many of the important native grass and herbaceous perennials, and even several woody species such as whitesage, budsage, and bitterbrush. Livestock graze the tender tops first, then the coarser leaves, and finally the stems. Often these preferred plants are eaten to the ground before others are utilized. If they continue to be eaten year after year, these species are significantly reduced in number and range, and are thus termed "decreasers."

Because livestock spend more time in areas where these 9 2. Increasers. decreaser species occur, trampling and other detrimental effects are concentrated there, compounding damage from the grazing itself. As these desirable plants dwindle, they are sought more and more fervently by hungry livestock, creating a vicious circle of species extirpation.

IMAGE

This bull seems to prefer barrel cacti to grass and mesquite.

Stockmen "mine" vegetation with livestock, often right down to bare dirt. (Richard Ginser)

As a result, the plants we see least on the range today are generally those livestock (and native animals) prefer most. The result of more than 100 years of livestock grazing has been virtual eradication of many of the most biotically productive native plant communities in the West.

Conversely, livestock graze less on the less nutritious, more fibrous, thorny, poisonous, and otherwise unpalatable plant species. Some species are protected from livestock by virtue of long taproots or extremely bitter taste, or because they hug the ground, possess stolons (runners) or rhizomes (underground stems), or are otherwise equipped to resist heavy grazing. These qualities, along with reduced competition for space, sunlight, water, and nutrients from decreasers, often allow these "undesirable" plant species to expand their numbers and territories. In other words, these "increaser" species fill the void left by the decreasers.

A livestock favorite, the distinctive sideoats grama was once a common resident of the West but, as a livestock decreaser, now survives as only a small fraction of its aboriginal population. (Helen Wilson)

An apparent increaser is not necessarily an increaser, however. Many areas are so denuded by livestock that certain plant species only seem to be increasers by simple virtue of being the only ones to survive in significant numbers. They have actually decreased in number and area, and only appear to be increasers in comparison to the ravaged decreaser species around them.

Nonetheless, many true increasers have indeed become dominant over large areas. Though these species were integral parts of original climax communities, they usually represented much smaller percentages of the total vegetation. Big sagebrush is a prime example. It originally composed 1/4 or less of the vegetation cover in bunchgrass communities throughout much of the Intermountain West. Today, on tens of millions of these same acres, big sagebrush forms essentially pure stands, interspersed not with grasses and forbs but with bare dirt. Depending on circumstances, prickly pear cactus may also be an increaser, and in some grazed areas prickly pear now grow so closely together that they are nearly impenetrable. Skunk cabbage and even wild iris can be increasers in heavily grazed wet meadows. Other prominent increasers include yarrow, tarbush, snakeweed, shadscale, rabbitbrush, mesquite, catclaw, and creosote.

Lakeview Cemetery in Montana's Red Rock Lakes Wildlife Refuge has not been grazed by livestock for 100 years. As a result of a century of livestock use, the thick native grasses and herbaceous plants on the left were replaced by the scraggly sage and other increasers on the right. (George Wuerthner)

9 3. Invaders:

Increasers do not encroach from without, but merely flu the empty niches within their own ranges left by ravaged decreaser species. If heavy grazing continues, even increasers are eventually killed out and their places taken by the true grazing "invaders" -- exotic herbaceous or woody plants, or opportunists native to that region but not to that site. These invader species may appear at the first sign of ecological stress, but do not become dominant until overgrazing is so severe that increasers decline.

Among the many notable invader plants are cheatgrass, tumbleweed, knapweed (all exotic to the US), halogeton, leafy spurge (native), a few species of mustards, filaree, thistles, and some shallow-rooted annuals and forbs (many of which are exotics). Most invader species are very hardy and resistant to drought, grazing, trampling, and other disturbances. Most are also unpalatable to livestock, provide less soil holding and building ability, are highly inflammable,and are of lesser value to wildlife. Many are thorny or poisonous to livestock. Annuals are prominent among invaders largely because they grow an entirely new generation of plants from seeds each year and are therefore less susceptible to cumulative damage from trampling and other impacts. Some invader infestations create conditions which cause populations of "pest" animals to explode, further favoring invaders over natural vegetation (discussed later).

The exotic plants saved the newly bared topsoil from water and wind erosion and from baking in the sun. And the weeds often became essential feed for exotic livestock, as these in turn were for their masters. The colonizing Europeans who cursed their colonizing plants were wretched ingrates. --Alfred W Crosby, Ecological Imperialism (Crosby 1988)

Ironically, invaders and increasers may play an important role in the restoration of overgrazed land. Without them there would often be little or no vegetation to hold soil, provide cover for wildlife, and so forth. Though not as valuable as native species, invaders and increasers are much preferable to bare dirt. They are all that keeps much of the Western range from becoming absolute wasteland. Invaders may pave the way for future restoration; if the land is protected from further overgrazing, most invaders and increasers will gradually be replaced by native vegetation. (Feral animals sometimes play a similar role.)

On the other hand, depending on the unique circumstances of each area, some exotic invaders may colonize overgrazed areas and remain dominant long after livestock are removed. In some areas these species show little obvious sign of yielding to the natives even after decades of nongrazing. Because of the long time frames involved it may thus seem that these vegetation changes are permanent. However, close inspection of these livestock-excluded areas reveals that on most a very gradual, steady recovery of native vegetation is indeed taking place. While some invaders -Bermuda grass and tamarisk, for example -- may be there to stay, most have begun to yield to the natives in areas given an extended reprieve from livestock.

Mostly because of livestock grazing, scores of increasers and invaders have become dominant on more than 150 million acres of Western range, or more than 115 of the West. Specific examples are plentiful. Indeed, most of the increaser and invader species listed above have replaced native flora on millions of overgrazed acres apiece.

Yellow star thistle.

Yellow star thistle, for example, is a spiny, 3' tall plant that produces numerous needle-sharp seedheads and which may be toxic to cows and horses if eaten in quantity. It is thought to have first arrived on this continent in California in the mid 1800s in shipments of contaminated alfalfa from southern Europe. The livestock explosion soon thereafter opened the way for star thistle to spread throughout the West. A recent San Francisco Examiner article explains: Cattle ranchers, major victims of the thistle, have contributed significantly to its spread. Without cattle and sheep, whose hoofs break down the delicate fungal mat that once covered most western soils, the star thistle's seeds probably wouldn't have outcompeted the West's native perennial grasses.

Overgrazing has helped spread yellow star thistle across tens of millions of acres throughout the West, 8 million in California alone. (Bashin 1990)

Cheatgrass, Bromus tectorum, is a prime example of a grazing invader. Originally from the Eurasian steppes, it spread quickly across the West with livestock in the late 1800s and early 1900s. Many stockmen initially welcomed the spread of cheatgrass (as they did tumbleweed), but soon discovered that as a forage plant it was much inferior to the natives it replaced, that the awned (barb-like) seeds lodged in the mouths and eyes of livestock and caused injury, and that it was explosively flammable. Today, cheatgrass covers tens of millions of and to semi-arid acres throughout the West, often in single-species stands such as the one above.

Bare dirt is desirable only where it occurs naturally. Except for drier regions, this generally includes only small percentages of the ground area. Overgrazing has probably resulted in more actual ground area in the West being converted to bare dirt sand, and gravel than to a vegetation cover of increasers or invaders. Yet, range literature invariably focuses on changes in species rather than overall reductions in plant cover. This obscures the severity of the problem.

Cows and sheep are everywhere on public lands, wandering into most every available nook and cranny with something edible on it. --Letter to the editor, High Country News

In describing these changes in Western vegetation, we speak of what scientists call "biotic succession," or the tendency of plant and animal communities to succeed or replace one another over a period of time in response to environmental or human influences. Biotic succession is influenced in two ways.

One influence is related to sudden changes in existing conditions. For example, extremely high winds in an area of dense coniferous forest may cause a "blowdown" of nearly all the trees. Soon thereafter a new community of plants begins to occupy the area, usually hardier "weeds" and forbs. These plants are gradually replaced by grasses and flowering perennials. Over the years this community is overgrown by a mixture of shrubs and bushes, which in turn is overgrown by a grove of aspens. Finally, the original conifers begin poking through and overshadowing the aspens, and eventually reclaim the area as a conifer forest vegetative community.

Quick changes in the environment, such as those induced by windstorm, fire, flood, drought, landslide, or insect outbreaks, are periodic natural occurrences to which biotic communities have been subject for millennia. Each "disaster" may cause dramatic changes. But because these disturbances occur infrequently and affect only limited areas, biotic communities reestablish and maintain their essential character. In the conifer forest, abrupt changes occur infrequently enough that most of the trees have time to reach maturity before the next disturbance hits. Although there are always some portions of the forest at earlier stages of succession, the forest as a whole maintains its coniferous character.

