Greater Caution Needed Before Supporting Thinning, Biomass Projects

INTRODUCTION

The rush to formulate new forest legislation that advocates thinning forests, use of biomass for energy production, and the presumption that our forests are “unhealthy” and/or that large fires and beetle outbreaks are undesirable may soon create a new threat to our forests. There are a host of different bills before Congress including legislation introduced by Mark Udall of Colorado, Jon Tester of Montana, Ron Wyden of Oregon, among others that are all predicated upon a number of flawed or exaggerated assumptions.

Some of this legislation is better than others, and some of it even has some very good things in the language and policies that are an improvement over present policies. Nevertheless, there are many underlying assumptions that are troubling.

THE FIRE SUPPRESSION CONUNDRUM

There is a circular logic going on around the issue of fuel buildup and fire suppression. Currently the major federal agencies including the Forest Service and BLM generally attempt to suppress fires, except in a few special locations like designated wilderness. Despite the fact that most agencies now recognize that wildfires have a very important ecological role to play, we are told by managing agencies that they must continue to suppress fires or face “catastrophic” blazes—which they consider to be “uncharacteristic”.

The problem is that thinning won’t solve the “problem” of large blazes because the problem isn’t fuels. By allowing the timber industry to define the problem and propose a solution we have a circular situation whereby the land management agencies continue to suppress fires, thereby presumably permitting fuels to build up, which they assert thus drives large blazes, creating a need for more logging and fire suppression. This cycle of fire suppression, logging, grazing, and more fire suppression has no end.

In addition, since thinning reduces completion, opens up the forest floor to more light, thus new plant growth, thinning can often lead to creation of even more of the flashy fine fuels that sustain forest fires. Unless these thinned stands are repeatedly treated, they can actually acerbate fire hazard by increasing the overall abundance of the very fuels which are most problematic—the smaller shrubs, grasses, and small trees that sustain fire spread.

In addition, thinning can increase solar penetration leading to more rapid drying and greater penetration of wind—both factors that aid fire spread.

This is not unlike the approach taken with predator control, whereby agencies for years have shot, poisoned, and trapped coyotes in the belief that they were reducing coyote numbers. But since coyotes respond to such persecution with greater fecundity, predator control becomes a self fulfilling activity whereby predator control begets more predator control.

While fire suppression (and logging, grazing, and so forth) may be a contributing factor in fire spread in some forest types (primarily ponderosa pine), they are not ultimately what is driving most large fires. Large blazes are almost universally associated with climatic features like severe drought, wind, and ultimately by shift in oceanic currents such as the Pacific Decadal Oscillation. Therefore fuel reductions will not substantively change the occurrence of large blazes.

Even if one wanted to buy into the fuels-is-driving- large blazes story, it would behoove us to rethink the range of solutions. The National Park Service, the only agency that does not have a commercial logging mandate, has effectively dealt with fuel reductions through wildlands fire and prescribed burning. At the very least, any fuel reduction that may be needed should be done by prescribed burning.

QUESTIONING FIRE SUPPRESSION

One of the underlying assumptions of all these pieces of legislation is the idea that our forests are unhealthy and possess unnatural fuel loads due to fire suppression or fire exclusion. There is, of course, a bit of truth to the generalization that some forest types may have had some fuel build ups as a consequence of fire exclusion, but whether these fuel build ups are outside of the historic range of variability is increasingly under scrutiny.

It’s also very important to note that the majority of all forests/plant types in the West like lodgepole pine, subalpine fir, aspen, juniper, red fir, silver fir, Engelmann spruce, western red cedar, Douglas fir in west coast ecosystems, and many others have such naturally long fire intervals, that suppression, even if it were as effective as some might suggest, has not affected the historic fire frequency.

Indeed, the majority of acreage of forest types burned annually tend to be characterized by moderate to severe fire, and are not the forest types where fuel build up is presumed to be a major problem—namely ponderosa pine forest type. Yet most people apply the ponderosa pine model of less intense frequent fires to all other forest types and thus assume that fire suppression has created unnatural fuel levels.

