Natural Regulation Concepts:

Defining terms: Natural Regulation, Stability and Dynamic Equilibrium

Adapted from Mark Boyce, Ch. 14, The Greater Yellowstone Ecosystem: Redefining America's Wilderness Heritage (1991)

Natural Regulation: Without environmental constraints, populations have the potential for exponential increase until ecological limitations become effective. As population size increases, declines in birthrates or survivorship are observed. Factors that change with population size are referred to as "density dependent". Scholars still argue whether density dependent or density dependent and density-independent processes are a part of the natural regulation of populations. By including density- independent factors in the definition, natural regulation becomes, the dynamic process of factors that change with population size and factors that change independent of population size (such as environmental factors: winter severity and drought). Natural regulation is also affected by multiple species, therefore; single-species populations are not acting independently. Models of natural regulation are non-linear and stochastic, where the potential for complex, or unpredictable, fluctuations exists.
Stability: Local stability: A system that returns to equilibrium after a small perturbation. Global stability: A system that returns to equilibrium after a large perturbation. Other uses of stability include persistence, resilience and boundedness. Stability can be used to describe a relatively stable population, or one exhibiting small fluctuation in abundance. Because this term has multiple meanings, defining the a particular usage is necessary.
Dynamic Equilibrium: Equilibrium is a stable point. Doug Houston used the term "dynamic equilibrium" to describe the northern range elk herd in Yellowstone, whereby a population is not driven toward the same equilibrium each year. The equilibrium point can change over time, depending on density independent factors, such as winter severity.

Discussion of Controversy Surrounding the Natural Regulation Paradigm:

Different authors and investigators have come to conclusions about the utility of Natural Regulation management in Yellowstone, which have resulted in polarized debate. A summary of quotes from sited professionals will be provided to present an unadulterated representation of views surrounding Natural Regulation in Yellowstone.

"Many Park Service policies developed and implemented since the Leopold and Robbins reports assume that Yellowstone is a large enough area to regulate itself. This assumption derives from empirical studies of intact natural ecosystems that, if not disturbed, do appear to be self-regulated. The problem with natural regulation policies in Yellowstone National Park is that the area is not an intact natural ecosystem. Moreover, with its road system, developments, and annual infusion of more than 2 million visitors, the area is far from being undisturbed." ¾ John J. Craighead, Ch.3, The Greater Yellowstone Ecosystem: Redefining America's Wilderness Heritage (1991)
"That the pristine condition of Yellowstone's ecosystem remained unproven mainly escaped notice. And the very inaccessibility of the data for and against the theory worked to its advantage. Natural regulation had developed an aura of the occult: only the initiate understood it. Independent scientists who did not know kept silent." ¾ Austin Chase, p. 69, Playing God in Yellowstone: The Destruction of America's First National Park (1987)
"The most important message from this study [which compares sites over time using photos dating back to the 1880's] is that the Yellowstone landscape is above all else magnificently dynamic. There is not 'correct' or 'pristine' fixed state, to which the Park ecosystem should be held, even if this were possible. In this sense the past serves as only a limited guide to the future because the intensity and frequency of the processes driving ecosystem change." ¾ Mary Meagher and Douglas Houston, Yellowstone and the Biology of Time (1999) taken from the Northern Range Newesletter.

These three quotes reveal a lot about the debate. It is apparent when reading the Chase quote and the Meagher/ Houston quote, that different definitions of natural regulation are being used (density-dependent vs. density-dependent and independent factors). Miscommunication aside, the argument is clearly polarized. One side needs proof that Natural Regulation works, the other side claims that "proof" can't be found because evaluation criteria are unknown for a dynamically changing population. Science and philosophy become muddled where empirical evidence is not available to resolve conflicting opinions.

Interviews

Professor Jim Agee: Fire Ecologist, University of Washington.

Question 1: What is your opinion regarding National Park Service management of elk in Yellowstone? Are you of the opinion that “Natural Regulation” works or doesn’t work. Why?

