Yellowstone's Northern Range - Greater Yellowstone Science ...

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THE NORTHERN RANGE 32 systems-range or forest-tended to reach a stable state, a sort of idealized equilibrium, that would be relatively easy to manage. In recent decades, however, instability has become more apparent as a fundamental characteristic of wild ecosystems, and has become especially important to students of wild ranges that are grazed only by native ungulates. Paleontology, as well as practical experience over the past 120 years, has shown us that ecological processes are far less predictable, and far more unruly (by human standards), than was previously supposed. This realization has led at least some observers, including park managers, to be more cautious about pronouncing a range "overgrazed, "unnatural," or "damaged," because we now realize that even without human influences, the conditions on a given range are far more variable than was once thought. Earlier assumptions about the nature of wildlands have been challenged as ecologists have realized that nature has little regard for the range management and wildlife management textbooks written earlier in this century. Research in wildland grazing systems, that is systems in which wild ungulates use the landscape with relatively little interference from humans, have focused on sites like Yellowstone's northern range-large nature reserves. The researchers report many interesting things, some of which are reviewed below. Perhaps most important of all, they report that a wild rangeland, grazed only by free-ranging native ungulates, may not look the same as a commercial livestock rangeland. Wild ungulates will not use the range in the same way that livestock do; they will use the plants differently and to a different extent, they will move as the seasons dictate rather than when humans decide to move them; their numbers will vary-sometimes dramatically-with environmental conditions; and the range's appearance will depend upon many environmental factors rather than upon close supervision by a human manager whose primary goal is to maintain the highest sustainable level of livestock production on that range. For all their localized imperfections in terms of human disturbances, reserves such as the northern range, are the closest modern humans can come to seeing truly wild ranges in today's intensively fanned world. This is not to say that either type of range should somehow be regarded as better looking, or better managed. One of the reasons Yellowstone National Park's policies have been drawn into range management controversies is that natural regulation is perceived as a threat to traditional range management beliefs. Though there are lessons commercial range managers can learn from wildland range ecologists. it has never been the intent of the National Park Service to place a value judgment on natural regulation that would rank it qualitatively above or below other range management practices or philosophies. On the other hand, Yellowstone's experience after nearly 30 years under the natural regulation policy suggests that for a commercial livestock specialist to come into Yellowstone National Park and judge its northern range by the standards of livestock management practices is as inappropriate as it would be for a wildland ecologist to expect a livestock range to resemble a wildland grazing system. Without a deep familiarity with local conditions-history, climate, soil, native plant composition prior to settlement, and other factors-these environments do not easily yield accurate assessments of their conditions. The notion that all ranges, regardless of their history and their management goals, can be judged by some standard "cookbook" approach will not work well in Yellowstone. Unfortunately, some participants in the dialogues over the condition of national park ranges are not aware of the importance of this philosophical difference in goals. This problem of perception is central to the Yellowstone northern range issue. Until the two differing perspectives are recognized, grim pronouncements from the livestock industry about Yellowstone's rangelands will continue, just as a host of wildland ecologists will continue to extol the health and wonder of the northern range and criticize the appearance of commercial ranges. These philosophical complications aside, there remain the fundamental scientific questions about the northern range, questions that have been asked and re-asked by generations of researchers.
