Fragile ecosystem

Nature’s bounty: Trees provide services worth $500 million to the world’s megacities

By naturally reducing pollution, processing stormwater and helping in energy saving, nature helps planning authorities avoid cut down certain expenses.

Most people probably don’t think of megacities – urban areas with 10 million or more residents – as being part of nature and hence in need of conservation efforts. New research shows that this perception is not just erroneous but counter-productive, however, as trees actually provide ecosystem services worth millions of dollars to the megacities of Earth every year and have the potential to be doing even more.

Just as they do in forests and other natural ecosystems, trees deliver a variety of ecosystem services in cities. They sequester carbon and reduce air pollution and stormwater runoff, for instance. They cut winter winds and help cool their surroundings in summer via shade and transpiration, as well, leading to avoided greenhouse gas emissions and lower energy bills for owners of homes and buildings.

“Trees have direct and indirect benefits for cooling buildings and reducing human suffering during heat waves,” Theodore Endreny of the College of Environmental Science and Forestry in Syracuse, New York, the lead author of a study published this month in the journal Ecological Modelling, said in a statement. “The direct benefit is shade which keeps the urban area cooler, the indirect benefit is transpiration of stormwater which turns hot air into cooler air.”

Economic value

In order to determine how much these services are worth to megacities, Endreny and team looked at 10 megacities on five continents that lie in five different biome types: Beijing, China; Buenos Aires, Argentina; Cairo, Egypt; Istanbul, Turkey; London, UK; Los Angeles, United States; Mexico City, Mexico; Moscow, Russia; Mumbai, India; and Tokyo, Japan.

The researchers used a tool called i-Tree Canopy to survey each megacity and estimate their levels of tree cover, which ranged from 8.1% in Cairo to 36% in Moscow. On average, about 20% of the 10 megacities examined for the study were covered in tree-based ecosystems.

The team also looked at the potential for each city to increase tree cover, and found that an addition 19% of the land area of each city would provide suitable terrain, on average.

Using detailed estimates of the magnitude and value of tree-based ecosystem services, Endreny and his colleagues determined that all of those trees provide an average of $505 million in benefits to each megacity every year, or about $1.2 million per square kilometre of trees. That’s $35 in free services provided by trees to each megacity resident.

The bulk of that $505 million annual average value of urban trees, some $482 million, is due to reduction of pollutants like carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter released by the burning of fossil fuels. The stormwater processing that is avoided by wastewater facilities thanks to trees is worth another $11 million per year, while carbon sequestration is worth $8 million and energy savings are worth $0.5 million, the researchers found

Endreny suggests that these benefits could be nearly doubled if those cities were to make use of additional land areas that are suitable for planting more trees.

“Megacities can increase these benefits on average by 85%,” he said. “If trees were to be established throughout their potential cover area, they would serve to filter air and water pollutants and reduce building energy use, and improve human well-being while providing habitat and resources for other species in the urban area.”

Endreny and his colleagues note that, as of 2016, there were 40 megacities with a combined 722 million residents, which is nearly 10% of the total human population, all of whom “would benefit from nature conservation plans where they work and live.”

The researchers write in the study that a shift in how we think about trees’ place in urban landscapes may be necessary to unlock the full potential benefits of urban trees, however: “The most common mind set separates cities from the rest of nature, as if they were not special kinds of natural habitats. Instead, awareness that urban systems are also nature and do host biodiversity and ecosystem services opportunities, should push urban people towards increased urban forest conservation and implementation strategies.”

Sergio Ulgiati, a professor at the University Parthenope of Naples, Italy and a co-author of the study, said in a statement that, in order to follow up on the findings of the present research, the University had created an Urban Wellbeing Laboratory to be jointly run by researchers and local stakeholders.

“A deeper awareness of the economic value of free services provided by nature may increase our willingness to invest efforts and resources into natural capital conservation and correct exploitation, so that societal wealth, economic stability and well-being would also increase,” Ulgiati said.

This article first appeared on Mongabay.

We welcome your comments at letters@scroll.in.
Sponsored Content BY 

Children's Day is not for children alone

It’s also a time for adults to revisit their childhood.

Most adults look at childhood wistfully, as a time when the biggest worry was a scraped knee, every adult was a source of chocolate and every fight lasted only till the next playtime. Since time immemorial, children seem to have nailed the art of being joyful, and adults can learn a thing or two about stress-free living from them. Now it’s that time of the year again when children are celebrated for...simply being children, and let it serve as a timely reminder for adults to board that imaginary time machine and revisit their childhood. If you’re unable to unbuckle yourself from your adult seat, here is some inspiration.

Start small, by doodling at the back page of your to-do diary as a throwback to that ancient school tradition. If you’re more confident, you could even start your own comic strip featuring people in your lives. You can caricaturise them or attribute them animal personalities for the sake of humour. Stuck in a boring meeting? Draw your boss with mouse ears or your coffee with radioactive powers. Just make sure you give your colleagues aliases.

Pull a prank, those not resulting in revenue losses of course. Prank calls, creeping up behind someone…pull them out from your memory and watch as everyone has a good laugh. Dress up a little quirky for work. It’s time you tried those colourful ties, or tastefully mismatched socks. Dress as your favourite cartoon characters someday – it’s as easy as choosing a ponytail-style, drawing a scar on your forehead or converting a bath towel into a cape. Even dinner can be full of childish fun. No, you don’t have to eat spinach if you don’t like it. Use the available cutlery and bust out your favourite tunes. Spoons and forks are good enough for any beat and for the rest, count on your voice to belt out any pitch. Better yet, stream the classic cartoons of your childhood instead of binge watching drama or news; they seem even funnier as an adult. If you prefer reading before bedtime, do a reread of your favourite childhood book(s). You’ll be surprised by their timeless wisdom.

A regular day has scope for childhood indulgences in every nook and cranny. While walking down a lane, challenge your friend to a non-stop game of hopscotch till the end of the tiled footpath. If you’re of a petite frame, insist on a ride in the trolley as you about picking items in the supermarket. Challenge your fellow gym goers and trainers to a hula hoop routine, and beat ‘em to it!

Children have an incredible ability to be completely immersed in the moment during play, and acting like one benefits adults too. Just count the moments of precious laughter you will have added to your day in the process. So, take time to indulge yourself and celebrate life with child-like abandon, as the video below shows.

Play

This article was produced by the Scroll marketing team on behalf of SBI Life and not by the Scroll editorial team.