A second type of change in biotic communities occurs very slowly, usually in response to long-term climatic or geologic changes. For example, a long-term change in the storm track could cause a drying trend in climate and gradually move a conifer forest back through succession, finally resulting in some type of plant community adapted to a drier climate -- perhaps, again, the grasses and flowering perennials. Or, colliding crustal plates may create a new mountain range, with a "rain shadow" effect on the range's interior side and eventually producing a biotic community more adapted to aridity. These kinds of changes usually occur so slowly as to be imperceptible to humans.

Succession is a sliding scale, but to humans appears to occur in steps. Each change in the essential character of a a biome [particular biotic area] is termed a "stage of succession." All biotic communities are constantly changing, moving from one stage to another on the scale of succession, in response to both short- and long-term fluctuations in the environment. Changes may occur very quickly, as with the forest blowdown, or extremely slowly, over thousands or even millions of years, as with the drying climate. We humans see the sudden changes as "disasters" and rarely recognize the slow changes.

This is not to say that succession proceeds as a smooth, predictable pattern. It is more like a general trend with numerous variables. The natural environment provides succession many diverse influences, once again complementing biodiversity.

Generally, the more complex a biosystem, the more stages of succession it is subject to. The conifer forest discussed above went through at least 5 stages. Most grasslands have several stages. The simplest and least productive biosystems may have only 2 or 3. For example, removing the vegetation from a creosote flat in the Mojave Desert usually results in a slight, temporary increase in a few native and/or exotic desert annuals and, eventually, the regrowth of most of the original creosote or a continuance of bare dirt.

A "climax community" is the final stage of succession -- a relatively stable biotic community natural to each unique physical environment, able to replace and regenerate itself and maintain its essential character over long periods of time. Every place on Earth with plant or animal life has a climax community. Each is determined by the area's unique set of long-term environmental influences, including climate, soil, and landform. Though the overall biotic character of each climax community is relatively stable, integral to each is a complex mosaic of areas in different stages of succession. This diversity strengthens systems dynamics and the climax community as a whole.

There are no "bad" climax communities; each is the one best suited to given conditions, and as such the most beneficial to the environment as a whole. Scraggly, scattered creosote with its few small companion plants is "good" on hot, dry desert flats because it is the most biologically productive stable community possible under such conditions. Nor are the earlier stages of succession 'bad," for each has an important role in augmenting biodiversity and reestablishing the climax community after it has been disturbed. Even the most hated "weed" has an important place in succession.

The radical disturbances caused by overgrazing would have only minimally affected the essential character of the Western range if it had occurred as infrequently as natural disturbances -- say 15 or 20 years apart, and for only a few days at a time. But heavy grazing usually occurs every year, for weeks, months, or even year-round. Chronically overgrazed land cannot progress along the stages of succession back to its natural state. Hence, natural systems progressively deteriorate, and plants and animals populations simply never recover.

On the other hand, when long-term changes constitute a permanent change in the environment, succession gradually provides an area with a new climax community. This type of change usually requires centuries, and isn't the type of change we've seen in the West. Before European intervention, grama-buffalo grass, tule marsh, scrub oak, sagebunchgrass, and scores of other major Western vegetative climax communities had existed relatively unchanged, aside from usual natural, periodic, localized disturbances, for many thousands of years.

What should be remembered is that Nature has already advanced each area's climax community as far toward the biologically productive side of the succession scale as possible for the given physical environment. Humans can temporarily increase the productivity of a given ecosystem only by artificially releasing energy stored in the ecosystem's biomass and soil, or by importing energy from other ecosystems. As a rule, drastic disturbances move succession toward the biologically less-productive side of the scale. The greater the disturbance, generally the less diverse and abundant the resulting biotic community. Continued livestock grazing leads to the replacement of climax vegetation with less and less productive plant communities and, finally, bare dirt, sand, and gravel. Recovery of the original climax

community is hampered because the foundation of the ecosystem is damaged. The resulting degraded biotic community does not represent merely a step down in succession or change in the climax community but a breakdown of the whole process.

--George Wuerthner, "The Price Is Wrong" (Wuerthner 1990b)

As a result of livestock grazing, numerous plant species throughout the West have been locally extirpated. In fact, hundreds of species likely were completely eliminated from many areas at the onset of heavy grazing in the late 1800s, even before knowledge of their existence could be documented. We will never know what has been lost. Because damage from overgrazing is often such a slow, insidious process, the gradual decline of many other species has not been properly linked to livestock.

For example, mushrooms and other fungi of scores of species grow in ranching areas of the West. But a century of overgrazing has so reduced the soil moisture, humus, host plants, and shading vegetation they depend on that many mushrooms are now rare in these areas. While some note that mushrooms grow prolifically on cowpies, these represent only a very small number of species, and some of these formerly grew on the dung of wild animals as well.

Livestock so drastically reduced many Western plant species in range and number that those species are now listed as Rare, Threatened, or Endangered. The following are a few examples:

The autumn buttercup is a species endemic to the upper Sevier River Valley in Garfield County, Utah. The Endangered Species Technical Bulletin reports:

Approximately 11 individuals survive on less than 0.01 acre of privately owned land that is highly vulnerable to continued grazing and habitat modification. Believing the species in imminent danger of extinction, the [govermment] has proposed to list it as Endangered.

Even so, the Bulletin reports that the rancher landowner wants to increase grazing in the area by building a new stock watering pond, although he "may be willing to allow construction of a protective fence."

Grama grass cactus is a little-known cactus that often grows within the fairy rings formed by grama grass or ring muhly grass. It grows long, papery spines which look remarkably like the curled, pale blades of old grama and muhly grass. "Hiding' in the dead layers of these grasses helps grama grass cactus escape predation by rodents and other herbivores. Overgrazing of its only habitat in parts of New Mexico and Arizona has drastically reduced the cover formerly provided by these grasses, while trampling livestock have killed many. Consequently, the grama grass cactus is listed as "rare."

Golden buckwheat (Epiogonum chrysops) is a distant relative of cultivated buckwheat. According to the Center for Plant Conservation, though thought extinct and last seen in 1901, it was rediscovered in 1988 in Malheur County, Oregon, on 3 barren, volcanic hilltops -- among the few places in its habitat not accessible to livestock.

The Tiburon Mariposa. lily (Calochortus tiburonensis) grows only on the rocky upper slopes of Ring Mountain on the Marin Peninsula, north of San Francisco. Here, a remnant population finds shelter from the livestock grazing that has ravaged the remainder of its habitat for more than two centuries.

The Arizona agave was federally listed as Endangered in 1984. A report by Rick DeLamater and Wendy Hodgson of the Desert Botanical Garden in Phoenix states that "agave stalks provide an irresistible food for cattle" and that the agave's habitat, "including what we thought to be the most inaccessible areas, shows severe degradation by overgrazing." Studies show that less than 0 of the stalks of 3 types of agaves in the area reached maturity undamaged. The report concludes:

Cattle, overgrazing on lands administered by the U.S. Forest Service, are cited as the major threat to [the Arizona agave's]survival as well as to the population dynamics of [other agaves in the area]. (DeLamater 1986)

Golden draba is a small member of the mustard family that grows in the spruce and alpine belts of California's high Sierra Nevada, where it has been relentlessly diminished by sheep and cattle grazing for more than 100 years. Golden draba is now listed as Rare in the state.

Clay phacelia is one of Utah's 190 globally Endangered species, many of which fell to livestock grazing. The world's only known population of this purple wild flower clings tenuously to a steep, shale-strewn hillside in central Utah. For years botanists have watched clay phacelia decline under the hooves of domestic sheep and have finally secured an agreement to erect a fence around the plants . . . rather than remove the sheep.

Colorado butterfly plant, Gila groundsel, Knowlton's cactus, Cusick's camas, Bitterroot milk vetch, solano grass. . . the list of livestock plant victims goes on and on. The Nature Conservancy reports that in California alone (which has nearly as many endemic plant species -- 1517 -- as all other states, except Hawaii, combined), more than 600 species are threatened with extinction. If nothing is done the state could lose 12% of its native plant species. Further, livestock grazing has been identified as a major factor in this threat. In Haw* livestock grazing, land clearing for pasture, development, and introductions of exotic species have caused a tenth of the estimated 1250 species of flowering plants that were present 200 years ago to become extinct. Probably half of the remainder has become Threatened or Endangered. The Center for Plant Conservation, in its Endangerment Survey Summary of December 9, 1988, offered a grim assessment:

3, 000 of the approximately 25, 000 [about 14,000 are in the 11

Western states] species, subspecies, or varieties of plants na

The Center estimates that 680 of the species at risk will be extinct in the US by the year 2000. While many Endangered plants are indigenous to comparatively small areas and have succumbed mostly to intensive development, livestock grazing has forced more Western species to become Rare, Threatened, or Endangered than any other factor.