Reply: “I am not very familiar with the management of elk in Yellowstone, but I am very familiar with natural regulation. For protected populations, I think natural regulation is a desirable goal. Can it occur? It is a question of scale. Natural regulation management would need to occur at a very large scale, and in the lower 48 states I don’t know of a single group of elk herds protected under one land base. Elk migrate across borders, an example of this being the elk migration maps of Yellowstone. If you look at the map, only one small herd is contained within the park during summer and winter seasons. The rest of the herds migrate out of the park to winter.”

“Let me provide a background on population dynamics. There are two kinds of carrying capacity. The first one being, “Ecological Carrying Capacity”, which includes the ecology of an area with out intervention, as found under natural regulation. The second one being, “Economic Carrying Capacity”, or the carrying capacity of hunted populations, which takes into account range management and keeping the population at a certain level of condition for the purpose of hunting. There are three major differences between these two types of carrying capacity. One, population size is higher under ecological carrying capacity, or a non-hunted population, than under economic carrying capacity. Two, condition of the herd is lower, on average, under ecological carrying capacity than it is under economic carrying capacity. Hunting can take out weaker individuals and increase overall vigor of a population. Three, reproductive rate is lower under ecological carrying capacity and major die offs may occur with the influence of food shortage and/or severity of winter.”

“For park and wilderness areas natural regulation is a desirable goal, but not possible due to scale. We also don’t know the significance of wolf predation on ungulate populations. I believe natural regulation is an honorable goal, some people don’t think so, but I do. But it is difficult to think that we can do this anywhere in the lower 48. This would provide reason to expand Yellowstone to include winter range. The purchase of winter rangelands would help the park achieve natural regulation because they could maintain a whole herd on one land base. Right now, summer range is unlimited due to increase in rangeland from fire. The effects of fire should increase the condition of elk herds from the additional lands that are now providing range forage. However, this will only exacerbate the problems associated with lack of winter rangelands, making reduced winter range a more significant factor than it already is.”

Question 2: How do you feel about winter-feed programs, such as the feed program on the National Elk Refuge in Jackson, WY?

Reply: “I have a neutral stance on winter feed programs. It depends on the management objectives. If natural regulation is the goal, then winter-feeding is not good. Feed programs may keep populations at an artificially high level, which if done for harvest is appropriate. But hunters should be the ones paying for the program, since they are the ones benefiting from it. In areas where there used to be a lot of winter range area, like Jackson Hole, winter-feeding can substitute for what would have been natural range. I have no philosophical opinion against winter-feeding. Again, it depends on the management objective. It is a tool in the bag, and you don’t want to rule it out.”

Question 3: What is your opinion regarding the ability of wild ungulate populations to overgraze rangelands? Do you feel that overgrazing is occurring in Yellowstone?

Reply: “Yes and yes. Ungulates do have the ability to overgraze, particularly if managing to ecological carrying capacity. The population will become limited by something, either winter or summer range. Lamar Valley is a very highly grazed area. The whole area looks like it has been hosed over. Elk have been responsible for decreases in Aspen and willow. High levels of grazing should be expected when managing for natural regulation. You can’t have your cake and eat it too. That’s not how natural populations work. Lamar Valley is clearly overgrazed. The problem with Yellowstone is that you have personalities involved. Yellowstone has enemies, and even when the opposing side makes some good points, the park will continue to defend their position largely because they don’t like the people opposing them. Also, under natural regulation, technically “overgrazing” can’t happen. High levels of grazing are expectable under this paradigm. I think the park has gone about defending their position in the wrong way. They say- Yellowstone is not overgrazed, and maintain that plant- herbivore dynamics are stable. They should come out and say- Yes, elk are highly grazing the system, but that is ok under natural regulation, instead of denying an effect. Where opposing arguments are at odds, you can’t listen to the arguments. They are political. You have to go out and investigate for yourself, and read the landscape. You have to call it the way it is, and keep your philosophical views out of the picture. In Yellowstone, both sides have twisted their argument to meet their views. After a decision about the level of grazing has been reached with out the influence of personal views, then you can ask, but is this level of grazing appropriate or not? That is where value judgments come into play. But the park and its opponents are mistaking value judgments for scientific judgments. For example, in the 1988 fires, 50% of the burned area was human caused. From the standpoint of natural regulation this was a huge disaster. But the fires are interpreted now as a grand natural event."