In particular the timber industry has adopted the convenient theme that fire suppression has created a presumed “fuel build-up” responsible for large wildfires. (Never mind that there were always large wildfires long before there was any effective fire suppression—for instance, the 1910 Burn which charred more than 3 million acres of northern Idaho and western Montana)

Thus logging proponents have created a “problem” namely fuel build up, and then by happy coincidence, have a solution that just happens to benefit them-- logging the forest.

Fire suppression may have influenced some low elevation dry forests like those dominated by pure ponderosa pine, but perhaps not nearly to the degree or over the large geographical area that timber interest and logging proponents try to suggest. Those who want to justify logging try to conflate low elevation forests with all forest types—many of which such as lodgepole pine—are very likely not affected by fire suppression due to the naturally long intervals between fires in these forests.

CLIMATIC DRIVERS OF LARGE BLAZES

The emphasis on fuel reductions has obscured the fact that nearly all large blazes are climate/weather driven events. Evidence is building that wet, cool climatic conditions may be more responsible for dense forest stands and/or lack of fires than anything to do with fire suppression. In other words, fire suppression may not be as effective as some suggest and any fuel build up may be within natural or expected range.

In addition, there is also a growing body of scientific analysis that calls into question the very methods and conclusions used to construct fire histories. These analyses suggest that historic fire intervals, even in lower elevation dry forests like ponderosa pine, are biased. Fire intervals may be far longer than previously assumed. Because of this longer fire interval, dense forest stands may be natural, and/or no different than what existed in the past. There is also new evidence for mixed “severity” (i.e. moderate change) fires as well as crown fires in these dry forests. The implications of these findings is that many forests, even low elevation forests, may well be within the historic range of variability.

LARGE BLAZES NECESSARY

One of the issues missed by thinning proponents is that the vast majority of all ecological work occurs in a very small number of fires—the big so-called “catastrophic” fires. Even though most agencies and environmental groups now profess to believe that wildfire is important to healthy forest ecosystems, they are not willing to let fires do the work.

For example, in the years between 1980 and 2003, there were more than 56,350 fires in the Rockies. These fires burned 3.6 million hectares (8.64 million acres) Most of these fires were small—despite all the fuels that has supposedly made conditions in forests ready to “explode”. Out of these 56,350 fires, the vast majority of blazes totaling 55,228 fires or 98% of all blazes only charred 4% of the acreage.

On the other hand, a handful of fires—1,222 or less than 2% of the fires accounted for 96% of the acreage burned. Even more astounding is that 0.1% of the fires or about 50 fires charred more than 50% of the acreage burned.

This suggests four things to me. First, fuels are not driving large blazes. There is plenty of fuel throughout the Rockies, but most fires never burn more than a few acres—despite all the fuels that is sitting around. Fire suppression if it was responsible for a fuels build up doesn’t appear to be creating a lot of big fires.

The few very large fires that everyone is concerned about occur during very special conditions of drought, combined with low humidity, high temperatures and wind. And these conditions simply do not occur very often. When they do line up in the same place at the same time than you get a large fire—no matter what the fuel loading may be. My conclusion is that large blazes are climate driven events, not fuels driven.

Finally, the take home message for me is that even if we were successful at stopping big blazes through thinning and/or fire suppression, we would be in effect eliminating fire from the landscape. Since almost everyone today at least professes to the goal of restoring fire, than we have to tolerate the few large blazes—not try to stop them. Of course, it appears that despite our best efforts with logging, thinning, and all the rest, we have not had that much influence on eliminating the large blazes.

FRAMING THE ISSUE

One of the other major problems I have with the way many organizations have chosen to work on these issues is the way they “frame” the issues. When words like “working landscapes”, “restoration” , “unhealthy forests” “catastrophic blazes” “beetle outbreaks” are used in any discussion related to forests, they solidify in the public’s mind that there is a major problem with our forests, and more importantly that the “cure” is some kind of major invasive manipulation of forest ecosystems.