However, grazing’s greatest impact on native vegetation has been -- far more than any other human influence -- the depletion and extirpation of species over large areas. Though they may not have been reduced to the point of imminent extinction, hundreds of native plant species have been reduced to only fractions of original populations over vast expanses, and have been eliminated entirely from many areas. Livestock grazing continues to be by far the most prevalent, insidious, and destructive force affecting native Western vegetation.

--David L. McWilliams, Rock Springs, CO, letter to the editor, 3-2-88 Casper Star-Tribune

While grazing and trampling have wiped out much Western vegetation directly, livestock have also damaged native biotic systems in countless subtle and complex ways. For example, livestock negatively affect the composition, range, distribution, density, size, health, diversity, and vertical stratification of Western vegetation:

• Density refers to the number of individual plants of a given species within a given area, or how closely spaced individuals of a plant species are. The term also refers to the spacing of vegetation in general. Density usually indicates the importance or dominance of a particular species in a plant community; but, since density values indicate nothing about size, health, or how widespread a species is, this is not always so. Generally, livestock grazing has decreased the density of beneficial natives and increased the density of harmiful exotics, with a significant decrease in overall combined plant density on most Western range (an increase in bare dirt). When livestock reduce or increase plant density, they once again negatively impact ecosystem dynamics. For example, overgrazing on bunchgrass/sagebrush rangeland in much of the Great Basin has so reduced the density of bunchgrasses that individual grass plants are no longer spaced closely enough to carry wildfires. The resultant loss of wildfire has given sagebrush a further advantage over grass because natural fire generally restricts the spread of sagebrush while actually stimulating the growth of many grasses.

When assessing range conditions, range professionals generally survey the composition, range, and density of vegetation, but give little consideration to the size and health of individual plants. While composition, range, and density are important, individual plants must also be full-sized and healthy for ecosystems to function properly. For example, a full-sized, healthy buckthorn bush in a natural, non-livestock area may produce 2 or 3 times more leaves, flowers, seeds, stems, and other organic materials than one in an overgrazed area. This superior bush will provide much more food, nesting, and shelter for wildlife. It will also supply more organic litter, better wind resistance, more shade producing branches, more soil holding roots, and so on.

Through the many influences described elsewhere in this chapter, livestock have caused most rangeland plants to be stunted and less vigorous today than in pre-livestock times. Wild sunflower plants in overgrazed areas are often only half the size of those in adjacent ungrazed areas. Sagebrush plants in grazed areas are typically short and misshapen, sparsely leafed, with many broken branches and little underlying organic litter. Cacti in livestock areas are often stunted, broken, and diseased.

Additionally, because range plants are heavily grazed or browsed, size relative to plants in ungrazed areas is reduced even further. For example, on most Western range grass plant density, health, and size has been decreased, but since livestock also keep most individual grass plants cropped to less than half their normal height, their size has been decreased relatively even more.

• Plant diversity refers to the number of different species as well as to the variety of plant types in a given area. Natural diversity is essential to ecological health and stability. In affecting all of the above negative changes in Western vegetation, livestock have greatly lowered plant diversity in most of the West. Heavily grazed areas commonly support less than half as many species and much less diversity of plant types. In Idaho an ungrazed stand of big sagebrush supported 31 species of plants, while a comparable grazed stand supported only 9 species (Ferguson 1983). Overgrazing nearly always simplifies ecosystems, further increasing their susceptibility to disturbances, including continued overgrazing.

Livestock likewise damage what is known as vertical stratification. Most natural plant communities are stratified, having a vertical arrangement of plants in several layers instead of an even distribution throughout all heights from the ground to the tops of the tallest plants. In the forest vertical stratification may be obvious as a surface layer of mosses and lichens, a low herb layer, a grass and tall herb layer, a shrub layer, a subcanopy tree layer, and a canopy tree layer. In grasslands, shrublands, and deserts, vertical

Natural diversity is a key to ecosystem health and stability. Ungrazed in the Sonoran Desert.

Inaccessible to cattle, this luxuriant mixture of vegetation assures high environmental quality.

Stratification may not be as well-defined, but is nearly always present nonetheless. All grasslands have at least 3 stratification levels, and some have 4 or even 5.

Each layer provides food, shelter, nesting, and other necessities critical to certain animals at certain times, and certain combinations of layers are likewise necessary to the survival of many animals. Each layer also contributes its unique benefits to soil, water, fire, and air systems and other interrelationships. Livestock grazing depletes or fragments ground surface and lower vegetation layers, and may over time also significantly impact upper woody vegetation layers.

One little-appreciated factor in rangeland dynamics is the role of dead plant material. As old leaves, stalks, stems, flowers, and other plant parts wither and die they are acted upon in various ways and their nutrients are recycled throughout the biotic system. This dead organic material is essential to vegetation, soil, water, animal, and fire dynamics. Inmost ecosystems, 115 to 1/2 of all biomass (overall amount of organic matter) consists of dead plant material.

Accumulation of plant litter on the soil's surface is an ongoing process, and Etter on the dry Western range depleted may require decades to replenish. Livestock inhibit or destroy the old growth vegetation needed as source material for organic litter. Particularly, they eat much of it and trample plants, damage soil, reduce available water, and cause other changes that ultimately deplete the amount of dead plant material. They break apart and scatter remaining organic litter. Additionally, much of the biomass that would otherwise eventually become dead plant material is removed from the ecosystem entirely when the domestic animal is moved off the range for eventual slaughter. Reduction of the organic litter layer has been extreme on most grazed land. On Nebraska's Sandhills Prairie, for example, removal of cattle for 4 years yielded a 300 + % increase in litter cover (Potvin 1984). Even in many forests, livestock are the main cause of organic litter depletion.

The importance of organic litter to plant growth is graphically demonstrated here. I threw 2 small piles of a neighbor's cut brush down in a bare spot. Several months later plants growing in the area covered by the litter had twice the height and several times more biomass per unit of area than the plants in the surrounding area.

Livestock grazing damages vegetation in many other ways that are little understood or appreciated. For example, the leaves and branches of many plants in and to semi-arid climates possess patterns or structures that gather rainfall and run it in toward the center of the plant, thus increasing the amount of water available to its roots. When livestock remove leaves or break branches, or otherwise alter plant patterns and structures, they reduce water-trapping capabilities. Conversely, water-stressed plants become more brittle and susceptible to physical damage from livestock.

Another example concerns plant reproduction. When livestock strip off the vegetation cover and deplete and displace the organic litter layer, they expose seeds on or immediately under the ground surface. Pecking and scratching birds and other foraging animals may then consume the seeds, leading to sparse regeneration. If you have ever had the bare ground of your garden de-seeded by foraging animals, you will appreciate this factor.

Moreover, many plants depend on lateral growth or rooting of broken segments for their spread. Others send runners out across the ground's surface that put down roots at certain intervals, creating new plants. Some have branches that sag as they mature, make contact with the ground, and send down roots at those points. Others, such as most cacti possess segmented branches that break off easily, fall to the ground, and send down roots from points of contact.

Success for plants that spread in such ways depends primarily on (1) the health of the parent plant and spreading portion, (2) the condition of the soil and amount of ground moisture, and (3) how well and how long the spreading portion of the plant makes contact with the ground. Consequently, livestock prevent the establishment of new plants by (1) damaging or killing the parent plant and spreading portion, (2) damaging the soil and causing it to dry out, (3) trampling and shuffling, thereby preventing the spreading portion from "seating" properly onto the ground and making prolonged, close contact. Further, trampling livestock often pull out or break off the small roots that have established themselves. Even where livestock aid in the spread of plant reproductive segments, such as cholla cactus, their other harmful effects usually result in reduced net reproduction. I have seen this in some deserts, where in ungrazed areas cholla sections fall off and reproduce successfully around their parent plants, while in nearby grazed areas where cattle have scattered cholla "balls" randomly across the landscape (to the great discomfort of my ankles), so few of the segments have rooted that their overall reproduction rate is far lower.

In most natural biotic communities, plants shade and protect each other. A closely spaced arrangement of undamaged plants provides "nursery protection" for seedlings and ground-level plants, shading them from the sun and helping protect them from foraging animals, wind, hail, frost, etc. To a lesser degree, it does the same for mature plants. It also conserves essential soil moisture by protecting the ground from the drying effects of sun and wind. In the soil, close spacing creates an interlocking network of roots which helps stabilize both the plants and the soil that anchors them. Tall, closely spaced, fully vegetated plants are even less susceptible to damage from trampling because, together, they form a thick mat which disperses hoof impact on each individual, including its roots.

