Ecological Dynamics on Yellowstone's Northern Range (2002) / Chapter Skim
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One of the most contentious issues is the management approach in place since the late 1960s called "natural regulation." Under natural regulation, ecological processes within the park generally are left to function free of direct human interventions, or, as described by the National Park Service (NPS) , "natural environments evolving through natural processes minimally influenced by human actions." Concern has centered on the ecosystem of the northern range of YNP, especially about the effects of natural regulation on ungulate populations and subsequently their effects on vegetation.
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However, other scientists end resource managers note thatungulates have influenced vegetation on the northern range for thousands of years and believe that natural density-dependent factors such as forage availability, predation, and disease are regulating population dynamics so that current conditions fall within the natural range of variability. In recent years, the controversy over natural regulation has heightened, especially in the northern range wintering range of Yellowstone's elk herds.
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From page 3... ...
Although YNP's natural regulation policy involves little intervention within the park, ecological processes in the region are profoundly influenced by human activities outside the park. The underlying belief that national parks should, to the maximum extent possible, harbor natural ecosystems has fostered extensive debates about how to react to ecosystem change in the parks and how to determine when such change is caused by humans.
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Because some component of the ecosystem may appear to be disrupted—e.g., effects of heavy grazing in the northern range and degradation of its riparian areas some people criticize natural regulation. Supporters of natural regulation argue that, in the face of constantly changing biotic and abiotic environments, current conditions are within the range of natural variation and that Yellowstone is not in ecological trouble.
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, but it is noticeable and is perhaps the ~ a r g e s t f a c t o r i n fl u e n c i n g t h e v a ~ ~ e y fl o o r s . T h e m a j o r fl o o ~ s o f ~ 9 9 6 a n ~ ~ 9 9 7 , which caused changes in the park's streams and their associated riparian communities, are examples of rapid geomorphological change.
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From page 6... ...
From the 1930s through the 1960s the NPS hunted and trapped elk to reduce their populations because park scientists during this period considered the northern range highly degraded by an excessive population of elk. By the late ~960s, when YNP adopted natural regulation, the northern range elkpopulation had been reduced from some 10,000 animals to fewer than 5,000.
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From page 7... ...
to regulate elk end bison populations in the northern range. There is a strong density-dependent signal in northern range elk and bison population dynamics, but their responses differ: bison tend to expand their range to areas outside YNP when their population exceeds roughly 2,500, whereas reproductive rates in elk decline when their populations exceed roughly ~ 5,000.
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From page 8... ...
Recent restoration of wolves to YNP may allow evaluation of their role in aspen and willow recruitment and maintenance, but scientific information is lacking to understand the role of past development and hunting outside the park on elk behavior and migration patterns. All tree-sized aspen in the northern range are now more than 80 years old, and in the absence of recruitment their abundance will continue to decline.
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Such conclusions reflect subjective value judgments in addition to objective observations. For example, some people compare the northern range unfavorably with nearby ranches, but that reflects a mixing of values.
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For these reasons, true natural regulation in YNP that is, really letting nature take its course with no human intervention is not possible. YNP's practice of intervening as little as possible in the ecology of ungulates within YNP will likely allow the persistence of the northern range ecosystem and its major components as long as there is no large change in climate.
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From page 11... ...
Thus, long-term scientific investigations and experiments to provide solid scientific evidence for evaluating management options are needed. · The NPS educational and outreach program can play an important role in fostering public understanding of the complex and dynamic nature of ungulate ecology in the GYE, which is an essential adjunct to effective management of the northern Yellowstone ungulates.
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From page 12... ...
The study should evaluate the likely consequences of a full range of potential management options from doing nothing to actively controlling predators andproviding winter feed.
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A comprehensive research effort is needed to assess the influence of seasonal densities, distribution, movements, and activities of people within YNP and adjacent areas on wildlife species, their habitat use patterns, behavior, foraging efficiency, effects on vegetation, and other aspects of their ecosystem relationships. · The effects of changing land-use patterns in the landscape surrounding Yellowstone must be understood with regard to its expected influence on the park's biota and natural processes, such as fire.
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From page 14... ...
14 Ecological Dynamics on Yellowstone's Northern Range require resolving conflicting policy goals, bolstering incomplete scientific information, and overcoming management challenges. Doing so will require all the vision, intellectual capacity, financial resources, and goodwill that can be brought to bear on them.
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