One must be careful about how you frame this issue. Even though most environmentalists do not support large scale commercial logging of our national forests, and have a lot of sidebars on how any logging should be done to address ecological concerns, when environmental groups say things like “we need to maintain our timber industry to restore the forests” the public just hears that our forests are a mess and the ONLY solution is more logging. I maintain that is not a message environmentalists want to be conveying. The public does not hear the sidebars, nor the cautionary words, rather they hear that we need to log our forests, and do so in a big way or ecological Armageddon is about to befall the West.

WHAT IS PRUDENT BEHAVIOR?

There is an important lesson in science called the precautionary principle. In the absence of full understanding of a problem, it is usually best to prescribe the least invasive and least manipulative actions. Conservation groups would be wise to apply this principle to forest policy.

That doesn’t mean I don’t support some “restoration” activities. To make an analogy, let’s look at the issue of wolf restoration. Putting wolves back on the land restores predation influences, but this is a very different thing than allowing hunters to kill elk. Especially because it allows the wolves, and natural conditions like drought, etc. t o determine what is the “right” number of elk and deer, not some agency with an agenda to sell licenses. Hunters influence elk differently than wolves and logging is different than say fires. Just as an elk killed by a wolf leaves behind carrion that other animals can use, a forest with fire leaves behind a lot of biomass that helps to sustain many other functions in the forest.

Logging short circuits those ecosystems functions. As with hunting whenever you have a commercial enterprise involved in natural resource policy, it distorts the conclusions and it’s convenient to ignore anything that suggests the activity—whether hunting or logging is creating problems.

NEW PARADIGM

There is a growing challenge to many of the assumptions about fires and its influence on forests. These challenges to assumptions about constitutes forest “health” and the historic role of large blazes and beetle influences is not unlike the challenges to common assumptions about predators that began with people like Adolph Murie, George Wright, and other scientists back in the 1930s and 1940s who started to question predator policy. These early ecologists were not only challenging politicians and citizens, but many other scientists who were advocates of killing predators to create “healthy” populations of deer and elk.

I need not remind many conservationists that there are still plenty of scientists around that will support killing predators like wolves, despite decades of research about the ecological need for top down predators. So assurances that any logging on public lands will use the “best” science are not reassuring to me. When there is a commercial/economic aspect to any management, that tends to distort and often compromise the science and scientists that are consulted. It would naïve for anyone to believe that this is any difference when dealing with fire and forest policy issues, especially when there’s an economic benefit to some industry and/or individuals for the policy.

QUESTIONING SUPPRESSION

There is a growing scientific body of work that is challenging the notion that fire suppression is responsible for dense forests and/or that crown fires, even in low elevation forests consisting of ponderosa pine and/or Douglas fir. The implications of this for forest policy are significant for if this is correct, our current conditions are not outside of the historical normal range of variability, especially when you consider past climatic conditions that are similar to the current dry, warm conditions.

One can find plenty of scientists who think our forests are out of whack, and prescribe logging to reduce fuels and so forth, however, if one is monitoring the scientific literature one would find enough evidence here and there to question the current assumptions about “forest health” and the presumed need for logging.

At the very least, it would seem a prudent approach to avoid endorsing logging when there is at least some evidence to suggest that our forests are not as out of whack as previously assumed, and/or that logging cannot do what advocates suggest—like restore the ecosystem or prevent large blazes.

PROBABILITY OF FIRES

Another unchallenged assumption of those prescribing thinning to protect say old growth ponderosa pine is the idea that somehow without thinning, we would lose all the old growth to fires. However, that ignores the low probability that any particular acre of land will burn in a fire. For one thing, most fires are small as mentioned earlier. They do not burn more than a few acres and go out. The few fires that do grow into large blazes occur under very special climatic/weather conditions of extreme drought, high wind, low humidity and high temperatures. These conditions do not occur that frequently, and to this you must provide an ignition. So even if you have drought, wind, low humidity, etc. you may not get a blaze.