An obscure indirect effect of livestock: According to the photographer, a botanist for the National Park Service, on overgrazed ranges hungry rodents may eat patches from saguaros and other cacti. (Charles Conner)

A grazed hillslope in a BLM Wilderness Study Area offers mostly cactus, snakeweed, rocks, and bare dirt. (Dale Turner)

A comparable ungrazed hillslope in the same area is covered with a lush diversity of grasses, flowering plants, shrubs, soil surface microflora, etc., as well as cactus and snakeweed. (Dale Timer)

In sum, to the great harm of the environment, livestock have converted huge areas of the West to unpalatable, poisonous, thorny, unnatural, and comparatively unproductive vegetation or bare ground.

But, of all man's activities, grazing by livestock has been the most widespread and prolonged use and has had the most profound effect upon the Nation's ranges. --US Forest Service, "An Assessment of the Forest and Range Land Situation in the United States" (USDA, FS 1980)

The Forest Service defines range as "land that provides or is capable of providing forage for grazing or browsing animals [read: 'livestock']." By this definition more than 80% of the West qualifies as range, including a complex array of more than 40 major ecosystem types, all of which have been significantly degraded by ranching. We may divide these into 4 basic categories:

--Florence Williams, "The West's Time Capsules" (Williams 1990)

Grass is a relatively recent botanic lifeform, having first appeared "only" about 60 million years ago. Prairie grassland developed around 15 million years ago, large herds of herbivores evolving along with it.

When settlers migrated west they found more than 1/3 of what was to become the 11 Western states covered primarily with grass. The extensive interior basins, valleys, plains, plateaus, hills, and even mountains supported a great assortment of climax grassland and grassland/shrubland combinations. But this new grassland was quite different from the more familiar lush, soggy pastures of the eastern US and northern Europe.

Prairie grasses are chiefly sod-forming, meaning they form a dense mat of stems and roots. Most have rhizomes, while a few have stolons. These structures produce a series of new shoots as they spread away from the parent plant. Sod grasses and most other prairie plants are perennials, coming up year after year from the same underground root system. Once established, they depend much less upon seeds than new buds for their spread. They rely on summer rainfall, and their growing season extends well into summer. Therefore, in the West sod grasses generally are limited to

the Great Plains and portions of adjacent inter-Rocky Mountain plains, riparian areas, moist valley bottoms, the wet Pacific Northwest, and some high elevations.

Precipitation over most of the West is low during the summer months (and low overall), most of it ending by June. The grasslands there are dominated by bunchgrass, plants that grow in groups of upright stems, each tuft appearing as if held in a bunch. Single plants may form a hundred or more shoots, but these do not spread laterally as mats; they instead form dense clumps of aerial stems. Bunchgrasses generally rely on lingering winter moisture and spring precipitation. They mature and set seeds by mid-July, and become dormant in the dry summer. The plants may put on a new burst of growth during wet periods in the fall, especially in warmer climes.

A third category of Western grasses is the annuals, which live through the growing season, produce seeds, and then die. Each year a completely new generation is produced from seeds. Annual grasses normally inhabit mainly the dryer portions of the West, where precipitation is infrequent and erratic. Because their growing period is limited, most are smaller and less nutritious than bunch and sod grasses. Western annual grasses include wild oat, many of the bromes (foxtails, cheatgrasses), and some of the fescues and lovegrasses. Many are exotics.

Native annuals have been greatly depleted and even extipated from many areas by overgrazing. Over even greater areas, however, ranching's "desertifying" effects have eliminated perennial ground cover and created conditions favorable to annuals. In most of these areas, exotic annuals have outcompeted the native annuals and perennials, replacing them on tens of millions of Western public acres. Due primarily to livestock grazing most of the West's annual grass cover is now composed of increasers and invaders, including many exotics.

Some Western grasses may vary in their growth-form, developing as sod, bunch, annual, or some composite form of these, depending on conditions. Thus, livestock grazing tends to transform sod grasses into bunchgrasses and bunchgrasses into annuals.

Hundreds of different grasses are native to the West. Originally, much of the Midwest and intermountain prairie was carpeted with the rhizomatous grasses big and little bluestem, needle and thread grass, blue and hairy grama, and western wheatgrass; the stoloniferous buffalo grass; and the usually bunching wire grass. Large portions of Idaho and eastern Washington and Oregon were covered with Sandberg bluegrass, Idaho fescue, and the chiefly bunching, though sometimes rhizomatous, bluebunch wheatgrass. Scattered across many parts of the Great Basin were bunchgrasses such as bluebunch and western wheatgrass, bottlebrush squirreltail, sheep fescue, and Indian ricegrass. At least 23 million acres of California's valleys and hills (about 1/4 of the state) were spread with a great diversity of short and tall perennial bunchgrasses, including purple and nodding needlegrasses, with some sod grasses in moister areas. Finally, much of the mid-elevation portions of the Southwest supported lush stands of black and sideoats grama, Arizona cottontop, tobosa, wire, and other bunchgrasses.

The individual species vary greatly in their ability to withstand grazing pressure, but as a group the sod grasses generally fare much better. They have co-evolved over millions of years with herds of large, hooved herbivores -mainly buffalo, but also elk, deer, pronghorn, and bighorns -- and, before the Pleistocene extinctions, with others -camels, horses, mammoths, mastodons, ground sloths, etc. These grasses are adapted to occasional heavy grazing, and if not grazed too often will usually rejuvenate, even after being cropped to the ground. They have a high percentage of vegetative to flowering stems, so grazing has less impact on reproduction. Their new stems emerge horizontally, and their growth points are low to the ground, helping protect them from grazing damage. As mentioned, once established, sod-forming grasses depend much less on seeds than on new buds for their spread. Their root systems are rugged and extensive, able to withstand tremendous trampling. A dislodged piece of root sod, thrown on bare ground nearby, may even reroot!

Generalized depiction of the 3 major grass forms: annual (left), rhyzomatous (center), and bunch (right). (Helen Wilson)

Semi-wild buffalo on a healthy prairie range in Badlands National Park, western South Dakota.

Depleted prairie grassland in Montana. (USFS)

All this is not to suggest that livestock have not been very destructive to the sod grasslands of the West, for they surely have. Where not under the plow, these grasslands have been seriously degraded by domestic grazing animals. Sod grasses are much more resistant to heavy foraging by large herbivores. However, they have been far more heavily grazed by livestock than have bunchgrass communities. To the untrained eye, the moist, uniform green of a sod grassland may look to be in much better condition than the scruffy tan, grey, and green of a bunchgrass community, but relative environmental damage may be similar.

Even the most pro-ranching of sources acknowledge the serious damage that livestock grazing has done to the prairie grasses of the West. For example, in the contemporary textbook Range Management, the authors have listed the results of 20 range studies done on short- and mixed-grass prairies in 7 Western plains states. Their table compares herbage production measured on moderately grazed sites to that measured on comparable sites ungrazed for 5 to 60 years. Of the 20 studies, 19 showed greater herbage production on the nongrazed sites, with an average of 68% more on the nongrazed sites. (Holechek 1989)

Jared Smith in 1895 described the aboriginal great Western grasslands:

The prairies in their wild state were covered with the richest possible grass flora. There was no similar region that had so many useful species and so few poisonous or injurious ones. Almost any square mile of the whole event of territory could furnish in one season 50 kinds of grasses and native forage plants, grasses that would make from one and a half to two tons of hay per acre as rich as that from an Old World meadow. (Smith 1895)

In 1899 Smith reported:

It is the common testimony of the older stockmen that in the early eighties the grass was often as high as a cow's back, not only along the river bottoms, but also on the uplands far from the creeks and rivers... The grazing capacity of large bodies of Land has been reduced within a period of twenly years from one head to 2 to 5 acres, to one head to 20 to 25 acres. (Smith 1899)

In 1940 grazing professional Kling L. Anderson reported in "Deferred Grazing of Bluestem Pastures":

Old grazing records show that prior to 1900 most of the bluestem pastures could be stocked at the rate of two acres for one mature cow or steer for a grazing season of six months beginning May I.... At the present time the average grazing capacity is about seven acres per animal.

Similar references abound. Today, these once-lush prairie grasslands have recovered little, and in many ways continue to deteriorate. Many experts estimate that they have lost 50% or more of their productive potential to a century of livestock grazing.

Further east, ranching and, later, farming combined to devastate the comparatively well-watered tallgrass prairie. Tallgrass prairie is the world's most damaged ecosystem, in terms of percentage of land corrupted. According to The Nature Conservancy- "Once blanketing 142 million acres, tallgrass is considered extinct as a fully functioning natural ecosystem."

