Invasives and Natives
We as landscape designers look to enhance the local outdoor setting through the use of natural materials. Often times there are many native species and materials that can accomplish the aesthetic we are searching for. When designing for the quintessential Colorado architectural styles of American Bungalow or Mountain Rustic, the use of natives to match can be ideal. Local stones and local species can round off the great Colorado archetypes that we are chasing. Many times in the era we live in though, architectural styles are imported. In these circumstances, the landscape pallet of locals might not be the complete pallet desired. In such circumstances it is important to consider import choices carefully.
Historically, very little attention was paid to invasive species. To date, across the western world, we are battling the mistakes of the past. Because of the lack of attention when importing horticulture, we now have pests such as the nightmarish fire ants, the emerald ash borer that devastates out forests, and the Asian tiger mosquito that many of us know well. Many times however, it is the plants themselves and the weeds hitchhiking in the soil that can be the most destructive to the ecosystem. One of the best examples of this is the Kudzu vine. A vine introduced in the late 1800s, Kudzu was hailed as a great planting solution for erosion control. Now having made its way into the wild, the vine can grow up to a foot a day, completely overtaking even entire trees and shading them to death. Now kudzu, like many other species, are a constant battle wreaking havoc across the continent.
With that said, there is nothing inherently evil about the use of foreign vegetation in the landscape. It is only when the species used have the capacity to spread into the wild, and outcompete the native vegetation, that it becomes an issue. So, how do we as landscape architects in a challenging horticulture climate like Colorado, with limited off season color in the native pallet, responsibly preserve the ecosystem while creating beautiful outdoor spaces? For that, we have a number of considerations.
- One option is to simply use foreign species that will not survive our winters as highlights within the landscape for seasonal “pop”. In this circumstance we preserve the ecosystem by using annuals that don’t have the capacity to become invasive.
- A second option is the use of sterile cultivated hybrids and single gendered plants so that the species do not have the capacity to reproduce and spread into the wild. In this way we can scour foreign locations for incredible plant species and use them without ill effects.
- Another consideration is the use of regional plants from close climates cultivated locally. Over time these species from nearby can acclimate and begin to withstand our winters. In this way we are simply expanding the range of semi native species and pushing the envelope of their domain slightly. An acceleration of a natural evolution if you will.
- Lastly, we can consider the use of species that can survive in the urban environment, where we enhance the native soils and irrigate, but would be unable to survive outside of that micro-ecosystem. With the use of sustainable systems such as rain water collection and home composting, there can be no real environmentally damaging effects.
With all this in mind, in the end, it is important to remember our role as environmental stewards. When the opportunity to propagate endangered local species back into the environment presents itself, we should take it. Natives aren’t to be forgotten or ignored as they often have become in recent years, but that doesn’t mean that a landscape that that uses foreign species as highlights is necessarily failing in our role in creating a sustainable future.
In design, we don’t always have to reinvent the wheel. There is a big world of ideas out there to learn and develop off of. Colorado may not have a great history of landscape architecture but there are areas of the world with similar environments that do, and we can learn from them. One of those, for us here, is Scandinavia. (i.e. Norway, Sweden, Finland and Denmark.) Humanity has been practicing landscape design for many centuries in these countries. The way they design for the harshness of winter, to avoid bare bleak landscapes is inspiring. They design for it, instead of suffering through it.
As contemporary architecture progressively takes its foothold here too, we can again look to our Scandinavian friends for inspiration. As major arbiters of this post modern era of architecture, they push the envelope of landscape design as well. How do you extend the contemporary aesthetic from the structures themselves into the spaces between? There are few cultures more progressive than the Scandinavians in this regard.
At the end of the day though, the best teacher of landscape design is nature itself. To go into the natural environment and recreate the juxtapositions and symbiosis there, produces some of the best results. Few places on earth will take your breath away like the fjords and archipelagos of sparsely inhabited and untainted far northern Europe. A reminder of how nature looked before people and what we can do to bring it back.