Well-kept lawns are beautiful and create a lovely environment for the whole family to enjoy. But what is their role in the ecosystem – and do they produce oxygen like trees?
Lawns do produce oxygen. Grass takes carbon dioxide from the air and produces oxygen through photosynthesis. A healthy green lawn is very efficient at producing oxygen, and a 50ft2 lawn will create enough to meet the oxygen needs of a family of four every year.
Let’s dig down (not into the lawn!), into the subject of lawns producing oxygen, and consider their role in the ecosystem…
How Much Oxygen Does Grass Produce?
Grass is a plant, so it takes in carbon dioxide from the air and produces oxygen through the photosynthesis process. A healthy lawn is very efficient at producing oxygen, and a 50ft2 lawn will create enough per annum to meet the oxygen needs of a family of four.
A golf course produces enough oxygen for at least 4,000 people. With 40 million acres of lawn in the US alone, our gardens have the potential to produce a lot of oxygen.
This is only effective with a lovely, green lawn, however. Yellowish or dry grass doesn’t have enough green chlorophyll in it, which is a vital part of photosynthesis. So, if you have a dry lawn, it’s not producing as much oxygen as it might otherwise.
Does Grass Produce More Oxygen Than Trees?
Grass does produce more oxygen than trees. Figures vary – which is to be expected, as there are many different species of both. We’ve heard figures of grass producing around three times the amount of oxygen than trees.
However, if you want grass to be at its most green (and we’re talking about in the climate sense rather than its pigment sense, here), don’t mow it. Constantly cutting your lawn will affect its oxygen production, as well as its ability to store carbon (and we’ll look at this in a moment).
Does Grass Clean The Air?
Grass actually cleans the air from dust, dirt, and other impurities (like carbon dioxide). The blades of grass trap the impurities from the air, then when the dew wets the grass, these get drawn into the soil. The microbes in the soil help to break down these polluting impurities.
Apparently, turf cleans about 12 million tons of impurities from the air every year, and that’s just in the USA. It’s a sophisticated and clever system, and one that’s literally going on beneath our feet.
Grass will similarly purify pollutants in rainfall. The rain is filtered through the grass, and the pollutants are broken down as they pass through the root zone, just like the dust and dirt is.
Is Grass a Good Carbon Sink?
Your lawn is a good carbon sink. A “carbon sink” is a natural environment that stores carbon-based compounds, rather than releasing them into the atmosphere. In the US, about 5% of the carbon dioxide from the atmosphere is captured by humble grasses.
Once it’s been captured by your lawn, the carbon dioxide is then “sequestered” and turned into organic matter. Instead of being released into the air as a greenhouse gas, carbon compounds become useful fertilizers for the grass. The healthy grass can then continue to photosynthesize, forming a virtuous circle.
Grass is now being used as a carbon offset. Frequent flyers sometimes pay to plant trees to offset the carbon emissions generated by their flight. These days, the frequent flyers are also paying ranchers not to cut their grass: take a look at this fascinating article about carbon offsetting in Scientific American.
Does Cutting Grass Release CO2?
So, if ranchers are paid not to cut their grass, does that mean that mowing is a bad idea? Frequent lawn maintenance can actually do more harm than good when it comes to releasing CO2 into the environment. For example, a gas-powered leaf blower can release more hydrocarbons than a pick-up truck.
While your grass will act as a carbon sink, busily capturing carbon from the atmosphere, the act of cutting that grass not only limits its photosynthesizing potential, but it also releases carbons into the air through lawn mower pollution.
The answer: switch from gas-powered yard tools to electric ones, or even better, mechanical ones. Now, we appreciate that if you have a large lot of smallholding, you’re not going to go over the grass with a push lawn mower. The answer is to cut down on how often you cut the grass – and longer grass creates all sorts of environmental benefits as well as reducing your carbon footprint.
Are Lawns Bad For The Environment?
Areas of grass are definitely good for the environment. As we’ve already read, grass is a carbon sink that produces oxygen, cleanses pollutants, and purifies rain water. However, the way we manage our lawns (frequent mowing, using polluting lawn mowers and other gas-powered tools, artificial fertilizers and so on) can sometimes mean that our grass is less than green.
Arguably, a lawn can be self-sustaining if you leave the clippings to rot back in as fertilizer. You can reduce your environmental impact by using a push mower instead of an electric or gas-powered model, and then leaving the clippings to rot down.
What about watering? Well, some might say that it’s poor eco management to water a dry lawn, especially during a drought or if you live in a dry zone with little rainfall. However, if the lawn is better at photosynthesis the more green chlorophyll it possesses, is keeping it watered actually such a bad thing?
The answer is look after your lawn, but do everything in moderation. Mow less frequently (once every two weeks should be plenty) and use the clippings as your fertilizer. If you have a large grassed area, let sections of it grow taller and cut paths through it, creating a haven for wild flowers and bugs.
What is The Role of Grass in an Ecosystem?
As we’ve just mentioned, if you leave your grass to grow, you’re creating a perfect environment for plants and animals. It provides food, shelter, and nesting materials for all sorts of critters, such as birds, bugs, bees, and bunnies. We all know that grass is essential for larger grazing animals such as cattle; however it’s also a vital food source for a whole variety of animals.
Grass also plays a wider role in literally looking after the earth. Its dense root system helps to prevent soil erosion. A healthy root system keeps the soil in place, while above the ground, the blades of the grass protect the topsoil from the weather. Grass absorbs excess water, preventing runoff, and as we spoke about earlier, it also filters out impurities.
Does Grass Make Your Yard Cooler?
Yes, grass does actually make your yard cooler! We’ve all had that wonderful feeling of stepping onto the grass barefoot on a hot afternoon. The grass instantly makes us feel cooler – and there’s a good reason for this.
On a warm day, the air surface temperature above your grassed area is up to 14 degrees Fahrenheit cooler than it is over your asphalt drive or concrete patio.
Grass is nature’s air conditioning for your yard, offsetting solar heat through the cooling action of evaporation.This cooling effect benefits your entire yard, and this can actually extend to your home, too. The cooler your yard on a hot day, the cooler your house will be.
Interestingly, artificial turf actually absorbs more heat than hard surfaces, so if you’re considering installing a fake lawn, you’ll need to take this into account.
It’s fascinating to discover all these amazing scientific facts about the role of grass in the ecosystem.
In the end though, if we’re lucky enough to have a garden – we should just enjoy our lawns for the leisure opportunities they offer us.
As there are few things nicer than lying on a rug on the grassy lawn in the warm sunshine, sipping a chilled drink, and simply enjoying being out in your yard.