--Katey Palmer, biologist (Palmer 1988)

Unlike sod grasses in the prairies of the central region of the US, Western bunchgrasses generally did not co-evolve with great herds of buffalo and other large, hooved herbivores. This different evolutionary history, combined with less precipitation, less dependable precipitation, and other factors, leave them ill-adapted to intensive grazing or trampling. To varying degrees, most bunchgrasses are severely damaged by livestock. Bunchgrasses generally show less ability than sod-forming grasses to adequately restore leaf area lost to grazing. Their ratio of flowering to vegetative stems is high, so their ability to reproduce after being grazed is low. Their new stems emerge vertically, with growing points elevated and exposed to grazers. Regrowth from trampled stems is unlikely, and tufts of even partially uprooted bunchgrass often die, even under moist conditions.

A cover of grass does not necessarily mean all is well. This slope in the Jackass Mountains of eastern Oregon is covered with cheatgrass, a livestock-spread exotic that replaced the much more beneficial native bunchgrasses and other plants. (George Wuerthner)

Pronghorn, bighorns, elk, mule and white-tailed deer were often present in the bunchgrass communities, but their smaller numbers and herd sizes, different behavior, and, importantly, their lower body weight prevented them from having as great an impact as did buffalo. Buffalo did occur west of the Great Plains, but in much smaller numbers and limited distribution. As evidence of this, scientists report that in the Intermountain West there are no native species of Onthophagus, a genus of dung beetle which occurs in association with dense herds of large mammals. In contrast, there are 34 species of the genus native to the Great Plains.

Native Western bunchgrasses have probably suffered as much at the hands of the grazing industry as any other plant group. For example, bluebunch wheatgrass is native to semiand land throughout Idaho, western Montana, eastern Oregon, and eastern Washington. It grows in 2-foot-high clumps, primarily at lower elevations. Individual plants can live 50-100 years. A cool-season grass, most of its growth occurs in spring; in the typical hot, dry summers it goes dormant. During wet periods in autumn it may break dormancy and grow until early winter.

Light grazing of bluebunch wheatgrass during summer dormancy, when most carbohydrate reserves are stored in roots, usually causes minimal damage to the plant. In fact, before the advent of fire suppression, wildfires burned these grasslands frequently with no long-term ill effect. But truly light livestock grazing is almost unheard of. As traditionally practiced, livestock grazing depleted the bunchgrasses repeatedly during one season, every year. In contrast, fires burned them at irregular but periodic intervals of perhaps 5 to 20 years. Cattle ate the grasses, converted them to energy, heat, body weight, and manure, then left the range completely, whereas fires left many more nutrients on the range in the form of ashes. And livestock trampled heavily.Over many thousands of years, the grasses adapted to influences of native animals and fire, but they have not adapted to the intensive grazing, trampling, and other impacts of exotic livestock.

IMAGE

Sign amidst lush grass in Badlands National Park, SD. Livestock have been banned from about half of the roughly 100,000-acre Park, making the ungrazed portion one of the largest ungrazed -- and healthiest -- grasslands in the West.

Bluebunch wheatgrass, at one time grew tall and abundantly throughout much of its range. Today, after a century of overgrazing, most of it has been replaced by cheatgrass, other exotics, and bare dirt.

As early as 1910, excessive grazing, as well as accidental and grazing industry-caused arson fires, reduced perennial bunchgrass on Idaho rangeland by 85%, diminishing the land's grazing capacity by 40%-75% (Ferguson 1983). Today, cheatgrass accounts for 75%-95% of southern Idaho's herbage production (Palmer 1988). Studying overgrazed Utah National Forests in 1918, range professional A.W Sampson reported that "these and similar eroded lands would originally support a cow or the equivalent in sheep on from one-third to one-fifth the acreage required at the present time (Sampson 1918)." Conditions in Utah haven't changed much since.

In the hills and valleys of California, the native bunchgrasses and rhizomatous grasses were so incessantly grazed that today about 95% of the herbaceous cover in uncultivated areas is composed of non-native species, mostly cheatgrass and other weedy annuals from Europe (Holechek 1989). Exclusion of livestock for 16 years from a Southwestern semi-grassland site resulted in 45% more grass cover, a comparatively heterogeneous plant community, and 4 times more shrubs than adjacent grazed areas (Bock et. aL 1984). Concerning the Great Basin, Gleason & Cronquist state in The Natural Geography of Plants, "Heavy grazing has caused considerable diminution of the grasses over much of the area, until in some places there is no native grass left (Gleason 1964)." The story is similar all around the Western United States. One magazine article on livestock grazing concludes:

Overgrazing became a greater problem [than farming] with increasing numbers of cattle [on the prairie]... ... In the Desert Grassland . . . many factors may have been involved [in historic vegetation changes], but cattle grazing is thought to have been the most important... Livestock grazing is also considered the primary cause of vegetation changes in the Palouse Prairie [northwest US] and California Grassland associations.

-John L. Vankat, The Natural Vegetation of North America (Vankat 1979)

An intact, natural grassland is a wonderland of life and beauty. A healthy bunchgrass community may hold anywhere from a few to over 20 species of bunchgrass, a great variety of herbaceous, flowering plants, many brush and cactus species, trees along drainages and perhaps scattered around the landscape, yuccas, a carpet of soil lichen and mosses between the larger plants, even mushrooms -in all, hundreds of species all growing together, along with an amazing variety of animals, as a complex yet harmonic intermingling of lifeforms.

Prairie-type grassland generally is not so rich in diversity of plant types, but usually contains an average of 125-150 plant species and numerous animal species. Here one finds many different grasses and flowering plants. Perennial forbs are widespread, especially members of the sunflower and legume families. Annuals typically comprise less than 5% of plant species. Thick stands of bushes and trees commonly line drainages, and woody plants, cacti and other "desert" vegetation may occur where the influences of soil, landform, fire, animal impact, and other factors create suitable habitat. While generally less biotically diverse than the bunchgrass community, prairie grassland usually has many more individuals and a much greater biomass per unit of area.

Grass is beautiful.

Unfortunately, grassland is not widely appreciated in this country. Indeed, probably most US Americans have a bias against grassland and other unlimbered landscapes, assuming that trees are the natural and proper vegetation cover for the land. Charles A. White of the Iowa Geological Survey rightly challenged this assumption in 1870, saying, "There seems to be no good reason why we should regard the forest as any more a natural or normal condition of the surface than the prairies are (Malin 1956)." Indeed, grassland generally has the deepest, most fertile and productive soil, highest erosion resistance and water retention, and greatest biomass of animals of all the major bioregions.

Nevertheless, probably most people when traveling through a landscape of grass consider it with indifference. To them, grassland is monotonous and one-dimensional. Although literally thousands of kinds of plants and animals are found in the grass country, there is little conspicuous enough to excite their interest. No doubt much of the public's attitude toward grassland stems from the fact that most of the West's originally lush, productive ranges have been turned into scenes of desolation by a century of overgrazing. Exposed often to cross-fenced landscapes of closely cropped grass, bare dirt, and scattered cows, people simply don't have any idea what a healthy grassland would be like.

Correspondingly, there are few champions of grassland in this country. Defenders of the West's mighty forests, mountain ranges, rivers, lakes, canyons, and other such spectacular areas can be counted in the millions. Though grassland and semi-grassland probably cover more of the West than all of these areas combined, the vast majority of those interested in grass and grassland are connected with the ranching industry. With this in mind, it is no wonder that Western grassland continues to be abused.

-William Voigt, Jr., Public Grazing Lands (Voigt 1976)

When a plow rips into the earth, exposing the soil and uprooting native vegetation, even the most unobservant can see a big change. When a logging outfit cuts a forest, the results are painfully obvious. When a copper company scalps a hillside, leaving tailings in piles at the bottom, the destruction is immediate and evident.

Not so with livestock. Grazing damage usually occurs in slow increments. Like the hour hand of a clock, changes are imperceptible, yet relentless. Of all the major land uses, livestock grazing is not only the most destructive but the most insidious.

Squirreltail.

USDA reports that 718 million acres of unforested grassland and semi-grassland in the US are grazed by livestock (Akers 1983). Unfortunately, healthy, intact native Western grassland has been almost totally eliminated by cow and plow, and, to a much lesser extent, development. On public land, its destruction has been caused almost exclusively by livestock grazing and ranching activities.

Though we usually think of rangeland as being grassland, this is just one of several major Western vegetation types grazed by livestock. All other major Western vegetation divisions have been severely affected as well.