In addition, even big blazes do not consume all the forest. Most large fires burn in a mosaic pattern for a host of reasons, the likelihood that any particular acre of old growth will burn is extremely small.

Finally, since thinning effectiveness even under the best circumstances rapidly declines over time, in order to protect old growth stands, thinning of that particular location in a forest must be very recent otherwise new growth generated by the opening of the forest, reduced competition, etc. often negates any advantage created by forest manipulation (logging).

LOGGING IS NOT BENIGN

Even if one disagreed with these new insights and interpretation of forest an ecosystem, and the presumed effectiveness of thinning projects, that doesn’t necessarily lead to logging as the “cure”. It wasn’t that long ago we heard many groups outlining the many ways that logging created ecological outcomes that were undesirable—the spread of weeds, changes in the abundance of snags, and down wood, that human activity in the woods disturbs and displaces sensitive wildlife, that disturbance of the land and use of logging roads (even temporarily logging roads) adds sediments to our streams, and so forth. Most of those critiques are still valid today, but we don’t hear that kind of criticism coming from many environmental groups anymore. This silence and unwillingness to continuously remind the public that logging has many, many negative impacts on forest ecosystems has compromised the environmental effectiveness as defenders of our public forests. After all who is going to assume that role if environmental groups do not continuously remind the public that logging has many unexamined and ignored externalities.

LESS MANIPULATE ALTERNATIVES EXIST

Even if one did not want to challenge the common perception that we have an “emergency” as Senators Wyden, Udall, Tester and others proclaims, logging isn’t necessarily the only or the best way to address this presumed emergency.

The National Park Service does fuels reductions and ecosystem restoration without logging. They have a long track record demonstrating that one can modify fuels and restore the ecological value of wildfire to the landscape without logging, and without jeopardizing communities. Yosemite NP, for instance, does prescribed burning in the crowded Yosemite Valley as does Muir Woods adjacent to Muir Woods, as well as many other national parks. That is not to suggest that prescribed burning will alleviate all concerns, but at the very least, it should be the approach that environmentalists advocate. Prescribed burning combined with natural wildfire can “restore” forest resilience as well as reduce fuels. Such an approach avoids many of the negatives associated with commercial logging, including the need for roads, the disturbance of water drainage by roading, soil compaction, removal of biomass, and so forth.

REDUCE HOME FLAMMABILITY AS FIRST DEFENSE AGAINST FIRE

There is an abundance of evidence to suggest that if community security is a concern, the best way to achieve that is through reduction of flammability of homes and the area immediately around the community, not wholesale logging for the forest ecosystem. Jack Cohen’s research at the Missoula Fire had demonstrated that thinning the forest is not the best way to protect homes.

Advocating for logging as the “cure” is like suggesting that the best way to reduce elk herds is by hunting, instead of being an advocate of wolf restoration. Any time you get an economic activity involved in natural processes you compromise the integrity of the goals and measures.

ADVOCATE FOR NATURAL PROCESSES

Even if the majority of you believe our forests are out of whack and are unwilling to accept the critiques from those who suggest that our understanding of forest ecosystems may be incorrect, that doesn’t mean one has to be a hand maiden for the timber industry. Nature does the best management—that is why we all are advocates for wilderness—we believe that allowing wild places to determine what is right for the landscape is the best way to preserve “healthy ecosystems”. If the forests are overstocked as some may want to conclude, than let natural processes select which trees should survive and do any thinning that is necessary using insects, disease, drought, fire, wind storms, and all the other mechanisms that regulate plant communities—and Nature will do a far better job of determining which trees should survive than any forester.

Our role as humans is to get out of the way as much as possible, not to intrude and advocate for invasive solutions like logging. The only role for logging on public lands that I see is to strategic as listed below.

