Ecological Impacts of Monoculture Lawns

Today, our lawns are generally made of one or a few species of grasses pre-packaged as a generic "grass" starter. Compare the makeup of your lawn to your local forest or park- there's a huge difference in the diversity of species, right?

This is because ecosystems are incredibly complex, and there are a lot of moving parts involved in maintaining an ecosystems's homeostatsis- or balance between parts. Just like the human body, an ecosystem needs certain levels of nutrients/minerals while ridding itself of waste in order to function properly.

So why are monoculture lawns bad in an ecological sense? Well..

[1] - Lawns are "dead zones"

Ecosystems develop over time through a process called succession. Succession describes the slow colonization (or takeover) and resulting changes in species composition of an specific area. The end goal of succession is an area's climax community, which is the area's ecologically stable state. Ever wonder how a forest can grow back after a fire or outbreak of disease? That's succession!

The reason why you constantly fight with "weeds" is also because of succession. When humans clear land for development- whether it be for housing or business - it essentially acts like a fire, rendering the land completly bare and ripe for cultivation by pioneer species. Pioneer species are hardy species like lichen and mosses that can withstand the poor conditions of a barren enviroment. A pioneer species' inital interactions with the soil prep the enviroment for intermediate species to join as well, eventually leading to the enviroment re-stablizing as it's climax community.

Lawns usually don't have a lot of shade, and don't have the nutrient rich soil, making them ideal land for pioneer species to set up shop. The problem then is that people don't want anything but grass in their lawn, so it becomes a constant battle between the "weeds" and your landmower- which boils down to a lot of time, physical labour, and gas used in an what is ultimately a losing battle.

[2] - Lawns require a lot of additional enrichment

In nature, soil nutrients are used & replenished through natural cycles (carbon, nitrogen, phosphorus, etc..). Just like us, plants also need nutrients that they cannot make themselves, and thus must supplement from their environment. Climax communities are stable because each species works together to mainatin the ecosystem's specific requirements. Monoculture enviroments can't normally do this, so they must be artifically enriched with nutrients via fertilizer and other garden mixes. But, because are no species to offset the monoculture's drain on soil nutrients (whether it be grass, gardens, crops etc), the soil becomes nutrient-poor overtime and thus requires more and more fertilizer to offset this. This results in the overuse of fertilizers that are high in nitrogen and phosphorus, which can leak into nearby water sources.

Contaminated water can become unsafe to drink for both humans and other animals, and can also cause massive growth spikes called blooms. These blooms can block light and use up lots of oxygen very quickly, which can leave bodies of water completely uninhabitable. Even worse, certain species of algae also produce quantities of microcystin during these blooms. Microcystin is a hepatoxin (harmful to the liver), and can cause pensteadtitis (yellow fat disease) in animals and may cause liver/colorectal cancers in humans.

[3] - Lawns are water sinks

In nature, grasses regulate the water cycle via evapotranspiration, which is the sum of water movement between land and the atmosphere. Evapotranspiration is also good at cooling microclimates, which can maintain a good temperature balance between common urban building materials such as ashphalt and concrete which often hold onto heat- granted the grass is has acess to enough water. Grasses are very good at transporting water because of their physiology, but they don't hold water well. Coupled with the expectations of "healthy" looking lawns, you'll end up wasting a lot of water...

Fertilizer and pesticides can also be washed into the water table by the overwatering required to maintain lawns. This is a obvious problem for drinking water, but water contaiminated with high levels of nitrogen/phosphorus can result in acid rain as well.

[4] - Lawns negatively affect air quality

In addition to climate regulation, healthy grass is also key protection against soil erosion- the key word being healthy here. Grass that is dehydrated (or dead) cannot protect the topsoil effectively, and thus puts soil at risk of wind erosion. For flat land with little tree cover, that can cause dust pollution, which can cause both health problems as well as damage agriculture. The Dust Bowl, in which the North American prairies were subject to massive dust storms during the 1930s, were caused by the resulting wind erosion (aided by ongoing drought) after farmers destroyed acres of grassland.

[5] - Lawns are associated with species imbalance

Monoculure enviroments invite uneven distribution of ecological success and result in population shifts, which results in some species becoming more abundant and thus seen as 'nuisances'. Overabundance can put serious strain on a habitat's ability to maintain a population, which can cause overflow into other habitats- including human habitats, which can result in habituation towards humans. This means an animal (or animals) in close proxity to humans can loose their fear of humans, which often results in said animal(s) becoming dependant on humans for a food source. Wild animals that no longer fear humans spend more time around us, and thus are more likely to hurt someone- which ultimately leads to them being put down, even if it was an accident or misunderstanding.

Population shifts can also force out other species that suddenly cannot compete, thus decreasing the overall diversity of an ecosystem which increases the risk of ecosystem collaspe from die-offs.


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  • Simmons, M., Bertelsen, M., Windhager, S., & Zafian, H. (2011). The performance of native and non-native turfgrass monocultures and native turfgrass polycultures: An ecological approach to sustainable lawns. Ecological Engineering, 37(8), 1095–1103.