Forest

At the beginning the mountains and heavily timbered areas were used but little [for livestock], but as the situation grew more acute in the more accessible regions, the use of these areas became general and in course of time conditions within them were even more grave than elsewhere, for experience had demonstrated that they were in strong demand. The mountains were denuded of their vegetation cover, forest reproduction was damaged or destroyed, the slopes were seamed with deep erosion gullies, and the water conserving power of the drainage basins became seriously impaired.

--Albert F. Potter, sheepman, principal founder of the US Forest Service and its first Chief of Grazing, in "The National Forests and the Livestock Industry," 1912

Knee- and thigh-high grasses of several varieties and river grass 8' tall (top right) blanket this ungrazed bottomland along a remote stretch of the Green River in northeast Utah.

On an area of Arizona grassland fenced from livestock for 40 years, we picked the 24 seedheads of different grass species above the line. On an adjacent comparable area outside the exclosure, we found only the 6 species below the line.

When Europeans arrived in the West they found much of it -- 25% according to Forestry Almanac -- timbered, especially along the Pacific Coast and at higher elevations in the interior. There was a wondrous variety of forested areas, from immense stands of the world's largest trees in the Pacific Northwest to tiny forests of pigmy pinyon-juniper on rocky slopes in the Great Basin to impressive cottonwood and mesquite bosques in riparian areas of Southwest.

Over the years more than 90% of the West's commercially exploitable old-growth forest has been logged, and though most of this has regrown with trees, little of it attains aboriginal forest health and integrity. (In the US as a whole, less than 5% of pre-European old-growth remains intact.) Since the Western deforestation of the 1800s and early 1900s, many areas have been cut again, some 2 or 3 or more times, with tremendous environmental impact. Today this plunder continues at an accelerating pace.

Though few people realize it, Western forests are also heavily grazed, generally with higher livestock densities than on open landscapes. For a century, nearly every forest in the West, even in the soggy Northwest, has been degraded by livestock. (On a recent stay in Mountain Home State Forest in California, we found cattle damage even in a densely vegetated sequoia grove amid the world's largest trees.) Indeed, as mentioned, in the early years of exploitation ranching was of much greater consequence than was logging in National Forests, and the US Forest Service was largely an outgrowth of the grazing industry (Foss 1960, Roberts 1963, Voigt 1976).

(Source: Vankat 1979)

About 70% of the total area of Western National Forests, or roughly 100 million acres, is currently managed for ranching -- essentially all that "feasibly" can be -- with by far most of this land grazed by livestock on some regular basis (USFS 1988). BLM reports about 25 million acres of forested land in the West, the vast bulk of it grazed (USDI, BLM 1987). And there are millions of acres of grazed state, other public, and private forest. The US Department of Agriculture reports that 246 million acres, or 63% of US forest, is "used for pasture" for livestock (Akers 1983).

Aside from logging, livestock grazing has caused and is causing far more damage to Western forests than any other forest use. This fact may not be readily apparent, for a number of reasons. But before discussing these it would help to understand just what a forest is.

A forest is more than just trees. According to ecologist George Wuerthner, a forest includes "the interrelationships between trees, soils, water, insects, fungi, fire, wildlife and a host of other influences most of us don't even know exist, much less understand." As with grasslands, healthy forests are a rich mixture of species, natural processes, and complex interrelationships. Through the millennia the right balance has been achieved for each unique geographic area. Though trees are the dominant plant type in a forest, there usually is an understory of brush and a ground cover of mixed grasses, forbs, and flowering plants, many able to subsist on scant sunlight. These plants serve many purposes to the trees and the forest as a whole, including holding and building soil, retaining water, moderating temperature, providing beneficial insect habitat, and so forth.

The natural forest is usually a jigsaw puzzle of different vegetation communities at different stages of growth. This mosaic provides diversity for overall health and biologic regeneration in case of fire or other disturbance. Likewise, the trees in healthy forests are of varying ages and sizes, from tiny seedlings to centuries-old giants, dispersed fairly randomly to assure maximum regeneration and distribution. Natural disturbance and fallen dead trees allow sunlight to reach lower levels, and through natural processes the larger forest trees usually are spaced far enough apart so that lower branches and some young trees receive adequate sunlight. This also allows smaller plant species to prosper between the larger trees, in turn helping sustain the forest as a whole. Directly underneath each tree, within its "fall line," is found a thick duff of fallen needles or leaves, twigs, bark, catkins or cones, and other tree parts. In this way each tree provides itself a rich compost that supplies nutrients, conserves moisture, builds topsoil, moderates soil temperature, and benefits the tree in many other ways.

Cattle in BLM forest. (BLM)

To most of us, as long as there are trees everything seems "park-like" and fine. When livestock strip off the grass and small plant cover of a forest, the large trees ("the forest") remain. Though the ecosystem maybe greatly damaged, we cannot see the whole forest for the trees, so to speak.

But when a forest's smaller plant cover is denuded, the large trees themselves and the forest as a whole are eventually affected. Soil erosion intensifies; soil moisture decreases; air and soil temperatures reach greater extremes; localized, low-level air movement increases; humidity decreases; beneficial animal habitat is destroyed; seed beds are damaged. Thus, in the long run large trees may become stunted, experience reproductive failures, be damaged by disease or insects, and so on. New trees cannot replace those that die since seedlings cannot establish in the overgrazed dry, hard ground.

Trees are likewise harmed when their underlying compost layer is disturbed. Normally, this organic litter layer is loosely matted together, cool, moist, aerated, and full of nutrients and beneficial microorganisms. Cattle in particular drag their feet as they walk, and all livestock tear apart and scatter this fertile overlayer, exposing it to light, cold, and heat, while at the same time compacting the underlying duff and soil, preventing aeration and, indirectly, killing microorganisms. As a result, trees suffer from a lack of moisture and nutrients that causes them to shed leaves, grow meager foliage, produce fewer and less fertile seeds, and be more vulnerable to insects and disease.

Dead trees and branches fall to the forest floor, where they may take longer to decompose than they did to grow. On the ground they are gradually reduced to humus by bacteria, fungi, and small insects. Like huge time-release vitamin capsules, they slowly release their nutrients into the soil and to plant roots.

These logs and branches may be periodically burned off by fires, without which they might accumulate to levels where they provide excessive fuel that results in highly destructive conflagrations. Where overgrazing depletes too much combustible organic ground cover, it prevents the spread of fire, or fire hot enough, to ignite these large branches and logs. In some sparsely forested areas where accumulation of duff alone isn't sufficient to carry fire, depletion of ground cover by livestock has reduced or eliminated forest fires altogether, to the forests' overall detriment (see Fire section of this chapter).

Ponderosa pine, eaten, stunted, and distorted by cattle -- one of the few survivors in a tree plantation in Prescott NF, AZ. (Rod Mondt)

This juniper, eaten and broken, stunted by general environmental degradation caused by livestock, probably will not survive.

This ash is likewise damaged and stunted.

Many people have a hard time believing that cows and sheep eat trees. Nevertheless, trees are a significant part of the diet of both in many areas. Trees preferred by livestock include oak, ash, walnut, willow, birch, aspen, alder, and

cottonwood, though if need be they will eat almost any tree. Many times I have seen cattle eating pine, even pinyon pine!

Livestock eat the leaves and twigs from branches as far up the tree as they can reach (about 5 feet with cows), leading to the familiar "browse line" common in pictures of the African savanna. Livestock also eat tree saplings, and in winter leafless saplings; in some areas these compose a significant portion of their diet. According to the Forest Service, "Proper utilization of ash, walnut, etc. is 40% to 60% of available twigs." Many public land grazing allotment management plans expressly call for 30%-70% or so annual "utilization" of tree seedlings, and often more is taken. Thus, again, as large trees die from old age or the effects of overgrazing and small trees are eaten by livestock, the forest declines. Very sparse or even aged stands of trees often indicate a history of heavy livestock use.

While cattle browse trees and damage forest ecosystems, they may also physically injure trees more directly, often by crashing through them and snapping off lower branches or breaking off small trees completely. Cattle also scratch against trees, breaking branches and rubbing off bark. They gouge trunks with their horns, opening the trees to disease and parasites. And they gnaw on bark to the point of girdling and killing trees. Wild animals such as elk and bears also injure trees, but they usually do so in more heavily forested areas where the damage usually adds to forest diversity and stability. Conversely, damage done by cattle is worst in the least forested areas.

In the drier parts of the West, mainly the Great Basin and Southwest where most forests are small and sparsely treed to begin with, livestock have been particularly destructive.

Trees are dying on this deteriorating BLM range. They are stunted; lower branches are gone; soil beneath is barren and damaged; saplings are eaten. This bottomland may have been covered with trees 150 years ago.

Cattle-grazed oak grove. Note lack of lower branches, ground cover, small trees. When old trees die, none will take their place. Santa Barbara Co., CA.

