The American Yellowstone National Park is 150 years old. Researchers have identified significant changes in the park over the course of a century and a half. The five most important.
Yellowstone National Park in the United States celebrates its 150th anniversary this yeare birthday. On March 1, 1872, President Ulysses S. Grant signed the Yellowstone National Protection Act, creating the world’s first national park, according to the Guinness Book of World Records. In the 150 years since its inception, Yellowstone has not only grown into a unique scenic area and a beloved tourist attraction, but it is also a valuable research area for scientists. In the century and a half, researchers have been able to identify important changes. Smithsonian Magazine outlined what makes today’s Yellowstone different from the same area 150 years earlier.
1. The most obvious change is undoubtedly the disappearance and return of the wolf. Thousands of years before Yellowstone became a national park, wolves roamed here. You would expect the declaration of Yellowstone National Park in 1872 to benefit the wolves that were already on the verge of extinction at the time. But nothing is less true. While all kinds of animals were now protected, the wolves went unprotected because they killed more popular animals like deer and bison. The animals were even actively hunted in Yellowstone and in the early 1920se century they were massively poisoned. Between 1924 and 1926, the last wolves in Yellowstone were killed.
A lone wolf was seen sporadically in the following years, but no wolf packs existed for decades. This immediately had a catastrophic effect on the landscape. The absence of wolves caused the number of wapitis and coyotes to explode, throwing the entire ecosystem out of balance: willows and aspens were immediately eaten and given no chance to grow. Fewer trees mean fewer songbirds. In addition, riverbanks eroded because there were fewer trees to hold the soil, which in turn had consequences for beavers who could no longer build dams. And these are just a few examples of the negative consequences.
Several scientific studies have shown that the decline of the ecosystem in Yellowstone was linked to the disappearance of the wolf. It would take years, but 14 wolves were brought to Yellowstone from Canada’s Jasper National Park in 1995, and another 17 the following year. Since then, that early pack has grown to more than a hundred wolves within the park’s protected boundaries. About 500 wolves now live in the Greater Yellowstone area (ten times the size of the national park itself). Scientists have followed wolves’ impact on the ecosystem from the beginning and are constantly making new discoveries to this day.
Among other things, the wolves ensured that the herd of Wapitis is stable today. There were far too many of these large deer for that, and large numbers had to be shot every year. Now the park has about 6,000 Wapiti, and the number does not fluctuate from year to year: no huge growth in good years and massive deaths in years with little food. The decline in the number of wapiti gave young trees a chance to grow again, it was easier for beavers to build dams again and the number of fish increased because they thrive better in shaded and colder water. The wolves are even said to be partly responsible for changing the course of the rivers in the park.
2. The boundaries of Yellowstone National Park have hardly changed, but neither have the natural areas surrounding the park: the Greater Yellowstone Area. This area was originally ten times the size of the national park itself, but it is rapidly decreasing in size.
The State University of Montana study “Trends in Vital Signs for Greater Yellowstone Application of a Wildland Health Index” shows that the area’s population has tripled since 1970. That number is expected to double by 2050. In addition, tourism has increased tremendously. In particular, large groups of ‘backcountry’ hikers disturb and remove animals from the places where they normally forage, sleep and eat. Today, Yellowstone National Park is surrounded by houses on almost all sides. This ensures that the link between the different ecosystems is broken and, for example, wolverines can no longer move from one alpine forest to another.
Another problem is the invasive plants and grasses that are spreading outside the park by horses and other domestic animals and are increasingly invading the national park. That plant species displace native plants that are much more nutritious for wildlife. In recent years, collisions between wild animals and humans have also become much more frequent. To give an example: ungulates stay within the park boundaries in summer but often cross the boundaries in winter to look for food. And now that the area around Yellowstone is becoming less natural and more populated, it’s causing more problems.
