Some Challenges with a “Natives-Only” Approach to Gardening
Native to when? Pre-European settlement? Before human arrival? Natural landscapes have changed and will continue to change over time due to climate change and to disturbances. While there’s a healthy debate among scholars about Native Americans’ impacts on natural landscapes prior to 1492, their hunting and agricultural practices certainly had at least some effect on the combinations of wild species that thrived in different locations. What is helpful about these questions is that they draw us to consider practices that enabled Native Americans to live quite sustainably within the natural constraints of their environments. But because our natural and cultural contexts have changed so much since then, reconstructing natural communities that resemble those of a few hundred years ago does not guarantee resilient biodiversity today.
Native to where? A narrowly-defined locality or a wider region? Advocates correctly point out that native plants tend to have more biological interrelationships with other native species, reflecting thousands of years of co-evolutionary adaptation. Douglas Tallamy’s book The Nature of Oaks: The Rich Ecology of Our Most Essential Native Trees describes interesting and compelling examples of this. Since your local climate is changing, our advice would be to focus on your ecoregion when selecting natives. The National Wildlife Federation’s guides pertaining to keystone and host plants are helpful for this.
How “natural”? Wild ecotypes only? Cultivars produced via breeding? Some argue for wild ecotypes (specimens collected locally in the wild) are to be preferred because plant breeders (who produce cultivars, or cultivated varieties) typically have priorities (such as ornamental qualities) that do not necessarily align with ecological priorities (such as resilience to environmental stress). However, we feel this is problematic for two reasons:
- This claim is based on an implicit assumption that breeders have little or no interest in ecologically aligned traits.
- Breeders do have a marketing incentive to produce cultivars that thrive in a range of environmental conditions.
While consideration #1 may be partially true sometimes, consideration #2 also provides a market incentive for gardeners to reward breeders who do make this a priority.
Most importantly, all these considerations about “natives” look back in time, when instead it is more crucial to consider the climate in 20-50 years to which your garden will need to adapt. Yes, there are natives well-suited for adapting to climate change in your area, but there are also non-natives that can do this while serving important ecological functions. It may help to think of these as “climate natives.” Such species may help to provide some cover for more vulnerable native plants, an important aspect of your refugia.
When deciding what to plant, it is the ecological functions that should take priority. This is a point that Douglas Tallamy also made in Nature’s Best Hope, noting that:
“In my view, ‘native’ is not a label a species earns after a given period of time. It is a term that describes function. For example, a plant should be considered a native when it acts like a native—that is, when it has achieved the same ecological productivity that it had in its evolutionary homeland, when it has accumulated the same number of specialized relationships that had been nurtured by the native plants it displaced, and when it has accumulated the same number of diseases, predators, and parasites that species that evolved in North America must endure” (p. 52).
Since climate change is going to present ecological and evolutionary challenges for most of our garden species, including the natives, it is helpful to recognize that nearly all plant communities will be under a great deal of adaptive pressure for the rest of your life. Gardeners will be wise to monitor species interactions (such as frequency and diversity of pollinator visits to the different flowering plants in their gardens). Any species that attracts pollinators is likely beneficial for co-evolutionary adaptation.
One more point worth making… People often contrast natives with invasives, as if these are opposites. But these are actually different categories. Biologically speaking, the opposite of native is non-native (or exotic). These terms help us categorize plants with a long local history from those that are relative new-comers. The other category is invasive versus non-invasive, which helps us to distinguish species that tend to aggressively take over a habitat versus those that tend to stay put. These distinctions help us understand that there are invasive natives, invasive non-natives, non-invasive natives, and non-invasive non-natives. Most ecological gardeners focus their efforts on non-invasive native plants, but refugia gardeners may also wish to include some non-invasive non-natives or maybe even a few invasive natives. It is the invasive non-natives that cause the most trouble for gardeners.
More Refugia Gardening Principles and Practices
1-Diversifying for the future
*Why not natives only?
2-Focusing on ecological functions
3-Enhancing natural landscapes
4-Co-creating with nature
5-Cultivating relational caring
Refugia Gardening 