Lone pinyon pine shade tree begets cattle "sacrifice area."

In fact, most forests in these areas show more overall damage from ranching than from logging or any other activity. Due to aridity, ecosystems here are especially vulnerable to most of the livestock influences discussed.

In the summer, cattle often congregate under the largest, shadiest trees in these forests to spend the hottest part of the day. Here, they rut about, chew their cud (which they do about 8 hours a day), digest their food, and generally rest from eating (another 8 hours a day). The cattle shade tree is a common sight throughout the drier West: lower branches eaten or broken away; bark stripped from the trunk; bare, pounded dirt for many yards around; and piles of dusty manure scattered everywhere.

Many streams throughout the West are littered with the remains of what were once vigorous aspen groves. Aspen reproduce by sending up shoots from roots. If these young plants are constantly grazed off, eventually the parent trees will die of old age and aspen will disappear from the site.

--Livestock Grazing on Western Riparian Areas (Chaney 1990)

Though livestock affect all Western forest types in many ways, generally broadleaf woodlands experience more harm than do coniferous, largely because the former's saplings are more succulent and palatable. Among the most heavily damaged, for example, have been the West's shimmering aspen groves. Most are ravaged by livestock that eat and trample aspen sprouts and seedlings and other low-level vegetation, damage soil and bare it to the elements, and in many cases allow brush to take over.

The grassy oak woodland of Mediterranean California has for more than 2 centuries been experiencing a steady decline in oak trees, mostly due to cattle and sheep eating saplings. Five years after the University of California fenced 40 acres of its 4550-acre San Joaquin Experimental Range from livestock, the fenced plot supported 345 oak saplings per acre -- many times more than adjacent grazed land. According to The Nature Conservancy, an estimated 94% of California's interior broadleaf woodland has been significantly damaged or destroyed, largely by the livestock that use the vast bulk of it.

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California's beautiful oak woodlands are disappearing. Trees die or are cut, and few young ones take their place. The only small oak in this scene survives behind the protective barbs of the roadside fence.

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Ungrazed by livestock, a mountain meadow in summer vibrates with life.

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This meadow in a Wyoming National Forest is a pretty scene, but the grazing sheep do extensive damage. (George Robbins Photo, Jackson, WY)

Forest meadows are among of the most forage-productive areas in the West, so ranchers historically have made a concerted effort to concentrate their animals there. Large numbers of cattle are still driven into meadows to graze through the summer, and vast flocks of sheep are herded slowly through them, leaving devastation in their wake. The beautiful mountain meadows of the West have thus been especially hard-hit by overgrazing. Because they usually remain moist and green even when overgrazed, few people understand the magnitude of the damage.

Additionally, most of the overgrazed "meadows" found today on flats and valley bottoms in Western forests are actually artificial pastures. They were created by (or for) early stockmen who cut down trees to maximize forage for their livestock. Because of their prime growing locations, these "meadows" once contained some of the largest trees and most productive portions of the forest. Even where timber harvesting was the original reason for cutting, ranchers have prevented the forest from growing back by continuing to cut young trees and allowing their livestock to damage the land and eat and trample saplings.

A "meadow" (cleared livestock pasture) in a central California forest. Note stumps, lush vegetation on fenced roadside.

--Dave Foreman, Confessions of an Eco-warrior (Foreman 1991)

The West's riparian groves have suffered more overall from livestock than have any other timbered lands. Situated on bottomlands along perennially flowing or moist drainages, these luxuriant stands of huge trees included various combinations of cottonwood, sycamore, alder, elder, boxelder, maple, willow, walnut, hackberry, mesquite, and others. Most covered hundreds or even thousands of acres and harbored an amazing variety and abundance of plants and animals. Riparian areas were the center of life in the West.

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Remaining live oak awaits its fate while shading its destroyers. When it dies there will be none. According to D.A. Duncan and W.J. Clawson in a presentation titled Livestock Utilization of California's Oak Woodlands, a study at the Hopland Station in the northern California foothills showed that after 5 years of protection from livestock an ungrazed study plot had 554 oak saplings per acre, compared to 0 saplings per acre on a plot grazed by sheep.

On public land most riparian groves have been virtually eliminated by overgrazing and grazing-induced flooding, and to a lesser extent by flooding caused by logging and unnatural fires, woodcutting, dams, and development (much of all this also a result of ranching). Overgrazing in watersheds caused drastic flooding that swept away the very bottomland these magnificent groves used to inhabit. Where large trees do remain, they may give the impression of riparian health; however, often all that survive are "historic" trees -- large individuals that were established before intensive livestock use began, or that established at some point in history when livestock grazing slacked off for a period. When these historic trees die they aren't replaced as long as heavy livestock use continues because saplings are eaten before they grow large enough to withstand intensive browsing. This appears to be the case along the Wild and Scenic Missouri River in Montana, where University of Montana researchers have discovered that livestock grazing is a major factor in the decline of the plains cottonwood; the deterioration has been masked to most observers because the remaining large historic trees give a false impression of riparian health (Wuerthner 1991).

Hardest hit have been the verdant cottonwood and mesquite bosques of the Southwest; by far most of them have been destroyed. The Fremont cottonwood/Gooding willow community, for example, is the rarest of the 104 major plant communities in North America. Although it never covered more than 1%-2% of the Southwest, livestock grazing led the way in reducing its area to (according to The Nature Conservancy) less than 1/1000 of 1% of Arizona and less than 1/100 of 1% of New Mexico. The most sensitive riparian areas succumbed first to the initial grazing frenzy of the late 1800s, but modern ranching prevents recovery and continues to cause new damage to riparian areas throughout the West (see Riparian Areas in this chapter). Generally, livestock grazing diminishes tree cover. However, under certain conditions overgrazing may increase the range and density of several kinds of trees.

Pinyon pine and juniper are the primary examples. These trees, often in mixed stands termed "P-J," currently cover about 75 million acres, about 1/10 of the semi-arid West. To justify destroying them to increase livestock forage, ranching advocates have greatly exaggerated the extent of their spread, but there is little doubt that pinyon and juniper have expanded their territory since the 1800s, "taking over" perhaps 20 million acres previously dominated by grass and grass/shrub combinations.

The exact reasons for this have not been determined, but it is no coincidence that overgrazing and P-J spread have occurred almost simultaneously. Overgrazing in P-J and potential P-J areas is very common, and the thin soils normally associated with this vegetation type make it highly sensitive to livestock influences. We know that livestock disperse juniper seeds through feces and their trampling tends to favor P-J seedlings over competing vegetation. And obviously livestock would rather eat grasses and most other herbaceous plants than pinyon and juniper. By stripping off this organic understory, however, livestock have precluded the natural fires that used to kill tree seedlings and revitalize forbs and grasses. This, in combination with the ranching industry's intentional war against natural fire, has eliminated most natural fire from most Western rangeland. Subsequent lack of fire, more than overgrazing directly, appears responsible for the spread of pinyon-juniper.

Whatever the cause, the new P-J "forests" are comparatively dry, eroded, and devoid of plant and animal life -- as overgrazed as the grassland and semi-grassland they replaced. They are a human creation, like golf courses, and wherever they have been artificially produced by livestock the livestock, rather than the trees, should be removed.

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As young trees are eaten or succumb to other ranching impacts and old trees die, remaining trees (often used as shade) become foci for environmental damage, intensifying their extirpation.

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A fenceline ungrazed on both sides. Note small oaks on both sides.

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Most Western forest is grazed by livestock.

Because Western forests became fully stocked somewhat later than open rangelands, their greatest overall rate of livestock degradation probably occurred in the early 1900s (particularly during World War 1). Forest conditions at that time have been described with terms like "devastation" and "holocaust"; indeed, many areas resembled barren deserts scattered with trees.

Thus, the forests were divested of their natural productivity, and those forests we think we know today are operating at much less productive levels. Livestock grazing may now seem less intense, especially compared to the historic past or to the more obvious damage of current open range grazing. Be that as it may, most Western forests are still stocked many times beyond their true carrying capacity, and this pressure perpetuates the dynamic state of degradation begun a century ago. Destructive modern range development (next chapter) has augmented this state, and in some ways cumulative damage continues to mount.

Decades of differences in livestock grazing have apparently resulted in more juniper and less mesquite on the far side of the fence, vice versa on the near side. Gila NF, NM.

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(Source: Vankat 1979)

Primarily because woody plants block sunlight and occupy space that could be used by forage grasses, brushland/shrubland is the most maligned major biotic community in the West. The ranching establishment considers it a hindrance to profits and has waged unrelenting war against woody plants (see Plant Enemies in next chapter).