GRASSLANDS 33 Among the complications affecting northern range research today is the fact alluded to by Houston (1982), that North American grazing systems were not studied until their native grazers had been manipulated or, in many cases, entirely removed. In Yellowstone, modem studies of herbivory are being conducted after a century of ongoing climate change, as well as varying manipulation of herb i vores and their range; even a several-year study of vegetation trends in the 1980s or 1990s, cannot fully inform us about the condition of that vegetation in earlier times. For example, the long-term vegetation exclosures on the northern range were not constmcted until after the drought of the 1930s; they do not necessarily reflect historic or ancient conditions in those areas. In the following paragraphs, we summarize some of the recent research findings regarding the northern range. Keep in mind that much work is still underway; there is still much to be learned about this complex ecosystem. Thus, what follows is only a summary of the recent work on the northern range. Readers interested in learning more should consult the many scientific papers, reports, and publications cited at the conclusion of this book. First, the concept of overgrazing required clarification. In many recent dialogues about the northern range, different participants meant different things by the term "overgrazing," resulting in great confusion and frustration. To test different concepts of overgrazing and how they might apply to the northern range, Coughenour and Singer (1991, 1996c) compared the Yellowstone natural regulation hypothesis to four other models or concepts of overgrazing. They noted that even among traditional professional managers, deIinitions of the term "overgrazing" vary greatly. Coughenour and Singer compared the concept of overgrazing as viewed by "a range manager, a wildlife manager, a model of natural regulation ... , the Yellowstone natural regulation hypothesis, and a model of natural regulation that is less dependent on equilibrial assumptions." They did this by comparing the criteria of each of these definitions-in other words, they compared precisely what range conditions each viewpoint used to define overgrazing, and discovered that, by any of these definitions, it would be difficult to judge the northern range as overgrazed. Coughenour and Singer concluded that the concept of overgrazing in Yellowstone has been significantly influenced by the perceptions of range managers and ecologists of the historical periods they have represented. For example, the climate of the 1930s added greatly to a perception of overgrazing at that time, though it was a random environmental event-an extended and severe drought-that set up the conditions observed at the time, rather than the short-term actions of the grazing animals. Coughenour and Singer agreed with Houston (1982) that the perception of an overgrazed northern winter range was predicated on the assumptions that: 1) elk populations increased due to protection within the park; 2) few elk wintered in the park prior to 1878, and that instead, most elk had migrated out of the park each winter; and 3) human development and ranching outside the park excluded elk from winter ranges, and unrestricted hunter harvests on the park boundary further eliminated migration patterns. They further concluded that early acceptance of the idea that the northern range was overgrazed followed directly from principles of range management published in the 1940s, though these principles were only applicable to domestic livestock. GRASSLAND SPECIES COMPOSITION AND ABUNDANCE Changes in species composition (that is, the assortment of species present on a given site) can be seen as a sign of overgrazing. Studies therefore addressed this condition. On low-elevation winter range sites, no differences in species composition were documented between grazed sites outside and ungrazed sites within exc10sures protected from any grazing since the late 1950s (Reardon 1996, Singer 1996a). Large ungulate herds and intensive grazing do not appear to be negatively affecting native or Alpha diversity (Singer 1996a; Coughenour and Singer, Colo. State Univ., and U.S. Geol. Surv., unpubl. data). The evidence
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Page 89 and 90: ELK POPULATION ISSUES 73 1996d), so
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THE NORTHERN RANGE 82 Competition t
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THE NORTHERN RANGE 88 not aware of
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THE NORTHERN RANGE 90 tion size, an
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THE NORTHERN RANGE 92 activity (95
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THE NORTHERN RANGE 96 factors were
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THE NORTHERN RANGE 102 complex set
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THE NORTHERN RANGE 104 practically
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THE NORTHERN RANGE 106 appear suppr
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AppendixA. Conferences, Meetings, a
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lJO Year Estimate Comment Source 19
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lJ2 , Estimated # of Elk Year Date
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lJ4 Winter Total Count 1967-68 397
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116 Year Date of Count Parkwide Par
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118 Counts and estimates of mule de
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120 Northern Yellowstone winter ran
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122 Population estimates and reduct
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124 Actual count Inside Outside Est
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Pronghorn counted during spring sur
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128 Year 1939 1940 1941 1942 1943 1
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Ground and aerial counts of bighorn
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REFERENCE LIST NOTES ON THIS REFERE
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Pages 199-210 in Carbyn, L.N., S.H.
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Yellowstone National Park. Technica
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mammal mortality in the 1988 Yellow
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National Park. International Journa
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Mehus, C.A. 1995. Influences ofbraw
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__ , and __ . 1996a. Preburn root b
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Pages 127-138 in F.J. Singer, ed. E
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some northern Yellowstone elk. M.S.
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I I I I I
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