WHEN TO SUPPORT LOGGING/THINNING

If you must support logging, make sure it is very limited, and framed not in terms of forest health, but as a useful way to reduce human anxiety. Logging around houses and communities to reduce public anxiety over fires may be a political necessity. A fire break of significant size around the perimeter of a community may reduce public fears about large fires; however, as has been shown in numerous cases around the West fuel breaks alone will not ensure that homes are safe. Flammability of individual homes must be addressed.

DOES GRAZING BENEFIT GRASSES?

GEORGE WUERTHNER

INTRODUCTION

One of the most persistent myths perpetuated by the livestock industry and its proponents is the assertion that grasslands benefit from herb ivory. Actually this is not a new issue since it has been contested for decades in the ecological literature and largely resolved with most botanists and other ecologists concluding that the purported “benefits” from herb ivory—must be placed within a contextual framework that sees cropping of plants by animals and plant adaptations as largely an antagonistic response. Nevertheless, this has not stopped livestock proponent (Knight et al 2001) from repeating the same argument that livestock grazing benefits grasslands. Some (Savory 1999) even go further suggesting that if ungrazed, grasslands may deteriorate or become “degraded.” Over-rest, not overgrazing, they warn, is the problem (Savory 1999, Knight et al. 2001) in much of the West. Such assertions, of course, conveniently legitimize the exploitation of rangelands by the livestock industry and deserve careful scrutiny from conservationists.

CONFUSING TOLERANCE AND NEED

Grasses and large herbivores have co-existed for millions of year. In many ecosystems large mammal herbivores consume between 20-50% of the annual net primary productivity (Detling 1988). Over that time plants evolved mechanisms that allow them to survive, and even flourish with grazing animals. Grazed plants tend to have higher nitrogen levels (because they have a larger percentage of rapidly growing tissue), that are more palatable and often more nutritious to herbivores. Nevertheless, claims that grass require, rather than merely tolerate herb ivory demonstrate confusion between “tolerance” and “need.” Many grassland plants have developed mechanisms that permit them to persevere in spite of harm from herbivory. The ability to tolerate adverse impacts, however, should not be interpreted as evidence of “need.”

The blanket application of assertions that grasslands need large mammal herbivory pressure can easily be refuted by a quick tour of the West. Even in the Great Plains where the alleged benefits of large mammal herbivory are said to be greatest, there are numerous sites that remained ungrazed by large herbivores of any kind—whether livestock or bison, yet do not “suffer” from ecosystem degradation or decline. That is not to say there are no differences between grazed and ungrazed sites. There are sometimes differences between ungrazed sties and grazed sites in plant species, shifts between plant groups favored by C3 to C4 pathways and genetic responses (Detling 1988). And studies have demonstrated that even grazing by small herbivores such as prairie dogs can causes striking changes in plant species composition. One study in South Dakota found that 25 years of prairie dog grazing had caused the replacement of grasses by forbs (Coppock et al. 1983)

MOST WESTERN PUBLIC LANDS WERE NEVER GRAZED BY LARGE HERVIVORES

Over most of the West, arguments about the potential benefits of large mammal herbivory are a moot point. The vast bulk of public lands that are grazed by domestic animals including the Great Basin, Southwest, California grasslands, Palouse Prairie of eastern Washington, Oregon and adjacent parts of Montana and Idaho, and alpine and subalpine basins throughout the Rockies, had few , if any large herds of grazing mammals like bison (Baker 1978, Mack and Thompson 1982). Plants in these regions poorly tolerate any but the lightest amounts of grazing pressure.

