During a COVID lockdown in Brisbane, three researchers made the decision to count every living thing in their shared home. They knew what they were doing because they were trained ecologists. The number was what caught them off guard. The property was home to 1,150 different species by the end of their year-long census, including plants, animals, fungi, things with too many legs, and things with none at all. Prior to the survey, the average ecologist they polled estimated 200.
The discrepancy between people’s perceptions and what actually coexists with them in suburban areas is precisely the kind of issue that needs more attention than it receives.
Because, contrary to popular belief, suburbs are not ecologically dead zones. They are untidy, constantly changing, remarkably vibrant, and increasingly inhabited by species that have no historical place there.
Approximately 72% of the plants on any given property were not native to the Eastern United States, according to a Rochester, New York research study that examined 101 suburban gardens. Japanese barberry, a plant that is currently prohibited in New York State, was present in nearly half of the gardens because homeowners purposefully planted it rather than it being unintentionally dispersed by birds. It’s an eye-catching detail that sticks. People selected it. The catalog contained it. Against the fence, it looked nice. Nobody gave what followed much thought.
Suburban invasion ecology functions essentially in this way. Seldom is it dramatic. It’s not about kudzu engulfing a barn overnight or pythons falling from trees, though those tales do exist. More often than not, it’s a burning bush here, a Japanese barberry there, or a butterfly bush by the mailbox that, according to the catalog, is “pollinator-friendly” but has since spread into the woodlot behind the neighborhood. The mechanism is aesthetic preference, supported by decades of nursery trade that put aesthetic appeal and hardiness ahead of ecological compatibility.
It’s possible that a form of collective inattention rather than malice is the root of the issue. Drought tolerance, quick growth, and resilience are characteristics that attract nurseries, but they also make a plant challenging to manage once it leaves the garden bed. Escape is also not uncommon. According to research, at least 82% of the invasive woody plant species that exist today in the United States were first brought in purely for aesthetic reasons.
Sitting with a certain irony is worthwhile. The same suburban homeowner who maintains a habitat garden and installs bird feeders may have a row of invasive shrubs ten feet away, outcompeting any native understory that once grew there and offering cover. It’s not quite hypocrisy. It’s more akin to a knowledge gap disguised as good intentions.
However, any straightforward description of suburbs as ecological catastrophes is complicated by the Brisbane study. Indeed, there were invasive species, such as a flatworm that caused native snail populations to decline on multiple continents. However, there were also 56 spiders, 436 moth and butterfly species, reptiles residing beneath the garage, and bees dozing off in the hedges after dark. The image is actually quite intricate.
It turns out that suburban areas serve as a sort of ecological middle ground, neither the intact web of a forest nor the cleared monoculture of a cornfield. They attract both exotic species that find the altered, milder, human-tended environment surprisingly hospitable and native wildlife searching for habitat fragments in ways that are difficult to predict and manage.
The Brisbane researchers discovered something practically helpful: fewer well-kept lawns, low-maintenance shrubs, and fewer pesticides greatly increased the number of species discovered. It implies that the structure of suburban space is more flexible than it appears, but it is by no means a perfect solution. Over time and across thousands of properties, the decisions people make about plants, lawns, and what gets pulled and what is left alone add up to something that functions ecologically like policy.
An ecosystem cannot be saved or destroyed by a local garden. However, the combination of what suburbanites decide to grow and what they unintentionally introduce is influencing the local ecology in ways that scientists are just now starting to map accurately. You probably don’t realize what’s living outside your back door. And about fifteen years ago, some of it came in an ornamental nursery pot.
