The emotionally-charged native plant debate only seems to be growing. Well-meaning but misinformed decision-makers continue to institute native plant policies with pressure from special interest groups. Most recently, North Carolina’s General Assembly weighed in on the side of emotional appeal rather than research-based information in mandating “that native trees, shrubs, and other vegetation are [to be] used for landscaping at state parks, historic sites, and roadways.”
Don’t get me wrong – I love native plants and recommend the use of well-suited native plants in gardens and landscapes. I’m co-author of a book that helps gardeners in the Pacific Northwest choose native species that are likely to thrive in their gardens. But the belief that native plants are superior to introduced species in urban and other unnatural areas is just a knee-jerk reaction to the very real environmental and ecological problems we face. It gives believers a false sense of accomplishment in that they can reverse significant threats such as climate change, wildlife extinction, and pollinator decline simply by using native plants rather than introduced species.
Supporters for this native-only policy list the same tired (and false) reasons that native plants are superior to introduced plants. Here are some of those reasons cited in the North Carolina decision, along with my commentary:
“There are many environmental benefits to native plants, and they are much more likely to thrive in our weather and soils” (North Carolina Department of Natural and Cultural Resources Secretary D. Reid Wilson)
- The concept of nativity is subjective and many scientists argue that such a subjective division makes it difficult to study, much less discuss, the benefits and drawbacks of introduced plants .
- This post by Dr. Bert Cregg bursts the bubble on some of the native plant superiority myths.
- Native soils are not the same as compacted, amended, and otherwise disrupted soils found outside natural ecosystems.
- There is no research to support that native plants thrive in soils that have been disrupted by development and urbanization.
“Native plants are adapted to the state’s environment and more likely to thrive, especially during drought.”
- Roadways, state parks, and historical sites are not natural environments (though some parts of parks and historical sites could be).
- Plants that can adapt to disturbed environments are most likely to thrive. Some of these are called weeds.
- Plants that can survive periods of drought have morphological and/or physiological adaptations for doing so. It has nothing to do with their nativity.
“They support pollinators essential to food production and ecosystem health and boost otherwise declining bird populations that depend on insects associated with native gardens.”
- One of the basic tenets of ecology is that new resources are exploited by existing members of a food web. What happens with one species of insect or bird or plant is not the big picture – ecology is the big picture.
- This blog post by Dr. Bert Cregg discusses a paper showing that exotic species can grow more quickly than native plants, but they are eaten more by herbivores.
- This blog post looks at some of the research on insectivorous birds that contrasts with the claim that native birds require native insects.
- The most biodiverse landscapes are those with a high diversity of plants. The vertical structure of a landscape, created by the varying heights of trees, shrubs, and other plants, is crucial for bird habitat. I’ve published both a research article and fact sheet on this topic.
“Native plants, especially grasses, are better able to store carbon, thereby reducing greenhouse gases.”
- Native plants have supercharged photosynthesis? There’s a Nobel Prize waiting for someone to demonstrate that.
- Trees and other long-lived woody plants are best for storing carbon. Certainly not grasses. And the nativity of the woody plants is irrelevant to carbon storage.
“Native plants provide habitat for birds and other pollinators, are more resilient, and require less fertilizer and other maintenance.” (Brian Turner, policy director at Audubon North Carolina)
- Birds and plants have complex and often unexpected relationships. This post discusses a review article on the interaction between birds and those plants who depend on them to spread their seeds.
In June 2023, North Carolina’s Department of Cultural and Natural Resources installed a new 100% native plant garden in front of their DNCR headquarters. In comparing the before and after photos of the site, I’ve got a few observations.
- If storing carbon is important (as stated earlier), then cutting down all those trees and shrubs (which don’t appear to be invasive species) was an interesting decision.
- Why not just add a native garden to the existing landscape? That would have increased the plant diversity and retained the vertical structure, which is highly important for biodiversity.
- If we want stable, biodiverse landscapes in our urbanized environment, we must include the use of introduced species – especially trees.
“This policy is a big win for birds and everyone who cares about North Carolina’s wildlife. It just makes sense. ” (Brian Turner, policy director at Audubon North Carolina).
- Nope. It’s a big win for dogmatic belief systems.
There are many things that we can do in our gardens and landscapes to maximize biodiversity. Spouting false claims about native plant superiority, garden shaming those who don’t eliminate introduced plants, and forcing communities, cities, and states into lock-step on what can and can’t be planted is not part of that process.