PLANT ADAPTATIONS TO HERBIVORY PRESSURE

East of the Rockies on the Great Plains, bison, antelope, elk, and other herbivores were locally abundant, and this has led some to speculate that such grasslands are dependent upon herbivory pressure for their ecological health. Some of the evidence used to support this contention are the presence of high concentrations of silicates (Brizuela et al 1986), ground-level meristems, vegetative reproduction (as opposed to seed), increased tillering and the ability to translocate resources from roots to leaf production referred to as “compensatory growth” (McNaughton 1986, McNaughton et al. 1988). These and other adaptations of Great Plains grasses are often cited as an indication that the Great Plains grasses evolved with large grazing mammals. While there is no doubt that many of these adaptations help plains grasses to cope with herbivory, it’s a stretch to then argue that they “need” to be grazed by livestock or even native herbivores like bison.

Some livestock advocates while unwilling to suggest that grasslands benefit from livestock may nevertheless argue that livestock herbivory under proper management does little harm (Laurenroth et al. 1994), thus should not preclude livestock grazing on public or private lands.

While most evolutionary ecologists would have no problem with the statement that adaptations to herbivory may help a plant to cope with herbivory pressure, they do not necessarily agree that grasslands “need” to be grazed or they will somehow become degraded in the absence of grazing influences. Indeed, the overwhelming evidence is to the contrary.

For instance, Belsky (1986) finds that while herbivory may benefit certain plants by reducing competition or removing senescent tissue, no convincing evidence supports the theory that herbivory benefits grazed plants. Belsky and Painter (1993) warn that uncritical acceptance of research purporting to demonstrate benefits from grazing may result from misinterpretation of evolutionary ecology.

Other authors warn that the differences in height, leaf length, and other morphological characterizations of grazed vs. ungrazed plants often used to indicate greater “vigor” may be misleading because of “possible grazing-related genetic differences between plants in sites with different grazing histories” (Painter et al 1989).

Finally, lack of overwhelming evidence of harm as reported by Lauenroth et al. (1994) from livestock herbivory under certain conditions does not necessarily mean no harm is occurring. This is an especially convenient position for livestock proponents to take since range professionals who are usually livestock proponents conduct most research. Such researchers can not be perceived to be unbiased observers. The kinds of questions and research one conducts often determine the kinds of answers one finds. Range professionals are not necessarily going out of their way to find examples of harmful impacts from livestock. Their findings are countered to some degree by others such as Licht (1997) that focuses on ecosystem harm resulting from livestock production.

PLANT ADAPTATIONS ARE ANTAGONISTIC RESPONSE TO HERBIVORY

Indeed, the presence of high levels of silicates, sharp awns, low nutritional quality, and vegetative modes of reproduction may be a consequence of a long association with herbivores, but these adaptations suggest an antagonistic relationship not a beneficial one. Much as alarms, multiple locks and bars over windows in a high crime neighborhood may suggest a long association with thieves, one would never claim that the presence of these devices indicates a “beneficial” relationship between criminals and victims of criminal activity. The fact that some businesses may persist in the presence of high crime does not necessarily mean they need it. Indeed, all these “compensatory” factors “cost” the business more energy and resources. That some businesses may be successful in spite of these costs should not be taken as evidence that they “need” or “thrive” in the presence of thieves.

Similarly the production of sharp awns, vegetative reproduction (which is inferior to sexual reproduction with seeds), and the ability to replace lost photosynthetic material are adaptations to herbivory that have a real cost to plants (Holland and Detling 1990). These authors state “the decrease in root biomass along the grazing chronosequence is probably caused by repeated grazing and reduced allocation of carbon belowground.” Even grazing by bison has a similar effect. Johnson and Matchett (2001) found that bison “grazing decreased root growth, especially in heavily grazed patches.” Even grazing by smaller mammals like prairie dogs can substantially reduce root biomass (Whicker and Detling. 1988) In other words, plants respond to grazing pressure by reduction in the amount of roots produced. This has real consequences to the plants living in arid and semi arid climates including the Great Plains since over all root biomass determines the ability of plants to capture soil moisture and thus survive periodic drought common in these environments.