3. On the plus side, the bison thrive in Yellowstone. Yellowstone is the only place in the United States where bison have lived continuously since prehistoric times. Currently, the Yellowstone herd is the largest free-ranging group on public land in the United States. The animals exhibit natural behaviors such as migration, fights during the heat period and with rivals. Less than a century ago, the bison had all but disappeared from Yellowstone.
The story is well known: In the past, the prairies of the United States were almost black with bison. Native American tribes hunted the animals on foot and without firearms, killing no more than they needed. That changed drastically when white European Americans began exploring the western part of the country around 1800 and inflicted a mass slaughter on the bison. Even after Yellowstone was declared a national park in 1872, the animals were not safe there. At one point there were only twenty left and the park rangers decided to get involved to increase the bison population. They brought about twenty tame bison from a ranch to Yellowstone with the intention of mixing the two groups together. And that’s exactly what happened. They had offspring together, and by 1950 there were already 1,300 bison in the park. In 1990 there were even 3,000.
The disadvantage of this is that in winter, when there is less food, bison move outside the park boundaries and there they come into conflict with farmers. The bison eat the same as farmers’ cattle, can sometimes be dangerous to humans, and they can transmit brucellosis (a disease that causes abortions and stillbirths) to livestock. Therefore, it is still necessary to shoot some bison every year or move them to other areas.
4. Geysers change size and become larger or smaller. Yellowstone owes its unique landscape with more than 10,000 geothermal phenomena (more than in the rest of the world combined) to the underground supervolcano. This volcanic system is constantly changing. Even the world-famous Old Faithful volcano is less reliable than its name suggests. In the 1870s, the geyser spewed water into the air every 60 to 70 minutes. Since the 1950s the intervals have been getting longer and longer to about 94 minutes now.
An even greater change can be seen at Steamboat Geyser, which is the tallest active geyser in the world at around 120 meters high. This geyser was always very unpredictable and was often silent for years – sometimes even fifty years. Since 2018, this steamboat is suddenly much more active, and an eruption takes place almost every week. This change probably has to do with subterranean magma shifts that force hot gases to escape.
Scientists also suspect that drought affects the height of the geysers. If the climate becomes warmer and drier in the future, there probably won’t be enough water for the spectacular eruptions we see today.
5. Yellowstone has become warmer and drier. Like the rest of the world, Yellowstone cannot escape global warming. The Greater Yellowstone Climate Assessment research shows that winters have become milder, summers warmer and growing seasons have become about a month longer. Compared to 1950, the average temperature in Yellowstone is currently 1.3 degrees Celsius higher.
The higher temperatures have also meant that precipitation falls more often in the form of rain and less often in the form of snow. Since 1950, there has been an average of 60 cm less snow per year. Spring starts a few weeks earlier, and therefore the moment when the most meltwater flows through the rivers also falls earlier in the year. This increases the risk of forest fires later in the year.
The changing climate also has major consequences for wildlife in Yellowstone. As the snow melts faster than in the past, flooding occurs more frequently and the nests of birds such as arctic grebes, white pelicans, cormorants and trumpeter swans are washed away. Another consequence associated with the rivers is that the water becomes too warm for fish such as trout. They then concentrate on smaller areas where the water is still cool, and this ensures that diseases are easily spread among the fish. It already happened in 2016.
According to the New York Times, the consequences will be even more serious in the future. Although ecosystems are constantly changing, climate change is occurring at such a rapid pace that plants and animals cannot adapt quickly enough. The drought is increasing wildfires in Yellowstone and preventing those forests from recovering. This results in the forests disappearing and more grasslands being created.
Invasive plant species will also conquer more and more territory, partly because – after a fire – they emerge faster than native species and thereby displace them. The invasive plants contain fewer nutrients and are more susceptible to fire. A good example of such an invasive grass species is fescue dravik. This grows early in the spring and draws all the moisture out of the soil. It also disappears quickly, making it harder for animals like wapitis and bison to find food later in the year in future summers. The animals will therefore leave the park in the summer in search of food and as a result the collisions between animals and people will occur even more often than is already the case.