Exactly 150 years ago, on March 1, 1872, the 18th US president, Ulisses Gant, signed the law called The act of dedication , by which a figure of protection was established for the first time in the world that is still in force: the National Park.
A national park is a protected space that is characterized by having a high ecological and scientific value, and by having features that are representative of the biogeographical region in which it is located.
The concept of national park was soon applied to the Royal National Park in Australia in 1879, and in 1890 Yosemite National Park was founded in California.
In the rest of the world it began to be applied well into the 20th century, and Spain established its first national park in 1918, in the Picos de Europa. Currently, Spain has 16 national parks. But it all started 150 years ago, in a vast natural area between the states of Idaho, Montana and Wyoming, Yellowstone National Park , a territory known as the Greater Yellowstone Ecosystem.
Yellowstone Ecosystem Outline
The national park has up to 1,700 species of native plants , of which the coniferous forests stand out, occupying 80% of the park’s surface. Of the eight species that make up these forests, the most representative is the lodgepole pine ( Pinus contorta ). Also of great importance is the Yellowstone River, which runs through the park, with its riparian vegetation , a refuge for a large number of creatures.
Among the animals that inhabit the park there are 285 species of birds , including aquatic birds and birds of prey, and 67 species of mammals, among which large ungulates stand out, such as bison, Canadian deer and elk; the beaver and the otter inhabiting the river; rabbits, hares, squirrels and marmots on the riverbanks; small predators, such as the wolverine, the weasel, the fox, the coyote or the badger; felines, such as the Canadian lynx, the bobcat and the cougar; and the most representative and iconic of the park: the grizzly bear, the black bear and the gray wolf.
The Loss of the Yellowstone Wolf
The gray wolf is perhaps the most important species in the Yellowstone ecosystem, and it is painful how this conclusion was reached. In 1914 , in an ill-fated attempt to protect elk populations in Yellowstone, wolves, along with many other predators, were declared undesirable animals and generous amounts of public funds were allocated for their eradication. The last pack of wolves in the park was exterminated in 1926. The extermination of a native species, completely integrated into the ecosystem, caused what was called a trophic cascade effect of such magnitude that it went down in the history books.
The total absence of wolves, the main predators of elk and deer, caused an exaggerated increase in their population . In a short time, the large ungulates became a real plague in the park, while a significant amount of plant biodiversity was being lost due to the overexploitation of these herbivores. Poplars, willows, and other forms of riparian vegetation were reduced to almost negligible levels .
Without those forests, the birds disappeared, and the beavers, who needed the wood to build their shelters, migrated elsewhere. The beavers and their prey disappeared, the otters lost their habitat, the river overflowed its course, blurring the landscape.
On the other hand, without large predators controlling the coyote population, it exploded, wreaking havoc on populations of small mammals, which could no longer hide in the vegetation, and outcompeting weasels, foxes and eagles.
The first solution raised in Yellowstone was the hunting control of large ungulates. In the 1960s, hunting parties went hunting to reduce the number of deer and elk. In 1969 hunting was stopped, hoping that from then on the population of large herbivores would regulate itself. Nothing could be further from the truth. Within a few years, overpopulation was once again an ecological problem.
The trophic cascade
In 1995, after much debate and study, it was finally understood where the root of the problem lay, and it was decided to reintroduce wolves. Although there were a few, its effects were not long in being observed. Not only did they start hunting some of these big deer and elk, but they had a major behavioral change; they began to avoid the riverbeds , where they were more exposed to predators, and in a few years, the riparian vegetation was restored .
The banks of a new channel, different from the old one, were strengthened again and erosion decreased. With the resource of wood again available, the beavers returned, and with their activity, they stabilized the river, allowing the otters to return . The new riparian forests provided refuge for returning birds and small herbivorous mammals preyed upon by coyotes.
The coyote population was brought back under control, and weasels, foxes and eagles, with their prey now recovered, also returned to the region.
Park administrators in the early 20th century had little or no idea of the repercussions that the extermination of the wolf would have on the ecosystem. The concept of “trophic cascade” was not yet known, and much less was it known that it could go in both directions . At that time, scientists thought that ecosystems were built from the bottom up, from the base of the primary producers—plants.
The observations at Yellowstone demonstrate, however, that top-down effects must also be taken into account, and may in fact play a crucial role in the ecosystem. On the other hand, they made the mistake of assuming that hunting control could be sufficient to achieve equilibrium in the ecosystem, without taking into account that the role of an apex predator is not only to hunt, but also to compete with other predators and to modulate the behavior of their predators. dams.
Human invasion of natural spaces is the cause of habitat destruction and species extinction. But the restoration of wolves in the world’s first national park is a prime example of how we humans have the power to own up to our mistakes and make changes for the better. Perhaps the experience in Yellowstone National Park, which turns 150 today, can give us a glimmer of hope.
REFERENCES:
Hampton, H. D. 1971. The Nation’s First National Park. En How the U.S. Cavalry saved our national parks. Indiana University Press.
Jackson, M. K., Tatton, N. R., et al. 2021. Wolf Recovery in Yellowstone National Park. En Reference Module in Earth Systems and Environmental Sciences (p. B9780128211397001000). Elsevier. DOI: 10.1016/B978-0-12-821139-7.00078-7
National Park Service & U.S. Department of the Interior. 2021. Park Facts – Yellowstone National Park. https://www.nps.gov/yell/planyourvisit/parkfacts.htm
Ripple, W. J., & Beschta, R. L. 2012. Trophic cascades in Yellowstone: The first 15years after wolf reintroduction. Biological Conservation, 145(1), 205-213.
DOI: 10.1016/j.biocon.2011.11.005