Question (in Response to Question 3): I know you have a background in rangeland ecology. Aren’t there measurements the park, or the opposing side, could have taken to demonstrate quantitatively whether overgrazing has occurred? Why doesn’t this database exist?

Reply: "Both sides felt that if there were data, they would be on shakier ground. If they had data, they would have to except that the data may not support their views. It is political."

Question 4: Do you feel that elk are a threat to the spread of Brucellosis?

Reply: “I don’t know. I have heard that there has been an established case where it has happened in a controlled setting. That means it isn’t impossible in the wild. It used to be the argument that spread could not happen- that is wasn’t possible. But would it be a significant amount? Probably not. It is not likely to be a major problem. But because it is possible, this requires a revision in our thinking. The park could figure out where high concentrations of cattle and elk/ bison interactions occur, and manage or monitor activity in those problem areas. The whole issue with ecosystem management is that it crosses borders, with different management objectives. They could put up an elk fence or a harvesting program in problem areas, but I don’t think there is tremendous need to worry about this. We do need to monitor, because it is possible.”

Professor Ken Radaeke, University of Washington, Wildlife Biologist:

Question 1: What is your opinion regarding National Park Service management of elk in Yellowstone? Are you of the opinion that "Natural Regulation" works or doesn't work. Why?

Reply: "Does it work? That depends on how you define natural regulation. Ungulate numbers are not constant they fluctuate up and down, so when you ask does it work- the question is work for what? Can it work in Yellowstone- Yellowstone is just a portion of the larger Yellowstone ecosystem. Other management of elk outside the park affects elk coming in and out of Yellowstone. The elk cross boundaries, and the park can't control how the elk are managed off their land. You have to ask, what are the conditions that exist to make populations naturally regulate? I don't believe that populations do or can regulate. They fluctuate dramatically. It's fairly well established in the profession that natural regulation is not a reasonable paradigm for wildlife management. Predators may be able to moderate the fluctuations in elk populations, but the jury is still out."

Question 2: How do you feel about winter-feed programs, such as the feed program on the National Elk Refuge in Jackson, WY?

Reply: "In some areas where winter range has been eliminated you have two choices: if you want elk, you have to feed them, if you don't want elk don't feed, and they will starve. It comes down to a simple question do you want elk or not. Feeding really perpetuates the problem of loss in winter range. It would be better to try to buy up property from private landowners. In the long run feeding is not sustainable. But there are a lot of people who benefit from the feeding. It's a tourist attraction, and the USFWS gets funding from hunter revenues generated by the elk population. Another question that comes up is how do you keep the elk benefiting from winter feed programs with in reasonable numbers to sustain the population that goes back into the park."

Question 3: What is your opinion regarding the ability of wild ungulate populations to overgraze rangelands? Do you feel that overgrazing is occurring in Yellowstone?

Reply: "If you look at Houston's book, it's arguable, but I think it is possible. Natural systems crash and come back, which is clear evidence that elk can overgraze. Yellowstone has probably been overgrazed historically. It's really a value judgment. What is natural vs. un-natural? You are looking at a snap shot in time, and you don't necessarily know what was happening before that led to present conditions. You could visit the park when lots of green up is occurring, or you could go there when it's in a drought, and elk numbers are up- it depends. If you took five experts out to rangelands and ask is this overgrazed you'll get five different answers, because it is a judgment call."

Question 4: Do you feel that elk are a threat to the spread of Brucellosis?

Reply: "No. It is not a problem."

Question to reply: Why do you think people are concerned with bison spreading Brucellosis to cattle, but not worried about elk causing the same problem?

Reply: "Everyone has pushed elk having Brucellosis under the rug, and just don't recognize it as a problem. The general public takes the view that if animals look alike they can transmit the disease easier. Bison look more like cattle than elk do, so they are worried about the bison. The reason Brucellosis is a big deal to Montana is they need to have "Brucellosis- Free" status for the ranching industry in order to be competitive with the market. There are only around 5,000 cows even at risk. I would rather they condemn those lands for ranching, and give it to the Park. But that is my bias, because I think bison are more important."