Humans take up a lot of space. While more and more natural ecosystems are transformed into urban landscapes, natural environments are unfortunately displaced in the process.
These disruptions are not only limited to the structures we build. In landscape development, the overwhelming trend is to plant showy ornamental plants in place of the original occupants.
Many of these plants come from exotic locations far removed from the planting site. While many non-native plants are interesting and showy, planting these foreign plants instead of native plants has been shown to have devastating effects on local wildlife.
Insects are especially impacted by changes in plant types, as many species have maintained close relationships with specific plants over hundreds of millions of years and are unable to travel long distances in search of food or nesting sites.
As plants and animals have evolved side by side over time, a constant battle has taken place between the two.
Eager to ward off unwanted grazers, many plants have developed chemical cocktails that are distributed throughout their whole. Many of these chemicals serve to make the plant either unpalatable or downright poisonous.
Not to be easily outdone, hungry herbivores slowly developed resistances to these chemicals in order to continue their feasts.
This back and forth eventually forged close bonds between these plants and animals, sometimes even leading to symbiotic relationships.
Some species are so intertwined with their chosen plants that survival without them is simply not possible. Many butterflies, for example, have developed specific plants on which to rear their offspring.
The famous monarch butterfly can only raise its young on a diet of milkweed leaves, as their caterpillars depend on incorporating the milkweed’s latex and other phytochemicals into their own bodies as a way to ward off predators.
Most other insects have similarly close relationships with plants. When their preferred plants are removed or become unavailable, these animals have little choice but to leave or die.
Even worse still, when a foreign plant is placed into such an environment it can actively harm anything unlucky enough to take a bite, as the locals haven’t evolved a resistance to its unique chemical defenses.
The insects that can utilize exotic plants are the toughest of the lot, and are usually generalist species that don’t depend on any single plant to survive.
Even while these heavyweights buzz and bound happily around your garden, do not forget that they may have been removed from their natural environments depending on the plants you have chosen.
Many of the insects that we see in developed landscapes are only able to utilize a small fraction of their inherited abilities due to the loss of the plants that they evolved alongside.
This leads to extreme population declines in both insects and the animals that depend on them for food. A recent study by the University of Delaware in conjunction with the Smithsonian Migratory Bird Center highlighted the sobering impact that non-native plant species can have on certain birds.
It seems that the less native plants in an area, the harder it is for insectivorous birds like chickadees to raise their young. Their research points to the statistic that once the total amount of native plants in a landscape drops below 70 percent, it is unable to support the volume of insects needed to feed growing chickadee families. To a certain extent, the more non-native plants we plant, the more native wildlife we unwittingly exclude from our landscapes. Planting native plants wherever possible can help to restore some of the food, shelter, and nesting sites that have been lost and are sorely needed by a host of local animals.
Brannen Basham and his wife, Jill Jacobs, operate Spriggly’s Beescaping, a business dedicated to the preservation of pollinators. Contact him at firstname.lastname@example.org.