Unfortunately, few people of any persuasion have much good to say about brush. Perhaps this is because brush is not conveniently open to human access; you cannot walk over it as with grass or under it as with trees. Maybe it is because brush provides few apparent benefits to humans; it is not easily conquered and molded to our will. Or maybe it is because a thick stand of brush is hidden, mysterious, and even a little scary. Certainly it has much to do with the grazing industry's vilification of it for over 100 years.

Brush (bushes) and shrubs are woody plants, with brush generally being larger and more tree-like, while shrubs are low to the ground. Scrub oak, greasewood, laurel, locust, sumac, winterfat, rabbitbrush, saltbush, tarbush, cliffrose, mountain mahogany, hawthorn, snakeweed, manzanita, acacia, chokecherry, ceanothus, creosote, serviceberry, Mormon tea, jojoba, soapberry, bur sage, burro brush, bitterbrush, blackbrush, buckbrush, buckthorn -- hundreds of varieties of brush and shrubs inhabit the West. Brushland and shrubland are areas where these woody plants are the predominant vegetation.

Though occasionally growing as dense, single-species stands, woody plants usually grow in mutually beneficial combinations of species. As with forests and grasslands, the natural brushland association is most often composed of a rich array of plant types and species.

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Healthy, ungrazed sagebrush range also supports abundant grasses, flowering plants, cryptogams (see Deserts in this chapter), and animal life. Commonly, less than 10% of the ground is bare. This brushland in Craters of the Moon National Monument, ID gets only 10" annual precipitation.

Brushland performs all the essential functions of any other plant community. It builds and maintains soil, absorbs and retains water, blocks the elements, and all the rest. Even where brush forms tight, closed stands, it performs these jobs admirably. The ground beneath these stands is blanketed with a rich cover of organic litter dropped by the brush above. Pull back this thick layer and you'll find the soil beneath moist and dark, as it is well protected from sunlight, heat, cold, rain, wind. And, despite misconceptions, brush and shrubs provide habitat for the many and varied animals adapted to them.

While it is true that in some respects brushland has a lower capacity to perform these functions than does grassland or forest, as with any natural plant cover brushland is the most productive, stable biotic community for the given environment. The key here is health. Neither grassland nor brushland nor any other vegetation type perform natural functions well if abused by livestock.

Forget ranching industry "information"! Bushes and shrubs are not merely "transitional" plants or "disturbance species" occupying space until some other kind of vegetation takes their place, though they sometimes do play that role. Rather, they are part of the climax community throughout large areas of the West. This is well-documented by the journals of early explorers and by scientific study.

Indeed, when Europeans arrived in the West they found much of it cloaked with brush and shrubs. Nearly every Western ecosystem supported woody vegetation, and even the grasses of the prairie were often interspersed with shrubs, such as buckbrush. There was a great diversity of woody plant communities, from widely spaced, low-growing, mixed desert shrubs in the lower Sonoran Desert, to vast sagebrush/grass-covered plains in western Wyoming, to huge stands of dense chaparral in California's hills and mountains, to tiny thickets of mixed shrubs in rocky outcroppings in eastern new Mexico to . . . The US Geological Survey identifies 15 major shrubland and grass-shrubland divisions in the West, with scores of subdivisions.

Today, most original brushland survives, though most has been damaged and much has been altered beyond recognition. Public lands ranching has played the major role in its deterioration. According to USDA, in the US (mostly in the West) shrubland range is in even worse condition than grassland range, with 55% and 53%, respectively, producing at less than 40% biotic potential and 85% of both producing at less than 60% potential (USDA, USFS 1980).

Brushland is affected by overgrazing in most of the same ways as grassland and forest. Brush and shrub seedlings are eaten and trampled. Mature plants are overbrowsed, giving them an excessively "hedged" appearance; many brush species, mountain mahogany for example, are highly desired as browse. Branches are broken and trampled. Plants eventually lose vigor, roots and branches die back, centers die out, and reproduction fails. Livestock strip off the ground cover of grasses and other small, herbaceous plants. They trample, displace, and destroy the organic litter layer and soil cryptogamic layer common to many brushlands (see Deserts in this chapter). Rain runs off instead of in, soil erodes ... The whole familiar series of harmful effects proceeds.

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Here, grazing cattle have converted dense shrubs interspersed with grass to scattered shrubs, woody debris, and no grass. Northern Nevada BLM.

As with pinyon-juniper, some brush and shrub species -particularly catclaw, sage, snakeweed, and mesquite -- are resistant to grazing. As with P-J, they have in some areas become increasers or invaders at the expense of grass; thus, the grazing industry's "brush invasion." Overgrazing can indeed increase the range and density of brush, but onlysome species under certain conditions.

According to many range professionals, grazing's indirect effects, more than grazing per se, are responsible for the spread of these woody plants. For example, in his study

of vegetational changes on Southwestern grassland and semi-grassland, The Desert Grassland, Robert R. Humphrey concludes: The principal environmental

(Humphrey 1967) These 5 factors are most commonly cited as leading to the spread of brush throughout the West. Though Humphrey and most other range pros seem

reluctant to state the obvious connection between livestock grazing and these other factors, I will do so here:

• (1) Climate, Humphrey agrees, has been a minor factor; in fact, there has been insignificant change in climate (see Air section of this chapter).

• (2) Grazing by livestock is listed as1 of the 2 major factors, along with lack of fire, for the spread of woody plants. There are many influences involved, including: spread of seeds through fecal droppings (probably important to the spread of mesquite, for example); selective grazing (livestock eating the most palatable species and leaving the woody plants); trampling of smaller plants; reduced competition (removal of plant species that formerly served to limit other plant species' growth); damage to soil and water systems, which may favor woody plants over grasses; and removal of combustible plant matter which previously served to carry range fires.

• (3) Plant composition changes, including the increase in woody vegetation around the West, as previously explained, has been caused largely by overgrazing.

• (4) Rodent and rabbit population increases have also contributed to the increase in woody plants in some areas. These animals have accomplished this primarily by eating the more palatable species, spreading seeds in their droppings, and storing seeds underground, where they later germinate.

Cattle on this New Mexico state range have decreased nearly all plant life, including brush by perhaps 50%. Roadside at right. Foreground was bladed.

The heavy cattle grazing to the left of the fence at center has caused a definite reduction of shrub and brush cover on this steep, rocky, semi-arid BLM range in central Arizona. Probably unbeknownst to the viewer, however, the lighter grazing to the right of the fence has caused a significant vegetation decline as well.

Increases in rabbits and other rodents are caused by the livestock industry in 2 basic ways: First, predator slaughter hasallowed rodent populations to fluctuate wildly in many areas, causing them to periodically overuse smaller vegetation, favoring brush. Second, livestock grazing and certain ranching management techniques (next chapter) favor the spread of weedy species on which some rodents may thrive.

• (5) Lack of fire is, according to Humphrey, the major cause of the invasion of woody vegetation into Southwestern grassland and semi-grassland. Unfortunately, Humphrey failed to make the connection between the grazing industry and the lack of natural fire during the past 100 +years. Perhaps this is because range professional circles frown upon directly blaming ranching for anything more than the most obviously deleterious.

At any rate, by eating and trampling and causing other changes that radically decrease the amount of combustible material, livestock have eliminated natural fire from much of the range. Without periodic fire to rejuvenate grasses, destroy bush seedlings, and burn back small bushes, woody plants often have the advantage. This and the grazing industry's fire suppression campaign have been the 2 main elements snuffing out natural range fire in the West (see Fire in this chapter and Fire Management in Chapter IV).

Humphrey has changed his thinking somewhat. His recent book, 90 Years and 535 Miles, compares photographs made in 1892-1893 in 205 locations along 535 miles of the US-Mexican border between El Paso and Yuma with recent photographs of the same locations. Conclusions on these comparisons were difficult because the 1892-1893 photos were made after many years of devastating overgrazing, and directly following a period of severe drought in which thousands of cattle in the area died of thirst and starvation. Even so, the photos and Humphrey's on-the ground comments document a nearly universal reduction in grass and perennial herb cover, often accompanied by an increase in brush and annual forbs. A great many of his comparisons identify the impact from livestock as the probable main cause of change. Humphrey now concludes that climate "may be in part responsible for this change," that grazing is "in large part responsible for the change," and that "in many areas close grazing reduced the potential fuel; in others, fires would have been extinguished because they were seen as consuming valuable forage." (Humphrey 1987)

As a rule, increases in woody species from overgrazing are most pronounced in semi-arid regions. Livestock grazing in deserts usually decreases all vegetation, while grazing in moist regions generally causes native herbaceous perennials to be replaced by herbaceous increasers and invaders rather than woody vegetation. Large increases in bare dirt are common with livestock grazing everywhere.