• WHO says few public health interventions deliver the same benefits as green spaces in cities.
• Trees reduce the impact of extreme weather, block UV rays, and absorb noise.
If you want to know how important green space is for cooped up urban dwellers, imagine Michuki Park in downtown Nairobi on its first weekend after it opened on August 14.
Families ventured into it in disbelief. One showed their children the neat botanical signs on the trees. A father skipped with his daughter on a paved path. It was a dangerous dumpsite, remembered a young man straight from church. Another said he would be back to hear the sound of birds.
Excitement is also palpable in the line for Nairobi’s Karura Forest. Never have its 1,000-hectares – defended from land grabbers by Nobel laureate Wangari Maathai in 1999 and secured by activists and the Kenya Forest Service in 2010 – been more appreciated. Weekend visitors have doubled since the onset of Covid-19
It represents the kind of green space all cities need but too few have. “There has been a massive influx,” says Eli Kogei, who runs its tree nursery. “Schools are closed, and families are at home. By 11 am children are restless. You come and walk with them. When you get home, they are refreshed and can do their assignments.”
The forest is a boon too to adults who live in a growing culture of processed food and long sedentary hours in traffic. In Kenya non-communicable diseases account for more than 50 per cent of hospital admissions.
“Many are diabetic or have high blood pressure and have been advised to exercise,” says forest scout Peter Kamau. “They really value it.”
All cities need parks. And it should not require a global crisis to make this clear. But Covid-19 has triggered incredibly positive change in Kenya. During lockdown, the government has almost doubled usable green space in Nairobi, created hundreds of green jobs, invited the public to plant roundabouts, and called for “optimal urban forest cover” in its draft Forestry Act.
Urban green space includes street trees, school yards, roadside vegetation, parks, playgrounds, green corridors and urban woods.
The World Health Organization says few, if any, other public health interventions can deliver the positive health and social outcomes that green space in cities can, including heightened immune function and less respiratory disease.
Robert Nasi, head of the Center for International Research in Forestry, says cities are warmer than surrounding areas and concentrate poorly fed people. So they are ideal incubators for pathogens and disease vectors. Urban forests and trees mitigate this by cooling air and filtering pollutants all the while capturing carbon and sheltering biodiversity.
UN Food and Agriculture Organization says trees make cities more livable by reducing the impact of extreme weather, blocking harmful UV rays, and absorbing, refracting and dissipating noise. Crime can even go down. A study in the US city of Baltimore found a 10 percent increase in tree canopy was linked to a 12 percent decrease in crime.
Yet in developing countries urban green space lags far behind the 9 square metres per person that the World Health Organization recommends. And affluent areas are greener than packed slums. This is problematic, says Cecil Konijnendijk, professor of urban forestry at the University of British Columbia, as marginalised populations can benefit the most from local green space.
Inspired? See the World Forum on Urban Forests’ Call for Action and promote these steps that your city can take.
1.Measure tree stock and increase tree canopy especially where it is sparce.
2.Plant indigenous trees. Studies in Kampala and Addis Ababa found over 70 percent of street trees are exotic.
3.Plant fruit trees: 80 percent of people in informal settlements in Nairobi are food insecure.
4.If a donor or engineer, look beyond grey infrastructure like storm drains. “Green infrastructure” can reduce disasters like floods and extend the life of the built environment by years.
5.Hire city foresters. Trees pay back many times over.
With or without the pandemic, shade and places to walk and play are profound human needs. All other capitals in Africa and indeed the world have the capacity to follow Nairobi in making their cities happier, cleaner, wealthier and safer with trees.
Watson is the chief of Partnerships at the Center for International Forestry Research CIFOR and World Agroforestry ICRAF