By Casey Reynolds executive officer at Turf Producers International
Urbanisation is not a new reality, and neither are the ecological impacts that come with it.
As more people move inward towards larger urban centers with better infrastructure, amenities, city planners are continually looking for the right balance between developing new urban hubs and maintaining natural environments.
Globally, more people live in urban areas than in rural areas, with 55 per cent of the world’s population now residing in urban areas as of 2018, compared to1950 where only 30 per cent of the World’s population was urban By 2050, 68 per cent of the world’s population is projected to live in an urban environment, and Australia is no different, with an increasingly larger proportion of the population living in urban areas.
One of the many questions that city planners have to consider when planning a new development are the impacts of land development on our native ecosystems.
How much space can remain undisturbed? What is the cost/benefit of leaving undeveloped land versus paving over it with roads or digging foundations for homes and businesses?
Many of us know that there is value in natural spaces, but can it be measured or is it really just this elusive, intangible concept/idea? Fortunately, there is an emerging area of science called Ecosystem Services that is helping find the answers.
Ecosystem Services refers to the many benefits that humans freely gain from healthy ecosystems and the natural environment.
These benefits can include things like pollination of plants from insects, nutrient cycling, oxygen production, capturing of particulates from the air, food production, and more. In urban and suburban settings, these services can be provided by natural areas, wetlands, forests, and yes – even landscapes and turf lawns grass.
Turf lawns capture carbon dioxide, produce fresh oxygen, remediate disturbed soils, cool the air around hardscapes, capture and filter storm runoff, prevent erosion of precious topsoil, and provide a habitat for countless soil dwelling arthropods and micro-organisms.
Beginning in 2018, Turfgrass Producers International (TPI) and The Lawn Institute funded reviews of current scientific literature and undertook new research projects to help tell this story.
There are many species of turf that perform well in lawns.
While they are often different in appearance and management requirements, they all share several common traits.
Turfgrasses are monocot plants with fine leaves and a fibrous root system, which have evolved from grazed pastures to form dense ground cover at low heights to tolerate mowing and traffic.
These traits make them ideal for use in lawns and convey many of the benefits mentioned above.
First, the fine leaf texture and dense ground cover of a managed turf means lots of leaf surface area for carbon uptake and evaporative cooling.
The fibrous root systems and various stem tissues of grasses are extremely effective at depositing atmospheric carbon dioxide into the soil.
This results in turf lawns exhibiting an enormous rate of carbon sequestration in their first 25-30 years after establishment and several research studies have reported that residential lawns can store up to twice the amount of organic carbon than agricultural soils.
One research study reports that turf lawns can sequester more than 3 tonnes of carbon per hectare each year, and another study reports that in the United States, urban grasslands can capture the carbon equivalent to the annual emissions of 3.9 million cars.
Want visible proof of this? Look no further at the subsoil in lawns and you can see the top layer of dark organic matter above of the mineral soil. This is visible evidence of carbon deposition, and the depth of this layer will increase overtime.
The turf plant itself, with its dense cover, fibrous root system, stem tissue, and thatch layer, effectively serves as a blanket protecting not only the soil beneath it from erosion, but also providing a habitat for the arthropods and micro-organisms that thrive beneath our feet.
Ecosystem Services refers to the many benefits that humans freely gain from healthy ecosystems and the natural environment.
Research on the rainfall capture and runoff reduction show that turf is one of the most effective plant species for protecting disturbed topsoil and nearby watersheds. Turf buffer strips have been used for many years to decreases surface water flow and increase filtration in riparian, agricultural, and forested watersheds.
Compared with bare ground, natural turf creates resistance to lateral water flow across the soil surface, which increases infiltration into the soil, thereby reducing runoff velocity and volume. For instance, a 200 square metre lawn can capture over 3,500 litres of water before runoff occurs.
The thatch alone can capture almost 1,000 litres .
Multiply this by every lawn in Australia and you quickly see that millions of litres of water can, and are, being captured or diverted from watersheds, which has a cost saving when you consider the associated infrastructure that would otherwise be required to manage this water if lawns and landscapes weren’t present.
One of the reasons turf lawns can capture so much rainwater is the thriving ecosystem of organisms and micro-organisms they host.
Turf lawn ecosystems made up of perennial grass species, even when intensively managed, support a diverse fauna of arthropods, including herbivores, natural enemies and decomposers.
The effects of these organisms on the macro and micro-pore space in home lawns contributes to higher soil water infiltration rates and water-retention capacity compared to many other landscape types.
Looking even closer, the soil microbiome is made up of a complex network of micro-organisms including bacteria, fungi, and single-celled organisms, and recent research has shown that turf lawns significantly enhance soil microbial diversity when compared to bare soil.
These micro-organisms are vital to soil health and sustainability and are supported by the high carbon sequestration rates of the turf they flourish under.
The Lawn Institute is committed to educating consumers on the value of home lawns and will continue to fund research in this area.
It will also have a new home of its own, with a new website to be launched in February of 2021.
Be sure to check out www.TheLawnInstitute.org to learn more about the many environmental benefits of urban and suburban lawns.
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