Even when such negative overall effects on plant biomass is not found, does not mean that grazing enhances grasslands. Evidence such as increased growth rates, higher total biomass, increased seed production occasionally (very rarely) found in clipped or grazed plants used by livestock proponents (Savory 1999, Knight et al. 2001) to argue that herbivory “benefits” plants can be more properly termed responses to injury (Belsky et al. 1993).

NEW LEAVES COME AT THE EXPENSE OF ROOTS

Plants respond to clipping by herbivores in the same way that your body responds to hypothermia. It shuts down blood flow to less “vital” parts of the body and tries to maintain a core temperature. After losing its leaves to a herbivore, the plant says “May Day” May Day”-- I need to grow some new leaves because I’ll “stave” if I can’t photosynthesize. I have to maintain my “core” food production abilities. A grass plant responds by translocating energy from roots to leaf production much as the body shuts down blood flow to extremities when core temperatures are declining due to hypothermia. But just as it comes at a cost to other bodily functions, the translocation of energy from roots (where extra carbohydrates are usually stored) to the production of new leaves comes at a cost in root growth. Less root mass, for instance, can cause such plants to die during drought periods. In making the “decision” about responses and resource allocation, a plant places leaf replacement first since it needs to “eat” over the reduction in root mass “gambling” that it can grow enough new roots in time to compensate for these changes before the next drought.

Indeed, all studies that demonstrate a “benefit” from herbivory are done in laboratory conditions where water and nutrition are unlimited and competition does not exist. Or as Jaramillo and Detling (1988) have pointed out findings of reduced production of individual plants in field exclosures may be as much the result of greater competition among plants than due to any positive direct effects on plants as a consequence of herbivory.

Furthermore, many of these plant adaptations such as the ability to replace lost photosynthetic material by translocating resources from roots to leaves or ground level meristems may also be adaptations to other influences like fire that may have some positive benefits for grazed plants as well. Such adaptations do not always demonstrate a long continuous association with herbivory pressures.

ABOVE GROUND BIOMASS ONLY PART OF THE PICTURE

The usual evidence cited by most livestock proponents to demonstrate that herb ivory “benefits” grasslands involve the measurements of overall ABOVE GROUND biomass production. This is partially due to the fact that measuring roots and other below ground parts is difficult to do without killing the plant. Furthermore, most range researchers are primarily interested in the growth of leaves and stems since these are the parts of the plant that are forage for livestock.

Above ground biomass (which excludes roots, which is the largest part of the grass plant biomass) can increase under herbivory pressure. If you crop a grass during the growing season, it will respond by growing more leafy material. If you measure the leafy material prior to cropping and measure the new material produced in respond to cropping as well, the overall biomass of this leafy material we be greater than what you had if you had not cropped the plant at all. In addition, the remaining unclipped leaves on a plant will sometimes increase their photosynthetic output by up to 35% in response to the loss of other leafy material.

ECONOMIC VS BIOLOGICAL VALUES

If your concern is production of above ground biomass to feed livestock, than one might be willing to call these responses a “benefit”. However, we must be clear to note that this is an economic value, not a biological or evolutionary value. The young trees that are planted after clearcutting also produce more biomass per acre annually than old growth forests, but few would argue that clearcutting old growth forests is entirely a biological benefit. All of these “compensatory” factors can be thought of as “coping” mechanisms to injury or disturbance.

The response of grasses to cropping is somewhat analogous to the respond of coyotes to control. There is much evidence in the scientific literature that coyotes can increase pup reproduction and survival in the face of persecution. If we humans shoot, trap and poison coyotes, they respond to this “pressure” in the same way that plants respond to grazing. They compensate to survive. Exploited coyotes reproduce at a younger age and produce more pups that survive into adulthood. So if you are using overall pup production as a measurement or “indicator” of benefit, than shooting, trapping and poisoning coyotes could be argued to “benefit” coyotes. Of course, most environmentalists would be loath to argue that we should shoot, trap and poison coyotes because we wind up getting “more” coyotes overall. Few would argue this is a “benefit” except for Wildlife Services, which gets paid to kill coyotes.

