In the United States, lawns seem synonymous with well-kept homes. They offer recreational pastimes through games and sports, as well as a spot to sit and enjoy the outdoors. Many homeowners find great gratification in caring for their lawns, keeping them carefully groomed and fertilized to prevent any imperfections from appearing on their landscape. Yet, while many take pride in the pristine appearance of their lawns, they fail to recognize one vital fact: they are creating ecological wastelands.
Lawns generally consist of a grass species known as Kentucky Bluegrass, Poa pratensis. Despite its name, the grass is not native to North America and instead is naturally found in Europe, northern Asia, and the mountains of northern Africa. As it is not a native species, it is not well suited to the climate of the United States and requires copious amounts of water and treatment to maintain its pristine appearance. Additionally, non-native plants are unable to provide communities with the vital ecosystem services they require to thrive.
Native plants are important for the health and biodiversity of pollinators, and thus the survival of entire ecological communities. They have coevolved with organisms for thousands of years to provide them with food sources and nurseries in exchange for pollination. A single native plant has the potential to support upwards of 400 pollinator species, while nonnative or ornamental plants can support one or two—and sometimes none.
While the impact of lawns on the biodiversity of terrestrial organisms may be clear, their impact on the health of marine ecosystems may be more convoluted. As described, lawns require the removal of large amounts of native plants. These native plants not only support communities of pollinators and other native organisms but also have deep and complex root systems. These root systems allow rainwater to permeate the ground, replenish groundwater supplies, and be cleaned by the soils and sediments below ground. Without the opportunity to be cleaned by the roots and below ground sediments, the runoff brings all of the contaminants from lawns with it. Without native plants, rainwater flows directly into storm drains and nearby water systems.
Lawn pollutants are composed of pesticides used to control undesirable plants or repellents for insects which may cause irritation or harm to homeowners. Additionally, things like salt from sidewalks in the winter, oil from cars, and particles from rooftops may be washed into water sources due to the impermeability created by lawns. Pollutants can also include excess nutrients, found on lawns from pet feces and fertilizers. These contain key nutrients to marine and aquatic ecosystems, most notably phosphorus and nitrogen.
Pesticides contain harmful chemicals linked to cancers, disruptions to human hormonal cycles, and skin irritation for children and pets, and are sprayed on lawns with the intention of killing things; it’s obvious why we would not want these potentially polluting our waterways, but why are nutrients bad?
Marine ecosystems are limited by nitrogen, meaning growth and abundance are limited by the amount of nitrogen within a system. When nitrogen increases, organisms at the base of the food chain such as photosynthetic plankton and algae have population explosions. The increase of algae and planktonic organisms causes the waters to lose clarity, making it harder for light to penetrate through the water and reach the seagrass. Algal blooms also cause the oxygen available in a system to decrease, thus killing many aquatic organisms that are unable to survive in low oxygen conditions.
Homeowners can aid in the restoration of the health of our waterways in many ways. A more practical impact includes ceasing—or at least decreasing—the use of pesticides or fertilizers on lawns. Removing non-native ornamentals, and incorporating native plants into the landscape also provides a way to begin the restoration of natural ecologies for the area, without fully tearing up existing lawns. The most drastic action homeowners can take is to kill their monoculture lawns, and instead create a native plant oasis by restoring native biodiversity on their land. Grants such as US Fish and Wildlife Services “Slow the Flow” grant exists to help provide homeowners with funds to begin such transformations. Even if they do not own a home, they can still take action to reduce the effects of lawns. Public spaces are dominated by lawns and gardens, and the subsequent ornamental species, pesticides, and fertilizer use that is often associated with them. Contacting local organizations and representatives and urging them to convert these spaces into more ecologically productive ones can contribute to the restoration of our waterways.
Some places have begun to implement policies towards minimizing the effects lawns may have on surrounding water sources. In 2013, a regulation was passed in Nantucket restricting the use of fertilizers on domestic and government maintained lawns to “improve and restore the quality of Nantucket’s water resources.” While this regulation, and many like it, are positive steps forward, it is important that they are actually enforced by the appropriate agencies once enacted to ensure their impact. Additionally, in order to truly restore the natural process of terrestrial plants, it is important to restore native biodiversity in our yards and public spaces to the best of our ability.
Fertilizer guidelines. Nantucket Land Council. (2017, May 24). Retrieved October 29, 2021, from https://www.nantucketlandcouncil.org/education/fertilizer-guidelines/.
Kentucky bluegrass. (n.d.). Retrieved October 29, 2021, from https://aggie-horticulture.tamu.edu/plantanswers/turf/publications/Bluegrass.html#:~:text=Kentucky%20bluegrass%20is%20native%20to,not%20native%20to%20North%20America.
You can volunteer your land. Slow The Flow. (2021, October 11). Retrieved October 29, 2021, from https://slowtheflow.net/you-can-volunteer-your-land/.