Is planting Non-Natives that are Non-Invasives OK?

There is a widespread belief that native plants are superior to non-native plants because of their adaption to local environmental conditions. There’s also an association with non-native plants as being harmful to biodiversity, primarily because they are improperly grouped with known invasive species. In fact, it’s safe to say that non-native plants have been vilified in the past few decades, and it’s resulted in a bias that has been embraced by the public, the government, conservationists, and many scientists throughout the world. However, there is research that suggests that these non-native, non-invasive plants CAN provide for richer biodiversity and benefit our local ecosystems. 

According to an article published in Nature Magazine, Don’t Judge Species on their Origins, the authors claim “Many of the claims driving people’s perception that introduced species pose an apocalyptic threat to biodiversity are not backed by data… The effects of non-native species may vary with time, and species that are not causing harm now might do so in the future. But the same is true of natives, particularly in rapidly changing environments.” What’s even more interesting is how the authors define “nativeness” as not a sign of always having positive effects. They point towards a native mountain pine beetle which is suspected to be killing more trees than any other insect in North America. 

Some studies have actually found that certain non-native plants can actually attract a greater abundance of pollinators than their native counterparts. One study published in the Journal of Pollination Ecology in 2019 concludes, "We propose that using native and non-native plants improves habitat gardening by increasing opportunities for attracting a richer diversity of bee species and for longer periods." Why is this so important? It's because ~75% of the world's plants need pollinators to help reproduce. Did you know that 1 out of every 3 bites of food we take comes via the work of a pollinator? Like it or not, pollinators are crucial to our food supply.

In a time when pollinating populations are in decline, having a variety of non-invasive plants- whether native or non-native- is really important. Three major culprits have contributed to this decline- pests & pathogens, exposure to agrochemicals, and habitat loss/degradation.

Planting non-natives can actually help mitigate pest issues and use of agrochemicals Let’s take a deeper look.

Pests in the form of aphids, worms, slugs, etc are a gardener’s worst nightmare. Often times, we resort to sprays, both chemical and organic, to resolve these issues. However, less known to people is the fact that this problem can actually be taken care of naturally in a healthy and biodiverse ecosystem. Pest-infected plants emit a semiochemical known as “herbivore-induced plant volatiles” (HIPV) or green leaf volatiles into the air to lure in the particular species of natural enemy most likely to prey upon the specific pest present on the plant. 

When we spray a foreign substance- whether chemical or organic- we are disrupting this natural defense mechanism. However, in order for nature to take care of our pest problems, we need to create an environment in the garden where beneficial insects will visit. 

Beneficial insects include bees but also wasps, flies, beetles (think ladybug), and more. These beneficial insects eat pests for protein but also need carbohydrates produced by plants in the form of nectar. And the best place for plants to obtain nectar is through flowers- whether it’s in the form of wildflowers or vegetables that have gone to bolt to produce seed. 

Having non-invasive, non-natives in the garden is a great way to diversify. We really recommend reading “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” if you want to learn more. While the author, Jessica Walliser, certainly advocates for planting natives, she also says, “Many of the plants commonly recommended for luring in beneficial insects are non-native species… I would be remiss if I didn’t point out the fitness of several non-native plants as nectar for many natural enemies."

When done right, a garden that promotes enough biodiversity to enable nature to take care of pests ultimately helps address the pest and agrochemical issue. While we can’t control how some commercial farmers farm using monocultural practices with agrochemicals, we certainly can control what happens in our back and front yards. We do also need a bit of patience, not spraying every time we see a pest but rather giving time to see if nature can resolve the issue assuming we've created a biodiverse ecosystem. 

Researchers at Indiana University’s Environmental Resilience Institute published a study in May 2019 that revealed warming temperatures affect native and non-native flowering plants differently. The study suggests that non-native plant species may be better at shifting their flowering time compared to native species, indicating that natives may be more susceptible to climate change. The ability to flower is really important because it determines whether the plant will produce seeds and survive as a species. There may be a time when we need to rely on non-natives to ensure that we continue to have the flowers needed for pollination. 

An article published by the Yale School of Forestry & Environmental Studies takes this observation one step further in an article titled Native Species or Invasive? The Distinction Blurs as the World Warms. Countless plant species have been documented to shift their seeds higher into the mountains in response to the warmer climate, a trend that isn’t expected to stop. “For decades, conservation biology has characterized the movement of species into new habitats as potential invasions of alien species with the capacity to threaten local ecosystems. This approach, and its underlying classification of wild species as either “native” (and thus worthy of protections) or “alien” (and thus likely not) has been the subject of growing controversy in recent years."

In the past, global trade and travel was the main contributor of moving “exotic” plants out of their local ecosystems. Today, our global economy continues to drive this but climate change is causing species to be “on the move”. When we think beyond plants, there are wild animals who are on the move in mass exodus, escaping warming seas and desiccated lands. Their movement to new areas will ultimately disrupt those ecosystems. Will we discriminate against these newcomers that are doing what is engrained within them to survive even though they won’t be native to their new habitats?

All of our research has led to this conclusion- We live in a world that is changing and beliefs that may have once held merit need to be revisited. Do we want to grasp onto beliefs that were established and backed by evidence from a world that is no longer the same as the world we live in today? No. We are entering into unchartered territory, and it’s important for us to continuously question how changing environments impact prior beliefs.  

As evolutionary ecologist Madhusudan Katti said “Humans are the most invasive species on earth.” We as a species have successfully adapted to a changing world and at the cost of the ecosystems around us. We want to emphasize that we are fully supportive of planting native species, but we must also recognize that some non-natives that are non-invasive, can also play important roles in their adoptive ecosystems and simply eradicating them is not an ideal solution. 

We’ve said this once and we’ll say it again. Sustainability is not a black and white topic and there are so many factors to consider. No answer is right or wrong and our goal is to provide you with a baseline understanding so that you can start to form your own opinions and hopefully do more research.