Biodiversity is the Spice of Life: Naturalist Notes
Close your eyes and picture yourself walking along your favorite trail at the nature center. Think about all the life surrounding you. In the water, there are lily pads and pickerelweed, while the prairies are filled with Cup plant and Echinacea. In the sugar bush, the Maples tower overhead. Listen to all the noise, from the katydids to the chickadees, and to the green frog at the edge of the pond. As you take in all this beauty, take a moment to think about how complex and intertwined it all is. Everything you see and hear, and even the things you can’t see, have a role. Every part contributes to the health of the ecosystem, so an imbalance in one variable can compromise all the life in that area. For example, if the cattails were removed from the water's edge, there would be fewer roots preventing soil erosion, which would lead to more sediment entering the water, affecting the plants and animals living there. It's like a game of Jenga – as you remove blocks, the structure becomes unstable until it eventually falls over.
This is a very simple example of the importance of biodiversity. Biodiversity is defined as the variety of life on Earth. It is studied at many levels, with the highest being the Earth as a whole, but you can also look at the biodiversity in your own backyard. Biodiversity can be broken down into three components, all of which are equally important: species biodiversity, genetic biodiversity, and ecological biodiversity. All of them are threatened by the invasion of non-natives, both plants and animals.
Non-native invasives are species of plants and animals that were not originally found in this area and adversely affect the ecosystems. Invasives outcompete our native species for resources and threaten their survival.
Species biodiversity is just as it sounds: the different types of species of plants and animals that live in a particular ecosystem. The more variety of species in an area, the higher the biodiversity, which typically means a healthier ecosystem.
An example of how invasive non-native plants are affecting species biodiversity is glossy buckthorn (Rhamnus frangula). This shrub is native to Eurasia and was brought over in 1849 to be used as a lawn ornament. Glossy buckthorn has a long growing season and retains its leaves late into the fall. Its alternate leaves are kind of ovate and somewhat shiny or glossy (hence the name). A great identifying feature is the bark – brown to grayish with light-colored lenticels or speckles. This plant poses a threat because it grows in dense stands, choking out the sunlight from the tree seedlings, saplings, and other ground cover. Since glossy buckthorn monopolizes the resources, it creates a monoculture. Where glossy buckthorn is present, you will find fewer native wildlife that depend on a greater variety of native vegetation.
Genetic biodiversity refers to the variation of genes within a species. This is an important factor because with more genetic variation, a species is less susceptible to disease.
Invasive bittersweet (Celastrus orbiculatus), formerly known as Oriental bittersweet or Asiatic bittersweet, is another ornamental plant that was brought over from China, Japan, and Korea and is now wreaking havoc in our forests. In autumn, invasive bittersweet is fairly easy to spot due to its orange berries. Its leaves are alternate, glossy, and rounded with finely toothed edges. This woody vine threatens native plants from the forest floor to the tree canopies. Invasive bittersweet creeps up trees, girdling them and making the trees susceptible to wind damage because the bittersweet weighs down the tops of the trees. As it grows, it shades out the understory, inhibiting the growth of plants below. Unfortunately, invasive bittersweet is compromising the genetic integrity of American bittersweet (Celastrus scandens) through hybridization with our native plant. So, not only does Oriental bittersweet affect the ecosystem in which it's found by damaging tall trees and preventing undergrowth from sprouting, but due to hybridization, it threatens the genetic biodiversity of American bittersweet.
Ecological biodiversity refers to the differences in ecosystems, from different types of forests on the planet to prairies, tundras, ponds, and oceans. Each ecosystem has something unique to offer.
Autumn olive (Elaeagnus umbellata) is a woody shrub with dark green leaves on top and silver on the bottom. You often see them along the roadside. This invasive plant from China, Japan, and Korea was introduced in 1830 as an ornamental plant and has since been planted for wildlife food and cover. This plant likes to grow in prairies, open fields, and wood edges. It fixes nitrogen in the soil, which threatens native plants that need nutrient-poor soil to grow. Additionally, autumn olive changes the landscape from open fields to shrubby stands, which affects wildlife that prefers the openness of a prairie or field.
These are just a few examples of how non-native invasive plants are threatening biodiversity. Invasive species threaten to outcompete their native counterparts, hybridize with the natives, or change the landscape as a whole. Native plants and animals provide a natural check and balance system, and without this system, plants and other wildlife will start disappearing from an ecosystem.
Imagine yourself overlooking the pond, and all you see is Phragmites australis, common reed grass – not as picturesque, is it?
However, it doesn’t all have to be doom and gloom. There is a lot we can do. It all starts with taking a walk through your own property and assessing what you have. After identifying some of your plants, it's time to start controlling any invasives you may have. Fall is the time to work on woody plants like autumn olive, Oriental bittersweet, and glossy buckthorn. Smaller seedlings of any of these plants can be pulled right up. For larger plants, cut them and, if needed, paint the stump directly with herbicide. When spring comes, work on plants like garlic mustard (Alliaria petiolata) or dame’s rocket (Hesperis matronalis), pulling them before they have a chance to flower and produce seeds. Continue pulling invasive plants before they have a chance to flower throughout the year. You won't eliminate all of them in one year, but if you stay vigilant, they will become more manageable. If everyone starts managing the spread of invasive species on their own property, it will slow down the overall distribution caused by these species. Also, when planting next spring, make sure to choose native plants, as these will help increase biodiversity. There are many other threats to biodiversity, but taking these steps will be a start in repairing some of the damage done. Plus, you will have a healthier backyard ecosystem.
Submitted by Cathy Wesley, naturalist, August 2023