DEFINATION OF HEALTH NEEDS CLARIFICATION

As explained previously above ground biomass production or even a large number of species recorded for a site does not necessarily make the site “healthy.” Sites that are disturbed may actually record more species in total numbers but deviate greatly from expected natural conditions. Most grassland ecologists agree that a “healthy” landscape tends to low rates of soil erosion, low rates of exotic species invasion, dominance by natural ecological processes as periodic wildfire that are expected on that site, wildlife and plant species in some kind of natural range of abundance and distribution again expected on that particular site and other criteria that broadens the definition of what exactly is ecological health.

GREAT PLAINS ECOSYSTEMS DO NOT DEGRADE IN THE ABSENCE OF LARGE MAMMAL HERBIVORY

Even the presence of large migratory grazing herds of bison and other native ungulates as occurred on the Great Plains doesn’t mean that these plant communities “need” to be grazed or somehow will become degraded from herbivory pressure. To see the fallacy of argument, observe the right of ways along rural highways and railroads throughout the Great Plains. Many thousands of miles of these rights of ways are neither grazed by large ungulates nor cropped in any other way (i.e. mowing). The fact that these remain luxuriously clothed in grasses suggests that herbivory is not necessary for “ecosystem health.” Similar examination of the tops of isolated buttes (Square Butte in Montana), rugged side hills and slopes of badlands as along the Missouri River Breaks, Badlands National Park and other sites where no large herbivores regularly grazed demonstrates that even on the Great Plains herb ivory is not necessary to maintain ecologically stable plant communities.

EXAMPLES OF NON-GRAZED GREAT PLAINS SITES

The following natural areas have neither bison nor livestock yet some are used, as research natural areas because of they remain as ecological standards against which livestock grazed sites are measured. These non large herbivore grazed Great Plains sites include many isolated buttes, mesas, steep cliff faces along rivers such as the Yellowstone, and tops of badlands found throughout the plains that are inaccessible to large herbivores for a variety of reasons.

Among the sites that I personally know have no large herbivory pressure but exhibit intact and healthy grasslands are the top of Square Butte, Montana, Devil's Tower National Monument, Wyoming, Makoshika State Park, Montana, Terry Badlands WSA, Montana, Agate Fossil Beds NM, Nebraska, Cherry Creek State Park, Colorado, Seedkadee NWR, Wyoming (this is on the edge of the plains and may be considered part of the Great Basin by some), Fort Stevenson State Park, ND, Badlands NP. (Badlands has bison grazing about 65,000 acres of the park, but according to the resource person I interviewed there is no “major ungulate grazing on much of the park."), Medicine Lake NWR Montana (some is ungrazed mid-grass prairie), Niobrara NWR Nebraska (bison are found on a small part of this mostly grassland area, but the majority has no livestock or bison). Scotts Bluff NM, Nebraska, Chatsworth State Park, Colorado, Boyd Lake SP Colorado, Boulder City Open Spaces, Colorado, Greycliffe Prairie Dog Town State Park, Montana, Ulm Pishkun State Park, Montana, Guadalupe National Park, Texas, and Springer Wildlife Management Area, near Torrington, Wyoming.

CONCLUSIONS

The debate over whether grasslands require herb ivory by large animals like livestock is at the center of much debate over continued grazing of public lands. Those who argue that grasslands require grazing misinterpret or conveniently ignore a great deal of scientific research that suggests that moderate to heavy grazing pressure is detrimental to grazed plants—even though plants do have coping adaptations that enable them to survive herb ivory effects.

At the very least the abundance of these sites suggests that the absence of large herbivore grazing pressure is not necessary for ecosystem health and calls into question the assertions that Great Plains grasslands or other grassland ecosystems require or need large mammal herbivory to remain “healthy.”

REFENCES:

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