Okay, I preface this posting with the acknowledgment that as an urban ecologist, who is concerned about biodiversity conservation, I regard lawns as bad because they are like concrete to most species and have very little benefit for wildlife. But are lawns bad, considering all the other activities and consumption patterns we urbanites partake in?
Now, we all (myself included) are impacting the environment. Each of us consumes energy in our homes and work, fly airplanes and drive cars, eat fast food, and consume goods on a daily basis that ultimately impact natural resources. But where do lawns stand in the ranking of environmental impact?
Tough question, as lawns, are part of the American psyche and linked to suburbia and household aesthetics. It is an American tradition to maintain lawns. One only has to step out the front door to hear the hum of weed whackers, lawn mowers, and other maintenance equipment that are used to maintain lawns. Since Lancelot "Capability" Brown introduced manicured lawns in England, this concept has spread around the world, and we spend an awful lot of time and money on lawn care. In North America, lawns have passed croplands as the primary managed land cover and are reported to occupy over 128,000 square km -- larger than the states of Nevada and Massachusetts combined. But because everybody cares primarily for their own turf, the cumulative impacts of daily lawn maintenance are not really on the radar for most folks.
However, lots of lawn mowers and other maintenance equipment are used daily. People are irrigating, fertilizing, and using a range of pesticides and herbicides to maintain a "weed-free" and lush lawn. This can translate into a huge quantity of chemicals that are dumped on lawns; for example, in 1996, the U.S. consumed over 2,650,000 tons of fertilizer on non-agricultural land. In urban landscapes, a whole slew of studies show a decrease in native plants and animals and an increase in exotic plants and animals. Although many factors are involved, monoculture lawns are a primary culprit as they offer very little habitat for most species. In terms of water consumption, irrigating lawns (on average) takes about 200 gallons per person per day (and much of this is potable water!). In terms of carbon, if one uses high fertilization and irrigation rates, turfgrass actually emits more carbon dioxide than it sequesters. Fertilization of lawns also releases nitrous oxide, another greenhouse gas that affects climate change. Pesticides do not target only the pest species in most cases, and other non-target critters are killed that provide an ecosystem service for us (e.g., bees and pollination services)
Ecosystems far away from urban areas are impacted. For example, there is a hypoxic zone (hypoxia means little oxygen) that forms every summer in the Gulf of Mexico. One identified culprit for this dead zone is excess nutrients entering the Gulf -- fertilizers from agriculture, golf courses, and urban lawns are a major component of excess nutrients that flow into the Gulf.
The impacts stemming from lawns and lawn maintenance affect environments across local, regional, and global scales. But they do have some benefits for our society. We do have many recreation sports (e.g., soccer) and gathering places (e.g., parks) that promote exercise and places for humans to socialize. In certain situations, turf can also stabilize the soil and decrease ambient temperatures (i.e., asphalt is hotter than grass).
On the balance of things though, I think lots of opportunities exist to reduce the amount of lawns in urban areas and change the way we maintain these landscapes. Here are some pointers to reduce your impact:
- Even where foot traffic is high, you can replace turfgrass with a ground cover that you walk on and it requires less maintenance -- take a look at perennial peanut.
- Remove turfgrass from areas between the sidewalk and the curb -- those areas are almost impossible to maintain sustainably.
- When using fertilizer, use less of it (the grass does not need to be blue-green!) and use slow release, organic fertilizer instead of water-soluble fertilizer. If you use water-soluble fertilizer, make sure it is applied only when no rain is in the forecast as it will just run off your property in a rain storm.
- Avoid the use of any pesticides as they kill insect diversity. When used in vegetable gardens, try organic alternatives, biocontrol, and other methods to reduce the use of pesticides.
- Take time to calibrate your irrigation system to minimize water applied to your yard. If you see it running down the curb, something needs to be done!
- Avoid the practice of removing every "weed" in a lawn. Take a less industrial approach and permit a mixture of turfgrass and other plants. Simply mow as usual.
- Get rid of the power lawn mower and replace with a reel mower that requires no fuel to get the job done.
- Compost all yard waste and prevent the extra "energy cost" it takes to remove and dispose of yard waste.
- Organize neighborhoods to create larger patches of natural habitat. Many wildlife species need large patches in order to survive. Thus talk with you neighbor to let your borders go wild.
- If you have a lawn maintenance company, ask questions and request a greener alternative over conventional lawn maintenance.
Thus, lawns are not bad if they are managed appropriately. I do think we have too much lawn and we need to reduce lawn cover in urban areas. Do not underestimate the power of one person changing their landscaping practices in a neighborhood. A local example of using natives, reducing turfgrass, and changing fertilization and irrigation practices can help others see that there is another way. Plus, because one spends less on materials and less time on maintenance, the benefits to one's pocketbook and free time is huge!