The Fading Colors of the Paramo

How an invasive species became an iconic part of the Colombian landscape

In last week’s blog, I talked about some really cool native plants you can encounter while hiking in the high Andean plains of Colombia. Today, I will focus on how introduced species can also become an integral part of local ecosystems.

Even at four degrees from the equator, where the average daylight and temperature barely fluctuate throughout the year, nature expands and contracts with the annual cycles. As the seasonal rains subside and the winds pick up in the dry months of Colombian summer, the raging greenery of the Andean mountains begins to fade. The barely perceptible shift in the shades of green occurs gradually from June to August. It is not nearly as dramatic as in places like Colorado or California which go from emerald to golden brown, but nevertheless, you can notice the fresh leaves lose their vibrance, as if covered by a thin layer of dust.

I love to observe these subtle color changes. As I hike over a dry, windy ridge covered in prickly shrubs, I notice a pop of silver-bluish color on top of the hill. The unmistakable hue gives away its source from a great distance: the solitary watchers peering over the valley are eucalyptus. These noble trees stand out among the shorter, curlier native vegetation with their tall, straight posture and coin-like leaves that look as if they are covered by frost. They look out of place in this environment, and it’s because they are: the iconic silvery trees that are so common in Colombia are actually an invasive species.

Eucalyptus was introduced to the New World from Tasmania and Australia via Spain in the second half of the 19^th century. The Spaniards initially planted the exotic tree for ornamental reasons; however, thanks to its rapid growth, eucalyptus soon became the darling of the timber industry. The agricultural lands of the Cantabrian Coast were transformed by a massive reforestation campaign that created a beautiful sea of turquoise-silver groves that spilled over into the Atlantic Ocean.

In its native lands of Australia and Tasmania, there are more than 300 species of Eucalyptus. However, only four are common in Colombia. In this tropical country, the eucalyptus trees have become typical of the landscape of the Bogotá savanna. Just like in Spain, the eucalyptus was initially introduced for city beautification purposes, but soon spread to the surrounding areas and integrated into the local ecosystem. A little over a century since its introduction, eucalyptus blossoms have become one of the primary food sources for the local bees as well as many species of hummingbirds, flowerpiercers, and the gorgeous yellow-backed oriole.

Although eucalyptus has made itself quite at home in Colombia, it is still an invasive species. The main concern associated with its rapid spread is that it chokes up the native flora and fauna. The tall eucalyptus trees are extremely water-intensive, soaking up the limited resource from the ground and reducing the biodiversity of the understory. The native trees characteristic of the bosque seco (dry woods) ecosystem are much shorter, so they get overshadowed by the blue aliens. To add to that, eucalyptus groves can cause uncontrollable fires because of their height and the fact that they are filled with highly combustible oils.

But as with most ecological issues, the eucalyptus dilemma is not black and silver. Some scientists in Colombia have even proposed planting eucalyptus to save the native forests. Sounds counterintuitive? The rationale behind this is the fact that eucalyptus grows an average of 6-8 meters (20-25 feet) per year, which means that it could replace a lot of the native species that are currently being used in construction. Some have even suggested creating more farms of the fast-growing for the paper industry as a measure against deforestation, while others have widely criticized this effort¹.

To Plant or Not to Plant

The question of whether to cut down or plant more eucalyptus trees is up for debate. But why did Colombia, one of the most biodiverse countries in the world, introduce and widely adopt this exotic species in the first place? After all, we would not have this problem if not for human interference.

When the eucalyptus was introduced to Bogotá in the late nineteenth century, it was one of the most popular trees to plant in the city. It looked sophisticated and refined compared to the local trees, which were taken for granted until they started to disappear and teeter on the edge of extinction. By mid-century, urban ecologists began taking a more critical look into how to re-integrate the native flora back into the city landscapes, replanting the trees that have been growing in this area for thousands of years.

It is pretty sad that driving species to the brink of extinction is what it takes for us to start caring about the native flora and fauna. But as we think about preserving the diversity of nature, we should not forget about the urban biomes. Cities are starting to be recognized as emergent ecosystems, which, if managed well, can harbor a large variety of plants and animals, including migratory, endemic, and introduced species. Medellín, for example, has developed a program for planting more than 200 native tree species, to further diversify the 500 tree and shrub species already growing there – one of the highest numbers in the world.

As our world becomes more global and changes ever faster, it is becoming harder and harder to control what happens within its rapidly evolving environment, and nearly impossible to preserve nature in its untouched, native state. One thing to think about is — “introduced” does not always mean bad. Many plants that are essential to the Colombian economy and culture today – like bananas, pineapple, and coffee – are all non-native.

Eucalyptus is considered to be “naturalized” by many scientists, which means it has adapted well to its new home oceans away. And the local environment has embraced it, too. For example, this hardy tree is used as a medicinal plant and a source of fuel for people living on the outskirts of Bogotá that do not have the luxury to think about nature conservation. In fact, many of them have become intimately dependent on the resources this immigrant tree provides. It did not take that long for them to adopt the blue aliens as a part of their families. And as you can imagine, parting with one’s adopted family is a lot harder than conservationists will have you believe.

This blog post is part of a series on the intricate interaction of native and introduced species. If you liked this post, I think you will also enjoy the one below.

1.       If you are interested in a deeper dive into the issues of land and resources in Colombia, here is a great article: https://www.wrm.org.uy/bulletin-articles/monoculture-tree-plantations-in-latin-america-how-why-for-whom