This is the nineteenth in a series of articles from the staff of the Nature & Wildlife Discovery Center that will provide resources, ideas, and suggestions for families during the “Protect our Neighbors” phase of the COVID-19 pandemic. Watch for future articles with outdoor activity ideas for students and families. The public can help the nonprofit NWDC get through this challenging time by making a donation at https://hikeandlearn.org/donate-covid-19-pandemic-relief/. Membership information also is available.

No, not real aliens. At least not the extraterrestrial kind, which literally means “from beyond the Earth.” The kind we have in our ecosystem are from our planet, just places far away, and run the gamut from invasive to naturalized. Depending on who you ask and when, they can be good or bad. Ecosystems are constantly adapting to changing conditions, and their blend of species changes over time. Our ecosystem has changed significantly in the time since Pueblo was established with the introduction of many new plants and animals. Some of these species are familiar to us and have become ingrained in our understanding of both the landscape and the cultures who presently live here.

What “invasive” means can actually change, too. This is because ecosystems are not static. Evolution, via natural selection for successful traits, is a constant process, and responds to ecological changes. These are common, especially biological ones like new plants or animals moving in and putting pressure on existing communities. They also result from physical factors like wildfire or drought. In fact, the most significant physical change in our time is the measurable warming of average temperatures each year; it is forcing animals, including humans, to adapt. Individuals adapt, but species evolve; adaptation can occur quickly, but evolution takes many generations. As organisms face warming temperatures, some of them adapt to these changes by moving to areas that more closely reflect the temperature range they evolved in over thousands of years. This puts them into already-occupied habitats, and into ecological competition.

What separates an invasive species from a naturalized species? Both are non-native, but have differing impacts. An invasive species is able to take off and spread beyond control, often out-competing native species for resources (think Russian olive), while a naturalized one can grow and survive without human help, but doesn’t cause other species to vacate an environment (think dandelions). Non-native species are recent entrants, evolutionarily speaking, to an ecosystem. Native species in the United States are generally regarded as those which were part of the ecosystem prior to European colonization. This is tough to pin down, as modern catalogs of species didn’t exist prior to then. Using ethnographic info from tribal traditions, art, oral stories, and foodways, as well as early accounts of observation, has allowed scientists to understand how ecosystems looked prior to the Columbian exchange, when people, plants, animals, and ideas began to move back and forth across the Atlantic Ocean. Not all of this movement was positive, but it has shaped the world we know today.

Who can easily picture Italian food with no tomatoes, or Plains Indian tribes without horses, or Slovenian dishes without potatoes, or Mexican cuisine without carne asada? These all represent movements of species that had significant effects on the cultures that would come to make up modern Pueblo. More recently, the introduction of species like the Siberian elm, the emerald ash borer, Tree-of-Heaven, and the zebra mussel have brought change to Pueblo. Head to the mountains and you’ll witness another change that blurs the notion of invasiveness: trees in Beulah with various fungal infections, commonly called witch’s brooms. Or head up to Westcliffe to see the destruction of spruce forests by the native spruce beetle. As conditions change toward warmer and drier winters and summertime drought stress, the trees have not been able to adapt to handle the pests they evolved alongside, and the natives have taken on characteristics of invasives in their own habitat.

Ecosystems are complicated, and change is a fundamental characteristic. Our growing knowledge of ecology can only capture a fraction of the complexity, but this complexity can be appreciated well in a place like Pueblo: diverse, a meeting place, and always ever-changing.

Hazel moved to Pueblo last year but has a long history in the region. He is an Environmental Educator for NWDC and has worked for years to foster an appreciation for the wonders of nature and especially the amazing landscapes of southern Colorado. He can be reached at hazel@hikeandlearn.org.